アークイオンプレーティング法により形成したＣｒ‐Ｓｉ‐Ｎ皮膜の機械的特性およびバイアス電圧の影響

Abstract

Cr-Si-N coatings were prepared by incorporating several atomic percentage of Si to CrN, using an arc ion plating method. In order to change the Si content in the coatings, CrSi targets of 5, 10, 15at%Si were used. The bias voltages were changed from 0 to −250V. Silicon wafers and carburized Chromium Molybdenum Steels (SCM415) were used as the substrates. The aim of this study is to investigate the influence of Si incorporation and bias voltage on the structure and mechanical properties of the coatings. The hardness of the coatings increased drastically up to Hk4000 at 3at%Si with only a very small quantity of Si incorporated. The hardness was also influenced strongly by the bias voltage and increased with increasing bias voltage, attaining maximum at around −60V and then decreased with increasing bias voltage. This can be explained by the change of internal stress of the coatings. The adhesion of the Cr-Si-N coatings was a little smaller than that of the CrN coatings, but within a lower bias voltage range of 0˜−30V. The critical load on scratch test was 60N, the same as that of the CrN coating. The X-ray diffraction (XRD) profiles showed that the coatings with a low content of Si incorporated to CrN presented a polycrystalline structure consisting of nano-crystalline CrN which seemed to be separated from each other by an amorphous Si-N(a-Si-N) phase. It was assumed that the high hardness of the CrSiN coatings was mainly attributed to the formation of a composite structure of nc-CrN and a-Si-N and the decrease of the CrN grain size.