Abstract
The surface modification process by EDC(EDC: Electrical Discharge Coating), which has been applied to cutting tools and die molds, is expected to realize a thick hard layer as an alternative technology to metal plating, laser alloying and spray welding. However, the thick layer production process has not been clarified up to now. Therefore this study was performed to clarify the process and the inner structure of a thick piling layer produced by using a TiH2 composite electrode. It is found that the piling process consists of two different processes, which are separated to the transition process at the initial machining and the stability process with a constant growth rate. Within the transition process, thickness growth rate, hardness changing, atomic components rate and electrode wear rate are influenced remarkably by the layer thickness. This transition process has been proceeding until the thickness reaches around 10μm of the piling layer.
