Piston is one of the main moving parts of diesel engine. The gas pressure is transmitted to the crankshaft through the connecting rod to realize the transformation of heat energy into mechanical energy.The working condition of the piston is rather harsh, it is with a temperature of 1400-1800 DEG C, and the pressure Up to 13MPa gas phase contact, resulting in a large thermal stress and alternating mechanical stress. It is seriously corroded by the gas, and it has strong friction and impact with the cylinder wall under the boundary lubrication condition