Effect of Oxidation on Surface Properties of AISI H13 Tool Steel Nitrided by Atmospheric-Pressure Plasma

Abstract

Atmospheric-pressure plasma nitriding of AISI H13 tool steel is performed using a dielectric barrier discharge method. As the surface of the sample nitrided by atmospheric-pressure plasma is oxidized, the surface characteristics are considered to be different from those of conventional plasma nitriding in a vacuum. In this study, the surface properties of the nitrided layer such as tribological properties generated by atmospheric-pressure plasma nitriding are investigated. The results show that the surface and crosssectional hardness of the nitrided sample increase as the amount of nitrogen gas increases. By contrast, the surface and cross-sectional hardness of the nitrided sample increase as the amount of hydrogen gas decreases. Moreover, the surface luster of the nitrided samples changes unlike the untreated samples; however, the surface roughness of all the nitrided samples is similar to that of the untreated samples. When compared with an untreated sample, the friction coefficient and wear resistance of the nitrided sample are improved. For this reason, we consider that the nitriding in this research also causes oxidation by oxygen, similar to oxynitriding. Samples with oxidation film formed by atmospheric-pressure plasma nitriding have excellent wear resistance and friction coefficient, demonstrating the superiority of atmospheric-pressure plasma nitriding for treating small components.

Surface Modification of AISI H13 Tool Steel via Atmospheric-pressure Plasma Nitriding and Superheated Steam Treatment

“…The friction coefficient of the hybrid-treated sample was approximately 0.28, which was the lowest among all samples. In a previous report, the friction coefficient was low when an oxide film formed on the nitrided layer 15) . The friction coefficient of the hybrid treatment is lower than that of the steam treatment, and the reasons are considered to be as follows.…”

“…Moreover, limited products can be processed via conventional plasma nitriding due to its vacuum atmosphere. Therefore, we are developing a plasma nitriding method that is conducted at atmospheric pressure 13,15) . However, the friction coefficients of atmospheric-pressure-plasma-nitrided samples are higher than those of samples treated using other nitriding methods.…”

Effect of Sputtered Fe on the Plasma Nitriding Mechanism of AISI H13 Tool Steel Using Electron-Beam-Excited Plasma

“…Plasma nitriding can be used to increase the surface hardness, wear resistance, fatigue strength, and corrosion resistance of steel while maintaining its core properties. [1][2][3][4] A diffusion layer is generated on the surface of a nitrided sample, followed by the formation of a compound layer on top of the diffusion layer. The plasma (ion) nitriding mechanism is often explained using Koebel's model.…”