Chromium metal polishers

It is hard to generalize about the chemical reactivities of a group of elements since reactivities depend upon two factors (A) the relative stability of the specific compounds formed compared with the reactants used up, and, (B) the rate at which the reaction occurs. In special cases there are other complications. For example, chromium metal (familiar in the form of chrome plate) is highly reactive toward oxygen. Still, a highly polished piece of chromium holds... 

Chromium(IIf) oxide utilized in the manufacture of chromium metal by aluminothermic reduction, as a pigment and as a polishing agent. 

As the above-mentioned formation of zirconium hydride shows, not only metals but also various compounds can be the end product of a thermitic process. Silicides, such as the compound BaSi from the peroxide and oxide with silicon, have been quoted by Ullmann from German patents. The lower oxide of titanium (TiO) has been described as obtainable from the dioxide and magnesium. A very hard form of artificial corundum (crystalline aluminum oxide) of superior quality for grinding and polishing operations is the byproduct of the above-described production of chromium metal. ... 

Gr. chroma, color) Discovered in 1797 by Vauquelin, who prepared the metal the next year, chromium is a steel-gray, lustrous, hard metal that takes a high polish. 

FSM Sosnowiec manufactures automobile lamps, door locks, and window winders for the Polish-manufactured Fiat cars. The lamp bodies are made of zinc-aluminum alloy and then copper-nickel-chromium plated. The door locks and window winders are made of steel and then zinc plated. The wastestreams contain cyanide and the heavy metals chromium (VI), copper, zinc, and nickel. The company carries out the traditional treatments of detoxification, neutralization, and dewatering.29... 

The high hardness of chromium oxide resulting from its crystal structure is exploited in polishing agents for metals and in brake linings. Addition of a small amount of chromium oxide to magnetic materials of audio and video tapes imparts a self-cleaning effect to the sound heads. 

CHROMIUM. [CAS 7440-47-3[. Chemical element, symbol Cr. at. nil. 24. at. wi. 51.996, periodic table group 6. mp 1837- 1877°C. bp 2672 C, density 7.2 g/cm. Elemental chromium has a body-centered cubic crystal structure The metal is silver-white with a slight gray-blue tinge, very hard (9.0 on the Mohs scale), capable of taking a brilliant polish, not appreciably ductile or malleable. The element is not aflected by air or HyO al ordinary temperatures, but when heated above 200°C, chromic oxide CryOt is formed. There tire four stable isotopes f0Cr. and, Cr through wCr. Fuur radioactive isotopes have been identihed, all with comparatively short half-lives 4 Cr. Jl,Cr. 1 Cr. and 5Cr, The element was first identified by Vauquelin in 1797. 

Uranium is a while metal, ductile, malleable, and capable of taking a high polish, but tarnishes readily on exposure to the atmosphere. Finely divided uranium burns upon exposure to air, and the compact metal burns when heated in air at 170 0 Uranium metal slowly decomposes water at ordinary temperatures and rapidly at 100 0 is soluble in HC1 and in HN03 and is nnattacked by alkalis. Chemically related to chromium, molybdenum, and tungsten and, like thorium, is radioactive. In the radioactive decomposition radium is formed. Discovered by Klaproth in 1789. 

Many of the finishes applied to other types of metal products can also be applied to zinc die castings, although some differences in formulation as well as occasional differences in method of application may be desirable. The types of finishes applicable to zinc die castings include mechanical finishes (buffed, polished, brushed, and tumbled) electrodeposited finishes (copper, nickel, chromium, brass, silver, and black nickel) chemical finishes (chromale, phosphate, molybdate and black nickel) and organic finishes (enamel, lacquer, paint and varnish, and plastic finishes). Electrodeposited coatings of virtually any metal capable of electrodeposition can be applied to zinc die castings. 

In addition to its use in making steels, chromium is widely used to electroplate metallic objects with an attractive, protective coating (Section 18.12). Chromium is hard and lustrous, takes a high polish, and resists corrosion because an invisible, microscopic film of chromium(III) oxide shields the surface from further oxidation. 

Polished, matt, and brushed finishes may be obtained and, in addition, other decorative effects from embossed, oxidized, and etched foils. The surface may be lacquered, anodized, or chromium-plated to prevent oxidation, and can be coloured to simulate other metals like brass and bronze. 

Emphasis was first placed on the adsorptive behavior of Compound D on the surface of chromium because that metal has the following desirable properties (a) it is an excellent adsorbent for carboxylic acid groups (5) (b) a large body of data is available on the properties of adsorbed, monomolecular films of aliphatic (16), partially fluorinated (13), fully fluorinated (2), and chloro-fluoro carboxylic acids (2) (c) the metal surface can be readily and reproducibly cleaned by standard metal-lographic polishing techniques and (d) there is a hard, coherent, thin-film oxide on the surface (18). 

A channel for Th-FFF is relatively simple. It is usually composed of two metallic blocks (with high heat conductivity, preferably copper) with highly polished even surfaces between which a spacer is clamped. The actual dimensions of the metal block are usually 40-60 cm length, 3-6 cm width and a thickness of 2-3 cm. Electrolytic nickel and chromium plating increases the mechanical and corrosion resistance. In both blocks side holes are drilled into which thermistors, which serve for control and regulation of the temperature of both blocks and thus also of the temperature gradient between the two main channel walls, can be inserted. 

Chromium is a hard, steel-gray, shiny metal that breaks easily. It has a melting point of 3,450°F (1,900°C) and a boiling point of 4,788°F (2,642°C). The density is 7.1 grams per cubic centimeter. One important property is that chromium can be polished to a high shine. 

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