Coatings producers

Thermal—Oxidative-Resistance Coatings. The thermal stabihty of coatings produced by either covalendy or noncovalendy incorporating 2,4-dinitroaniline into an inorganic siUcate network and coating it onto a sapphire substrate has been examined (67). Although some increase in the thermal... 

The microstmcture and imperfection content of coatings produced by atomistic deposition processes can be varied over a very wide range to produce stmctures and properties similar to or totally different from bulk processed materials. In the latter case, the deposited materials may have high intrinsic stress, high point-defect concentration, extremely fine grain size, oriented microstmcture, metastable phases, incorporated impurities, and macro-and microporosity. AH of these may affect the physical, chemical, and mechanical properties of the coating. 

Other decoratively plated coatings produced in quantity are copper and copper alloys. Copper-plated hardware for cabinetry, lighting fixtures, household trim, and other uses is protected using a top coat of clear lacquer. Copper plating finishes are available with a variety of post-treatments to simulate antique or mstic appearances. 

Fig. 4.37. Depth (temporal) profile obtained on a multilayer coating produced by plasma vapor deposition (PVD) using optimized rf-glow discharge conditions. Layer thickness ...

The coatings produced by metal spraying have an unusual structure which is characteristic of the method of formation. They are composed of small particles usually not more than 0-01 mm in diameter which, having reached the surface in the molten condition, have splashed outwards and then solidified. Figure 12.27 (left) shows in section the irregular form of the flattened particles. In transverse section the surface profile is undulating (Fig. 12.27 (right)). 

Calorised Coatings The nickel- and cobalt-base superalloys of gas turbine blades, which operate at high temperatures, have been protected by coatings produced by cementation. Without such protection, the presence of sulphur and vanadium from the fuel and chloride from flying over the sea promotes conditions that remove the protective oxides from these superalloys. Pack cementation with powdered aluminium produces nickel or cobalt aluminides on the surfaces of the blade aerofoils. The need for overlay coatings containing yttrium have been necessary in recent times to deal with more aggressive hot corrosion conditions. 

Couch, D. E. and Connor, J. H., Nickel-Aluminium Alloy Coatings Produced by Electrodeposition and Diffusion , J. Electrochem. Soc., 107, 272 (1960)... 

Zinc coatings produced by plating have the advantages that the thickness can be accurately controlled according to the protection desired. 

There has been some renewed interest in the use of tin-zinc alloy electroplate as a substitute for cadmium coatings on steel . It has been pointed out that tin-zinc coatings produce less loose corrosion product than zinc during full outdoor exposure... 

Tubes and Perforated Tubes Electrodepositing nickel non-adherently all over the curved surface of a cylinder, and then sliding off the coating, produces a tubular nickel product. Some tubes manufactured in this way are plain, but most are perforated. They are used industrially for screen printing textiles, carpets and wall paper . 

Numerous proprietary electrolytes have been developed for the production of harder and brighter deposits. These include acid, neutral and alkaline solutions and cyanide-free formulations and the coatings produced may be essentially pure, where maximum electrical conductivity is required, or alloyed with various amounts of other precious or base metals, e.g. silver, copper, nickel, cobalt, indium, to develop special physical characteristics. 

The coating equipment under this heading may be used in permanent factories, but is often set up at temporary coating yards close to the location where the pipes are to be laid. The coating produced is usually 2-3 mm per pass. 

Fig. 14.5 Type of coating produced by mechanical flood coat and wrap machine...

COATINGS PRODUCED BY ANODIC OXIDATION Tabic 15.1 Traditional anodising processes... 

Diffusion Coating a coating produced by diffusion at elevated temperatures. 

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