Tribological properties of sulfurized-nitrided layer prepared by a two-step method

The tribological properties of nitrided layer and sulfurized-nitrided layer of AISI 4135 steel were investigated under oil lubrication, and the layers were prepared by the ion nitriding treatment and a two-step method as the ion nitriding plus sulfurizing duplex treatment, respectively. A ball-on-disc friction and wear tester was adopted to evaluate the tribological performance. Scanning electron microscope (SEM), scanning Auger microprobe (SAM) and X-ray photoelectron spectroscope (XPS) were used to identify the morphologies and chemical compositions of the treated layer and the worn surface. It was presented that the sulfurized-nitrided sample with a thin FeS layer possessed much better tribological behaviors than the nitrided sample, including load carrying capacity, wear resistance, friction reduction and duration time. The mechanism was supposed that the decomposed activated S atoms of FeS layer promoted a new FeS chemical reaction film formation, which induced to the thin FeS layer playing as a solid lubricant for a longer time.     

Tribological behavior of NiTi alloy against 52100 steel and WC at elevated temperatures

The dry tribological behavior of a Ti–50.3 at.% Ni alloy at temperatures of 25 °C, 50 °C and 200 °C was studied. The wear tests were performed on a high temperature pin-on-disk tribometer using 52100 steel and tungsten carbide pins. The worn surfaces of the NiTi alloy were examined by scanning electron microscope. The results showed that in the wear tests involving steel pins, the wear rate of the NiTi decreased as the wear testing temperature was increased. However, for the NiTi/WC contact, a reverse trend was observed. There was also a large decrease in the coefficient of friction for the NiTi/steel contact with increasing wear testing temperature. The formation of compact tribological layers could be the main reason for the reduction of the wear rate and coefficient of friction of the NiTi/steel contact at higher wear testing temperatures.     

Effectiveness of high-frequency ultrasonic peening treatment on the tribological characteristics of Cu-based sintered materials on steel substrate

The effects of high-frequency ultrasonic peening (HFUP) on the tribological characteristics of Cu-based materials sintered on low carbon steel by a powder metallurgy (P/M) technique were investigated. The friction and wear properties of the Cu-based materials were studied using a pin-on-disk reciprocating tribotester sliding against a hardened steel ball under dry and oil-lubricated conditions. Scanning electron microscopy (SEM) was utilized to analyze the worn surfaces and to assess the wear mechanisms. Experimental results showed that the HFUP process led to a reduction in friction and wear of the Cu-based materials in both dry and oil-lubricated conditions. This was attributed to the increase in hardness of the HFUP treated specimen. It was also found that the friction coefficient was independent of the normal load but decreased with increasing sliding speed. In addition, inclusion of Fe in the Cu-based material was helpful in reduction of friction and wear. SEM analyses showed that abrasive wear was the dominant wear mechanism of the specimens. The results of this work demonstrate the effectiveness of HFUP in improving the tribological properties of Cu-based materials.     

牙科陶瓷材料的摩擦学性能研究进展

陶瓷材料因其优异的耐磨性、化学稳定性、生物相容性和美观性被广泛用于牙齿缺损和缺失修复。本文首先介绍了牙科陶瓷材料的化学成分、微观结构和力学性能,基于陶瓷材料的磨损与磨蚀机制,归纳总结了牙科陶瓷材料摩擦学性能优化方面所取得的进展,指出陶瓷材料和天然人牙摩擦学性能失配严重制约了陶瓷修复体的临床应用,进而从室验介质、对摩副以及载荷、位移和循环次数等方面分析汇总牙科陶瓷材料摩擦学性能的体外测试方法。最后,从仿生摩擦学角度探讨了牙科陶瓷材料的未来发展趋势,并指出研制仿生陶瓷基复合材料是解决陶瓷修复体与天然人牙摩擦学性能失配难题最具潜力的策略。     

