Papers by Keyword: Nitriding Process

Abstract: Nitriding of tools and engineering components is a well-established surface modification procedure in many industries to ensure operational efficiency. The focus of this work is laid on understanding the influence of nitriding processing technology on the resulting surface properties which strongly dominate its tribological performance. Therefore, nitriding layers based on salt bath and plasma procedure were realised using 31CrMoV9 substrate. The surface roughness before nitriding was set to a R_a value of ~0.16 μm which corresponds to at technically fine grinded surface. 3D measurements as well as SEM micrographs of the nitrided surfaces were compared to the original surface prior to the nitriding procedure. Additionally, cross-section microscopy and hardness depth profiles were done to describe nitriding layer structure and nitriding hardness depth (NHD). Results show a correlation of nitriding processing parameters with the resulting compound layer formation and nitriding hardening depth (NHD). An increase of surface roughness during nitriding can be correlated with the growth of ɛ-nitrides on top of the surface.

Abstract: This paper presents investigation of cavitation erosion resistance of nitrided austenitic stainless steel X5CrNi18-10. The diffusion layers were produced by using different parameters of reactive atmosphere (N₂:H₂). The microstructure, chemical composition and phase identification of the modified layer were examined using scanning electron microscopy, glow-discharge optical emission spectrometer and X-ray diffractometry, respectively. Cavitation erosion resistance of produced surface layers was investigated in a rotating disc facility. As a property characterizing the cavitation erosion resistance of manufactured surface layers were proposed incubation period and mass loss after 330 min of cavitation test. It was found that cavitation erosion resistance of modified surface layers is lower than reference material (not treated X5CrNi18-10 stainless steel).

Abstract: This paper presents investigations of nitrided cases after the glow-discharge nitriding process. The nitrided cases were obtained by using a different chemical composition of gas mixture at the temperature of 450^OC. The glow-discharge nitriding process was carried out on austenitic stainless steel, grade of steel X5CrNi18-10. The chemical composition and phase identification of the nitrided cases were examined by using the glow-discharge optical emission spectrometry (GD-OES) and X-ray diffractometry (XRD)

Abstract: This paper presents investigation of surface layers. The diffusion layers were produced by using different parameters of reactive atmosphere (N2:H2). The research of the surface layers was performed using scanning electron microscope (SEM). The results of energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) analysis are presented. Research reveals the influence of chemical constitution of reactive atmosphere on the change of properties of nitrided layers.

Abstract: Ceramic composites containing BN and Al can be machined easily into complex shape, the hardness of the composites can also be improved by surface hardening process of in situ reaction between Al and BN. However, the reaction of Al and BN is a volume reduced one and the porosity will increase during the hardening treatment.. In order to solve this problem, a surface nitriding process was developed. Put the pre-sintering samples (with designed shapes) into a vacuum furnace in nitrogen atmosphere and reheated to high-temperature, so that the residual Al after pre-sintering would react with N2 completely, and change to AlN which has higher hardness. The phase transformation and microstructure were observed and the mechanical and other properties were also measured. The results showed that the surface nitriding process could increase the hardness, bending strength and density obviously. The porosity decreased sharply compared with the general hardening treatment.