Anticorrosive plating

Cathodic protection equipment has been used very successfully in water tanks and HW and steam boilers as anticorrosion devices for 100 years or more. Such equipment comes in many shapes and sizes, and comprises a sacrificial anode of either zinc or magnesium alloy, either bolted directly to a suitable internal water-wetted (cathodic) metal surface, or self-contained by enclosing the anode with a suitable cathode (such as a silver plated base metal). Usually several devices are required for any boiler, more for larger units and less for smaller ones, and these require replacement every one to two years. 

Bullet jacket materials include gilding metal cupronickel cupronickel-coated steel nickel zinc-, chromium-, or copper-coated steel lacquered steel brass nickel- or chromium-plated brass copper bronze aluminum/alumi-num alloy Nylon (Nyclad), Teflon- and cadmium-coated steel (rare). Black Talon bullets have a black molybdenum disulfide coating over the metal bullet jacket which acts as a dry lubricant. Steel jackets are frequently coated both inside and outside as an anticorrosion measure. Gilding metal is by far the most common bullet jacket material. Tin is claimed to have lubricating properties and is sometimes incorporated in bullet jacket material. The alloy is known as Lubaloy or Nobaloy and contains 90% copper, 8% zinc, and 2% tin. 

Chromium trioxide is used in the following applications in chromium plating, in copper stripping, in aluminum anodizing, as an anticorrosive, in photography, in hardening microscopic preparations, and in purifying oil and acetylene. 

Use Precipitating silver salts for photographic plates, medicine (for its bromide ion), analytical chemistry, process engraving, textile finishing, fire retardant, anticorrosive agents. 

A further progress perspective in the field of water-based paints could be their use for painting ships [205]. However, these studies are only in the beginning. The main difficulty is corrosion prevention. Maximum protection from stress corrosion cracking is ensured by alkyd paints combined with phenolic epoxy paints during a 6.5-year exposure [206]. These data were obtained on pre-contaminated steel plates. In Russia now water-based dispersion primers with anticorrosive properties have been developed and manufactured [207]. This was possible after incorporation of corrosion inhibitors combined with surfactants into the formulations. 

Water-soluble Cl significantly improve the protective ability of oil, alkyd, alkyd-styrene and alkyd-nitrocellulose coatings (Fig. 3.41), for example, 3wt% of water-soluble potassium chromate guanidine. Cl has been introduced into the lacquer base, after which a 20-pm-thick single-layer coat has been applied on a plate of low-carbon steel (St 2). The time until the appearance of corrosion traces under the coating has been recorded on exposure to atmosphere at 100% humidity and a temperature of T = 18-25°C. The results presented in Fig. 3.38 prove that the introduction of this Cl has perceptibly improved the anticorrosion properties of lacquer coatings [1]. 

Detroit and New Orleans. Frequency of chromium dermatitis was highest in constmc-tion workers using cement. Other occupational exposures associated with chromium sensitivity include chromium plating, tanning of leather, application of anticorrosive agents, and printing. Oral ingestion of chromium com-poimds can sometimes lead to skin reactions in sensitive people. Hexavalent chromium com-poimds are more potent inducers and elicitors of skin sensitivity than trivalent chromium compoimds, probably because Cr+ com-poimds can penetrate die skin more readily than Cr+ compoimds. 

Uses Anticorrosion pigment for paints metal protective coatings colorant in PVC resins pyrotechnics chrome plating reagent sulfate ion control in electroplating baths... 

IRRAS can be extremely useful for studying in situ the corrosion and anticorrosion mechanisms [295]. For example, in order to understand high-temperature corrosion processes on AISI type 304 stainless steel, Guillamet et al. [284] measured the spectra by IRRAS of a steel plate exposed for 1 min to air at high temperatures. Comparison with the vlo bands of a series of oxides indicated that the main product is a-Fc203 (not Fc304, as suggested earlier for corrosion of... 

One solution to protect galvanized steel-plate against corrosion is a singlecoat system consisting of a polymer matrix mixture with a corrosion inhibitor. In our case, we propose blends made with fluorinated polymers for the matrix and phosphonated (co)polymers for the inhibitor part. The proportion of this type of additive favoring adhesion and anticorrosion properties is used in a few percent of cases. 

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