碳化硅/碳化钨硬面密封摩擦副的摩擦磨损性能和机理研究

实验研究了干摩擦和水润滑条件下, 常压固相烧结碳化硅陶瓷(SSiC)及常压液相烧结碳化硅陶瓷(LPSiC)分别与碳化钨(WC)组成的硬面配对摩擦副的滑动摩擦磨损性能。在干摩擦条件下, 与LPSiC/WC摩擦副相比, SSiC陶瓷由于具有更大的晶粒尺寸和硬度, 导致SSiC/WC摩擦副具有更大的摩擦系数和更小的磨损量。磨损区域的SEM形貌结合面扫描分析、微区XRD分析结果表明: 微犁沟和微断裂导致SiC陶瓷的磨损, 疲劳损伤导致WC材料的磨损, 而摩擦过程产生的摩擦热导致磨出的WC颗粒氧化成无定型WO₃。在水润滑条件下, 与SSiC/WC摩擦副相比, LPSiC/WC摩擦副具有更大的摩擦系数和更低的磨损率。在干摩擦和水润滑条件下, 与SiC陶瓷作为动摩擦副配对相比, SiC陶瓷作为固定摩擦副的摩擦配对具有更小的摩擦系数和质量损失。     

Effect of Different Surface Treatment Methods on the Friction and Wear Behavior of AISI 4140 Steel

In this study,the effects of various surface treatments on the friction and wear behavior of AISI 4140 steel have been evaluated.Sample surfaces of AISI 4140 steel were treated by quenching,carburizing,boronizing and plasma transferred arc (PTA) modification.The microstructural characteristics of surface treated steel samples were examined by optical microscopy and scanning electron microscopy (SEM).The mechanical properties of the samples including the surface roughness,microhardness,and abrasive and adhesive wear characteristics were also evaluated.Wear tests were applied by using a block-on-disc configuration under dry sliding conditions.The wear behavior and friction characteristics of the samples were determined as a function of sliding distance.Each sample group was compared with the other sample groups,and it was observed that the carburized samples demonstrated the lowest weight losses;however,PTA-treated samples demonstrated the lowest coefficient of friction in comparison to the other sample groups at the same sliding distance.     

三种机械密封材料的摩擦磨损性能研究

研究了3种核主泵用机械密封陶瓷材料(氮化硅、氧化铝和碳化硅)在室温干摩擦条件下及水润滑条件下分别与氮化硅陶瓷球对磨的摩擦磨损性能。研究结果表明,在与氮化硅球干摩擦的3种材料中氧化铝陶瓷具有最大的摩擦系数和最小的磨损质量,氮化硅具有最小的摩擦系数。在氮化硅陶瓷自配对摩擦副摩擦磨损试验中,水润滑条件下氮化硅摩擦系数及摩擦质量损失都有很大程度的减小,且摩擦系数随转速增加而减小。综合考虑力学性能和摩擦磨损性能,选择氮化硅陶瓷作为核主泵机械密封材料更合适。     

高性能陶瓷人工髋关节材料摩擦磨损研究发展

陶瓷已经在人工髋关节假体制作中获得一定的应用,并且有更大的潜力以待开发.对于陶瓷人工髋关节假体,其摩擦磨损性能是决定其寿命的最重要的性能之一,而体外的摩擦磨损测试对于确定其摩擦磨损性能有着重要意义.本文综述了国内外对于氧化铝、氧化锆、氮化硅和碳化硅四种陶瓷的摩擦磨损性能的研究结果,并且结合作者的工作对其进行评论.     

