PN＋PECVD Duplex Treatment On The Surface Of H13Steel: Preparation And Mechanical Properties

The failure of mold is generally from the surface. Various surface treating techniqueshave been developed to improve the surface properties of the mold. It is an effective methordto prolong mold life. Low-temperature chemical heat treatment was widely used in industryby its low cost of the process. But its low surface hardness can not meet the needs ofindustrial production. With the maturity of the vapor deposition technique, deposition of hardthin films on the die steel surface can greatly improve the surface hardness. However,multiplex treatment on the surface of mold will further enhance the life of mold.In this study, plasma-enhanced chemical vapor deposition （PECVD） was employed toprepare nitrided layer, Ti （CN） films and diamond-like carbon （DLC） films on H13steel. Theproperties of Ti （CN） films by metal-organic plasma chemical vapor deposition on H13steelby plasma nitriding （PN） pretreatment were studied. The hardness of surface and section,adhesive strength, friction and wear properties for room and high temperature of H13bydifferent treatments were analyzed. Explore the impact of the negative bias voltage andhydrogen on structure and properties of DLC films. The structure and properties of DLC filmswere analyzed by Raman spectrum, X-ray photoelectron spectroscopy, Scanning electronmicroscope, micro-hardness tester and ball-disc friction and wear properties. The structureand properties of DLC films on H13after plasma nitrding were studied. The results show that:1. The thickness of the white layer of H13steel plasma-nitrogen with argon ionsputtering can be thinned. It is the highest that surface hardness of the H13steel for duplextreatment of PN+Ti （CN）, the value of hardness is2173Hv0.025,15. The adhesive strengthbetween flims and substrate that by multiplex of PN+Ar sputting+Ti （CN） is above100N.Thefriction of room and high temperature of H13by duplex treatment was lower than singletreatment. After duplex treatment, the wear rate of H13steel reduced from6.37×10^-6mm³/mm to1.2×10^-8mm3/mm in room temperature and reduced from9.56×10^-5mm³/mm to8.3×10^-6mm³/mm in high temperature.2. The DLC films were prepared by PECVD were compact and hydrogen-containingcarbon film of nitrogen and oxygen adopt. The formation of N and O were C-N bonds andC-O bonds in the film. The deposition rate of DLC films was increasing with the negative biasvoltage reducing. And H₂was benefit for improving the deposition rate of DLC films. Thehighest quantity of SP³bonding was30.03%at negative bias voltage1000V and without H₂.The highest hardness for997HK0.025,15and low friction coefficient for0.04845of DLC films under the parameter of negative bias voltage1000V and without H₂.3. DLC films prepared on nitriding layer. The hardness of DLC films on nitriding layerwas higher than prepared on H13by untreated. The adhesive strength between films withsubstate was improved. The friction coefficient and worn were reduced, so the wear resistantproperties of H13was improved.