| Diamond-like carbon (DLC) films are attractive for industrial applications with high hardness, low friction coefficient and chemical inertness. Low stress is essential for practical applications of DLC films. In this article, DLC gradient multilayer films with relative low stress by Ti doping were prepared and the mechanical properties of DLC films were studied.Samples of Ti-DLC film with different Ti concentration were prepared by filtered cathodic vacuum arc deposition. The results show that hardness and stress are decreasing with Ti concentration increase as a whole, but the friction coefficient is increasing with higher Ti concentration. Ti concentration of all samples is from5.3at.%to18.0at.%, the stress is about half of undoped DLC films. DLC film with different Ti concentration can act as modulate layer, to release stress of multilayer DLC films.During DLC films deposition, Fe element was doped in the surface layer by ion sources, and intermittent Ar ion bombardment interrupted films continual growth. Multilayer DLC films were prepared by intermittent ion bombardment; it possesses similar hardness, half of stress and lower friction coefficient of DLC films without ion bombardment. Such DLC films can act as the outmost layer of multilayer DLC films.On the base of study of Ti-DLC film and undoped DLC films, Ti doped DLC gradient multilayer films were prepared on GT35alloy steel. The thickness of films reaches to2.2μm; the stress is from2.1GPa to2.2GPa, which is about half of undoped DLC films; the hardness is similar as undoped DLC films, the value is from Hv5200to Hv5500, the adhesion excel to35N/mm2, the stable friction coefficient is about0.09. The results show that Ti doped DLC gradient multilayer films possess excellent mechanical properties. |
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