2016 Volume 57 Issue 3 Pages 362-367
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 Ti25Mo25C50 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 (fN2) and reached to a minimum hardness of 16.4 GPa at fN2 = 2.0 ccm. Contrarily, at over fN2 = 3.0 ccm, the hardness drastically increased with increasing fN2 and reached a maximal value of 32 GPa, and then slightly decreased again with further increase of fN2. 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 columnar structure. The friction coefficient decreased with increasing fN2 and the film deposited at fN2 = 5.0 ccm showed a minimum value of 0.27. The simple oxidation test in air indicated that lubricious MoO3 is easy to be formed in the film deposited at a high fN2, which should cause the reduction of friction coefficient.