Study of Si-containing amorphous layer by electrical discharge coating

Abstract

Electrical discharge machined surface using the silicon (Si) electrode has excellent corrosion resistance because of the formation of an amorphous layer. In this study, Si-containing amorphous layer which was comparatively thick (about 10 μ m) was formed by electrical discharge coating, and the characteristics of this layer were investigated. Detailed metallographic analyses showed that the Si-containing amorphous layer had 7wt% of Si and the fine structures with crystalline existed in this layer. From the water jet test, it became clear that the Si-containing amorphous layer had excellent erosion resistance in addition to excellent corrosion resistance. Furthermore, the Si-containing amorphous layer had comparatively low friction coefficient and high wear resistance. The heating test showed that the Si-containing amorphous layer was kept amorphous in 500 degrees or less and that when the heating temperature exceeded 600 degrees, the layer crystallized so that the microcrystals of Fe3C and α-Fe were deposited.