Abstract: A new type of tri-component phosphating solution containing Zn²⁺,Mg²⁺,and Ni²⁺ at medium temperature,has been developed by adding Zn²⁺,Mg²⁺,and Ni²⁺ into base phosphating solution.And the formulation of phosphating solution was defined.Performance of phosphating film was evaluated with dribble blulestone and sodium chloride etching by the methods of national standard.Influences of the factors,such as acidity,temperature,and time,on the quality of phosphating film were studied and discussed.Experimental results showed that the film formed in the phosphating process had the best level of corrosion resistance when phosphating temperature at 65 ℃ and phosphating time in 10 min.Moreover,the phosphating film thus obtained was compact,dark gray,and uniform in crystal structure.  

Key words: phosphating at mediun temperature, tri-component, phosphating solution