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Immersion zinc plating is an electroless (non-electrolytic) coating process that deposits a thin layer of zinc on a less electronegative metal, by immersion in a solution containing a zinc or zincate ions, Zn(OH) 2− 4. A typical use is plating aluminum with zinc prior to electrolytic or electroless nickel plating.
The chromate coating acts as paint does, protecting the zinc from white corrosion, thus making the part considerably more durable, depending on the chromate layer's thickness. [ 8 ] [ 9 ] [ 10 ] The protective effect of chromate coatings on zinc is indicated by color, progressing from clear/blue to yellow, gold, olive drab and black.
Zinc is extracted from the purified zinc sulfate solution by electrowinning, which is a specialized form of electrolysis. The process works by passing an electric current through the solution in a series of cells. This causes the zinc to deposit on the cathodes (aluminium sheets) and oxygen to form at the anodes. Sulfuric acid is also formed in ...
Galvanization (also spelled galvanisation) [1] is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are coated by submerging them in a bath of hot, molten zinc. [citation needed]
Plating is a finishing process in which a metal is deposited on a surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for ...
Such zinc electroplating or zinc alloy electroplating maintains a dominant position among other electroplating process options, based upon electroplated tonnage per annum. According to the International Zinc Association, more than 5 million tons are used yearly for both hot-dip galvanization and electroplating. [ 1 ]
Solutions prepared from dissolving zinc hydroxide or zinc oxide in a strong alkali like sodium hydroxide, which contains various zincate anions, are used in the metal plating industry, in processes such as immersion zinc plating and electroplating (electrogalvanization). Any of these techniques may be called zincate process. [3]
The main phosphating step can be preceded by an "activation" bath that creates tiny particles of titanium compounds on the surface. [10] The performance of a phosphate coating depends on its crystal structure as well as its thickness. A dense microcrystalline structure with a low porosity is usually best for corrosion resistance or subsequent ...