| With development of modern industry,working parts urgently requires good tribological properties at elevated temperatures and in other harsh environments. In recent years, with the tribology research focal point changing from the traditional hydrodynamic lubrication system to friction material and surface engineering, Polymer solid lubricating materials received increasing attention. Polyamide-imide (PAI) materials have both amide and imide structure, and have become self-lubricating polymer solid research focus because of its excellent self-lubricating, wear-resistant, heat-resistant properties.The polyamide-imide was prepared by using the method of the acid chloride and the method of diisocyanate. The impact of acid-binding and reaction time in synthesis process and heating method, curing time and curing temperature in curing process on PAI synthesized by acid chloride are studied by intrinsic viscosity method.The impacts of curing temperature on the structure and the thermal stability of PAI coatings synthesized by diisocyanate method are studied by IR, TGA, hot dissolution method.The reaction time and temperature, and the curing time and temperature are identified by intrinsic viscosity method. The bett6r preparation process and curing process was selected from these two methods. The solid self-lubricating coating of polyamide-imide was prepared while the solid lubricating group-molybdenum disulfide, tungsten disulfide and graphite was added with the polyamide-imide as film. Using reciprocating friction tester, CLSM, the contact angle measurement to analyze and characterize the property of friction and wear, surface morphology and water contact angle. The results showed that:1. The intrinsic viscosity can be effectively enhanced for the method of acid chloride when the acid binding agent is triethylamine and the optimum reaction time is 8 hours. The mode of heating has hardly influence on the intrinsic viscosity of polyamide-imide during the process of curing when it bellows to high temperature curing and the optimum reaction time is 2 hours and the optimum curing temperature is 150℃.2. When the curing temperature is 250℃ of the method of diisocyanate, the gelation rate is about 11%, the mass loss rate is only 25.5% when the temperature is 800℃ and the gelation rate is more than 95% in the temperature of 800℃. The absorption intensity of characteristic peaks of NH and C=O increases with the rise of curing temperature. The coating has well properties of friction and wear and heat resistance when the molar ratio of the monomers:TMA:MDI=16:17, the reaction temperature is 140℃, the reaction time is 2 hours, the curing temperature is 250℃, the curing time is 2 hours.3. When the loading is 800N, the additional of MoS2, WS2 and graphite solid lubricating powder can significantly reduce the coefficient of friction of PAI. When the additional of MoS2 particles is 30%, the coefficient of friction is to 0.1744, when the additional of graphite particles is 10%, the coefficient of friction is to 0.1752 and the coefficient of friction of WS2is between 0.30 to 0.33; When the coefficient of friction of the coating PAI with the additional of particles reduces, the wear scar width is relatively small, wear scar is lighter and surface morphology shows smoothly; The water contact angle can significantly increase due to the additional of the solid lubricating particles, and the water contact angle of the coating PAI increase significantly with the reduction the coefficient of friction.When the additional of MoS2 particles is 30%, the weight rate of water contact angle is to 50.16%, when the additional of graphite particles is 10%, the weight rate of water contact angle is to 65.14%, and the weight rate of water contact angle of PAI coatings added WS2is between 0.30 to 0.33. |
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