Effect of surface roughness and reciprocating time on the tribological properties of the polyimide composites

Novel polyimide (PI) composites were designed and prepared as a frictional material for ultrasonic motors (USM). The effect of roughness and reciprocating time on the tribological properties of PI composites was specially investigated for simulating USM operating condition. These typical PI composites were designed along with the special characteristics of USM by filling proportional solid lubricants and nanoparticles, and prepared using classical hot-press sintering. The friction and wear behavior of PI composites with different surface roughness polished by SiC sandpaper and various reciprocating time was carried out on a pin-on-plate tribo-meter against GCr15 steel pin. The worn surface was observed by SEM to reveal wear mechanisms. Experimental results indicated that the coefficient of friction and specific wear rate increased with an increase of surface roughness which was detrimental for USM to prolong the service life. The coefficient of friction and wear volume will increase with an increase of reciprocating time due to fatigue wear, but specific wear rate will decrease with the minimum value of 2.1 x 10(-6) mm(3)/N m. This study can provide significant guidance for USM to optimize frictional surface and running-in time. POLYM. ENG. SCI., 59:483-489, 2019. (c) 2018 Society of Plastics Engineers