2012 Volume 48 Issue 6 Pages 204-210
Effect of colloidal silica addition in a chromate coating film on interfacial physical adhesive force between the coating film and a paint layer was studied. The physical adhesive force resulting from the chromate film on a steel sheet and the paint layer coated steel sphere was evaluated by an interfacial pull-off test. The interfacial force was measured by deflection of an aluminum cantilever beam which was bonded the painted steel sphere. Two kind of steel sheets modified with chromic acid which contained colloidal silica or no silica were prepared. Physical adhesive force was higher with colloidal silica containing chromate treated steel sheet than with no colloidal silica treated steel sheet. The effect of colloidal silica on the physical adhesive force shows the same tendency of adhesive strength evaluated as the peeling probability with the cross-cut method and the critical strain energy release rate at interfacial crack initiation using an end notched flexure specimen. These results are verified that the addition of colloidal silica in chromate film is effective to increase the physical adhesive force with paint layer, so the adhesive strength become stronger.
