In an article entitled "Anodic Oxidative Modification of Egg White for Heat Treatment," Japanese researchers found that treating an egg with an electric current will rid it of any noxious odor.
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The anodic current is the flow of electrons into the anode from a species in solution.
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The porous nature of anodic alumina films was discovered in the 1930s and further elaborated in the 1950s–1970s. Processes for producing anodic aluminum oxide membranes using chromic acid, sulfuric acid, oxalic acid, or phosphoric acid appear in a patent attributed to Alan W. Smith of the Boeing Company in 1974.A. Smith (1974) "Process for producing an anodic aluminum oxide membrane". The formation of AAO with highly ordered 2D hexagonal porous structure was first demonstrated in 1995.
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A Michaelis–Menten curve was obtained between the anodic potential and the power output of an acetate-driven MFC. A critical anodic potential seems to provide maximum power output. Potential mediators include natural red, methylene blue, thionine, and resorufin. Organisms capable of producing an electric current are termed exoelectrogens.
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Since the anodic reaction occurs very quickly, the charge transfer limits are thought to occur at the cathode.
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Anodic protection impresses anodic current on the structure to be protected (opposite to the cathodic protection). It is appropriate for metals that exhibit passivity (e.g. stainless steel) and suitably small passive current over a wide range of potentials. It is used in aggressive environments, such as solutions of sulfuric acid.
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The water in the anodic loop is lost because of the anodic reaction, but mostly because of the associated water drag: every proton formed at the anode drags a number of water molecules to the cathode. Depending on temperature and membrane type, this number can be between 2 and 6.
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Attempts to save a metal from becoming anodic are of two general types. Anodic regions dissolve and destroy the structural integrity of the metal. While it is almost impossible to prevent anode/cathode formation, if a non-conducting material covers the metal, contact with the electrolyte is not possible and corrosion will not occur.
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There are two major categories of EPD chemistries: anodic and cathodic. Both continue to be used commercially, although the anodic process has been in use industrially for a longer period of time and is thus considered to be the older of the two processes. There are advantages and disadvantages for both types of processes, and different experts may have different perspectives on some of the pros and cons of each. The major advantages that are normally touted for the anodic process are: #Lower costs compared to cathodic process.
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However, any more anodic metals in contact with copper will be corroded since they will essentially be sacrificed to the copper.
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An anodic protection system includes an external power supply connected to auxiliary cathodes and controlled by a feedback signal from one or more reference electrodes. CORRWIKI , retrieved 8 September 2010 Careful design and control is required when using anodic protection for several reasons, including excessive current when passivation is lost or unstable, leading to possible accelerated corrosion.
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Chromic acid solution is also used in applying types of anodic coating to aluminium, which are primarily used in aerospace applications. On the International Space Station, it is used to control bacteria growth in the wastewater storage tank. A chromic acid/phosphoric acid solution is also the preferred stripping agent of anodic coatings of all types.
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Fuel cells rely on catalysts for both the anodic and cathodic reactions. Catalytic heaters generate flameless heat from a supply of combustible fuel.
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This process, referred to as anodic levelling, can be subject to incorrect analysis when measuring the surface topography. Anodic dissolution under electropolishing conditions deburrs metal objects due to increased current density on corners and burrs. Most importantly, successful electropolishing should operate under diffusion limited constant current plateau, achieved by following current dependence on voltage (polarisation curve), under constant temperature and stirring conditions.
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Anodic protection (AP) is a technique to control the corrosion of a metal surface by making it the anode of an electrochemical cell and controlling the electrode potential in an zone where the metal is passive. Anodic protection is used to protect metals that exhibit passivation in environments whereby the current density in the freely corroding state is significantly higher than the current density in the passive state over a wide range of potentials.Néstor Pérez " Electrochemistry and corrosion science", Kluwer Academic Publishers, 2004 (google books).Anodic protection : theory and practice in the prevention of corrosion, by Olen L. Riggs, Jr. and Carl E. Locke, Plenum Press, New York, 1981 Anodic protection is used for carbon steel storage tanks containing extreme pH environments including concentrated sulfuric acid and 50 percent caustic soda where cathodic protection is not suitable due to very high current requirements.
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Besides the two major categories of anodic and cathodic, EPD products can also be described by the base polymer chemistry which is utilized. There are several polymer types that have been used commercially. Many of the earlier anodic types were based on maleinized oils of various types, tall oil and linseed oil being two of the more common. Today, epoxy and the acrylic types predominate.
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For a redox reaction written as a reduction at the equilibrium potential, electron transfer processes continue at electrode/solution interface in both directions. The cathodic current is balanced by the anodic current. This ongoing current in both directions is called the exchange current density. When the potential is set more negative than the formal potential, the cathodic current is greater than the anodic current.
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The phenolic antioxidants for cocoa powder, dark chocolate, and milk chocolate can also be determined via cyclic voltammetry. In order to achieve this, the anodic peaks are calculated and analyzed with the knowledge that the first and third anodic peaks can be assigned to the first and second oxidation of flavonoids, while the second anodic peak represents phenolic acids. Using the graph produced by cyclic voltammetry, the total phenolic and flavonoid content can be deduced in each of the three samples. It was observed that cocoa powder and dark chocolate had the highest antioxidant capacity since they had high total phenolic and flavonoid content.
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Solutions of technetate(VII) react with the surface of iron to form technetium dioxide, in this way it is able to act as an anodic corrosion inhibitor.
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Conductive anodic filament, also called CAF, is a metallic filament that forms from an electrochemical migration process and is known to cause printed circuit board (PCB) failures.
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A gold micro-electrode array was used for the cyclic voltammetry and anodic stripping voltammetry. Cyclic voltammetry is a method to study ions by applying a waveform of varying potential and measuring the current–voltage curve. Anodic stripping voltammetry first deposits the metal ions onto the gold electrode with an applied potential. After the potential is reversed, the current is measured while the metals are stripped off the electrode.
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If the ionizable groups on the polymer are acids, the polymer will carry a negative charge when salted with a base. If the ionizable groups on the polymer are bases, the polymer will carry a positive charge when salted with an acid. There are two types of EPD processes, anodic and cathodic. In the anodic process, negatively charged material is deposited on the positively charged electrode, or anode.
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H. littorale has two types of hemoglobin, anodic and cathodic; anodic hemoglobin has a relatively low oxygen affinity and has marked Bohr effects, while cathodic hemoglobin lack significant pH effects. In H. littorale, cathodic hemoglobin has a pronounced reversed Bohr effect in which oxygen affinity increases with decreased pH. Cathodic hemoglobin has the purpose of safeguarding oxygen transport to tissues under hypoxic and acidotic conditions. H. littorale diet varies by age.
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The glass substrate encapsulation protects from environmental influences, e.g. humidity or contamination. Further, other materials are used for anodic bonding with silicon, i.e. low-temperature cofired ceramics (LTCC).
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Anodic and silicon fusion bonding do not require an intermediate layer, but do not tolerate surface roughness. Wafer-level packaging techniques based on a bonding technique with a conductive intermediate layer (conductive split ring) restrict the bandwidth and isolation of the RF MEMS component. The most common wafer-level packaging techniques are based on anodic and glass frit wafer bonding. Wafer-level packaging techniques, enhanced with vertical interconnects, offer the opportunity of three-dimensional integration.
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Further mechanisms supporting the bonding process of not completely inert anodic materials can be the planarization or polishing of surfaces and the ablation of the surface layer by electrochemical etching.
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Top-view scanning electron microscopy image of AAO Anodic aluminium oxide, anodic aluminum oxide (AAO), or anodic alumina is a self-organized form of aluminium oxide that has a honeycomb-like structure formed by high density arrays of uniform and parallel pores. The diameter of the pores can be as low as 5 nanometers and as high as several hundred nanometers, and length can be controlled from few tens of nanometers to few hundred micrometers. Porous AAO is formed by electrochemical oxidation (anodization) of aluminum in acid electrolytes in the conditions that balance the growth and the AAO films are formed with limited thickness. Anodizing aluminum has been widely used since early last century for corrosion protection and decorative purposes.
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Oxidation scanning probe lithography (o-SPL), also called local oxidation nanolithography (LON), scanning probe oxidation, nano-oxidation, local anodic oxidation, AFM oxidation lithography is based on the spatial confinement of an oxidation reaction.
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R&D; magazine 100 Awards. Access date Aug. 26, 2008. Also, metal nanofoams can be made by electrodeposition of metals inside templates with interconnected pores, such as 3D-porous anodic aluminum oxide (AAO).
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Nearly all animals have more than one kind of Hb present in the RBC. Multiple Hb isoforms (see isoforms) are particularly common in ectotherms, but especially in fish that are required to cope with both fluctuating temperature and oxygen availability. Hbs isolated from the European eel can be separated into anodic and cathodic isoforms. The anodic isoforms have low oxygen affinities (high P50) and marked Bohr effects, while the cathodic lack significant pH effects and are therefore thought to confer hypoxia tolerance.
