環境に優しい炭素薄膜の開発

摘要

近年，金属材料が過酷な条件で摺勤し合う自動車部品，工rn具部品等は，耐摩擦性，耐剥離性，表面平滑性，高寿命化がrn要求され，その使用環境も高温下，腐食雰囲気下など過酷にrnなってきている．また，「21世紀はエコの時代」と言われるrnとおり，低摩擦によるエネルギーの低減，油不要のドライ加rn工など環境への配慮を考慮したモノづくりが必要不可欠であrnる．このような要求に対して，環境に優しい薄膜開発の重要rn性が増しており，研究開発が盛んに行われている．特に，材rn料の硬度や耐摩擦?摩耗特性を改善し，部材の寿命を高めたrn硬質の炭素薄膜は急速に実用化が進んでいる．%A diamond-like carbon (DLC) film is characterized by its high hardness and low friction coefficient. These properties have quickly promoted their wide use in consumer products, such as tools, sliding components like dies, razor blades, and PET bottles. However, a DLC film has insufficient hardness. This has prevented its application to cutting tools for aluminum alloys of emerging demand. Therefore, this study addresses novel hard nanocarbon films, including high-density DLC films, nano-diamond films, and hybrid nano-dia-mond (HND) films as our new study objects. The hard nanocarbon films were formed on silicon wafers and tungsten carbide (WC) substrates. The film properties of hardness, composition, structure, and friction were analyzed. The result of high density DLC film hardness is high, 80-90 GPa, with a low friction coefficient of less than 0.1.rnWe have coated these onto cutting tools, conducted aluminum-alloy cutting experiments, and estimated their applicability. Results have suggested the degradation of cutting ability because of aluminum built-up; the cutting distance with a tungsten carbide tip was 20 m without coating and 200 m with a DLC coating. The cutting distance was extended to 4000 m with HND coating, which was a DLC film and nano-diamond multilayer. A high-density DLC film might even be extended up to 10000 m, that is, its lifetime could be lengthened to 50 times that of an ordinary DLC film.