Effects of alkaline cleaners and cleaning methods on phosphate coating weight and surface morphology

摘要

The effects of some alkaline cleaners and cleaning methods on the phosphate coating weight have been assessed. The morphologies of the phosphate coatings were investigated through scanning electron microscopy (SEM). Single alkaline cleaners are not advantageous to formation of fine phosphate coatings. Additives, such as sodium ethylene diamine tetraacetate, sodium glycerophosphate, sodium tripolyphosphate and trisodium phosphate, in compound alkaline cleaners, can mitigate alkali corrosion of metal, resulting in the surface roughness of metal being decreased. The coating weight of phosphate coating formed on the sample cleaned by compound alkaline cleaners is lighter than by the use of single alkaline cleaners. Compared with the immersion cleaning method, spray cleaning contributes to the formation of the tiny phosphate crystal grains.