Plasma nitriding is a thermochemical treatment to improve the surface properties of metallic materials, such as mechanical and tribological properties. The aim of this study is to compare the nitriding performance of conventional plasma nitriding (CPN) and cathodic cage plasma nitriding (CCPN) for AISI M2 tool steel at various temperatures (400°C, 450°C and 500°C). The forming tool is also processed in identical conditions, and its productivity performance in the manufacturing of nails for civil construction is also evaluated. The highest hardness is achieved while processing samples at 400°C, and better productivity performance while treating samples at 500°C, both in CPN and CCPN. Notably, the hardness and productivity performance achieved in this study, particularly using CCPN is significantly higher than the forming tool provided by the factory in which conventional processing techniques were used, and thus it suggests the effectiveness of CCPN in wide-scale industrial applications in forming tools.

The cathodic cage plasma deposition (CCPD) is an advanced technique recently developed from an active screen plasma nitriding system, which has been used for thin film deposition such as titanium nitride and titanium dioxide (TiO 2). These coatings can improve the physical, mechanical, and optical properties of numerous materials, and such coatings can be developed by several techniques. Unfortunately, the conventional deposition techniques exhibit certain drawbacks, including high cost, the complexity of the operation, very low pressure, and high processing temperature; as a result, CCPD is an advantageous technique. In this review, brief information on the deposition of titanium nitride and oxide coatings on steel alloys, titanium, glass, and silicon substrates, and the effect of control parameters on deposition efficiency is provided. The effectiveness of this system for the synthesis of thin films on various substrates, including insulators and conductors, is also summarized. The recent developments and applications of CCPD for titanium-based coatings are described in detail.

In this study, a combination of conventional plasma nitriding and cathodic cage plasma deposition (CCPD) at different temperatures (400 and 450 °C) is implemented to enhance the surface properties of AISI-M2 steel. This combination effectively improves the surface hardness and the formation of a favorable hardness gradient toward the core, which would benefit the load-bearing capacity of substrate. The duplex-treated samples exhibit iron nitrides Fe4N, Fe2−3N and titanium nitride TiN phases. The thickness of the hard-TiN layer is 1.35 and 2.37 μm, whereas the combined thickness of the hard film and diffusion layer is 87 and 124 μm, for treatment at 400 and 450 °C, respectively. The wear rate and friction coefficient are dramatically reduced by duplex treatment. The oxidative wear mechanism and adhesive wear mechanism are dominant for duplex-treated samples. This study suggests that the cathodic cage plasma deposition technique can attain a combination of hard film and diffusion layer. The plasma nitriding before CCPD is beneficial for attaining an adequate nitrogen diffusion layer thickness. The drawbacks of conventional TiN film deposition, such as “egg-shell” problems, can be removed.

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