STUDY ON PROPERTY OF ANTI-CORROSIN COMPOSITE COATINGS OF TANNIC ACID-H_2TiF_6/SiO_2 ON HOT-DIP GALVANIZED STEEL SHEET

摘要

The chromic acid often used on the metal surface treatment, but hexavalent chromium was considered as the carcinogen. In order to study a substitution of environmental protection coating, this paper studied on Tannic Acid-H_2TiF_6/SiO_2 composite coating from hot-dip galvanized steel sheet, and investigating the coating Corrosion factors on PMT, pH and film thickness. The results showed good performance of anti-fingerprint(⊿ E≤1.5), and the optimum operation condition is at pH = 4 and in the PMT range of 60-80 degree centigrade. Meanwhile, the anti-corrosion coating yellowing shown ⊿ b<2.0 when baked at 300°C for 20min, and after titrated by 100°C distilled water, the coating's powder coating and other damage does not occur.