| 摘要 |
A chemical conversion coating on ferrous, and zinc, and Al surfaces is produced by using an aq. acid soln. contg. in addn 1-20 g/l colloidal silicic acid (calcd. as SiO2) which is applied to the metal surface by spraying in an electrostatic field and/or with the aid of air. The spray coating is then dried pref. at elevated temp. The aq. acid soln is of known type such as a phosphating or chromting soln. contg. for example, phosphates, of Zn, Ni, Mn, Ca or the like, or a Zn phosphate. Soln of compn 0.1-50 g/l Zn, 1-500 g/l PO4, 0-50 g/l Ni, 0-50 g/l NO3, 0-50 g/l Fe or a chromic acid soln. contg. 5-50 g/l hexavalent Cr and 0-15 g/l trivalent Cr. to these solns being added 1-20 g/l colloidal silicic acid so as to improve adhesion of the resultant coating and corrosion resistance. |
