Cathodes, aluminum nickel

Nickel In not too corrosive environments (electronic devices, houseware, etc.), nickel coatings are often used on metals and alloys to prevent tarnishing or corrosion. The lifetime of the layer is proportional to its thickness. The main base metals protected by nickel are iron, zinc, aluminum (and its alloys), and copper. In combination with iron, zinc, and aluminum, nickel usually is cathodic. Therefore, to provide corrosion protection on these metals, the nickel layer must be dense and free of pores. 

The cathodic protection of plain carbon and low-alloy steels can be achieved with galvanic anodes of zinc, aluminum or magnesium. For materials with relatively more positive protection potentials (e.g., stainless steels, copper, nickel or tin alloys), galvanic anodes of iron or of activated lead can be used. 

Another study (200) presented IR data for a number of hydride and deuteride species. Using matrix-isolation spectroscopy in conjunction with a hollow-cathode, sputtering source (the apparatus for which is shown in Fig. 36), the IR-active vibrations of the diatomic hydrides and deuterides of aluminum, copper, and nickel were observed. The vibra-... 

Electrorefining has been used for the purification of many common as well as reactive metals. It has been seen that the emf or the potential required for such a process is usually small because the energy needed for the reduction of the ionic species at the cathode is almost equal to that released by the oxidation of the crude metal at the anode. Some metals, such as copper, nickel, lead, silver, gold, etc., are refined by using aqueous electrolytes whereas molten salt electrolytes are necessary for the refining of reactive metals such as aluminum,... 

Cathode Nickel may be an alternative for platinum metals in alkaline solutions due to its low hydrogen overvoltage and catalytic activity. The activity is especially high at the very fine dispersed Raney nickel , which is available from a layer of a nickel alloy on the cathode surface by dissolving the alloy metal (aluminum or zinc) in alkaline solution prior to use (e.g. [23, 24]. Raney nickel usually is not stable against oxygen and self-ignition in air may be possible). 

Molten Carbonate Fuel Cell The electrolyte in the MCFC is a mixture of lithium/potassium or lithium/sodium carbonates, retained in a ceramic matrix of lithium aluminate. The carbonate salts melt at about 773 K (932°F), allowing the cell to be operated in the 873 to 973 K (1112 to 1292°F) range. Platinum is no longer needed as an electrocatalyst because the reactions are fast at these temperatures. The anode in MCFCs is porous nickel metal with a few percent of chromium or aluminum to improve the mechanical properties. The cathode material is hthium-doped nickel oxide. 

Trigeminal trihalides are completely reduced by catalytic hydrogenation over palladium [62] and Raney nickel [63], and partially reduced to dihalides or monohalides by electrolysis using mercury cathode [57 ], by aluminum... 

Phthalimide was hydrogenated catalytically at 60-80° over palladium on barium sulfate in acetic acid containing an equimolar quantity of sulfuric or perchloric acid to phthalimidine [7729]. The same compound was produced in 76-80% yield by hydrogenation over nickel at 200° and 200-250 atm [43 and in 75% yield over copper chromite at 250° and 190 atm [7730]. Reduction with lithium aluminum hydride, on the other hand, reduced both carbonyls and gave isoindoline (yield 5%) [7730], also obtained by electroreduction on a lead cathode in sulfuric acid (yield 72%) [7730]. 

Numerous methods for the synthesis of salicyl alcohol exist. These involve the reduction of salicylaldehyde or of salicylic acid and its derivatives. The alcohol can be prepared in almost theoretical yield by the reduction of salicylaldehyde with sodium amalgam, sodium borohydride, or lithium aluminum hydride by catalytic hydrogenation over platinum black or Raney nickel or by hydrogenation over platinum and ferrous chloride in alcohol. The electrolytic reduction of salicylaldehyde in sodium bicarbonate solution at a mercury cathode with carbon dioxide passed into the mixture also yields saligenin. It is formed by the electrolytic reduction at lead electrodes of salicylic acids in aqueous alcoholic solution or sodium salicylate in the presence of boric acid and sodium sulfate. Salicylamide in aqueous alcohol solution acidified with acetic acid is reduced to salicyl alcohol by sodium amalgam in 63% yield. Salicyl alcohol forms along with -hydroxybenzyl alcohol by the action of formaldehyde on phenol in the presence of sodium hydroxide or calcium oxide. High yields of salicyl alcohol from phenol and formaldehyde in the presence of a molar equivalent of ether additives have been reported (60). Phenyl metaborate prepared from phenol and boric acid yields salicyl alcohol after treatment with formaldehyde and hydrolysis (61). 

Electroplating is achieved by passing an electric current through a solution containing dissolved metal ions as well as the metal object to be plated. The metal object acts as a cathode in an electrochemical cell, attracting metal ions from the solution. Ferrous and nonferrous metal objects are typically electroplated with aluminum, brass, bronze, cadmium, chromium, copper, iron, lead, nickel, tin, and zinc, as well as precious metals such as gold, platinum, and silver. Common electroplating bath solutions are listed in Table 7-1. 

Another example of promising research is the efficient electrochemical dicarbo-xylations of aryl-acetylenes with C02, using an uncomplicated bimetallic redox couple as the catalytic system. In this case, metallic nickel was used as the cathode and aluminum as the anode, to generate in situ carboxylation-active nickel species (Scheme 5.20) [61]. 

The efficient preparation of trimethyl(trinuoroinethyl)silane via the eleetroredaction of bromo-trifluoroniethane in dimethylformamide in the presence of chlorotrimethylsilane using a sacrificial aluminum anode and nickel foam cathode (area 20 cm ) containing tetrabutylam-... 

The choice of cathode materials is less restricted by corrosion considerations than the choice of anodes so few metals react readily with the medium that their use is impractical. Some of the most popular electrode materials are mercury, lead, tin, copper, iron, aluminum, platinum, nickel, and carbon. 

Use Aluminum alloys for structural parts, die-cast auto parts, missiles, space vehicles powder for pyrotechnics and flash photography, production of iron, nickel, zinc, titanium, zirconium antiknock gasoline additives magnesium compounds and Gri-gnard syntheses cathodic protection reducing agent desulfurizing iron in steel manufacture precision instruments optical mirrors dry and wet batteries. 

---