Mechanical and tribological properties of gradient a-C:H/Ti coatings

The unusual combination of high hardness and very low friction coefficient are the most attractive tribological parameters of DLC (diamond-like carbon) layers. However, their usability is strongly restricted by the limited thickness due to high residual stress. The main goal of the presented work was to obtain thick, wear resistant and well adherent DLC layers while keeping their perfect friction parameters. As a proposed solution a Ti-Ti _x C _y gradient layer was manufactured as the adhesion improving interlayer followed by a thick diamond-like carbon film. This kind of combination seems to be very promising for many applications, where dry friction conditions for highly loaded elements can be observed. Both layers were obtained in one process using a hybrid deposition system combining PVD and CVD techniques in one reaction chamber. The investigation was performed on nitrided samples made from X53CrMnNiN21-9 valve steel. Structural features, surface topography, tribological and mechanical properties of manufactured layers were evaluated. The results of the investigation confirmed that the presented deposition technique makes it possible to manufacture thick and well adherent carbon layers with high hardness and very good tribological parameters. Preliminary investigation results prove the possibility of application of presented technology in automotive industry.     

Novel plasma nitriding-oxidizing duplex treatment of AISI 316 austenitic stainless steel

In this work, plasma nitriding and plasma nitriding-oxidizing treatment have been performed on AISI 316 austenitic stainless steel. In order to evaluate its response to this treatment, their microstructures and wear resistance have been compared with conventional plasma nitrided. The treatment of plasma nitriding was performed at temperature of 450 °C for 5 h with gas mixture of N₂/H₂:1/3 whereas plasma nitriding-oxidizing was performed with the same parameters of plasma nitriding and temperature of 450 °C with gas mixture of O₂/H₂:1/5 for 15, 30 and 60 min. The structural, mechanical and tribological properties were analyzed using XRD, SEM, microhardness testing and pin-on-disk tribotesting. The results showed that oxidation treatment reduces wear resistance of plasma nitrided sample under high loads. Furthermore the tribological evaluation indicates that by increasing the oxidation time further reduction of wear resistance can be occurred. In addition, it was found that oxidation treatment after plasma nitriding provides an important improvement in the friction coefficient against a AISI 52100 steel pin and reduces surface roughness.     

Laser Surface Nitriding of Ti-6A1-4V Titanium Alloy

Titanium and its alloys are known for their high specific strength as well as fatigue and corrosion resistance. However, they suffer from poor wear and friction resistance, limiting their use in tribological applications. Nitriding of these materials may be carried out favourably to harden them and thus to improve both wear and friction resistance. The laser nitriding process involves using the intense energy of the laser to melt the surface in a nitrogen comprising atmosphere. This results in creation of a very hard layer consisting of dendritic structures of nitride. But the non-uniformity of the melt pool and cracks in the nitrided layers have been generally observed. Our study deals with the results of Ti-6Al-4V laser surface nitriding and with the effects of a sample preheating on the cracks generation.     

Tribological property and drilling application of Ti-C:H and Cr-C:H coatings on high-speed steel substrates

This study investigates the tribological properties and cutting performance of Ti-DLC and Cr-DLC doped metal coatings. The tribological properties of the coatings are evaluated by testing coated disks against an AISI 1045 steel counterbody under dry conditions using an oscillating friction wear tester, and then measuring the subsequent wear depth on the coated disk, the wear width on the steel counterbody, and the friction coefficient. The cutting performance of the coatings is evaluated by using coated high-speed drills to machine stainless steel workpieces, and then measuring the resulting flank wear and hole surface roughness. The results of the wear tests show that the Ti-C:H and Ti-C:H/TiC/TiCN/TiN coatings possess excellent tribological properties, including low coefficients of friction, low wear depths, and low wear widths. Regarding the machining tests, the Ti-C:H/TiC/TiCN/TiN coating has the lowest flank wear and yields the highest hole surface quality under both dry and cutting fluid drilling conditions. The single Ti-C:H coating has excellent tribological properties, but demonstrates a relatively poorer performance in the drilling of stainless steel. Finally, the Cr-DLC coatings all exhibit a poor cutting performance under dry cutting conditions.     

