Fabrication of self-lubricating coating on aluminum and its frictional behaviour

A self-lubricating anodic film has been formed on aluminum by anodization in phosphoric acid–base electrolyte and a subsequent technique containing ultrasonic impregnation and heat treatment. The results show that the ultrasonic impregnation after anodization of aluminum in an electrolyte of phosphoric acid and some additives can fill some PTFE into the holes of alumina and the surface hardness decreases little within appropriate ultrasonic time. The final heat treatment technology can increase the coating hardness greatly, especially to the alumina acquired by general anodization. With this fabricating method, the properties of anti-attrition and abrasion resistance of self-lubricating coating improved greatly.