Study Of CrAlN Film Deposited By Pulsed Bias Arc Ion Plating

CrAIN films were deposited by pulsed bias arc ion plating on HSS steel and 316L stainless steel. X-Ray Diffraction (XRD) was used to characterize the films' structure. With Scanning Electron Microscope (SEM), we characterized the films' surface and cross-section morphology. Energy Dispersive Spectroscope(EDS) and Electronic Probe Micro analyzer (EPMA-1600) was used to characterize element content and element distraction. The hardness of the films was tested with nanoindenter. Then we characterized the films' adhesion force with scratching method. The effect of pulsed bias and arc current on the films' composition, structure and properties was investigated, and the high temperature (900℃) oxidation resistance of the films was estimated.The results show that Al-content firstly decreases and then increases with the increase of the pulsed bias. The phase structure of the CrAIN films consisted of fcc-CrN and fcc-Al phase. With the increase of the pulsed bias, the film hardness varies and reaches the highest value 25GPa when pulsed bias was -300V. The film has very high adhesion force (higher than 70N). When pulsed bias varies from -100V to -700V, the films deposited at -300V exhibit the best synthesis properties.The Al-content increases with the increase of the Al target arc current and the decrease of the Cr target arc current. The films with the lowest Al-content have the rocksalt-type cubic structure, show a (111) preferential orientation. With the increase of the Al-content, the crystal structure does not change while the preferential orientation turns to (220). Due to the preferential orientation, the films with the lowest Al-content exhibit excellent friction and wear properties as well as the highest hardness (35Gpa).The high temperature oxidation experiments were performed in air under 900℃. The annealing time was 10h. The original and the oxidized samples were characterized by scanning electron microscopy and X-ray diffraction. The results show that films are stable up to 900℃ due to the formation of an aluminum-rich oxide film which blocks oxygen diffusion and prevents further film oxidation. So the films can protect the substrates effectively.