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The anodic bonding procedure is able to bond hydrophilic and hydrophobic silicon surfaces equally effectively. The roughness of the surface should be less than 10 nm and free of contamination on the surface for the procedure to work properly. Even though anodic bonding is relatively tolerant to contaminations, a widely established cleaning procedure RCA takes place to remove any surface impurities. The glass wafer can also be chemically etched or powder blasted for creating small cavities, where MEMS devices can be accommodated.
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The anodic metal was usually more corroded when its area was small as compared to that of the cathodic metal. #Alloys 52S-½H, 53ST, and Alclad 24ST were slightly corroded when in contact with each other but all wee anodic to alloy 24ST and were attacked when in contact with 24ST. #Alloy 52S-½H was the least attacked of the aluminum alloys when they were in contact with dissimilar metals. Alloy 53ST was usually considerably more corroded, while attack on 24ST and Alclad 24ST alloys was severe.
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When joined to 52S-½H and 24ST sheets, the zinc was attacked but was not corroded off to the same extent. #The magnesium alloys were very anodic to aluminum alloys, or to stainless steel. The adjacent aluminum alloys, especially 24ST and Alclad 24ST, were in turn severely corroded by a base produced during the formation of the resulting corrosion product, which was a basic magnesium carbonate. Dowmetal M proved anodic to Dowmetal H alloy. Painted panels exposed for 2 years to the weather were but slightly corroded.
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An illustration of how a biological photovoltaic system operates. Like other fuel cells, biological photovoltaic systems are divided into anodic and cathodic half-cells. Oxygenic photosynthetic biological material, such as purified photosystems or whole algal or cyanobacterial cells, are employed in the anodic half-cell. These organisms are able to use light energy to drive the oxidation of water, and a fraction of the electrons produced by this reaction are transferred to the extracellular environment, where they can be used to reduce an anode.
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The most obvious is in the appearance of the deposited film prior to the baking process. The cathodic process results in considerably more gas being trapped within the film than the anodic process. Since the gas has a higher electrical resistance than either depositing film or the bath itself, the amount of gas has a significant effect on the current at a given applied voltage. This is why cathodic processes are often able to be operated at significantly higher voltages than the corresponding anodic processes.
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The corrosion protection is primarily due to the anodic potential dissolution of zinc versus iron. Zinc acts as a sacrificial anode for protecting iron (steel). While steel is close to -400 mV, depending on alloy composition, electroplated zinc is much more anodic with -980 mV. Steel is preserved from corrosion by cathodic protection. Alloying zinc with cobalt or nickel at levels less than 1% has minimal effect on the potential; but both alloys improve the capacity of the zinc layer to develop a chromate film by conversion coating.
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Anodic films can also be used for several cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add interference effects to reflected light. Anodizing is also used to prevent galling of threaded components and to make dielectric films for electrolytic capacitors. Anodic films are most commonly applied to protect aluminium alloys, although processes also exist for titanium, zinc, magnesium, niobium, zirconium, hafnium, and tantalum. Iron or carbon steel metal exfoliates when oxidized under neutral or alkaline micro-electrolytic conditions; i.e.
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If this extremely cathodic region is placed close to an anodic source (e.g. a corroding ballast pipe), cathodic blistering may occur especially where the epoxy coating is relatively new. Mud retained in ballast water can lead to microbial corrosion.
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The anodic coating consists of hydrated aluminium oxide and is considered resistant to corrosion and abrasion.Aluminum Anodizing Process This finish is more robust than the other processes and also provides electrical insulation, which the other two processes may not.
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Using SRET it is possible to determine the anodic and cathodic sites of a corroding sample without the probe altering the corrosion process. SVET was first applied to and developed for the local investigation of corrosion processes by Hugh Isaacs.
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Anodophiles grow on the anode and consume biodegradable organic molecules to produce electrons, protons, and carbon dioxide gas, and as the electrons travel through the circuit they feed the external load. The HRT for this application is the rate at which the feed molecules are passed through the anodic chamber. This can be quantified by dividing the volume of the anodic chamber by the rate at which the feed solution is passed into the chamber. The hydraulic residence time (HRT) affects the substrate loading rate of the microorganisms that the anodophiles consume, which affects the electrical output.
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Anodic bonding is a wafer bonding process to seal glass to either silicon or metal without introducing an intermediate layer; it is commonly used to seal glass to silicon wafers in electronics and microfluidics. This bonding technique, also known as field assisted bonding or electrostatic sealing, is mostly used for connecting silicon/glass and metal/glass through electric fields. The requirements for anodic bonding are clean and even wafer surfaces and atomic contact between the bonding substrates through a sufficiently powerful electrostatic field. Also necessary is the use of borosilicate glass containing a high concentration of alkali ions.
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As the metal continues to corrode, the local potentials on the surface of the metal will change and the anodic and cathodic areas will change and move. As a result, in ferrous metals, a general covering of rust is formed over the whole surface, which will eventually consume all the metal. This is rather a simplified view of the corrosion process, because it can occur in several different forms.Shrier 1:2 CP works by introducing another metal (the galvanic anode) with a much more anodic surface, so that all the current will flow from the introduced anode and the metal to be protected becomes cathodic in comparison to the anode.
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In anodic bonding, wafers are sealed at high temperature and in the presence of electric field.S. Olcum, K. Oguz, M. N. Senlik, F. Y. Yamaner, A. Bozkurt, A. Atalar and H. Koymen, "Wafer Bonded Capacitive Micromachined Underwater Transducers", 2009 IEEE Ultrasonics Symposium, pp. 976-979, 2009.
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Electrons flow from the anodic areas into the electrolyte as the metal corrodes. Conversely, as electrons flow from the electrolyte to the cathodic areas the rate of corrosion is reduced.Peabody p.21 (The flow of electrons is in the opposite direction of the flow of electric current).
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Alternatively, metal (usually tin) can be electrolytically deposited in the pores of the anodic coating to provide more lightfast colours. Metal dye colors range from pale champagne to black. Bronze shades are commonly used for architectural metals. Alternatively, the colour may be produced integral to the film.
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Figure 1. Typical cyclic voltammogram where i_{pc} and i_{pa} show the peak cathodic and anodic current respectively for a reversible reaction. Cyclic voltammetry (CV) is a type of potentiodynamic electrochemical measurement. In a cyclic voltammetry experiment, the working electrode potential is ramped linearly versus time.
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Anodic bonding is first mentioned by Wallis and Pomerantz in 1969. It is applied as bonding of silicon wafers to sodium containing glass wafers under the influence of an applied electric field. This method is used up to date as encapsulation of sensors with electrically conducted glasses.
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In 2018-19 season, Thesprotos took the second place in the championship and qualified for the anodic barrels. Defeat Niki Volos on May 5, 2019 at Panthessal Stadium 0-1 and on May 12 at Igoumenitsa 2-0 and take the historic rise in the professional categories.
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It is not, however, compatible with aluminium wire or connectors. If the two metals are joined, a galvanic reaction can occur. Anodic corrosion during the reaction can disintegrate the aluminium. This is why most appliance and electrical equipment manufacturers use copper lead wires for connections to building wiring systems.
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In 2014 a demonstration device was made from a ceramic sheet made of anodic aluminum. It held two vanadium pentoxide nanotube electrodes separated by an electrolyte that carried the electrical charge between the two. The current collector was made of ruthenium. The individual batteries are connected in parallel.
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It is high enough, around 20 MPa, for most applications and comparable to those achieved with anodic bonding. The hermeticity ensures the correct function and a sufficient reliability of the bond and therefore the product. Further, the bonding yield of glass frit bonded wafers is very high, normally > 90 %.
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Aluminium-based nanogalvanic alloys are characterized by their galvanic microstructure, which comprises an anodic matrix consisting of aluminum, an aluminum alloy, and a cathodic dispersed phase of another metal composition. These other metals may be tin, magnesium, silicon, bismuth, lead, gallium, indium, zinc, carbon, or a mixture of these metals. These alloys produce hydrogen gas when the cathodic disperse phase forms galvanic couples with the anodic matrix and the resulting galvanic metal microstructure comes in contact with water or any liquid containing water. The nanostructured galvanic couple, with aluminium as the anode and the other metal element as the cathode, rapidly disturbs the formation of the native oxide layer and continually exposes fresh aluminium surfaces to hydrolysis.
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The depleted region is negatively charged, and if the sample is cooled to room temperature when the poling voltage is on, the distribution of electrons becomes frozen. After poling, positive charge attracted to the anodic surface and negative charge inside the glass create a recorded field that can reach 109 V/m. More detailed studies, show that there is little or no accumulation of cations near the cathode electrode, and that the layer nearest to the anode suffers partial neutralization if poling persists for an excessively long time. The process of glass poling is very similar to the one used for Anodic bonding, where the recorded electric field bonds the glass sample to the anode.
