1980 Volume 66 Issue 7 Pages 935-944
Car bodies made of cold rolled steel sheets are phosphated and electro-painted. In these processes, the surface contamination of cold rolled steel sheet may have influence on the performance of phosphate coating and that of paint coating.
In this work, the influence of surface film on corrosion resistance of cold rolled steel sheet afterward phosphated and electro-painted was studied.
The results obtained are as follows
1. The thickness of oxide film and that of carbonaceous film on steel sheet could be measured by ellipsometry.
2. In order to heighten the corrosion resistance of electro-painted steel sheet, oxide film needs to be controlled thinner than 160Å, and also carbonaceous film needs to be controlled thinner than 40Å.
3. The thickness of oxide film was in the range of 31Å to 102Å, and that of carbonaceous film was thinner than 35Å, when cold rolled steel sheet was degreased by electrolytic method, and then annealed by open-coil method.
