Effect of Arc Current on Wear Properties of CrN Film Deposited onto Tool Steel by Arc Ion Plating Method

Abstract

The wear properties of CrN mm has been investigated as a function of arc current which is one of the processing parameter of arc ion plating (AIP) method. CrN films were coated onto high-speed tool steel substrate under four arc currents of 50, 100, 150 and 200 A. CrN films were also examined using X-ray diffraction. The results obtained in the present study were summarized as follows. The dynamic micro hardness was hardly influenced by the arc current. For SEM observation, many droplets existed on the CrN film, which were generated by the dropping out of the macro-particle of non-evaporated Cr. The distribution of droplet depended markedly on the arc current. The wear weight was also dependent on the arc current. CrN film, which was synthesized at low arc current of 50 A markedly improved the wear resistance. For CrN film coated under the high arc current of 200 A, the wear resistance was less than that of film of 50 A. By the successive observation of wear track using optical microscope, the large adhesive matter was observed on the wear track. For opposite ball, the wear weight increased with decreasing the arc current. It was also seen from SEM observation and EDX that for the wear track, the adhesive matter was opposite ball. The area of adhesion of wear track for CrN film was less for 50 A than for 200 A. For 50 A CrN film, the decreases of adhesion contributed to increases in the wear resistance.