Anodization silicon carbide

After many attempts with several anode materials we found a stable anode. Silicon carbide and iron silicide, etc. in a conducting form are stable towards chlorine. The chlorine formed on the anode then reacts with the solvent (THF) forming chlorinated organic compounds. 

Therefore, we tried silicon carbide as the anode, which turned out to be completely stable against oxidation. Iron silicide and other silicides also seem to be stable. In our case, the reaction at the anode is the chlorination of the solvent. So, for instance, chlorinated products of THF can be detected by... 

Phosphoric Acid Fuel Cell (PAFC) Phosphoric acid concentrated to 100% is used for the electrolyte in this fuel cell, which operates at 150 to 220°C. At lower temperatures, phosphoric acid is a poor ionic conductor, and CO poisoning of the Pt electrocatalyst in the anode becomes severe. The relative stability of concentrated phosphoric acid is high compared to other common acids consequently the PAFC is capable of operating at the high end of the acid temperature range (100 to 220°C). In addition, the use of concentrated acid (100%) minimizes the water vapor pressure so water management in the cell is not difficult. The matrix universally used to retain the acid is silicon carbide (1), and the electrocatalyst in both the anode and cathode is Pt. 

Sponge Aluminum anodes Ti02 pigments Carbon raiser Silicon carbide Foundries Coke ovens... 

Recently, Hengge and coworkers reported that the use of a silicon carbide and a hydrogen electrode instead of sacrificial anodes was effective for the electrochemical coupling of halosilanes without formation of metal chlorides (equation 65)94. 

The PAFC is based on an immobilized phosphoric acid electrolyte. The matrix universally used to retain the acid is silicon carbide, and the catalyst for both the anode and cathode is platinum [8], The active layer of platinum catalyst on a carbon-black support and a polymer binder is backed by a carbon paper with 90% porosity, which is reduced to some extent by a Teflon binder [6,9]. 

Phosphoric acid fuel cells (PAFC) with concentrated H3P04 (in silicon carbide matrices) electrolyte, which transports H+ cations, generated at the anode, to an ambient-air-exposed cathode, where they are electro-oxidised to water at moderate temperatures. 

Aluminum spraying is used to coat less corrosion-resistant alloys. In the case of some composites, corrosion is due to the galvanic action between the aluminum matrix and the reinforcing material. Aluminum thermal spraying has been successfully used for the protection of the discontinous silicon carbide/aluminum composites, and continuous graphite/aluminum. Other protection procedures include sulfuric acid anodizing and iron vapor deposition on aluminum.44... 

Phosphoric-acid fuel cell (PAFC) — In PAFCs the -> electrolyte consists of concentrated phosphoric acid (85-100%) retained in a silicon carbide matrix while the -> porous electrodes contain a mixture of Pt electrocatalyst (or its alloys) (-> electrocatalysis) supported on -> carbon black and a polymeric binder forming an integral structure. A porous carbon paper substrate serves as a structural support for the electrocatalyst layer and as the current collector. The operating temperature is maintained between 150 to 220 °C. At lower temperatures, phosphoric acid tends to be a poor ionic conductor and poisoning of the electrocatalyst at the anode by CO becomes severe. 

The catalysts and electrode materials used in PAFCs are also similar to those in acidic H2/air fuel cells. Carbon-supported Pt is used as the catalyst at both anode and cathode, porous carbon paper serves as the electrode substrate, and graphite carbon forms the bipolar plates. Since a liquid electrolyte is used, an efficient water removal system is extremely important. Otherwise, the liquid electrolyte is easily lost with the removed water. An electrolyte matrix is needed to support the liquid phosphoric acid. In general, a Teflon -bonded silicon carbide is used as the matrix. 

Pt, which is not trivial over the projected lifetime for a PAFC. Migration of the platinum from the cathode towards the anode is due to the platinum being deposited, not on the anode catalyst, but rather on the silicon carbide matrix, adjacent to the anode, as a consequence of the small solubility of hydrogen in solution at the electrode/matrix interface. 

The use of sacrificial metal anodes inevitably leads to the formation of metal halides as by-products. This problem can be solved by the use of a silicon carbide electrode. The homo coupling takes place smoothly in an undivided cell without formation of metal halides [185]. A hydrogen electrode is also effective for this purpose [185]. 

Considering the influence of applied conditions on stoichiometry deviation in SiC under electrochemical treatment, let us also present some data related to silicon carbide anodization in the potentiostatic regime. The treatment was performed using HF-based electrolyte under conditions where anodic current density values are 4-10 mA cm-2. In spite of the value of the current being comparable with that used for the formation of nanoporous PSC structures, SiC anodization under potentiostatic conditions results in built-in adherent film ( anodic film in the... 

It is known that glass cannot be anodicafly bonded to glass. However, research has found that this can be realized by depositing an intermediate layer. The intermediate layer can be polysilicon, amorphous silicmi, silicon nitride, or silicon carbide [9]. This has opened an easy route to constmct glass-based microfluidic systems which are widely used for capillary electrophoresis. Other investigations into anodic braiding have... 

A phosphoric acid fuel cell (PAFC) uses liquid phosphoric acid as the electrolyte with protons as the charge transport species. The acid is normally imbedded in a solid matrix, such as porous silicon carbide (SiC) or a polybenzimidazole (PBI) membrane. The fuel cell operates best between 160°C and 210°C. The output power ranges from a few kilowatts to a few hundred kilowatts. The anode, the cathode, and the overall reactions are the same as Reactions 1.1,1.2, and 1.3, respectively. 

Classical phosphoric add fuel cells use phosphoric add as the electrolyte, which is immobilized in a Teflon bonded silicon carbide matrix. Phosphoric acid fuel cells usually work at temperatures around 200 °C and are able to tolerate carbon monoxide levels of up to 2 vol.% [1]. Platinum/ruthenium as the anode catalyst may improve the performance in presence of carbon monoxide, similar to PEM fuel cells [33]. 

A phosphoric acid fuel cell (PAFC) consists of an anode and a cathode made of finely dispersed platinum catalyst on a carbon and silicon carbide structure that holds the liquid phosphoric acid electrolyte. Typically, PAFC systems have an operating temperature of around 200°C. When used for the co-generation of electricity and heat, PAFC cells... 

Among new materials suggested for the porous electrolyte matrix in PAFCs, we mention a mixture of silicon carbide (SiC) and PTFE (Mori et ah, 1998). A suspension of the components is mixed in a ball mill for a long time, then spread onto the surfaces of the cathode and anode. This assures good contact between the electrodes and the electrolyte immobilized in the matrix. 

The results presented here are from experiments in an electrolyte consisting of separately dried KCl (>99% Fluka puriss. p.a., ACS reagent) and LiCl (> 99%, anhydrous Fluka puriss. p.a., ACS reagent) enriched with 0.5 mol% T1CI2 (99.98%, anhydrous Sigma-Aldrich) at approximately 700 K. Titanium wires (99.7%, metals basis Alfa Aesar) served as soluble anodes. All experiments were carried out with silicon carbide fibre SCS-6... 

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