Hardness and Wear Properties of Ti-Mo-C-N Film

Abstract

The hardness and wear properties of Ti Mo C N films were investigated by nanoindentation and ball on disc measurements, respectively. Ti Mo C N films were deposited onto a stainless steel substrate by a reactive RF magnetron sputtering in the mixture of argon (7.5 ccm) and nitrogen (0 6.0 ccm) gases using Ti 25 Mo 25 C 50 target. Ti Mo C film deposited without nitrogen gas flow showed a hardness of 34.8 GPa. The hardness drastically decreased with increasing nitrogen gas flow rate (f N2 ) and reached to a minimum hardness of 16.4 GPa at f N2 ＝2.0 ccm. Contrarily, at over f N2 ＝3.0 ccm, the hardness drastically increased with increasing f N2 and reached a maximal value of 32 GPa, and then slightly decreased again with further increase of f N2 . It was found by TEM observation that the drastic decrease in hardness is caused by the formation of nanocrystalline microstructure, while the increase in hardness is due to the microstructural change from nanocrystalline to columner structure. The friction coefficient decreased with increasing f N2 and the film deposited at f N2 ＝5.0 ccm showed a minimum value of 0.27. The simple oxidation test in air indicated that lubricious MoO 3 is easy to be formed in the film deposited at a high f N2 , which should cause the reduction of friction coefficient.