燃料电池空压机箔片气体轴承涂层摩擦学性能研究

In order to decrease wear during the start-stop process of the foil gas bearing for the fuel cell air compressor, a self-lubricating soft coating is required on the surface of the top foil. However, the existing polytetrafluoroethylene (PTFE)-based or epoxy-based soft coating have problems such as high friction coefficient or poor wear resistance. Therefore, in this paper, polyimide(PI)-based solid lubricating coating is prepared on nickel-based superalloy foils. The effects of coating thickness, mass fraction of MoS₂ nanoparticle and temperature on the tribological properties of the coating are studied and compared with commercial PTFE coating. The results show that with the thickness increasing, the friction coefficient of the prepared PI composite coating is basically unchanged at first and then increases, and there is an optimal coating thickness to minimize the friction coefficient. With the mass fraction of MoS₂ nanoparticles increasing, the friction coefficient and wear rate of the PI composite coating first decrease and then increase. When the mass fraction is 2.5%, the friction coefficient of the PI composite coating is as low as 0.173, and the wear rate is as low as 9.14×10^-6 mm³/(Nm). With the temperature increasing, the friction coefficient and wear rate of the PI composite coating first decrease and then increase, and the friction coefficient is in the range of 0.081~0.173, while the wear rate is in the range of 3.77×10^-6~9.14×10^-6 mm³/(Nm). Compared with the commercial PTFE coating, the maximum reduction of friction coefficient of PI composite coating is 43.4%, while the wear rate decreases by nearly two orders of magnitude.