Phosphate coating composition

摘要

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.