Comparison of film properties between hydrogenated and unhydrogenated diamond-like carbon films prepared by radio-frequency magnetron sputtering

We have deposited diamond-like carbon (DLC) films at various temperatures by radio-frequency magnetron sputtering using argon and hydrogen gases, and systematically investigated the structural, mechanical and tribological properties of the films. The structural properties were characterized by visible Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and Fourier transform infrared spectroscopy. The stress release of hydrogenated films occurs at lower temperatures than that of unhydrogenated films. The stress of the unhydrogenated film deposited at 400 degrees C increases in ambient air with increasing time after deposition, whereas that of the hydrogenated film deposited at the same temperature remains low. Similarly, the adhesion strength of the unhydrogenated film deposited at 400 degrees C decreases with increasing time, whereas that of the hydrogenated film deposited at the same temperature remains unchanged. The deposition with hydrogen gas results in reductions in friction coefficient and specific wear rate in ambient air.