.40 Of Cr Surface Multi-arc Ion Plating Process And Properties Of The Tialn / Tin Composite Coating

Gear failure takes the most important part of the failure of mechanical drive. When the gear is transfering power, it has to bear bending stress, contact stress and impact stress. So, the gear has a lot of failure modes. The conventional surface strengthening techniques such as whole quenching, surface quenching and nitride can not meet the needs of industrial production. The new surface strengthening techniques such as PVD and CVD have been concerned by people.40Cr steel substrate is coated with TiAlN/TiN films by Multi-arc ion technology. We study surface morphology, internal structure, microhardness, oxidation resistance and friction and wear properties of TiAlN/TiN coating in different process parameters. The butt materials are 99.99% purity titanium and 99.99% purity aluminum. The deposition parameters are as follows: pushed biasing is 0⁵00V, current of titanium target is 60A, current of aluminum target is between 40A to 80A, N₂ pressure is from 0.3Pa to 1.3Pa, deposition temperature is 200℃and time of coating is 90min.The results show that: the pushed bias voltage has a great influence in performance of TiAlN/TiN films. The excessively high pushed bias voltage can make the surface of films out of flatness and reduce the micro hardness of films. The same to pushed bias voltage if it is excessively low. The content of Ti and Al in films becomes more and more lower if the pushed bias voltage becomes more and higher; the current of titanium target also has a great influence in performance of TiAlN/TiN films. The surface of coating becomes more and more out-of-flatness by increasing of arc. The microhardness of coating is increasing when arc is increasing. But if the arc is too high, it may make the microhardness fall down. The content of Ti and Al in films becomes more and higher by the arc increasing; The higher N₂ pressure is from a beneficial effect on improving the surface morphology of TiAlN/TiN films. But if N₂ pressure is too high, it can make a phenomenon which we called"Nitrogen poisoning"on the surface of aluminum target and titanium target. The content of Ti and Al in films and microhardness become lower.Oxidation resistance of TiAlN/TiN films is batter than 40Cr and TiN film. 40Cr has been oxidized at 200℃. At 700℃, the oxide scale of 40Cr becomes thickening, cracking and shedding. TiN film has good oxidation resistance at 200℃, but has been oxidized completely at 700℃. TiN film has begun to drop and its color from golden to brown. TiN film can not protect 40Cr steel substrate at 700℃. Oxidation resistance of TiAlN/TiN films is perfect at 700℃. The films are integrity, no cracking and no peeling.The main experimental parameters of reciprocating sliding dry friction experiment are as follows: normal load is between 10N and 50N, linear velocity is 13188mm/min and each time is 10min. After comparing the friction properties of 40Cr and TiAlN/TiN films we find that both friction coefficient and wear loss of TiAlN/TiN films are lower than 40Cr. Meantime we also find that the friction coefficient of TiAlN/TiN films is reducing as the normal load increases.