Characterization and wear behavior of SiC coatings prepared by ion beam assisted deposition

We have studied the influence of temperature and ion bombardment during deposition on the structure and the tribological properties of Si coatings. A SIC target was sputtered with 1.2 keV Ar+ ions delivered by a Kaufman-type source and the growing films were continuously bombarded with 160 keV Ar+ ions. The microstructural state of the films was investigated by various techniques: transmission electron microscopy; glancing X-ray diffraction; and Fourier transform IR spectroscopy. It was found that SiC films prepared at room temperature without ion bombardment are amorphous whereas those deposited by dynamic ion mixing (DIM) exhibit the beginnings of a crystallization process into the beta-SiC phase. When the deposition temperature was increased up to 750 degrees C, the films prepared by DIM were more crystallized with a greater number of larger nanocrystalline grains of beta-SiC The wear resistance of TA6V (Ti 90 at.%-Al 6 at.%-V 4 at.%) substrates coated with SiC films is always reduced. However, the films prepared by DIM exhibit a lower wear rate as a result of increased adhesion. The crystallization of the films is discussed and analyzed as a consequence of collisional effects induced by the high-energy ion bombardment.