Effect of Post Treatment in Argon Environment of Plasma Nitrided Local Disc Brake

Plasma nitriding (also known as ion nitriding, plasma ion nitriding, or glow-discharge nitriding) is a method of surface hardening using glow-discharge technology to introduce nascent (elemental) nitrogen to the surface of a metal part subsequent diffusion into the material. Because of the formation of high compressive residual stresses in the case region, increasing surface hardness and depth parameters cause remarkable improvement in the mechanical properties of steels. In this study, the properties of a nitrided local disc brake were investigated. For that purpose, the material was nitrided at 400°C of temperature, 1.6 mbar of pressure, and 4 hours of time then followed by post-treatment in Argon (Ar) environment for various of holding time such as 10, 20, 30, 40, and 50 minutes. At these conditions the hardness increased in the range 123.1 - 223.3 VHN, the wear rate decreased in the range 21.7 × 10-9 - 3.1 × 10-9 mm3/mm kg, while before being nitrided the hardness and the wear rates were 113.5 VHN and 22.8 × 10-9 mm3/mm kg, respectively. The optimum condition for holding time during post treatments was 20 minutes. Besides that, the effect of various of N2: Ar mixture such as 90%: 10%, 80%: 20%, 70%: 30%, and 60%: 40% on the properties of local disc brake was studied. For various of gas mixing, the optimum hardness in the order of 252.7 VHN and wear rate in the order of 2.8 × 10-9 mm3/mm kg were achieved at 90%N2: 10%Ar of a gas mixture.
Keywords: Local Disk Brake, Ion Nitriding, Plasma, Post-treatment.