QPQ salt bath composite treatment technology is the latest metal surface strengthening technology in the world. The technology can greatly improve the wear resistance of products by infiltrating a variety of alloy elements into the metal surface. It is widely used in automobile, locomotive, engineering machinery, textile machinery, light industry machinery, instruments, tooling and other industries. Since German Degussa company launched QPQ technology, its users have reached more than 800 countries such as Germany, the United States, the United Kingdom and Japan. For example, General Electric [Ge] company in the United States has successfully replaced the hard chromium plating process, improved the wear resistance and corrosion resistance of locomotive diesel cylinder liner, reduced the cost, and eliminated the hazard of hexavalent chromium. Honda company in Japan has several sets of automatic QPQ equipment At home and abroad, more than 150 kinds of automobile and motorcycle parts use this technology, with an annual processing capacity of 60000 tons; Toyota and Japanese companies use this technology to process hundreds of tons of parts every month. Many domestic manufacturers, such as Volkswagen, use this technology to deal with a large number of crankshaft, mold, tools, automobiles, diesel engines, motorcycles, textile accessories, etc