中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 16 No. 3 June 2006 |
(Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering,
Jilin University, Changchun 130025, China)
Abstract:The gray phosphate coating was formed on AZ91D magnesium alloy from the zinc phosphating bath containing sodium metanitrobenzene sulphonate in about 4 min. The structure, surface morphologies and phase compositions of the phosphate coatings were observed and analyzed by using SEM, XRD and EDS. It is shown that the phosphate coating becomes denser and has less micro holes with increasing the concentration of sodium metanitrobenzene sulphonate in the bath in the range of 2.0 to 6.0 g/L. The addition of sodium metanitrobenzene sulphonate greatly increases the micro cathode sites for the formation of the phosphate coating and decreases the porosity of the coating.
Key words: zinc phosphate coating; magnesium alloy; AZ91D; sodium metanitrobenzene sulphonate; phosphating process