Advanced Surface Hardening Techniques Using Gas Process
Air Water Incorporated Japan (AWI) has succeeded in developing and commercializing new surface treatment technologies. One of them is the NV Nitriding process. Through an activation treatment using fluorine-based gas for the surface treatment of metals before the nitriding treatment, it is possible to remove the oxide film, such as the passive film, formed on stainless steels and Ni-based alloys and also to nitride these alloys on a mass-production scale. The activation effect afforded by fluoride enables nitriding at a temperature about 150°C lower than other conventional processes, achieving minimal thermal deformation and strain. Also, with this activation process, the range of selection of nitriding conditions such as temperature, gas composition and heat pattern has been considerably extended to enable the formation of a nitride layer optimum for the required characteristics of the treated metals. That is, this process can control the thickness of the nitride compound layer. NV Pionite treatment also has been developed as the soluble carbon diffusion process by which to ensure high corrosion resistance and high hardness in austenitic stainless steels using the above activation treatment.
Jang Hyun Sung, Chan Gyu Lee, Yong Zoo You, Young Kook Lee and Jae Young Kim
H. Fujikawa and T. Watanabe, "Advanced Surface Hardening Techniques Using Gas Process", Solid State Phenomena, Vol. 118, pp. 161-166, 2006