| Multi-phase composite coating which provides mechanical properties unachievable in uniform materials is a promising technique for new hard coating development. Structural1y, multi-phase composite films tend to be dense and fine granular structure because column propagation is periodically interrupted by the nucleation of another phase. Recently, we have synthesized WC-TiN multi-phase films by cathodic arc process. The microhardness of the WC-TiN films on cemented carbide were measured to be up to 4,000 ㎏/㎟ and these values were 1.5 times as hard as that of the WC and TiN single layer. Arc spot movement on WC cathode, however, is so slow that explosive particle emissions occur, resulting in lots of macro-particles and damages on the coating surface. In this study, super-hard WC-(TiAl)N coatings were deposited by arc-magnetron hybrid process and content of WC in the films were varied with power density of WC magnetron source. Hybrid process allowed compositionally gradient WC-(TiAl)N multi-phase coatings to be deposited with low macro-particles and good adhesion. It is noted that compositionally gradient WC-(TiAl)N coatings show super hardness of 5,000 ㎏/㎟. The present study introduces the hybrid process parameters involved and the formation behavior of WC gradient WC-(TiAl)N coatings were investigated by SEM, AES and XRD. |
|