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One study demonstrated the possibility of measuring the elastic modulus of individual nano-scale membranes suspended over porous anodic alumina.S. Steltenkamp, M. M. Muller, M. Deserno, C. Hennesthal, C. Steinem and A. Janshoff."Mechanical properties of pore-spanning lipid bilayers probed by atomic force microscopy." Biophysical Journal. 91. (2006) 217-226.
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The first commercial anodic automotive system began operations in 1963. The first patent for a cathodic EPD product was issued in 1965 and assigned to BASF AG. PPG Industries, Inc. was the first to introduce commercially cathodic EPD in 1970. The first cathodic EPD use in the automotive industry was in 1975.
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According to the IUPAC definition, mixed potential is the potential of an electrode (against a suitable reference electrode, often the standard hydrogen electrode) when appreciable fraction to the anodic or cathodic current arises from species of two or more different redox couples, but when the total current on the electrode is zero.
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Written as a reduction, cathodic current is positive. The net current density is the difference between the cathodic and anodic current density. Exchange current densities reflect intrinsic rates of electron transfer between an analyte and the electrode. Such rates provide insights into the structure and bonding in the analyte and the electrode.
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Bulk micromachining is the oldest paradigm of silicon-based MEMS. The whole thickness of a silicon wafer is used for building the micro-mechanical structures. Silicon is machined using various etching processes. Anodic bonding of glass plates or additional silicon wafers is used for adding features in the third dimension and for hermetic encapsulation.
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In comparison to polymer electrolyte water electrolysis, the advantages of alkaline water electrolysis are mainly: # Cheaper catalysts with respect to the platinum metal group based catalysts used for PEM water electrolysis. # Higher durability due to an exchangeable electrolyte and lower dissolution of anodic catalyst. # Higher gas purity due to lower gas diffusivity in alkaline electrolyte.
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By taking advantage of intrinsically high energy efficiency of SOFCs and process integration, exceptionally high power plant efficiencies are possible. Furthermore, SOFCs in the IGFC cycle can be operated so as to isolate a carbon dioxide-rich anodic exhaust stream, allowing efficient carbon capture to address greenhouse gas emissions concerns of coal-based power generation.
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Cyanoacetic acid is prepared by treatment of chloroacetate salts with sodium cyanide followed by acidification. Electrosynthesis by cathodic reduction of carbon dioxide and anodic oxidation of acetonitrile also affords cyanoacetic acid. Cyanoacetic acid is used to do cyanoacetylation, first convenient method described by J. Slätt. It is about 1000x more acidic than acetic acid, with a pKa of 2.5.
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Water in contact with the metal surface will normally contain dissolved oxygen. An oxygen cell can develop at any point where the oxygen in the air is not allowed to diffuse uniformly into the solution, thereby creating a difference in oxygen concentration between two points. Corrosion will occur at the area of low-oxygen concentration, which are anodic.
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This dye is coloured at alkali and neutral pH and is a small negatively charged molecule that moves towards the anode. Being a highly mobile molecule it moves ahead of most proteins. As it reaches the anodic end of the electrophoresis medium electrophoresis is stopped. It can weakly bind to some proteins and impart a blue colour.
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This attracted her to materials science and electrochemistry. Birss earned her doctorate at the University of Auckland as a Commonwealth Scholar, where she studied anodic films on silver electrodes. She was a postdoctoral researcher at the University of Ottawa, where she worked on the supercapacitive properties of hydrous metal oxides. During this post she specialised in Ruthenium(IV) oxide.
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Examples of insertion anode types researched include Sn, Mg2Sn. Grignard based ethereal electrolytes have been shown not to passivate; Magnesium organoborates also showed electroplating without passivation. The compound Mg(BPh2Bu2)2 was used in the first demonstrated rechargeable magnesium battery, its usefulness was limited by electrochemical oxidation (i.e. a low anodic limit of the voltage window).
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Finally, adjusting the geometries of the electrodes, e.g., by interdigitating anode and cathode units variously as rows of anodes and cathodes, alternating anodes and cathodes, hexagonally packed 1:2 anodes:cathodes and alternating anodic and cathodic triangular poles. One electrode can be nested within another. Carbon nanotubes and nanowires have been examined for various purposes, as have aerogels and other novel bulk materials.
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The ink receives impressions like traditional soft ground, resists the ferric chloride etchant, yet can be cleaned up with warm water and either soda ash solution or ammonia. Anodic etching has been used in industrial processes for over a century. The etching power is a source of direct current. The item to be etched (anode) is connected to its positive pole.
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Lanthanum strontium manganate (LSM) is the most common oxygen electrode material. LSM offers high performance under electrolysis conditions due to generation of oxygen vacancies under anodic polarization that aid oxygen diffusion.W. Wan, S.P. Jiang, Solid State Ionics 177 (2006) 1361–1369. In addition, impregnating LSM electrode with GDC nanoparticles was found to increase cell lifetime by preventing delamination at the electrode/electrolyte interface.
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This area becomes anodic, while part of the remaining metal becomes cathodic, producing a localized galvanic reaction. The deterioration of this small area penetrates the metal and can lead to failure. This form of corrosion is often difficult to detect due to the fact that it is usually relatively small and may be covered and hidden by corrosion-produced compounds.
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The anion can also be obtained by electrolysis of a saturated solution of rubidium carbonate in water. In addition, the peroxodicarbonate anion can be obtained by electrosynthesis on boron doped diamond (BDD) electrodes. The formal oxidation of two carbonate ions takes place at the anode. Due to the high oxidation potential of the peroxodicarbonate anion, a high anodic overpotential is necessary.
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Language: English, Database: CAPLUS, Application of a Kelvin Microprobe to the Corrosion of Metals in Humid Atmospheres By Yee, Shelgon; Oriani, R. A.; Stratmann, M. From Journal of the Electrochemical Society (1991), 138(1), 55–61. Language: English, Database: CAPLUS, Anomalous Heavy Atomic Masses Produced by Electrolysis By Oriani, R. A. Edited By:Hagelstein, Peter L.; Chubb, Scott R From Fusion Technology (1998), 34(1), 76–80. Language: English, Database: CAPLUS Effects of Applied Current Density and Potential Step on the Stress Generation during Anodic Oxidation of Tungsten in 0.1 M H2SO4 Solution By Kim, Joong-Do; Pyun, Su-Il; Oriani, R. A. Edited By:Filimonov, V. A From Electrochimica Acta (1995), 40(9), 1171–6. Language: English, Database: CAPLUS, Stress Generation during Anodic Oxidation of Titanium and Aluminum By Nelson, J. C.; Oriani, R. A. From Corrosion Science (1993), 34(2), 307–26.
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Development of a submerged microbial desalination- denitrification cell (SMDDC) to remove nitrogen and saline from subsurface water alleviates the demand for additional compounds acting as electron donors and instead produces both a net energy and clean, desalinated and denitrified water. In contrast to the typical MDC model, the SMDDC excludes a middle desalination chamber, but instead only contains an anode and cathode chamber separated by a polycarbonate plate and are parallel to the exterior AEM and CEM respectively. Nitrate is introduced through the AEM into the anode chamber through synthetic groundwater, then propagated as an effluent through the external loop to the cathode chamber, in which nitrate is reduced to nitrogen by the cathode and sodium influent. A wastewater feeding tank pumps water to the anodic chamber for subsequent oxidation of sludge by the anodic biofilm.
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Corrosion engineering involves good design. Using a rounded edge rather than an acute edge reduces corrosion, as does not coupling by welding or other joining method, two dissimilar metals to avoid galvanic corrosion. Avoiding having a small anode (or anodic material) next to a large cathode (or cathodic material) is good practice. As an example, weld material should always be more noble than the surrounding material.
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Cathodic modification is the retardation of anodic reaction as the result of an increase in the ability of an alloy to be passivated by the introduction of an active cathode into the alloy e.g. the alloying of stainless steel and titanium with platinum group metals (1). This is one way in which corrosion resistant alloys can be produced and the resistance of alloy against electrochemical attack increased.
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A method commonly used to protect a structural metal is to attach a metal which is more anodic than the metal to be protected. This forces the structural metal to be cathodic, thus spared corrosion. It is called "sacrificial" because the anode dissolves and has to be replaced periodically. Zinc bars are attached to various locations on steel ship hulls to render the ship hull cathodic.
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Longer HRTs reduce substrate loading in the anodic chamber which can lead to reduced anodophile population and performance when there is a deficiency of nutrients. Shorter HRTs support the development of non-exoelectrogenous bacteria which can reduce the Coulombic efficiency electrochemical performance of the fuel cell if the anodophiles must compete for resources or if they do not have ample time to effectively degrade nutrients.
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It has been reported that trace quantities of polonium trioxide form during the anodic deposition of polonium from acidic solutions. Although there is no experimental evidence for this, the fact that the deposit dissolves in hydrogen peroxide suggests that it contains polonium in a high oxidation state. It has been predicted that polonium trioxide may be formed by heating polonium dioxide and chromium trioxide together in air.
