When the cylinder liner is in operation, its surface will be in contact with the gas. The gas has the characteristics of high temperature and high pressure, and the piston ring will continuously move back and forth. These are a great test for the strength and rigidity of the cylinder liner. It must also have the functions of high temperature resistance and corrosion resistance. In the gas seal, the main purpose is to prevent the compressed gas and combustion gas from leaking out, and the heat tr