Polytetrafluoroethylene (PTFE) has excellent chemical stability, resistance to all strong acids, strong bases, strong oxidants, and does not work with various organic solvents. PTFE has a wide temperature range, and can be applied to -180 ° C to 250 ° C for a long time under normal pressure. After 1000 h treatment at 250 ° C, the mechanical properties change little. PTFE has a very low friction factor and is a good antifriction. Self-lubricating material has a static friction coefficient smaller than the dynamic friction coefficient. Therefore, it has the advantages of small starting resistance and smooth running. Because PTFE is non-polar, heat-resistant and non-absorbent, it is an excellent electrical insulating material. It also has excellent aging resistance, non-stickiness and non-combustibility.