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Sulfide stress cracking (SSC) is a form of hydrogen embrittlement which is a cathodic cracking mechanism. It should not be confused with the term stress corrosion cracking which is an anodic cracking mechanism. Susceptible alloys, especially steels, react with hydrogen sulfide, forming metal sulfides and atomic hydrogen as corrosion byproducts. Atomic hydrogen either combines to form H2 at the metal surface or diffuses into the metal matrix.
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The anodic terminus wraps itself around the outside of the inner tube and ends with the same sort of reference probe as was on the inside of the inner tube. It is filled with a reference solution of KCl and has contact with the solution on the outside of the pH probe by way of a porous plug that serves as a salt bridge.
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Researchers had previously claimed that either one or the other of the two factors was responsible for initiating crevice corrosion, but recently it has been shown that it is a combination of the two that causes active crevice corrosion. Both the potential drop and the change in composition of the crevice electrolyte are caused by deoxygenation of the crevice and a separation of electroactive areas, with net anodic reactions occurring within the crevice and net cathodic reactions occurring exterior to the crevice (on the bold surface). The ratio of the surface areas between the cathodic and anodic region is significant. Some of the phenomena occurring within the crevice may be somewhat reminiscent of galvanic corrosion: ;galvanic corrosion: two connected metals + single environment ;crevice corrosion: one metal part + two connected environments The mechanism of crevice corrosion can be (but is not always) similar to that of pitting corrosion.
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Historically, KOH was made by adding potassium carbonate to a strong solution of calcium hydroxide (slaked lime) The salt metathesis reaction results in precipitation of solid calcium carbonate, leaving potassium hydroxide in solution: :Ca(OH)2 \+ K2CO3 → CaCO3 \+ 2 KOH Filtering off the precipitated calcium carbonate and boiling down the solution gives potassium hydroxide ("calcinated or caustic potash"). This method of producing potassium hydroxide remained dominant until the late 19th century, when it was largely replaced by the current method of electrolysis of potassium chloride solutions. The method is analogous to the manufacture of sodium hydroxide (see chloralkali process): :2 KCl + 2 H2O → 2 KOH + Cl2 \+ H2 Hydrogen gas forms as a byproduct on the cathode; concurrently, an anodic oxidation of the chloride ion takes place, forming chlorine gas as a byproduct. Separation of the anodic and cathodic spaces in the electrolysis cell is essential for this process.
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The electroanalysis of glucose is also based on the enzymatic reaction mentioned above. The produced hydrogen peroxide can be amperometrically quantified by anodic oxidation at a potential of 600 mV.. The GOx is immobilised on the electrode surface or in a membrane placed close to the electrode. Precious metals such as platinum or gold are used in electrodes, as well as carbon nanotube electrodes, which e.g. are doped with boron.
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The agriculture industry uses 1 million pounds per year as a fertilizer. In particular, its use has been suggested for treatment of whiptail in broccoli and cauliflower in molybdenum-deficient soils. However, care must be taken because at a level of 0.3 ppm sodium molybdate can cause copper deficiencies in animals, particularly cattle. It is used in industry for corrosion inhibition, as it is a non-oxidizing anodic inhibitor.
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The anode is the oxidising electrode and as a result has a lower localised pH during electrolysis which also promotes desorption of some organic pollutants. Regeneration efficiencies of activated carbon in the anodic compartment are lower than that achievable in the cathodic compartment by between 5-20% for the same regeneration times and currents, however there is no observed residual organic due to the strong oxidising nature of the anode.
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The sodium forms an amalgam with the Hg cathode preventing side reactions and the hydrogen produced in the first reaction could be captured and reacted back with the sodium mercury amalgam to produce sodium hydride. Clasen's system results in no loss of starting material. For insoluble anodes, reaction 1 occurs, while for soluble anodes, anodic dissolution is expected according to reaction 2: 1\. AlH4− \- e− → AlH3 · nTHF + ½H2 2\.
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Generally, 1–2 wt. % of [Ca(NO2)2] with respect to cement weight is needed to prevent corrosion of the rebars. The nitrite anion is a mild oxidizer that oxidizes the soluble and mobile ferrous ions (Fe2+) present at the surface of the corroding steel and causes them to precipitate as an insoluble ferric hydroxide (Fe(OH)3). This causes the passivation of steel at the anodic oxidation sites.
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The coefficient of thermal expansion (CTE) of the processed glass needs to be similar to those of the bonding partner. Anodic bonding can be applied with glass wafers at temperatures of 250 to 400 °C or with sputtered glass at 400 °C. Structured borosilicate glass layers may also be deposited by plasma-assisted e-beam evaporation. This procedure is mostly used for hermetic encapsulation of micro-mechanical silicon elements.
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Submerged microbial desalination-denitrification cell supplied with synthetic groundwater and a wastewater supply for denitrification and desalination of influent groundwater . Traditional microbial desalination cell figure consisting of anodic and cathodic chambers, separated by an AEM and CEM. Contains middle desalination chamber. Increasing agricultural development is associated with the trend of elevated nitrogen concentrations in surrounding soil and groundwater composition due to the runoff of fertilizers and agricultural byproducts.
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The release of the electrons recycles the mediator to its original oxidized state, ready to repeat the process. This can happen only under anaerobic conditions; if oxygen is present, it will collect the electrons, as it has greater electronegativity. In MFC operation, the anode is the terminal electron acceptor recognized by bacteria in the anodic chamber. Therefore, the microbial activity is strongly dependent on the anode's redox potential.
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Another architecture is a periodic grouping of anodic and cathodic poles. For this design power and energy density is maximized by minimizing electrode separation. An innate non-uniform current density occurs and lowers cell efficiencies, reduces stability and produces non-uniform heating within the cell. Relative to a two dimensional battery the length (L) over which transport must occur is decreased by two-thirds, which improves kinetics and reduces ohmic loses.
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In the meantime electrolytic systems have been developed with additives to inhibit the reaction between anodic aluminum oxide and water, which solve most of the high leakage current problems after storage.J. M. Sanz, J. M. Albella, J. M. Martinez-Duart, On the inhibition of the reaction between anodic aluminum oxide and water The ability of non-solid aluminum electrolytic capacitors to have a stable behavior during longer storage times can be tested by using an accelerating test of storage the capacitors at its upper category temperature for a certain period, usually 1000 hours without voltage applied. This "shelf life test" is a good indicator for an inert chemically behavior of the electrolytic system against the dielectric aluminum oxide layer because all chemical reactions are accelerated by high temperatures. Nearly all today's series of capacitors fulfill the 1000 hours shelf life test, which is equivalent to a minimum five years of storage at room temperature.
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The pit contains a high concentration of metal (Me) chloride (MeCln) which hydrolyzes with water to produce the corresponding metal hydroxide (Me(OH)n), and n H+ and n Cl– ions, accelerating the corrosion process. In the pit, the oxygen concentration is essentially zero and all of the cathodic oxygen reactions take place on the metal surface outside the pit. The pit is anodic and the locus of rapid dissolution of the metal.princeton.edu, pitcorrosion.
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TTF/TCNQ charge-transfer salt, highlighting the segregated stacking In 1862, Henry Letheby obtained a partly conductive material by anodic oxidation of aniline in sulfuric acid. The material was probably polyaniline.The Nobel Prize in Chemistry, 2000: Conductive polymers, nobelprize.org. In the 1950s, researchers discovered that polycyclic aromatic compounds formed semi-conducting charge-transfer complex salts with halogens. In particular, high conductivity of 0.12 S/cm was reported in perylene–iodine complex in 1954.
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Strong electric fields are created by thermal poling of silica, subjecting the glass simultaneously to temperatures in the range of 280 °C and a few kilovolts bias for several minutes. Cations are mobile at elevated temperature (e.g., Na+) and are displaced by the poling field from the anode side of the sample. This creates a region a few micrometers thick of high electrical resistivity depleted of positive ions near the anodic surface.
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Electropolishing, also known as electrochemical polishing, anodic polishing, or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece, reducing the surface roughness by levelling micro-peaks and valleys, improving the surface finish. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating. It may be used in lieu of abrasive fine polishing in microstructural preparation.
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The first layer is a positive layer at the edge of the high potential plasma (the contactor plasma cloud). The second layer is a negative layer at the edge of the low potential plasma (the ambient plasma). Further investigation of the double layer phenomenon has been conducted by several people.Lapuerta, V., and Ahedo, E., " Dynamic model of a plasma structure with an intermediate double-layer, formed outside an anodic plasma contactor," Physics of Plasmas, Vol.
