Phosphate coating composition
OwnerWalter A. Vittands, William M. McGowaninventors
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Abstract
This invention relates to phosphating ferrous metal surfaces and more particularly, to new phosphating compositions characterized by the use of a cyclic trimetaphosphate as one of the phosphates comprising the phosphating composition. The cyclic trimetaphosphate permits lower operating temperature, increases the concentration tolerance of the phosphating solution to dissolved iron and provides an improved phosphate coating that is thinner, smoother and more corrosion resistant.
Claims10
In a phosphating composition for formation of a phosphate coating on ferrous based metal comprising an aqueous acidic solution of a primary phosphate, the improvement comprising a cyclic trimetaphosphate in solution in a concentration sufficient to improve salt spray resistance.
In a zinc phosphating composition for formation of a phosphate coating on ferrous based metal comprising an aqueous acidic solution containing a source of zinc and free phosphoric acid, the improvement comprising a cyclic trimetaphosphate in an amount of at least 0.001 moles per liter.
Dependencies are inferred from the claim text.