Tribological properties and thermal stability of various types of polyimide films

Thermal exposure experiments at 315 and 350 C were conducted on seven different types of polyimide films to determine which was the most thermally stable and adherent. The polyimides were ranked according to the rate at which they lost weight and how well they adhere to the metallic substrate. Friction and wear experiments were conducted at 25 C (room temperature) on films bonded to 440C HT stainless steel. Friction, film wear rates, wear mechanisms, and transfer films of the seven films were investigated and compared. The polyimides were found to fall into two groups as far as friction and wear properties were concerned. Group one had lower friction but an order of magnitude higher film wear rate than did group two. The wear mechanism was predominately adhesive, but the size of the wear particles were larger for group one polyimides.