Ti-Mo-N反応性スパッタ薄膜の硬さに及ぼす熱処理の効果

摘要

TiN硬質コーティング膜は高硬度を持ち耐酸化性に優rnれ，特性のバランスの取れたコーティング膜として，切削工rn具や医療材料，鋳型の離型材など，様々な分野で利用されてrnいる．近年では切削工具の長寿命化や医療器具，インプランrnト材の安全性向上が強く求められており，TiNコーティンrnグ膜の硬さ，耐酸化性，耐摩耗性，密着性などの改善が要求rnされている．%Effects of heat treatment on microstructure and hardness of Ti-Mo-N coating films were investigated for various N contents. Ti-Mo-N films were deposited onto a stainless steel substrate by a reactive RF sputtering process in the mixture of argon (7.5 ccm) and nitrogen (0～2.0 ccm) gases using Ti_(50)Mo_(50) target. X-ray results of as-deposited films indicated that the main phase of the Ti-Mo-N film was a bcc-(Ti, Mo) phase at a nitrogen flow rate (f_(N_2)) ≤ 0.2 ccm and a δ-(Ti, Mo)N phase at f_(N_2) over 0.3 ccm. The Ti-Mo-N films so obtained were heat treated in argon atmosphere at 300～1100℃ for 30 minutes. Hardness was measured by a nanoindentation system. The hardness of the Ti-Mo-N films deposited at f_(N_2) = 2.0 ccm hardly changed with heat treatment. In contrast, the hardness of the films deposited at f_(N_2) = 0.2 and 0.3 ccm was drastically increased by heat treatment at temperatures higher than 900℃. In particular, the film deposited at f_(N_2) = 0.3 ccm showed the maximum hardness of about 35 GPa by heat treatment at 1000℃ for 30 minutes. X-ray measurement and TEM observation indicated that the increment of hardness in the Ti-Mo-N film at f_(N_2) = 0.3 ccm is due to the formation of a bcc-(Ti, Mo) phase in a δ-(Ti, Mo)N phase.