镍基复合材料在水环境中的摩擦学性能及磨损机理研究

本文考察了Ni-SiC-石墨系复合材料在水环境中的摩擦学性能,并研究其磨损机理.结果表明:复合材料在水环境中的摩擦系数比干摩擦降低了一半左右,磨损率仅为干摩擦下的1/15,水环境中,负荷和速度的变化对摩擦系数的影响不大,摩擦系数基本保持在0.28～0.32之间,磨损率随负荷和滑动速度的增加而不断增加.磨损表现为机械微切削;摩擦副表面吸附水的边界润滑作用以及水的冷却作用使材料容易耗散摩擦热,塑性变形减小,严重粘着磨损明显减轻.水的存在使不锈钢偶件更容易发生氧化,同时暴露于磨损表面的SiC以及由于水的渗透而导致与基体脱粘的SiC,易被氧化生成SiO2,进而SiO2发生水合反应在磨擦对偶表面生成不均匀的SiO2·nH2O水合反应膜,起到了一定的减磨润滑作用,显著降低摩擦系数和磨损率.     

C/SiC摩擦材料的制备及摩擦磨损性能

通过化学气相渗透法(CVI)结合反应熔体浸渗法(RMI)制备了低成本、高性能的C/SiC飞机摩擦材料, 并模拟飞机正常着陆条件进行了摩擦磨损实验. 实验结果表明: C/SiC是比C/C更优的飞机摩擦材料, 具有动、静摩擦系数高(分别为0.34、0.41), 湿态几乎无衰减(约2.9%), 磨损小(约1.9μm/次), 摩擦性能稳定等特点. 并采用金相显微镜、扫描电镜等对C/SiC摩擦材料的摩擦面以及磨屑形貌进行了观察, 并对其磨损机理进行了探索. 结果表明, 磨损机理以磨粒磨损为主, 同时由于垂直于摩擦面的纤维束增强了其层间抗剪切能力, 从而提高了其抗磨损性能.     

Microstructural and tribological characterization of plasma- and gas-nitrided 2Cr13 steel in vacuum

Plasma- and gas-nitrided 2Cr13 samples were characterized using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and microhardness testing techniques. Nitrogen concentration profiles in the cross-sections of the nitrided samples were obtained by glow discharge optical spectroscopy (GDOS). Residual stress profiles along depth of the nitrided samples were measured using an X-ray stress tester. The tribological behaviour of the plasma- and the gas-nitrided samples in vacuum was investigated in order to analyse the effect of nitriding on wear resistance of the 2Cr13 steel. The results show the tribological properties of the 2Cr13 steel in vacuum are improved considerably by plasma nitriding and gas nitriding resulted from microstructure modification and surface hardening during nitriding. The plasma-nitrided samples have better wear resistance than the gas-nitrided samples under 30 N, while the gas-nitrided samples have higher wear resistance under 90 N. With increasing normal load from 30 N to 90 N, the wear mechanism shows a transition from mild adhesive and abrasive wear to severe adhesive or even delamination wear. The plasma-nitrided sample has thicker compound layer than the gas-nitrided sample, resulting that it exhibits more intensive delamination under high load of 90 N.     

Tribological properties of oxidised boride coatings grown on AISI 4140 steel

In this study, we investigated the wear behaviour of borided and borided + short-duration oxidized AISI 4140 steel. Boronizing was carried out in a slurry salt bath consisting of borax, boric acid and ferro silicon. Also, short-duration oxidizing treatment was applied to borided steel to produce glass-like boron oxide layer. The short-duration oxidizing was performed at 750 °C for 3 min. Optical and scanning electron microscope (SEM) cross-sectional examinations of borided layer revealed a needle-shaped morphology. The presence of non-oxide boride type ceramics FeB and Fe₂B formed on the surface of steel substrate was confirmed by classical metallographic technique and X-ray diffraction (XRD) analysis. The hardness of borides formed on the surface of steel substrate and unborided steel substrate were 1446–1690 HV_0.1 and 280 HV_0.1, respectively. The wear behaviour of borided steel were characterised by using a pin-on-disc technique. The borided and short-duration oxidized steels, in the form of pins were allowed to slide against a hard AISI 440C stainless steel disc (63 HRc). The sliding velocity of 1 m s^− 1 for borided and short-duration oxidized steel and the nominal load on the pin was 20 N. The highest wear rates were observed on disc slide against the base steel, whilst the lowest wear rates occurred during sliding against the borided and short-duration oxidized steel surfaces. It was observed that the friction coefficient of unborided (hardened + tempered) and borided steels ranged from 0.50 to 0.60, but after short-duration oxidizing, the friction coefficient of borided steel was dropped to 0.12.     

