Study On The Preparation And Properties Of TiAIN Films

TiAlN films were prepared using medium frequency magnetron sputtering. The influence of nitrogen flows on the structure and properties of the TiAlN films has been investigated systemically. Basing on the optimal process, the TiAlSiN films with different Si content were deposited by a hybrid PVD coating system which combined cathodic arc ion plating and a twin target mid-frequency magnetron sputtering. The influence of Si content on structure and properties were investigated. And then, the influence of AlSi targets currents on the high-temperature tribological properties was investigated. At last, the high-temperature tribological properties of TiAl(Cr、Mo、V、Y)N was investigated. The major conclusions of this thesis were drawn as follows:1. The deposition parameters (N2flows) had great effects on the structure and properties of the TiAlN films. With the nitrogen flows increasing the deposition of TiAlN films is decreasing, the Al/Ti ratio increasing first and then decreasing hardly. The films are made up of cubic crystalline TiN. The grain size became smaller and the columnar microstructure became looser. When the nitrogen flow comes to20sccm, the film shows the best hardness and bonding force.2. The TiAlSiN film has excellent mechanical properties and oxidation resistance, and the properties of the films were decided by composition and structure. The Si content affects the structure and properties of the TiAlSiN films. Therefore, the mechanical properties and oxidation resistance of TiAlSiN films also vary with the variation of the Si content. The hardness of TiAlSiN films increase with the Si content increasing first, and then decrease with the Si content increasing further. The Si3N4amorphous phase could strengthen the grain boundary, but the hardness will decrease because of the agglomeration of Si3N4amorphous phase. When the Si content was14.2at.%, the film has the best mechanical properties. In the process of wearing, the films will adsorb the moisture in the air and form a self-lubricating Si(OH)2tribo-layer, but when the Si content is about14.2at.%the agglomeration of Si3N4amorphous phase would make the Si(OH)2tribo-layer spread intermittently. The film has the best oxidation resistance with8.44at.%Si content. And the film remains intact section and surface morphology after oxidized at800℃for2h, the hardness of the film could still maintains at20GPa after oxidized at900℃for2h.3. As A1Si targets current increasing, the content of A1and Si in the TiAlSiN films increases gradually, and the hardness of the TiAlSiN films decreases gradually. The friction coefficient at400℃and600℃presents disorder. But at800℃the friction coefficient decreases because of the lubricating oxide. The film deposited at18Ahas the lowest friction coefficient and minimum wear rate.4. The addition of Cr reduces the wear rate of TiAlCrN film, but the friction coefficient is still high. The addition of Mo improves the tribological properties of the film at high temperature, and the friction coefficient is about0.38at800℃. The tribological properties of TiAlVN are better than TiAlMoN at800℃. The addition of rare earth element Y improves the oxidation resistance of the film, but the tribological properties did not be improved.