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Perchloric acid is produced industrially by two routes. The traditional method exploits the high aqueous solubility of sodium perchlorate (209 g/100 mL of water at room temperature). Treatment of such solutions with hydrochloric acid gives perchloric acid, precipitating solid sodium chloride: :NaClO4 \+ HCl → NaCl + HClO4 The concentrated acid can be purified by distillation. The alternative route, which is more direct and avoids salts, entails anodic oxidation of aqueous chlorine at a platinum electrode.
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Copper coulometer The copper coulometer is a one application for the copper- copper(II) sulfate electrode. Such a coulometer consists of two identical copper electrodes immersed in slightly acidic pH-buffered solution of copper(II) sulfate. Passing of current through the element leads to the anodic dissolution of the metal on anode and simultaneous deposition of copper ions on the cathode. These reactions have 100% efficiency over a wide range of current density.
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The wafers that meet the requirements are put into atomic contact. As soon as contact is first established, the bonding process starts close to the cathode and spreads in fronts to the edges, the process taking several minutes. The anodic bonding procedure is based on a glass wafer that is usually placed above a silicon wafer. An electrode is in contact with the glass wafer either through a needle or a full area cathode electrode.
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Niobium oxide powder can be prepared in a similar structure to that of tantalum powder and can be processed in a similar way to produce capacitors. It also can be oxidized by anodic oxidation (anodizing, forming) to generate the insulating dielectric layer. Thus two types of niobium electrolytic capacitors are marketed, those using a passivated niobium anode and those using a niobium oxide anode. Both types use niobium pentoxide (Nb2O5) as the dielectric layer.
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Lautarite, described as the most important mineral source of iodine, is mined in the Atacama Desert. Processing of the ore entails reduction of its aqueous extracts with sodium bisulfite to give sodium iodide. Via a comproportionation reaction, the sodium iodide is combined with the iodate salt to produce elemental iodine. Calcium iodate can be produced by the anodic oxidation of calcium iodide or by passing chlorine into a hot solution of lime in which iodine has been dissolved.
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At the anode, hydrogen and oxygen do not react at the iridium oxide catalyst. Thus, safety hazards due to explosive anodic mixtures hydrogen in oxygen can result. The supplied energy for the hydrogen production is lost, when hydrogen is lost due to the reaction with oxygen at the cathode and permeation from the cathode across the membrane to the anode corresponds. Hence, the ratio of the amount of lost and produced hydrogen determines the faradaic losses.
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Cross-section Photosensitive anodized aluminum, also referred to as photo anodized aluminum, photo metal or Metalphoto, utilizes the porous nature of unsealed anodized aluminum to create a sub-surface image, either through exposure and development of an anodic layer impregnated with silver compounds (Type 1), much like traditional black & white photography, or through use of a photomask (Type 2) in which the image is created through a variety of means, including chemical etching, color addition or color subtraction.
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No heterotrophic organisms are included in the anodic chamber - electrode reduction is performed directly by the photosynthetic material. The higher electrode potential of the cathodic reaction relative to the reduction of the anode drives current through an external circuit. In the illustration, oxygen is being reduced to water at the cathode, though other electron acceptors can be used. If water is regenerated there is a closed loop in terms of electron flow (similar to a conventional photovoltaic system), i.e.
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Compared to microbial fuel cells, which use heterotrophic microorganisms, biological photovoltaic systems need no input of organic compounds to supply reducing equivalents to the system. This improves the efficiency of light-to- electricity conversion by minimising the number of reactions separating the capture of light energy and reduction of the anode. A disadvantage of using oxygenic photosynthetic material in bioelectrochemical systems is that the production of oxygen in the anodic chamber has a detrimental effect on the cell voltage.
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An SOFC-GT system is one which comprises a solid oxide fuel cell combined with a gas turbine. Such systems have been evaluated by Siemens Westinghouse and Rolls-Royce as a means to achieve higher operating efficiencies by running the SOFC under pressure. SOFC-GT systems typically include anodic and/or cathodic atmosphere recirculation, thus increasing efficiency. Theoretically, the combination of the SOFC and gas turbine can give result in high overall (electrical and thermal) efficiency.
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Some fission products (such as 137Cs) are used in medical and industrial radioactive sources. 99TcO4− ion can react with steel surfaces to form a corrosion resistant layer. In this way these metaloxo anions act as anodic corrosion inhibitors - it renders the steel surface passive. The formation of 99TcO2 on steel surfaces is one effect which will retard the release of 99Tc from nuclear waste drums and nuclear equipment which has become lost prior to decontamination (e.g.
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The remarkably reversible oxidation-reduction behaviour has been extensively used to control electron- transfer processes in electrochemical and photochemical systems. The one- electron oxidized derivative of biferrocene has attracted much research attention. Substituents on the cyclopentadienyl ligands alters the redox potential in the expected way: electron-withdrawing groups such as a carboxylic acid shift the potential in the anodic direction (i.e. made more positive), whereas electron-releasing groups such as methyl groups shift the potential in the cathodic direction (more negative).
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In this study Kelvin potentials became more positive, indicating a more positive corrosion potential, with increased exposure time, due to an increase in thickness of corrosion products. As a final example SKP was used to investigate stainless steel under simulated conditions of gas pipeline. These measurements showed an increase in difference in corrosion potential of cathodic and anodic regions with increased corrosion time, indicating a higher likelihood of corrosion. Furthermore, these SKP measurements provided information about local corrosion, not possible with other techniques.
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Normally this is not an acceptable film cosmetically or functionally. The causes and mechanisms for rupturing are not completely understood, however the following is known: #Commercially available anodic EPD coating chemistries typically exhibit rupturing at voltages significantly lower than their commercially available cathodic counterparts. #For a given EPD chemistry, the higher the bath conductivity, the lower the rupture voltage. #For a given EPD chemistry, the rupture voltages normally decrease as the temperature is increased (for temperatures above the coalescence temperature).
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Melamine-formaldehyde type crosslinkers in particular are widely used in anodic electrocoatings. These types crosslinkers are relatively inexpensive and provide a wide range of cure and performance characteristics which allow the coating designer to tailor the product for the desired end use. Coatings formulated with this type of crosslinker can have acceptable UV light resistance. Many of them are relatively low viscosity materials and can act as a reactive plasticizer, replacing some of the organic solvent that otherwise might be necessary.
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In the presence of water, a high concentration of metal ions will exist under faying surfaces and a low concentration of metal ions will exist adjacent to the crevice created by the faying surfaces. An electrical potential will exist between the two points. The area of the metal in contact with the lower concentration of metal ions will be cathodic and will be protected, and the area of metal in contact with the higher metal ion concentration will be anodic and corroded.
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The effect was explained by Fowler and Nordheim in 1928. Lilienfeld moved to the United States in 1921 to pursue his patent claims, resigning his professorship at Leipzig to stay permanently in 1926. In 1928, he began working at Amrad in Malden, Massachusetts, later called Ergon Research Laboratories owned by Magnavox, which closed in 1935. In the United States Lilienfeld did research on anodic aluminum oxide films, patenting the electrolytic capacitor in 1931, the method continuing to be used throughout the century.
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One major industrial application involves use of activated carbon in metal finishing for purification of electroplating solutions. For example, it is the main purification technique for removing organic impurities from bright nickel plating solutions. A variety of organic chemicals are added to plating solutions for improving their deposit qualities and for enhancing properties like brightness, smoothness, ductility, etc. Due to passage of direct current and electrolytic reactions of anodic oxidation and cathodic reduction, organic additives generate unwanted breakdown products in solution.
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For example, polyglycols from the solder flux can enter the board and increase its humidity intake, with corresponding deterioration of dielectric and corrosion properties. Multi-layer substrates using ceramics suffer from many of the same problems. Conductive anodic filaments (CAFs) may grow within the boards along the fibers of the composite material. Metal is introduced to a vulnerable surface typically from plating the vias, then migrates in presence of ions, moisture, and electrical potential; drilling damage and poor glass-resin bonding promotes such failures.
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Milk chocolate had the lowest capacity as it had the lowest phenolic and flavonoid content. While the antioxidant content was given using the cyclic voltammetry anodic peaks, HPLC must then be used to determine the purity of catechins and procyanidin in cocoa powder, dark chocolate, and milk chocolate. Hops, the flowers used in making beer, contain antioxidant properties due to the presence of flavonoids and other polyphenolic compounds. In this cyclic voltammetry experiment, the working electrode voltage was determined using a ferricinium/ferrocene reference electrode.
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Anodizing changes the microscopic texture of the surface and the crystal structure of the metal near the surface. Thick coatings are normally porous, so a sealing process is often needed to achieve corrosion resistance. Anodized aluminium surfaces, for example, are harder than aluminium but have low to moderate wear resistance that can be improved with increasing thickness or by applying suitable sealing substances. Anodic films are generally much stronger and more adherent than most types of paint and metal plating, but also more brittle.