梯度自润滑复合材料在不同滑动摩擦下的摩擦学特性

梯度自润滑复合材料是一种新型润滑材料,利用粉末冶金工艺设计和制备了该材料,考察了其在不同摩擦条件下的摩擦学特性,并对其摩擦磨损机理进行了分析和研究.结果表明:梯度自润滑复合材料随着复合固体润滑剂含量的增多,摩擦学性能明显改善,但润滑剂含量过高将导致材料表面硬度过低;该材料适用于高载倚下的润滑部件;脂润滑条件下,复合固体润滑剂与润滑脂结合在摩擦面上形成的膏状润滑膜使梯度自润滑复合材料的摩擦学性能显著改善;在脂润滑高载荷条件下,梯度自润滑复合材料的磨损主要发生在磨损初期,之后磨损极小,摩擦系数也趋于减小.     

37CrMoMn钢渗氮处理微观组织与性能研究

对37CrMoMn钢钻杆接头进行气体渗氮处理,采用光学显微镜（OM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）、显微硬度计及磨擦磨损试验研究了渗氮层的显微组织、硬度及耐磨性能。结果表明：渗氮层厚达150μm,氮化形成的ζ-FezN相、ε-F-e3N相和Cr2N相等氮化物增强相,使表面硬度显著增加。渗氮层与基体材料相比摩擦系数显著降低,钻杆接头经过渗氮后,耐磨性提高了8倍。     

Comparative tribological studies of duplex surface treated AISI 1045 steels fabricated by combinations of plasma nitriding and aluminizing

Duplex surface treatments via aluminizing and plasma nitriding were carried out on AISI 1045 steel. A number of work pieces were aluminized and subsequently plasma nitrided (Al–PN) and other work pieces were plasma nitrided and then aluminized (PN–Al). Aluminizing was carried out via pack process at 1123 K for 5 h and plasma nitriding was performed at 823 K for 5 h. The fabricated steels were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and microhardness testing. Tribological behaviors of the duplex treated AISI 1045 steels were examined against tungsten carbide pin using a pin-on-disc apparatus at room temperature. The PN–Al specimen showed higher surface hardness, lower wear rate and coefficient of friction than the Al–PN one. It was noticed from the worn surfaces that tribo-oxidation plays an important role in wear behavior of both specimens.     

Sliding behaviour of nanophased AISI M2 tool steel obtained by mechanomaking and hot isostatic pressing

Abstract

The friction and wear behaviour of a nanophased AISI grade M2 tool steel was studied under dry sliding conditions and compared with that of a conventional AISI M2 steel. The nanocrystalline steel was produced by mechanosynthesis followed by cold and hot isostatic pressing. Slider-on-cylinder tests were performed against a ceramic coated countermaterial under loads of 10, 20, and 30 N and sliding speeds of 0.3 and 1.2 m s^-1 up to 10 km sliding distance. The nanocrystalline material underwent mild wear with low coefficient of friction under all testing conditions. The commercial M2 steel displayed distance dependent transitions from a regime of mild wear with low coefficient of friction, to a regime of severe wear with high coefficient of friction. The first tribological regime was due to the formation of a layer of iron oxides on the worn surfaces. In this regime, the wear resistance of both steels is mainly dominated by the mechanical properties of the carbides which have high load carrying capability. The second tribological regime, observed in the commercial steel, was due to the formation of cracks both on the mechanically mixed layer and at a depth beneath this layer, which also led to the detachment of carbides from the matrix. This abrasive ‘third body’ produced high wear damage of the commercial steel under high applied loads.