Papers by Keyword: Nitriding

Abstract: In the article changes in the structure and mechanical properties of R6M5 steel surface layer after electrolytic-plasma nitriding are shown. The optimal mode of electrolytic-plasma nitriding of R6M5 high-speed steel in electrolyte based on carbamide, which allows saturation of the surface with nitrogen from low-temperature plasma and get the modified layer of high hardness and wear-resistance. It is established, that after electrolytic-plasma nitriding reduced R6M5 steel wear rate and increases its resistance to abrasive wear. Perspectivity of use an electrolytic-plasma nitriding method to improve performance cutting tools made from R6M5 steel is shown.

Abstract: In this study, aluminum alloys were subjected to nitriding at 823 K for 0–18.0 ks using alumina and magnesium powders for improving their radiation performance. After nitriding, aluminum nitride films were formed on the aluminum substrate. The thickness of the formed films varied from 1.5 to 11 μm, and the color of the film surface was dark brown or black. The thickness of the aluminum nitride film increased with an increase in the treatment time. X-ray diffraction and electron probe microanalysis results showed that the film was composed of aluminum nitride, alumina, aluminum, and magnesium. Further, the film showed good adhesion at 0 ks.

Abstract: The seek for sustainability in the global economic scenario has led to the need for developing materials that provide higher productivity, greater speed of operation, extended lifetimes and enhanced surface finishing of engineering parts. To achieve these goals it is essential to modify the metal surface with respect to its behavior in situations of friction, wear and oxidation at high temperatures. In this work, we studied the impact of different surface treatment strategies involving atomic peening with Xe ions and low temperature plasma nitriding on the surface microstructure of AISI 4140steel and the consequences of those surface treatments on the residual stresses of TiN coatings deposited onto the pre-treated substrates. The results show that ion bombardment at 1000 eV leads to mainly sputtering of surface material and no appreciable surface activation could be obtained for the subsequent plasma nitriding treatment. In the sample subjected to simple plasma nitriding, the highest nitride content was found and a Ti-enriched transition zone deposition appears to build up during the coating deposition. Accordingly the residual stresses of the TiN coatings deposited onto the nitrided steel surface were significantly lower in comparison to those encountered in the coatings grown on the non-treated, only bombarded and bombarded followed by nitriding substrates.

Abstract: The evolution of residual stresses during short time gas nitriding of 33CrMoV12-9 steel grade is studied. It aims understanding the influence of nitriding parameters (temperature and nitriding potential) on the generation and evolution of residual stresses in the very first stage of nitriding. The samples are gas nitrided using a thermobalance during 2h30 and 5 hours for various temperatures and nitriding potentials. Residual stress analyses are carried out by laboratory X-ray diffraction.

Abstract: This paper presents a surface hardness improvement methodology of a wind turbine helical gear which is made up on EN36 alloy steel material. Now days the wind turbine gears are frequently failed due to high contact stress, due to sudden impact load, change of wind speed and wind directions. Pitting is a method of surface failure in a gear. So, to avoid the gear failures we need to improve the surface hardness of wind turbine gears by using Nitriding process. There are three modes of hardness test taken from this process to improve the hardness. They are before nitriding, after nitriding & without nitriding. By comparing the hardness test values, Gas Nitriding is the best suitable process to increase the surface hardness of a large size gear. By the method of improving surface hardness of wind turbine gear, the load withstanding capacity of the wind turbine gears are increased, pitting failure may be avoided at a desired level and the power production rate is increased.

Abstract: The article examines regularities of high-speed steel surface changes in the phase and structural states of during the electrolytic-plasma processing. It is determined that after modification by electrolytic-plasma influence on the surface of R6M5 high-speed steel formation of small pores, microdefects and fine inclusion. Surface modified layer consists of nitrogen austenite, nitrogen martensite and fine nitride particles.

Abstract: In order to improve both of the fatigue and tribological properties of commercially pure (CP) titanium, a low temperature nitriding process was developed. Cold rolling was introduced as pre-treatment of plasma nitriding to create fine grains which could accelerate the diffusion of nitrogen into the material. Surface microstructures of the nitrided specimens pre-treated with cold rolling were characterized using a micro-Vickers hardness tester, an optical microscope, a scanning electron microscope (SEM), X-ray diffraction (XRD) and electron backscatter diffraction technique (EBSD). Titanium-nitrides (TiN and Ti₂N) were formed on the surface nitrided at the temperature greater than 600 °C. Moreover, thicker compound layer was formed in the nitrided CP titanium pre-treated with cold rolling in comparison to the only nitrided one, resulting in showing higher hardness. 4-points bending fatigue tests were performed for the specimens treated with low temperature nitriding (600 °C), which could suppress the grain-coarsening, under the stress ratio R = 0.1 at room temperature. In addition, fatigue fracture mechanism of nitrided CP titanium was discussed based on the observations of microstructure and fracture surface.

Abstract: Plasma nitriding is a widely used technique to improve the mechanical properties and tribological properties of AISI 316L steel because it has many advantages over other surface treatment techniques. One of this advantage is plasma nitriding allows nitrogen introduce to steel at low temperature (below 500°C).In this study, nitriding of an AISI 316L was performed in high density plasma nitriding system using 70%N₂:30%H₂ gas mixture at 400°C and 480°C for 2, 4, and 8 hours. Optical Emission Spectroscopy (OES) with optical probe was used for plasma diagnosis. The properties of nitrided sample were investigated through microhardness measurement. The results show that N₂ ions and radicals are species predominantly formed in plasma.

Abstract: In this work the influence of electrolytic-plasma nitriding on the abrasive wear-resistance of R6M5 high-speed steel were under research. We registered that after electrolytic-plasma nitriding on R6M5 steel surface modified layer is formed with 20-40 μm thickness and with increased microhardness of 9000-12200 MPa. Testing mode for the nitrided samples high-speed steel on abrasive wear developed. It is established, that electrolyte-plasma nitriding allows to increase wear-resistance of R6M5 steel surface layer comparing to original. It was determined that abrasive wear-resistance of R6M5 steel surface layer is increased to 25% as a result of electrolytic plasma nitriding. Thus, studies have demonstrated the feasibility and applicability of electrolytic-plasma nitriding in order to improve cutting tools work resource, working under friction and wear conditions.

Abstract: This paper presents the results of research influence nitriding in electrolytic plasma on the tribological properties of low-alloy 40Cr steel. It is shown that the process of electrolytic plasma nitriding can significantly increase the wear resistance of the samples 40Cr steel. Found that after nitriding component adhesive wear mechanism is changed to abrasion.