Properties of POB reinforced PTFE-based friction material for ultrasonic motors

Polytetrafluoroethylene (PTFE) and its composite coating with various poly-p-oxybenzoyl (POB) proportions was prepared by spray suspensions. The friction and wear behavior were evaluated against a GCr15 steel ball on a ball-on-disc tribometer under dry sliding. The effect of the content of POB on the hydrophobic, mechanical and tribological properties of the PTFE-based coatings and the performances of the corresponding ultrasonic motors (USMs) were studied. Experimental results showed that the optimal content of POB not only increased the hardness, adhesion force and contact angle (CA), but also increased the coefficient of friction and wear resistance of the PTFE coatings. Especially, the wear rate of PTFE coating filled with 15 wt.% POB (3.42 x 10(-4) mm(3)/N . m) was only a quarter of pure PTFE. The morphologies of the worn surfaces of the PTFE coatings were observed by scanning electron microscopy to discuss the wear mechanism. The mechanical output properties of USMs were the best with filling of 10 wt.% POB into PTFE matrix.