Phosphating

What is Phosphating?

Phosphating is a forming process of phosphate chemical conversion film, sometimes referred to as phosphate film, in chemical and electrochemical reaction.

Phosphating can provide protection for the basic metal, prevent metal from corrosion at some level;

it can be used as the basic film, which can improve the adhesion and corrosion resistance of the coating layer;

It help to reduce friction and improve lubrication in the metal cold working process.

Used in Fasteners

Phosphating is cheaper than galvanization. But the corrosion resistance is worse. Fasteners should be greased to fix that after phosphating, and the degree of corrosion resistance depends on the performance of oil. For example, greasing with normal anti-rust oil will only pass 10 ~ 20 hours of salt spray test,  and high-grade anti-rust oil for 72 ~ 96 hours. But its price is generally 2 ~ 3 times of phosphating coating oil.

Phosphating used in fasteners commonly consists of zinc phosphating and manganese phosphate. Lubrication performance of ZP is better than MP, but MP will get better corrosion resistance andwear resistance. Its working temperature can reach 225 degrees to 225 degrees F (107 ~ 204 ℃).

Phosphating can avoid hydrogen embrittlement, when used in high strength bolts.