Dynamic Smoothening And Tribological Properties Of Pulsed-DC Sputtered DLC Based Nanocomposite Films
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K. P. Shaha, Y. T. Pei, C. Q. Chen & J. Th. M. De Hosson
Interface roughness and dynamic growth behavior of TiC/a-C nanocomposite films deposited by pulsed-DC magnetron sputtering were studied using atomic force microscopy and scanning electron microscopy. Upon increasing the intensity of concurrent ion impingement by raising the frequency of pulsed-DC sputtering, a transition from dynamic roughening to dynamic smoothening is revealed in the growth behavior of TiC/a-C nanocomposite films. Analyses of surface morphology and growth conditions imply that there is a transition of dominating growth mechanism from geometric shadowing to surface diffusion driven by impact-induced atomistic downhill flow process due to enhanced impingement of Ar+ ions, which occurs upon the change of pulse frequency from 100 kHz to 350 kHz. Also ultra-smooth TiC/a-C:H films were successfully grown on initial rough steel substrates (Sa ~ 6 nm) by pulsed-DC sputtering at 200 and 350 kHz frequency. These nanocomposite films exhibit superb toughness, wear resistance and ultralow friction. Keywords: dynamic roughening, smoothening, nanocomposite, rough substrates, pulsed-DC sputtering.
dynamic roughening, smoothening, nanocomposite, rough substrates, pulsed-DC sputtering