process. The temperature used is typical of all nitrocarburizing processes: 550 to 570 °C. The advantages of salt nitriding is that it achieves higher diffusion in the same period of time compared to any other method. The advantages of salt nitriding are: Quick processing time - usually in the order of 4 hours or so to achieve Simple operation - heat the salt and workpieces to temperature and submerge until the duration has transpired. The disadvantages are: The salts used are highly toxic - Disposal of salts are controlled by stringent environmental laws in western countries and has increased the costs involved in using salt baths. This is one of the most significant reasons the process has fallen out of favor in recent decades. Only one process possible with a particular salt type - since the nitrogen potential is set by the salt, only one type of process is possible Plasma nitriding Plasma nitriding, also known as ion nitriding, plasma ion nitriding or glow-discharge nitriding, is an industrial surface hardening treatment for metallic materials. In plasma nitriding, the reactivity of the nitriding media is not due to the temperature but to the gas ionized state. In this technique intense electric fields are used to generate ionized molecules of the gas around the surface to be nitrided. Such highly active gas with ionized molecules is called plasma, naming the technique. The gas used for plasma nitriding is usually pure nitrogen, since no spontaneous decomposition is needed (as is the case of nitriding with ammonia). There are hot plasmas typified by plasma jets used for metal cutting, welding, cladding or spraying. There are also cold plasmas, usually generated inside vacuum chambers, at low pressure regimes. Usually steels are beneficially treated with plasma nitriding. This process permits the close control of the nitrided microstructure, allowing nitriding with or without compound layer formation. Not only is the performance of metal parts enhanced, but working lifespans also increase, and so do the strain limit and the fatigue strength of the metals being treated. For instance, mechanical properties of austenitic stainless steel like resistance to wear can be significantly augmented and the surface hardness of tool steels can be doubled. A plasma nitrided part is usually ready for use. It calls for no machining, or polishing or any other post-nitriding operations. Thus the process is user-friendly, saves energy since it works fastest, and causes little or