Coatings chromium oxide

Hydrodynamic principles for gas bearings are similar to those involved with Hquid lubricants except that gas compressibility usually is a significant factor (8,69). With gas employed as a lubricant at high speeds, start—stop wear is minimized by selection of wear-resistant materials for the journal and bearing. This may involve hard coatings such as tungsten carbide or chromium oxide flame plate, or soHd lubricants, eg, PTFE and M0S2. 

Figure 12-8A. Piston rings. The piston rod is manufactured from heat-treated stainless steel and is coated with wear-resistant overlays, such as ceramic, chromium oxide, and tungsten carbide applied by plasma techniques. Piston rod cross-head attachment has mechanical preloading system for the threads. Rider rings and seal rings are manufactured from PTFE filled resins fillers are matched to the gas, piston speed, and liner specifications. Typical fillers are glass, carbon, coke, or ceramic. (Used by permission Bui. BCNA-3P100. Howden Process Compressors Incorporated. All rights reserved.)...

Other alloy additions in commercial use include iron (often a two-layer electroplated coating with less iron—typically 20% —in the under-layer to assist formability and more iron—often 80% —in the outer layer to assist paintability) cobalt (0.15-0.35%) similar amounts of chromium (the zinc/ chromium/chromium-oxide coating known as Zincrox) and a range of ternary alloys and of composite coatings. 

To appreciate the potential changes in food cans, it is necessary to describe briefly the steel-based materials used in modern can manufacturing operations. The tin can is made from a special grade of thin gage, low carbon, cold-rolled steel, which is generally referred to as a tin mill product. The base steel is coated with either tin, a chromium-chromium oxide system, or it is just cleaned and oiled. It may also be coated with organic coatings. 

Tin Free Steel—Electrolytic Chromium-Coated. A less expensive substitute for tinplate, electrolytic chromium coated-steel, has been developed and is designated TFS-CT (tin free steel-chromium type) or TFS-CCO (tin free steel-chromium-chromium oxide) (19). This material can be used for many products where the cathodic protection usually supplied by tin is not needed. A schematic cross section is shown in Figure 2. Electrolytic, chromium-coated steel is made by electro-lytically depositing a thin layer of metallic chromium on the basic tin mill steel, which is in turn covered by a thin passive coherent layer of chromium oxide. 

Chbihi, H., et al., CVD of Chromium Oxide Coatings onMetal Substrates from Chromium Acetyl acetone, Materials and Manufacturing Processes, 6(3) 469-480 (1991)... 

Chromium oxide is equally important as a colorant and in its other industrial applications. As a pigment, it is used predominantly in the paint and coatings industry for high quality green paints with special requirements, especially for steel constructions (coil coating), facade coatings (emulsion paints), and automotive coatings. 

Chromium rutile pigments with extremely high resistance to flocculation are obtained by applying a double-layer coating of oxides or oxide hydrates formed from tetravalent metals and oxides or oxide hydrates of aluminum [3.94],... 

Chrome-magnesite, 352—353, 383—385 Chrome Ore, 383 — 384 Chromite, 383—384 refractories, 385 Chromium oxide, 32, 389 Chrysotile, 48 Circular kiln, 299 Clay minerals, 33—34 Clays, 33-38, 313 Clinoensfatite, 46-48, 316-317 Coatings, 399—416 Coefficient of thermal expansion, see thermal expansion Coesite, 17 Colemanite, 142... 

Nanoparticles of iron and aluminum oxides and oxyhydroxides transport both organic and inorganic contaminants in the environment. The systematics developed here may be applied to understanding such natural nanocomposites. For example, it may be possible to treat coating of amorphous uranium or chromium oxides on nanophase (Fe, Al)OOH particles as a mixture of nanophase end-members from the point of view of energetics. 

Ceramic materials are also utilized in nuclear reactor components. Applications include insulation of pressure vessels with linings fabricated from silica and alumina-base ceramic bricks or fiber insulation pressure vessels made of prestressed concrete structures that enclose the entire reactor and secondary system wear-resistant surfaces produced by means of coatings such as chromium oxide or chromium carbide and shielding applications, which include materials such as concrete, graphite, and leaded glass ... 

The tin-free steel is made corrosion-resistant by a very thin coating of chromium phosphate, chromium or chromium oxide, or aluminium. Steel use for packaging purposes makes up around 5 percent of the total world steel consumption. Tin and chrome are in rather short supply tin makes up 0.4 percent, and chromium 0.01 percent of the Earth s crust, but because amounts used are so small, supply does not appear likely to be a problem in the near future, ... 

---