Study On Preparation And Properties About PN+PVD Duplex Treatment On The Surface Of H13 Steel

TiN films is the main hard coating material for tool and die. Preparation of TiN films by kinds of techniques have studied in-depth and used in protection of tools. However, in some tools and dies which have special high performance request, because of the adhesion strength between coating and substrate which is not enough, the breakage occurs easily in early days. To further study of the films, people mainly concentrate on the diversification, the more layers and dual processing to improve the performance of films. Plasma nitriding (PN) - Physical vapor deposition (PVD) is a new bonding technology, which attracts people's attention. The excellent adhesion strength and wear resistance of TiN films, which is deposited on plasma nitriding layer, have a significance about the recent research progress in films. In particular, it has a good effect on the adhesion strength of single-layer films.The first part of this paper has mainly studied the process of PN+TiN composite films which is deposited by multi-arc ion plating equipment. The results show that the optimal process parameters of PN+TiN composite films are those follows: the ratio of N2 and H2 flux, nitriding time, nitriding temperature, target current and deposition time are 3/2, 3 h, 500℃, 80 A and 60 min respectively. When the films prepared under these parameters, the depth of TiN layer is 4μm, nitriding layer is about 8μm, the adhesion strength is 45 N and the micro-hardness achieves 2200 HV0.05.The second part of this paper has made plasma nitriding and TiN films deposited by PVD separately, mainly studied the effect of nitriding time on the properties and morphology of PN+ TiN composite films and contrasted wear resistance between the single TiN films and PN+TiN composit films. The resules show that the micro-hardess and adhesion strength of PN+TiN composite films which is deposited after plasma nitriding on H13 are 2292 HV0.05 and 48N respectively. The micro-wear test indicated that, the weight loss, friction coefficient and wear scar width of PN+TiN composite films are less than the single TiN films'. PN+TiN composite films have more outstanding wear resistance than the single TiN films. The last part of this paper has discussed the mechanism of the duplex treatment to improve the micro-hardness and adhesion strength of the coating.