1989 年 40 巻 11 号 p. 1272-1276
The effects of surface conditions of galvannealed steel sheet on corrosion resistance in a single-coat acrylic-resin painting system that does not include the process of activation by TiO2 were investigated by measuring the width of delamination after an immersion test of scribed panels in a 3%NaCl aqueous solution. In analyzing the test results, electrochemical measurements were carried out in the phosphating bath to evaluate the phosphatability of the material.
As a result, measuring the polarization of the coating in the phosphating bath clarified that measuring τ (time-lag for self-passivation of the coating in the phosphating solution) is a suitable way to evaluate phosphatability of the coating. From a multiple regression analysis, it was shown that phosphatability, surface roughnes sand coating weight mainly effect the delaminated width of paint film. It was also clarified that the deterioration of phosphatability results from the enrichment of Al-oxide at the surface of galvannealed the coating.