Chromium Ill oxide

The oxidation of most mixlera alloys is dependent on the foimuiiun of a compact protective film of a slow growing chemically stable oxide such as chromium Ill) oxide. U Oi. alumina. AljOi. or silica. SiO>. The oxidation behavior of multicomponent y -strengthened alloys can be estimated hy considering the Ni. C . and AI. content of the alloy... 

The process of preparing a metal by reduction of its oxide by aluminum is called the alnminothermic process. For example, chromium can be prepared by igniting a mixture of powdered chromium(Ill) oxide and powdered aluminum ... 

H. Y. Shrivastava and B. U. Nair, Chromium (Ill)-mediated structural modification of glycoprotein Impact of the ligand and the oxidants, Biochem. Biophys. Res. Commun., 285 (2001) 915-920. 

Less than 15% of the ore is transformed into chromium compounds, principally chromates, dichromates, chromium(VI) oxide, chromium(III) oxide, and so on. Alkaline oxidative roasting of chromite in rotary kilns yields sodium chromate (see equation 1), which is leached out with water and typically converted into sodium dichromate with sulfuric acid (equation 2) or carbon dioxide (equations). Further treatment of sodium dichromate with sulfuric acid yields chromium(VI) oxide ( chromic acid ), while its reduction (with carbon, sulfur, or ammonium salts) produces chromium(III) oxide. Finally, basic chromium(Ill) salts, for example Cr(OH)S04, which are used as tanning agents for animal hides, also result from reduction of sodium dichromate. Heterogeneous chromium catalysts are used for the polymerization of ethylene. 

A basic work-up, following a Jones oxidation (as required when amino-ketones are the desired products) is facilitated by prior complexation of chromium(ill) with... 

Chromium is the most effective addition to improve the resistance of steels to corrosion and oxidation ar elevated temperatures, and Ihe chromium—molybdenum steels are an important class of alloys for use in steam power plants, petroleum refineries, and chemical-process equipment. The chromium content in these steels varies from 0.5 to Ill s. As a group, the low carbon chromium—molybdenum steels huve similar creep—rupture strengths, regardless of the chromium content, hut corrosion and oxidation resistance increase progressively vvith chromium content. Most of the chromium — molybdenum steels are used in the annealed or in the normalised and tempered condition some ol the modified grades have better properties in the quench and tempered condition. 

Chromium(ll) and vanadium(Il) compounds are promising one-electron reductants. For example, tris(picolinato)vanadate(lI), [V(pic)3]", (E° = -0.41 will reduce Fe(Ill) in iron oxide by a heterogeneous outer-... 

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