Papers by Keyword: Nitriding

Abstract: In the last twenty years, the manufacturing of titanium and its alloys for commercial use continued to expand. As this material has several very advantageous properties, leading to increasing applications in various industries, it is seldom used in mechanical engineering applications due to its tribological properties, which are unfavourable. The nitriding process is one of the most frequently used thermochemical processes designed to enhance the surface characteristics of titanium alloys and improve tribological properties. Various types of nitriding for titanium are studied, such as ion nitriding, plasma nitriding, laser nitriding and gas nitriding. This article provides a comprehensive examination of research papers on different advancements through a systematic literature review conducted in the period 2017-2023 about titanium nitriding for its process parameters, characteristics and functionalities of the product, particularly emphasising their contributions in surface characteristics and mechanical properties. The review seeks to offer an understanding of how the predominant processing factors, specifically temperature and time, affect the microstructure and the creation of novel phases. This review suggests a challenge for future researchers to investigate mechanisms of microstructure evolution and its impact on mechanical properties in conditioned environments to microhardness and ability to withstand rusting of titanium and its alloys.

Abstract: In cold forging processes, diamond-like carbon (DLC) coatings have become established as a wear protection for forging dies, featuring high hardness and advantageous friction properties. This counteracts the particular critical abrasive tool wear and increases tool life. A major disadvantage of DLC coatings is their low thermal stability. In this study, the influence of metallic elements (niobium, tungsten and chromium) in the treatment atmosphere of the coating process is investigated with the aim of increasing the temperature resistance of the DLC coating and enabling its application as a wear-protection measure for hot forging dies. Preliminary studies were carried out to investigate the influence of different treatment atmospheres on wear-reducing properties such as high hardness and coating adhesion depending on prior nitriding processes. The most promising metal-doped DLC coating, with 30 % tungsten in the treatment atmosphere, was used in serial forging tests. At a blank temperature of 1,200 °C and a moderate count of 100 forging cycles, wear was reduced by up to 60 % compared to the nitrided reference tool.

Abstract: The influence of different nitriding temperatures was investigated on the structures and mechanical properties of the treated specimens. Based on the research of nitriding temperature on the properties of pure titanium, the cause of the rresults can be discussed in this research. When the nitriding temperature is 1050°C, the cross-sectional hardness of the hardened layer reaches the maximum. At the same nitriding temperature, the bonding strength also reaches the maximum, which is related to the performance of the hardened layer. In summary, when the nitriding temperature is 1050°C, the nitriding of pure titanium can improve the overall performance.

Abstract: Nitrogen doped as-cast Co-Cr-Mo alloy with markedly enhanced hardness and wear resistance was successfully produced by pack nitriding process. Nitriding proses used the in-pack process using urea fertilizer as a nitrogen source. It was carried out with variations in temperature of 400°C, 500°C, 600°C and followed by annealing. The wear resistance of the specimen is tested using pin-on-disk. The total sample will be soaked in the lactic acid solution for 3 days. The results obtained from the After nitriding process, the hardness of of speciment N400 obtained a hardness value of 261.54 HV speciment N500 of 309.68 HV, and speciment N600 of 429.14 HV, the results of the hardness value increased in each speciment. The wear resistance value obtained for each speciment N400, N500, N600 is 2,81 x 10^-6 mm³/Nm, 7,50 x 10^-7 mm³/Nm, 1,87 x 10^-7 mm³/Nm. The nitriding process forms a layer on the surface of the as-cast Co-Cr-Mo, it’s called Layer of Cr-N which is the result of heating/decomposing urea fertilizer into nitrogen gas which can coat the surface so that Cr-N bonds are formed in the layer. The thickness of the Cr-N layer on the N400 specimen is 0.28 mm, N500 is 0.35 mm, N600 is 0.38 mm. In addition, the surface results that have been tested for wear resistance form quite fine scratches but the formation of abrasions, such as abrasion, abrasion groove, delamination, and cohesive failure

Abstract: The present study has been conducted in order to obtain iron nitrides layer on AISI4140 steel by using plasma nitriding treatment. As one of several parameters of this process, the nitrogen rate ranging from 10 to 70% with a step of 20% was chosen. The structure, the morphology, the thickness and the hardness of iron nitrides layer were investigated. As a result, the improvement of surface hardness of nitrided steel was identified related with the increase of compound layer thickness due to the increase of activation rate. The steel substrate treated at high activation rate presents hardness 3 times higher than that of untreated steel.

