Anodes, aluminum carbon

Oxyfluoride ions are discharged at the anode, forming carbon dioxide [124-38-9] and aluminum fluoride. The first oxygen can be removed more readily from Al2 02F4 than either the second or the oxygen from Al2 0Fg ... 

Zinc electrowinning Zinc in a sulfuric acid/ aqueous solution, lead-silver alloy anodes, aluminum cathodes, barium carbonate, or strontium, colloidal additives... 

A variety of nanomaterials have been synthesized by many researchers using anodic aluminum oxide film as either a template or a host material e.g., magnetic recording media (13,14), optical devices (15-18), metal nanohole arrays (19), and nanotubes or nanofibers of polymer, metal and metal oxide (20-24). No one, however, had tried to use anodic aluminum oxide film to produce carbon nanotubes before Kyotani et al. (9,12), Parthasarathy et al. (10) and Che et al. (25) prepared carbon tubes by either the pyrolytic carbon deposition on the film or the carbonization of organic polymer in the pore of the film. The following section describes the details of the template method for carbon nanotube production. 

In addition to the impregnation method with furfuryl alcohol, Kyotani et al. attempted to deposit pyrolytic carbon on the inside of the straight channels of anodic oxide film in the following way (9,12). They used two types of anodic aluminum oxide films with different channel diameters (30 and 230 nm). Each anodic oxide film... 

Che et al. recently demonstrated that not only propylene but also ethylene and pyrene can be used for the production of carbon tubes (25). They subjected anodic aluminum oxide template (channel diameter 200 nm) to either ethylene or pyrene gas stream at 900°C for 10 min and then the resultant carbon tubes were removed... 

Nickel compounds are of great importance industrially and a review is available on the use of nickel in heterogeneous catalysis, electroplating, batteries, pigments, ceramics and hydrogen storage.76 This concerns simple aqua complexes of nickel(II) with anions such as carbonate, halide, hydroxide, nitrate and sulfate. Nickel acetate and formate find similar use, and the acetate is employed in the sealing of anodized aluminum.77 [Ni(NH3)6]Cl2 has been shown to be potentially applicable in heat pumps.78... 

Using uniform and straight nanochannels of an anodic aluminum oxide (AAO) film as a template, CNTs can be prepared by pyrolytic carbon deposition on the AAO film [109-116]. Briefly, the AAO film was subjected to carbon deposition from the pyrolytic decomposition of propylene at 800°C, which resulted in a uniform pyrolytic carbon coating on the inner wall of the template nanochannels. Then, the AAO template was removed with HF washing, and only carbon was left as an insoluble fraction. The formation process of carbon tubes using this chemical vapor deposition (CVD) technique is illustrated in Figure 3.8. 

Anodic aluminum oxide film Carbon nanotubes... 

Kyotani, T., Tsai, L.F., and Tomita, A. Preparation of ultrafine carbon tubes in nanochannels of an anodic aluminum oxide film. Chem. Mater. 8, 1996 2109-2113. 

Anode elements are commonly prebaked low ash carbon blocks, since any ash residue ends up in the electrolyte. These are electrically connected to copper or aluminum bus bars (heavy electrical conductors) suspended over the cell, which also provide mechanical support and a means for vertical adjustment of the anode elements. An anode variant is the Soderberg paste option, which uses powdered petroleum coke formed into a paste with hard pitch. Electrical contact is established and mechanical adjustment provided by using specially shaped steel pins (Fig. 12.3). As the baked portion of this anode (Fig. 12.3) is gradually consumed, the paste approaches the molten electrolyte and the volatile components in the paste vaporize to leave a hard baked working anode element. Either type of anode element is consumed at the rate of 1-2 cm/day during normal operation, requiring periodic vertical adjustment to maintain an anode-aluminum metal pool spacing of about 5 cm. 

A Hall-Heroult electrolytic cell Is used to produce aluminum metal. It is made of a steel shell lined with carbon that forms the cathode. Anodes of carbon hang down into the solution of aluminum oxide dissolved in cryolite. ... 

A more defective form of sp carbon fibers, carbon nanotubules (CNTbs), grown by pyrolytic deposition of carbon into anodized aluminum oxide (AAO) nanochannels, are also used as nanoelectrode arrays for electrochemical sensors. Small graphitic crystallites are deposited on the inner surface of the nanochannels. Since the crystallites do not extend very long (less than micrometers) and are structurally discontinued, the resistance is orders of magnitude higher than CNFs... 

C. Chemical modification of the glued surfaces by the formation of passivating layers. The modification technique depends on the nature of the metal. The parts are most often subjected to acid pickling, e.g. aluminum alloys are anodized in sulfuric and chromic acids. It is preferable to anodize aluminum parts in sulfuric acid followed by treatment of the anodic film in a bichromate. There are several methods of pickling carbon and stainless steels, chemical oxidation of magnesium alloys as well as copper and titanium alloys before gluing [4]. 

One of the challenges in the synthesis of nanorods is to produce nanorods of uniform size and distribution in an easy and reproducible manner. If a template is provided for the synthesis of nanorods, the dimension/geometry of the template dictates the dimension of the nanorods. Templates have been commonly used to produce isolated oriented nanorods. The most commonly used templates are anodic aluminum oxide (AAO) or polycarbonate membrane (ion-track etched). Other templates include three-dimensional microporous materials, such as zeohtes, mica, glass, block-copolymer, and even carbon nanotubes. A template should contain uniform sized pores, be... 

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