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Lithium perchlorate is also used as an electrolyte salt in lithium-ion batteries. Lithium perchlorate is chosen over alternative salts such as lithium hexafluorophosphate or lithium tetrafluoroborate when its superior electrical impedance, conductivity, hygroscopicity, and anodic stability properties are of importance to the specific application. However, these beneficial properties are often overshadowed by the electrolyte's strong oxidizing properties, making the electrolyte reactive toward its solvent at high temperatures and/or high current loads. Due to these hazards the battery is often considered unfit for industrial applications.
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The electrolysis occurs in a specially designed reactor which allows the separation of the cathodic and anodic solutions. In this process, hydrogen gas and hydroxide ions can be produced at the cathode, leading to an alkaline solution that consists essentially of sodium hydroxide. At the anode, chloride ions can be oxidized to elemental chlorine, which is present in acidic solution and can be corrosive to metals. If the solution near the anode is acidic then it will contain elemental chlorine, if it is alkaline then it will comprise sodium hydroxide.
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This result does not necessarily reflect the true potential relationships involved, owing principally to inherent differences in the resistance of the various aluminum alloys to corrosion. #The aluminum alloys were anodic to stainless steel, nickel, monel and Inconel, and were severely attacked when exposed in contact with them. #Electrodeposited coatings of cadmium on SAE X4130 steel strips attached to aluminum-alloy panels were in excellent condition and intact after 2 years of weather exposure. Electrodeposited zinc coatings on the same steel were mostly corroded off when joined to Alclad 24ST and 53ST sheets.
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The alkaline properties and the anodic passivation properties of the borate ion enhance the anticorrosion performance. Commonly available barium metaborate pigment comes in three grades; Grade I is a barium metaborate itself, grade II is compounded with 27% zinc oxide, and grade III is compounded with 18% of zinc oxide and 29% calcium sulfate. Barium borate shows synergistic performance with zinc borate. Barium borate is used as a flux in some barium titanate and lead zirconate EIA Class 2 dielectric ceramic formulations for ceramic capacitors, in amount of about 2%.
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Many alkoxides can be prepared by anodic dissolution of the corresponding metals in water-free alcohols in the presence of electroconductive additive. The metals may be Co, Ga, Ge, Hf, Fe, Ni, Nb, Mo, La, Re, Sc, Si, Ti, Ta, W, Y, Zr, etc. The conductive additive may be lithium chloride, quaternary ammonium halide, or other. Some examples of metal alkoxides obtained by this technique: Ti(OCH(CH3)2)4, Nb2(OCH3)10, Ta2(OCH3)10, [MoO(OCH3)4]2, Re2O3(OCH3)6, Re4O6(OCH3)12, and Re4O6(OCH(CH3)2)10.
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The two reactions in the HyS cycle are as follows: # H2SO4 → H2O + SO2 \+ ½ O2 (thermochemical, T > 800 °C) # SO2 \+ 2 H2O → H2SO4 \+ H2 (electrochemical, T = 80-120 °C) : : Net reaction: H2O → H2 \+ ½ O2 Sulfur dioxide acts to depolarize the anode of the electrolyzer. This results in a significant decrease in the reversible cell potential (and, therefore, the electric power requirement) for reaction (2). The standard cell potential for reaction (2) is -0.158 V at 298.15 K, compared to -1.229 V for the electrolysis of water (with oxygen evolution as the anodic reaction).
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For example, using SVET, the influence of the grains and grain boundaries of X70 was measured. A difference in current densities existed between the grains and grain boundaries with the SVET data suggesting the grain was anodic, and the boundary relatively cathodic. Through the use of SVET it has been possible to investigate the effect of changing the aluminum spacer width on the galvanic coupling between steel and magnesium, a pairing which can be found on automobiles. Increasing the spacer width reduced the coupling between magnesium and steel.
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At the anodic surface, dissolution of the metallic lithium occurs, with the production of electrons and lithium ions during the discharge and electrodeposition during the charge. The half-reaction is expressed as: Li <=> Li+ + e- In analogy with lithium batteries, the dissolution / electrodeposition reaction causes over time problems of unstable growth of the solid-electrolyte interface (SEI), generating active sites for the nucleation and dendritic growth of lithium. Dendritic growth is responsible for the internal short circuit in lithium batteries and leads to the death of the battery itself.
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In series cell arrangement, a higher potential difference is required for a given current to flow because the cells connected in series have higher resistance. The same current would, however, flow through all the electrodes. On the other hand, in parallel or bipolar arrangement the electric current is divided between all the electrodes in relation to the resistance of the individual cells, and each face on the electrode has a different polarity. During electrolysis, the positive side undergoes anodic reactions, while on the negative side, cathodic reactions are encountered.
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His thesis, concerning the anodic formation of surface oxide films on platinum electrodes, was performed under the guidance of Herbert Laitinen. While at Illinois, he also worked with Howard Malmstadt to introduce a graduate lab and lecture course in the electronics of laboratory instrumentation. He is now Professor Emeriti of Chemistry at the University of New Mexico and Michigan State University. Prior to his move to the University of New Mexico in 1994, he was an instructor and assistant professor at Princeton (1959 –1966), then an associate professor and professor at Michigan State University.
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Electrophoretic Deposition Process Electrophoretic deposition (EPD), is a term for a broad range of industrial processes which includes electrocoating, cathodic electrodeposition, anodic electrodeposition, and electrophoretic coating, or electrophoretic painting. A characteristic feature of this process is that colloidal particles suspended in a liquid medium migrate under the influence of an electric field (electrophoresis) and are deposited onto an electrode. All colloidal particles that can be used to form stable suspensions and that can carry a charge can be used in electrophoretic deposition. This includes materials such as polymers, pigments, dyes, ceramics and metals.
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Apparatus for electrolytic refining of copper Most metals occur in nature in their oxidized form (ores) and thus must be reduced to their metallic forms. The ore is dissolved following some preprocessing in an aqueous electrolyte or in a molten salt and the resulting solution is electrolyzed. The metal is deposited on the cathode (either in solid or in liquid form), while the anodic reaction is usually oxygen evolution. Several metals are naturally present as metal sulfides; these include copper, lead, molybdenum, cadmium, nickel, silver, cobalt, and zinc.
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In 1949, he published the book Schachmeister denken (Dietmannsriel-Allgau 1949). In 1950, he was awarded the title of International Master by FIDE. In 1951, he earned a PhD in chemistry from Heidelberg University, and moved to Canada, then to the United States, settling in Philadelphia, where he took a job as a professor. After this, he and his wife Eva moved to Bell Telephone Laboratories, Allentown, Pennsylvania, where he made contributions to electrochemistry and anodic oxidation of silicon, was expert in neutron activation analysis, and published many papers, till his retirement in 1982.
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Electro-oxidation (EO), also known as anodic oxidation, is a technique used for wastewater treatment, mainly for industrial effluents, and is a type of advanced oxidation process (AOP). The most general layout comprises two electrodes, operating as anode and cathode, connected to a power source. When an energy input and sufficient supporting electrolyte are provided to the system, strong oxidizing species are formed, which interact with the contaminants and degrade them. The refractory compounds are thus converted into reaction intermediates and, ultimately, into water and CO2 by complete mineralization.
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Microbial desalination cells stem from microbial fuel cells, deviating by no longer requiring the use of a mediator and instead relying on the charged components of the internal sludge to power the desalination process. Microbial desalination cells therefore do not require additional bacteria to mediate the catabolism of the substrate during biofilm oxidation on the anodic side of the capacitor. MDCs and other bio- electrical systems are favored over reverse osmosis, nanofiltration and other desalination systems due to lower costs, energy and environmental impacts associated with bio-electrical systems.
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On the cooling water side of the condenser: The tubes, the tube sheets and the water boxes may be made up of materials having different compositions and are always in contact with circulating water. This water, depending on its chemical composition, will act as an electrolyte between the metallic composition of tubes and water boxes. This will give rise to electrolytic corrosion which will start from more anodic materials first. Sea water based condensers, in particular when sea water has added chemical pollutants, have the worst corrosion characteristics.
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Severe pitting corrosion problems caused by chloride ions on a truss beam of the Nandu River Iron Bridge (Hainan Province, China) leading to the complete rupture of a metallic element. Pitting corrosion, or pitting, is a form of extremely localized corrosion that leads to the creation of small holes in the metal. The driving power for pitting corrosion is the depassivation of a small area, which becomes anodic (oxidation reaction) while an unknown but potentially vast area becomes cathodic (reduction reaction), leading to very localized galvanic corrosion. The corrosion penetrates the mass of the metal, with a limited diffusion of ions.
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A common feature of this 1/f Poisson spectra is that it differs from the "white" Gaussian noise in which accuracy increases as the square root of the measurement time. The technique considers the reactions occurring at the metal–solution interface and suggests two currents flowing on each electrode as a result of the anodic and cathodic reactions. Once regarded as a source of bias and error that compromised electrochemical measurements it is now regarded as a rich source of information. The technique is widely used within the Corrosion engineering world as a useful Corrosion Monitoring technique.
