Abstract
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.
Highlights
A braking system is one of the most critical safety components of an automobile
Corrosion rate for nitrided samples at 90% N2:10% Ar and nitrided samples followed by 20 minutes post-treatment are 0.186 mm/year and 0.268 mm/year, respectively. These data show that the effect of Argon in the nitriding process and post-treatment deteriorate the corrosion properties
We have described the effect of Argon post-treatment environment on plasma nitrided local disc brake, followed by the experiment of N2:Ar of gas mixing
Summary
A braking system is one of the most critical safety components of an automobile. It is mainly used to decelerate vehicles from an actual speed to the desired speed. All braking system depends upon the frictional force to stop, to control or to prevent motion [4,5] Because these components are always rubbing against the surface of other components, these components will wear out quickly so that their service life will be reduced. There are many surface treatment methods used to improve the surface quality such as carburizing, nitriding, carbonitriding, induction hardening, shot peening, physical vapor deposition (PVD) and chemical vapor deposition (CVD) coating, etc. These treatments form a hardened surface layer with compressive residual stress, and the fatigue properties are improved by the surface layer [6]. In plasma DC nitriding process the components to be treated as a cathode, where the grounded wall of the reactor forms the anode
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