Abstract: One of the ways to develop existing methods of hardening is creation of hybrid technologies that combine the principles of chemical heat treatment and surface plastic deformation. This paper proposes a nitriding technology followed by ultrasonic treatment. As a result of such sequence, a surface layer is formed that has an increased hardness and depth of hardening, in comparison with combined methods used separately.

Abstract: One of the commonly used methods for the surface hardening treatment of pure titanium was nitriding. Based on the study of nitriding temperatures on the properties of the pure titanium, some conclusions can be drawn in this paper. The surface hardness of samples after nitriding was gradually increased firstly and then decreased with the processing temperature increasing. And the hardness of the diffusion layer reached the maximum value of 1792 HV when the processing temperature at 1050°C. At the same temperature, the indentation modulus also reached the maximum value of 270 GPa. The wear depth reached the minimum value at 1050°C. At different nitriding temperatures, the minimum of wear depth was 14.8 μm. In summary, when the processing temperature at 1050°C, the nitriding of pure titanium can improve the comprehensive properties.

Abstract: The internal combustion engine is the most expensive component of a car, which determines the reliability and efficiency of its use. Studies show that one of the most common reasons for the failure of KAMAZ diesel engines during operation is the underutilization of the crankshaft resource due to wear of parts and couplings that limit its resource. An increase in the resource of crankshafts can be achieved by improving the technological processes of restoration and repair. Full utilization of the resource of KAMAZ nitrided crankshafts is possible by surfacing worn journals only after removing a nitrided layer up to 0.4 mm thick from the journals surface using specialized equipment for electrical discharge machining. Electrical discharge machining is based on the removal of material particles from the surface by an electric discharge pulse between electrodes immersed in a liquid dielectric, in the channel of which a high-temperature plasma is formed.

Abstract: Iron nitride is a promising material for soft magnetic composite. In the current research, iron nitride compound was produced from natural iron sand, involving coprecipitation and gas nitriding. Prior to coprecipitation, natural iron sands were separated magnetically to obtain pure Fe₃O₄. Afterward, the coprecipitation was carried out to obtain nanosized Fe₃O₄. Gas nitriding of Fe₃O₄ powders was performed at different temperatures i.e. 500 °C, 600 °C and 700 °C, under flowing NH₃ gas. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) are used to investigate the phases obtained after the nitriding process. XRD patterns of the resulted powder indicate that nitriding temperature at 600 °C and 700 °C can produce iron nitride material, i.e. ε-Fe₃N. While nitriding temperature of 500 °C is not able to yield iron nitrides. SEM examination reveals that the ε-Fe₃N has irregular lamellar morphology. Some impurities are still detected, in the form of Fe₃O₄, Fe₂O₃, Ti₂O₃ and TiO₂. Further works regarding the examination of the magnetic properties of the powders will be carried out.

Abstract: When steel is nitrided, a compound layer mainly composed of iron nitrides, ε-Fe_2~3N and the γ’-Fe₄N phase, is formed on the steel surface. It is an extremely important industrial issue to clarify factors governing the formation of the compound layer during nitriding and to establish unified views on the mechanism of compound layer formation. Therefore, in order to clarify the effect of change in carbon concentration on the growth of the ε phase and the γ’ phase in the compound layer on nitrided steel, we evaluated the change over time in the concentration of the alloy elements in the surface layer, and the phases of the compound layer on nitrided steels containing various amount of carbon in the matrix. The results were that the change over time in the carbon concentration in the compound layer was mainly responsible for the change over time in the phases of the compound layer. Furthermore, it was discovered that the change over time in the carbon concentration distribution occurred because both increasing of carbon from the matrix to the compound layer, and decreasing of carbon from the surface of compound layer to the atmosphere. That caused the gradient change of chemical potential of carbon in the through-thickness direction of compound layer, and the phases of the compound layer were changed with the treatment time.