Coating of Die Steel Substrates with DLC/Ti Bi-Layered Films by Magnetron DC Sputtering

抄録

Coating of die steel substrates with DLC/Ti bi-layered films by magnetron DC sputtering was examined, in order to improve not only both the surface hardness and the wear resistance at the same time but also the adhesion between the deposited film and the substrate by relaxing the stress concentrated at the interface between them. The deposition of DLC/Ti bi-layered films onto the substrates was carried out in the atmosphere of argon. by sputtering of a titanium target followed by sputtering a carbon one. Under visual observation, the obtained DLC/Ti bi-layered films appeared to be adhesive while the DLC monolithic films deposited directly onto the substrates peeled off partly. Thus it was found that the DLC/Ti bi-layered films were more adhesive to the die steel than the DLC monolithic films. According to indentation hardness measurements, it was found that the surface hardness of the die steel could be improved by coating it with the DLC/Ti bi-layered films. Under optical microscopy, it was assumed that the deposited film could cover most of fine pits which had originally existed on the surface the die steel substrate. Furthermore, according to friction tests, it was found that the tribological property of the die steel could be also considerably improved by coating it with the DLC/Ti bi-layered films.