Process for the chemical surface treatment of an aluminous product with a view to its phosphating

摘要

This process for treating surfaces of products dip-coated in a bath of molten zinc and aluminum, and intended to be phosphated, involves pickling, preceding the phosphating, with a highly alkaline solution of high pH and containing zinc in solution. The process applies chiefly to products whose coating contains a high proportion of aluminum, particularly in the case of galvanized sheet metal, which it makes easier to phosphate. It is used for painted sheet metal for motor vehicles.