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The invention of LiS batteries dates back to the 1960s, when Herbert and Ulam patented in 1962, a primary battery employing lithium or lithium alloys as anodic material, sulfur as cathodic material and an electrolyte composed of aliphatic saturated amines.US 3043896A A few years later the technology was improved by the introduction of organic solvents as PC, DMSO and DMF obtaining a 2.35-2.5 V battery. By the end of the 1980s a rechargeable LiS battery was demonstrated employing ethers, in particular DOL, as the solvent for the electrolyte. Thanks to scientific improvements in the field, the potential of LiS batteries was highlighted.
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Coloured anodized aluminum key blanks Aluminium alloys are anodized to increase corrosion resistance and to allow dyeing (colouring), improved lubrication, or improved adhesion. However, anodizing does not increase the strength of the aluminium object. The anodic layer is insulative.. When exposed to air at room temperature, or any other gas containing oxygen, pure aluminium self-passivates by forming a surface layer of amorphous aluminum oxide 2 to 3 nm thick,. which provides very effective protection against corrosion. Aluminium alloys typically form a thicker oxide layer, 5–15 nm thick, but tend to be more susceptible to corrosion.
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Wafer-level packaging is implemented before wafer dicing, as shown in Fig. 3(a), and is based on anodic, metal diffusion, metal eutectic, glass frit, polymer adhesive, and silicon fusion wafer bonding. The selection of a wafer-level packaging technique is based on balancing the thermal expansion coefficients of the material layers of the RF MEMS component and those of the substrates to minimize the wafer bow and the residual stress, as well as on alignment and hermeticity requirements. Figures of merit for wafer-level packaging techniques are chip size, hermeticity, processing temperature, (in)tolerance to alignment errors and surface roughness.
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Dipped SAL-pearls, solid aluminum electrolytic capacitors SAL electrolytic capacitors (SAL meaning solid aluminum) are a form of capacitor developed for high capacitance in a small package, with a long and robust service life. They are aluminum electrolytic capacitors with anodic oxidized aluminum oxide as dielectric and with the semiconducting solid manganese dioxide as electrolyte. They are made of etched and formed aluminum anodes, which are folded for the dipped pearl types or wound into a roll for the axial style. The solid manganese dioxide electrolyte is formed onto this roll in a pyrolytic process, similar to that for solid tantalum capacitors.
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Unlike a normal AFM, the CAFM can be also used to perform local photolithography via bias-assisted local anodic oxidation (LAO). Nowadays the CAFM technique has expanded to many other fields of science, including physics, materials science, chemistry and engineering (among many others), and it has been used to study different materials and/or structures, including nanoparticles, molecules, nanowires, carbon nanotubes, two dimensional (2D) materials, coatings, photoelectricity and piezoelectricity (among others). As of June 14 of 2016, the CAFM had been used in 1325 journal research articles, and it has become a popular tool in nanosciences.
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Another price explosion for tantalum in 2000/2001 forced the development of niobium electrolytic capacitors with manganese dioxide electrolyte, which have been available since 2002.Ch. Schnitter, A. Michaelis, U. Merker, H.C. Starck, Bayer, New Niobium Based Materials for Solid Electrolyte Capacitors, Carts 2002T. Zednicek, S. Sita, C. McCracken, W. A. Millman, J. Gill, AVX, Niobium Oxide Technology Roadmap, CARTS 2002 Niobium is a sister metal to tantalum and serves as valve metal generating an oxide layer during anodic oxidation. Niobium as raw material is much more abundant in nature than tantalum and is less expensive.
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The working electrode is the electrode in an electrochemical system on which the reaction of interest is occurring. The working electrode is often used in conjunction with an auxiliary electrode, and a reference electrode in a three electrode system. Depending on whether the reaction on the electrode is a reduction or an oxidation, the working electrode is called cathodic or anodic, respectively. Common working electrodes can consist of materials ranging from inert metals such as gold, silver or platinum, to inert carbon such as glassy carbon, boron doped diamond or pyrolytic carbon, and mercury drop and film electrodes.
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Similar to the original configuration of the MDC, the SMDDC also includes an external circuit in which electrons are thus freed from the oxidation process of the sludge and drove through a closed, external circuit to the cathodic chamber. The toxic and pathogenic content of the wastewater are thus separated simultaneously with the denitrification of the groundwater, producing water that is thus filtered out as a usable effluent. Highest nitrate removal was exhibited when an external voltage (0.8 V) was applied to the circuit, transporting the ions to the anodic chamber and reducing nitrate via heterotrophic denitrification.
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Methanol on the anodic side is usually in a weak solution (from 1M to 3M), because methanol in high concentrations has the tendency to diffuse through the membrane to the cathode, where its concentration is about zero because it is rapidly consumed by oxygen. Low concentrations help in reducing the cross-over, but also limit the maximum attainable current. The practical realization is usually that a solution loop enters the anode, exits, is refilled with methanol, and returns to the anode again. Alternatively, fuel cells with optimized structures can be directly fed with high concentration methanol solutions or even pure methanol.
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When steel is immersed in water, adding a small concentration (55 ppm) of potassium pertechnetate(VII) to the water protects the steel from corrosion, even if the temperature is raised to . For this reason, pertechnetate has been used as an anodic corrosion inhibitor for steel, although technetium's radioactivity poses problems that limit this application to self-contained systems. While (for example) can also inhibit corrosion, it requires a concentration ten times as high. In one experiment, a specimen of carbon steel was kept in an aqueous solution of pertechnetate for 20 years and was still uncorroded.
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The dielectric nature electrically isolates anodic and cathodic areas on the surface of the part, minimizing underfilm corrosion that sometimes occurs at the interface of the paint/coating and substrate. Zinc phosphate coatings are frequently used in conjunction with sodium stearate (soap) to form a lubrication layer in cold and hot forging. The sodium stearate reacts with the phosphate crystals which in turn are strongly bonded to the metal surface. The reacted soap layer then forms a base for additional unreacted soap to be deposited on top, so a thick three-part coating of zinc phosphate, reacted soap and unreacted soap builds up which adheres to the metal surface even under extreme deformation.
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Conventional micromachining techniques such as wet etching, dry etching, deep reactive ion etching, sputtering, anodic bonding, and fusion bonding have been used in bio-MEMS to make flow channels, flow sensors, chemical detectors, separation capillaries, mixers, filters, pumps and valves. However, there are some drawbacks to using silicon-based devices in biomedical applications such as their high cost and bioincompatibility. Due to being single-use only, larger than their MEMS counterparts, and the requirement of clean room facilities, high material and processing costs make silicon-based bio-MEMS less economically attractive. ‘’In vivo’’, silicon- based bio-MEMS can be readily functionalized to minimize protein adsorption, but the brittleness of silicon remains a major issue.
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In brief, corrosion is a chemical reaction occurring by an electrochemical mechanism (a redox reaction).Shrier 10:4 During corrosion there are two reactions, oxidation (equation ), where electrons leave the metal (and results in the actual loss of metal) and reduction, where the electrons are used to convert water or oxygen to hydroxides (equations and ).Peabody p.2 In most environments, the hydroxide ions and ferrous ions combine to form ferrous hydroxide, which eventually becomes the familiar brown rust:Shrier 3:4 As corrosion takes place, oxidation and reduction reactions occur and electrochemical cells are formed on the surface of the metal so that some areas will become anodic (oxidation) and some cathodic (reduction).
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If the redox couple is reversible then during the reverse scan (from t1 to t2) the reduced analyte will start to be re-oxidized, giving rise to a current of reverse polarity (anodic current) to before. The more reversible the redox couple is, the more similar the oxidation peak will be in shape to the reduction peak. Hence, CV data can provide information about redox potentials and electrochemical reaction rates. For instance, if the electron transfer at the working electrode surface is fast and the current is limited by the diffusion of analyte species to the electrode surface, then the peak current will be proportional to the square root of the scan rate.
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Optimization of L can lead to significant improvement in areal capacity; an L on the size scale of 500 micrometres results in a 350% increase in capacity over a comparable two dimensional battery. However, ohmic losses increase with L, eventually offsetting the enhancement achieved through increasing L. For this geometry, four main designs were proposed: rows of anodes and cathodes, alternating anodes and cathodes, hexagonally packed 1:2 anodes:cathodes, and alternating anodic and cathodic triangular poles where the nearest neighbors in the row are rotated 180 degrees. The row design has a large, non-uniform current distribution. The alternating design exhibits better uniformity, given a high number of electrodes of opposite polarity.
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Diagram showing a mechanism of localized corrosion developing on metal in a solution containing oxygen The more conventional explanation for pitting corrosion is that it is an autocatalytic process. Metal oxidation results in localized acidity that is maintained by the spatial separation of the cathodic and anodic half- reactions, which creates a potential gradient and electromigration of aggressive anions into the pit.ASM Handbook, Volume 13, "Corrosion", , ASM International, 1987 For example, when a metal is present in an oxygenated sodium-chloride electrolyte, the pit acts as anode and the metal surface acts as cathode. The localized production of positive metal ions in the pit gives a local excess of positive charge which attracts the negative chlorine ions from the electrolyte to produce charge neutrality.
