论文部分内容阅读
In order to develop a lubricating film with excellent mechanical and tribological performance in wide temperature range, the Tin moS2/Ag composite films that constitute of hard ceramic and low-, medium-, temperature lubricating phases were prepared by using the pulsed laser deposition (PLD) techniques. Moreover, the microstructures, tribological properties of the composite films were investigated by XRD, SEM, UMT-3 tribometer, Raman spectroscopy, respectively. The results show that the Tin moS2/Ag composite film exhibit polycrystalline structure, which is composed of TiN, MoS2, Ag phase and is majority of TiN. According to the SEM and XRD investigation, the film show a flat and smooth surface morphology, and register a uniform and compact nanostructur. With the raising of test temperatures, the friction coefficients increase only a little from 0.05 at room temperature to 0.1 at 400 ℃, increase to 0.2 at 500 ℃ but decrease to 0.14 at 700 ℃, and is 0.33 at 900 ℃. On the base of XRD and Raman results of wear track, the lubrication depend on the layered structure MoS2 and soft metal Ag at room temperature, so possess the lowest friction coefficient and the wear track is very flat and smooth. At the temperature of 300 ℃ and 400 ℃, the wear track is wider than that of room temperature due to the metal Ag soften, and the contact area become larger under the action of loading force during the friction process. In addition, the MoS2 starts to decompose partly, but the undecomposed MoS2 is still able to exert its lubrication, the silver also play a critical lubrication in this case, and a layer of lubricating film formed on the wear track. When the temperature rises to 500 ℃, as can be seen from the wear track morphology that silver migrate apparently, the film lubrication rely mainly on silver and silver oxides due to the complete oxidative decomposition of MoS2. In the case of 700 ℃, the layered structure silver molybdates (such as Ag2MoO4, Ag2MoO7) generated through the tribochemical reaction were beneficial for lubricious effects, and the friction coefficient decrease to 0.14 from 0.2 at 500 ℃. Up to the temperature of 900 ℃, the friction coefficient is volatile and increase steeply due to wear failure of the film. The Tin moS2/Ag composite film deposited by PLD technique exhibit outstanding tribological properties below the temperature of 700 ℃, and the variations of the friction coefficient are minor ones. It is also anticipated that the composite films could be applied to lubrication in wide temperature from room temperature to 700 ℃.