Treatment of zinc-coated steel surfaces to reduce corrosion and improve adhesion comprises using a mixture of sand and zinc phosphate which is brushed on, or projected at, the surface

摘要

A process for modifying the surface of zinc-coated and Black steel surfaces comprises spraying or brushing on a mixture of sand, preferably composed of 0.15 to 0.6 mm aluminum oxide particles and zinc phosphate, preferably zinc orthophosphate x nH20 and zinc diphosphate x nH20 having a concentration of 01/30 wt.%. Additionally, titanium dioxide (1.1-10 wt. %) is preferably added to the mixture. The process preferably carried out using a pressure of 0.2 to 0.6 MPa, after which a wet phosphatizing process is carried in an acid zinc phosphate bath.