2021 Volume 61 Issue 3 Pages 945-952
A porous surface layer was formed by Al electrodepositing and Al dissolving on the surface of stainless steel using molten salt. Furthermore, the relationship between the morphology of the alloy layer produced by Al electrodeposition and the porous layer was clarified. As a result, Fe aluminide with high Al concentration was formed on the surface by lowering the Al electrodeposition potential. Then, in order to investigate the dissolution behavior of Al, the anodic polarization curves of the Al electrodeposited sample and the untreated sample were measured. An increase in the anode current was observed from around −1.2 V in the Al electrodeposited sample. On the other hand, an increase in the anode current was observed from around −0.8 V for the untreated sample. Therefore, the dissolution experiment was performed at −0.9 V, where Al dissolution occurs and SUS304 dissolution does not occur. The lower the potential during Al electrodeposition, the thicker the porous layer with higher porosity formed. As a result of point analysis of the composition of the porous layer, it was recognized to be an austenite phase having a lower Cr concentration than untreated SUS304. It is considered that Fe remains in the porous layer as Al is dissolved and that Fe diffuses at high temperature to form a porous layer. Thus, the sliding characteristics of the stainless steel with the porous layer and the untreated stainless steel were evaluated. The porous sample showed better characteristics than the untreated sample.
