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Quench polish quench (QPQ) is a specialized type of nitrocarburizing case hardening that increases corrosion resistance. It is sometimes known by the brand name of Tufftride, Tenifer or Melonite. Three steps are involved: nitrocarburize ("quench"), polish, and post-oxidize ("quench"). This process is often used when two or more of the following properties are required in a workpiece: * wear resistance * corrosion resistance * lubricity * fatigue strength. Common applications of the process are for piston rods of shock absorbers, cylinders and rods for hydraulic systems, pumps, axles, spindles and valves.〔 ==Process== The process starts with a standard salt bath nitrocarburizing cycle, which produces a layer of ε iron nitride. Next, the workpiece is mechanically polished; typical polishing processes include vibratory finishing, lapping, and centerless grinding. Finally, the workpiece is re-immersed into the salt quench bath for 20 to 30 minutes, rinsed, and oil dipped. This last step optimizes the corrosion resistance by creating a layer of iron oxide about 3 to 4 micrometers thick. It also gives the workpiece a black finish. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quench polish quench」の詳細全文を読む スポンサード リンク
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