A CLEAN Zn-Ca PHOSPHATING SOLUTION AT ROOM TEMPERATURE

A clean Zn-Ca phosphating solution used in surface pretreatment of iron and steel at room temperature was developed in order to perform clean phosphating production.The design idea was that all the molecules or ions involved in the phosphating solution could react with each other and form phosphating film,water,sediments or substances volatilized in the drying process of coating.The solution contains no nitrite and heavy metals (except for zinc).A colored film with a weight of 0.9g/m-2 was formed by immersing method at 5-40℃ for 5 to 7 minutes,which could be resistant to dropping CuSO4 solution for 130 to 190 seconds.No water washing is needed after phosphating.