Study of the Preparation of Micronized Zinc Phosphate Dihydrate with Potential for Application in the Phosphating Process

The protection of metal parts against corrosion damage is one of the most comprehensive areas of industrial chemistry and a wide range of methods exists to protect the surface from corrosive stimulators, including phosphating. A key phosphating process, the tricationic phosphating, consists of baths containing zinc dihydrogen phosphate and other cations, such as Zn2+, Co2+, Ni2+ or Mg2+. However, cobalt and nickel ions are classified as environmentally harmful and they are being actively excluded from industrial processes. The use of sufficiently micronized zinc phosphate dihydrate (µ-Zn3(PO2)2 · 2H2O) is one the possible approaches to significantly reduce or eliminate heavy metals from the phosphating process. The micronized zinc phosphate dihydrate serves as a nucleus on the metal surface to form a sufficiently high-quality phosphate layer. The study aims to find a procedurally optimal dispersion methodology suitable for application in the Czech Republic. The use of progressive grinding methods such as the jet mills is emphasized and shows promising results.