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Stress to the gate, relative to channel electrodes, can be applied in the form of fixed current or bias, driving ions toward - or away from - the electrolyte/channel interface where charge transfer occurs with free carriers. Upon insertion in the channel, the ionic charge is neutralized and the atomic species intercalate or bind to the conductive host matrix, in some cases yielding strain and localized phase transformation. Such reversible processes are equivalent to anodic/cathodic reactions in battery cells or electrochromic devices. Although in ECRAM, the programming of the memory element is defined not as a change in capacity or opacity, but by a change of channel conductivity associated with atomic species being inserted or removed as a result of the stress signal.
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A soil-based MFC Soil-based microbial fuel cells adhere to the basic MFC principles, whereby soil acts as the nutrient-rich anodic media, the inoculum and the proton exchange membrane (PEM). The anode is placed at a particular depth within the soil, while the cathode rests on top the soil and is exposed to air. Soils naturally teem with diverse microbes, including electrogenic bacteria needed for MFCs, and are full of complex sugars and other nutrients that have accumulated from plant and animal material decay. Moreover, the aerobic (oxygen consuming) microbes present in the soil act as an oxygen filter, much like the expensive PEM materials used in laboratory MFC systems, which cause the redox potential of the soil to decrease with greater depth.
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Sulfide inclusion as manganese sulfide (MnS) can also be the cause of severe pitting corrosion problems in low-grade stainless steel such as AISI 304 steel. Under oxidizing conditions and in the presence of moisture, when sulfide oxidizes it produces thiosulfate anions as intermediate species and because thiosulfate anion has a higher equivalent electromobility than chloride anion due to its double negative electrical charge, it promotes the pit growth. Indeed, the positive electrical charges born by Fe2+ cations released in solution by Fe oxidation on the anodic zone inside the pit must be quickly compensated / neutralised by negative charges brought by the electrokinetic migration of anions in the capillary pit. Some of the electrochemical processes occurring in a capillary pit are the same than these encountered in capillary electrophoresis.
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The data on which the Shannon model was built are restricted to experiments performed in cat cerebral cortex with 7 hours of stimulation under light anesthesia at 50 pps with 400 µs pulses (charge- balanced, symmetric, biphasic, anodic-first) using platinum surface disc electrodes of 1 mm² or larger, recessed, anodized sintered tantalum-tantalum pentoxide pellet electrodes of 1 mm in diameter, or iridium penetrating microelectrodes of 6500 µm². As a result of these restricted methods, Shannon states "A more comprehensive model of safe levels for electrical stimulation would also account for the effects of pulse rate, pulse duration, stimulus duty cycle, and duration of exposure." Additionally, further study has demonstrated that microelectrodes do not obey the Shannon criterion, and new approaches may be proposed to address these limitations.
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Concentrations of polyphosphates or phosphonates with zinc and chromates or similar compounds have been maintained in cooling systems to keep heat exchange surfaces clean so a film of gamma iron oxide and zinc phosphate may inhibit corrosion by passivating anodic and cathodic reaction points. These increase salinity and total dissolved solids, and phosphorus compounds may provide the limiting essential nutrient for algal growth contributing to biofouling of the cooling system or to eutrophication of natural aquatic environments receiving blowdown or OTC water. Chromates reduce biofouling in addition to effective corrosion inhibition, but residual toxicity in blowdown or OTC water has encouraged reduced chromate concentrations and use of less flexible corrosion inhibitors. Blowdown may also contain chromium leached from cooling towers constructed of wood preserved with chromated copper arsenate.
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The components discussed in this article are based on RF MEMS switches, switched capacitors and varactors. These components can be used instead of FET and HEMT switches (FET and HEMT transistors in common gate configuration), and PIN diodes. RF MEMS switches, switched capacitors and varactors are classified by actuation method (electrostatic, electrothermal, magnetostatic, piezoelectric), by axis of deflection (lateral, vertical), by circuit configuration (series, shunt), by clamp configuration (cantilever, fixed-fixed beam), or by contact interface (capacitive, ohmic). Electrostatically-actuated RF MEMS components offer low insertion loss and high isolation, linearity, power handling and Q factor, do not consume power, but require a high control voltage and hermetic single-chip packaging (thin film capping, LCP or LTCC packaging) or wafer-level packaging (anodic or glass frit wafer bonding).
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Grade 5 titanium, Titanium 6AL-4V (signifying the titanium alloy containing 6 percent aluminium and 4 percent vanadium alloy) is slightly harder than CP4 and used in the industry mostly for abutment screws and abutments. Most modern dental implants also have a textured surface (through etching, anodic oxidation or various- media blasting) to increase the surface area and osseointegration potential of the implant. If C.P. titanium or a titanium alloy has more than 85% titanium content, it will form a titanium-biocompatible titanium oxide surface layer or veneer that encloses the other metals, preventing them from contacting the bone. Ceramic (zirconia-based) implants exist in one-piece (combining the screw and the abutment) or two-piece systems - the abutment being either cemented or screwed - and might lower the risk for peri‐implant diseases, but long-term data on success rates is missing.
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Henry Moseley in his lab. The experimental position improved dramatically after research by Henry Moseley in 1913.Ordering the Elements in the Periodic Table, Royal Chemical Society Moseley, after discussions with Bohr who was at the same lab (and who had used Van den Broek's hypothesis in his Bohr model of the atom), decided to test Van den Broek's and Bohr's hypothesis directly, by seeing if spectral lines emitted from excited atoms fitted the Bohr theory's postulation that the frequency of the spectral lines be proportional to the square of Z. To do this, Moseley measured the wavelengths of the innermost photon transitions (K and L lines) produced by the elements from aluminum (Z = 13) to gold (Z = 79) used as a series of movable anodic targets inside an x-ray tube. The square root of the frequency of these photons increased from one target to the next in an arithmetic progression.
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Repair principles which do not improve the strength or performance of concrete beyond its original (undamaged) condition include: replacement and restoration of concrete after spalling and delamination; strengthening to restore structural load-bearing capacity; and increasing resistance to physical or mechanical attack. Repair principles for arresting and preventing further degradation include: control of anodic areas; cathodic protection, cathodic control; increasing resistivity; preserving or restoring passivity; increasing resistance to chemical attack; protection against ingress of adverse agents; and moisture control. Techniques for filling holes left by the removal of spalled or damaged concrete include: mortar repairs; flowing concrete repairs and sprayed concrete repairs. The filling of cracks, fissures or voids in concrete for structural purposes (restoration of strength and load-bearing capability), or non-structural reasons (flexible repairs where further movement is expected, or alternately to resist water and gas permeation) typically involves the injection of low viscosity resins or grouts based on epoxy, PU or acrylic resins, or micronised cement slurries.
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Antonio Luque. Based on 1977 US and Spanish patents by Luque, a practical bifacial cell was proposed with a front face as anode and a rear face as cathode; in previously reported proposals and attempts both faces were anodic and interconnection between cells was complicated and expensive. In 1980, Andrés Cuevas, a PhD student in Luque's team, demonstrated experimentally a 50% increase in output power of bifacial solar cells, relative to identically oriented and tilted monofacial ones, when a white background was provided. In 1981 the company Isofoton was founded in Málaga to produce the developed bifacial cells, thus becoming the first industrialization of this PV cell technology. With an initial production capacity of 300 kW/yr. of bifacial solar cells, early landmarks of Isofoton's production were the 20kWp power plant in San Agustín de Guadalix, built in 1986 for Iberdrola, and an off grid installation by 1988 also of 20kWp in the village of Noto Gouye Diama (Senegal) funded by the Spanish international aid and cooperation programs.
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Surface of an etched low voltage anode foil The cross-section view of etched 10 V low voltage and 400 V high voltage anode foils shows the different etching structure Ultra-thin- cross-section of an etched pore in a low voltage anode foil, 100,000-fold magnification, light grey: aluminum, dark grey: amorphous aluminum oxide, white: pore in which the electrolyte is active The basic material of the anode for aluminum electrolytic capacitors is a foil with a thickness of ~ 20–100 µm made of aluminum with a high purity of at least 99.99%.Production of Aluminum Electrolytic Capacitors, Panasonic PDF This is etched (roughened) in an electrochemical process to increase the effective electrode surface. By etching the surface of the anode, depending on the required rated voltage, the surface area can be increased by a factor of approximately 200 with respect to a smooth surface. After etching the aluminum anode the roughed surface is "anodic oxidized" or "formed". An electrically insulating oxide layer Al2O3 is thereby formed on the aluminum surface by application of a current in correct polarity if it is inserted in an electrolytic bath.
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