自润滑复合材料在小型冷轧机上的试用

用SF-2自润滑三层复合材料制成轴衬替代铸铜轴承,我厂应用在轧制复铝镀镍铁带和纯铝带的小型冷轧机辊颈传动处,取得了节电、节油和节约有色金属的理想效果。 SF-2复合材料是以钢为基体,铜网为中间层,并以填充适量的聚四氟乙烯(PTFE)、铅(Pb)、碳纤维(c-f)经改性的高分子材料聚甲醛(POM)为表面层的边界润滑材料。它具有高的承载能力和抗蠕变性,它使线胀系数降低,导热系数增高,从而提高了轴承的尺寸稳定性和PV极限值。它的抗压强度为2800公斤/厘米~2,摩擦速度在2.5米/秒以下,静摩擦系数0.015～0.15、动摩擦系数在0.01～0.1范围内,连续使用温度为40～100℃,间歇使用温度可达130℃,与金属耦     

速度与载荷对无铅铜铋轴承材料摩擦学特性的影响

采用粉末冶金法制备无铅铜铋双金属轴承材料,并在HDM-20端面摩擦磨损实验机上进行油润滑条件下的摩擦磨损试验,分析速度、载荷对其摩擦学性能的影响。结果表明:摩擦因数随摩擦速度、载荷的增加而减小,其磨损量、摩擦副表面温度均随速度、载荷的增加而增大;摩擦磨损过程中低熔点组元铋的析出起着较好的减摩、抗粘着作用,并存在铋的析出、熔化、磨损脱落的循环过程。     

含FeS铜基双金属轴承材料的摩擦学性能分析

采用传统粉末冶金方法制备含FeS的Cu基双金属轴承材料,并与不含FeS的Cu基双金属轴承材料作对比,在HDM-20端面试验机上进行摩擦磨损性能试验,在光学显微镜下观察分析材料的磨痕。结果表明:在润滑油充足的情况下,含FeS的铜基轴承材料的减摩特性和承载能力均优于不含FeS的铜基材料;在干摩擦的情况下,含FeS的铜基轴承材料的减摩特性明显优于不含FeS的铜基轴承材料。     

铁基金属塑料复合材料及其摩擦磨损性能

金属塑料复合材料是近年来在粉末冶金工艺基础上发展起来的一种新型减摩材料。本文介绍了铁基金属塑料复合材料的制造方法,研究了不同加碳量对基体机械性能的影响及不同载荷下的摩擦磨损性能。试验结果表明,该材料具有较高的机械强度和较好的摩擦磨损性能。当载荷在0-25kgf范围内,其摩擦磨损性能达到DU材料的水平。装车试验结果还表明,它的使用寿命为同类铁基含油轴承的二倍多。     

钛酸钾晶须增强聚苯醚复合材料摩擦学性能

采用熔融共混-传递模压成型方法制备了不同含量钛酸钾晶须（PTW）填充聚苯醚（PPO）共混物,在立式万能磨损试验机上进行摩擦磨损试验,利用扫描电镜观察了磨损表面以探讨材料的磨损机理．研究结果表明,经钛酸钾晶须填充的PPO共混物磨损量有所降低,但摩擦系数随PTW含量增加呈上升趋势,其最佳添加量为10（wt．）％左右．PPO共混物的磨损机制随着PTW含量的增加,从以粘着磨损为主转变为以磨粒磨损为主．     

氟金云母玻璃陶瓷摩擦磨损性能研究

在MPX-2000型摩擦磨损试验机上考察了不同载荷下氟金云母玻璃陶瓷与碳钢对摩时的摩擦磨损性能,用金相显微镜观察和分析磨损表面形貌,测试了摩擦系数和玻璃陶瓷的磨损率,并探讨了材料的磨损机理。结果表明,随着载荷的增加,摩擦副的摩擦系数明显增大,有较大波动。     

Pb在快凝Al-Si基减摩材料中的作用

研究AJ-Si基减摩材料中Pb含量与材料力学性能和摩擦磨损特性的关系，分析了材料的微观组织，结果表明，Pb能够提高减摩性能，改善材料的摩擦磨损特性。     

列车制动用Cu基粉末闸片材料摩擦磨损性能分析

列车的制动性能与闸片材料的摩擦磨损性能关系密切,在MM-1000Ⅱ型摩擦试验机上测试了自制的Cu基粉末列车闸片材料在不同制动速度下的摩擦磨损特性。结果表明:随着制动速度的增大,摩擦表面的微凸起遭到破坏,摩擦因数随之降低,磨损量增加;在材料接触表面产生大量的摩擦热,造成基体软化,减小了基体对材料中SiO_2等硬质颗粒的夹持能力。摩擦因数和稳定系数均随制动速度增加而降低;而摩擦温度和磨损量随制动速度增加而提高,尤其是在制动速度大于8 r/s时,摩擦表面温度上升,造成基体软化,硬质颗粒脱落,加速了材料的摩擦磨损。为列车制动用Cu基粉末闸片材料摩擦磨损性能的研究提供了理论基础。     

真空常温下空间用铜基粉末冶金摩擦材料的摩擦学行为及可靠性寿命

在真空常温下,对空间摩擦副进行大负荷服役条件(400 N)可靠性寿命摩擦循环试验,考察空间用铜基粉末冶金摩擦材料的摩擦磨损特性,探讨摩擦材料的可靠性寿命并揭示其摩擦磨损机理。结果表明:铜基摩擦材料在真空常温大负荷摩擦循环试验条件下,摩擦磨损过程可分成三个阶段:第一阶段(1~1 400次试验),摩擦因数由0.28增加到0.61,并趋于稳定,磨损机理以磨粒磨损为主;第二阶段(1 400~2 700次试验),摩擦因数稳定在0.61左右,磨粒磨损和粘着磨损并存;第三阶段(2 700次试验后),摩擦因数逐渐下降,磨损机理转变为较强的粘着磨损和疲劳磨损,材料表现为失效,整个试验过程中,摩擦因数稳定系数均高于0.9。研究表明,研制的铜基摩擦材料在真空常温条件下可满足转位机构和空间机械臂等的可靠性需求。     

45CrNiMoVA与PCrNiMo配副的摩擦磨损特性

 在自制的销盘式干滑动摩擦磨损实验机上研究了45CrNiMoVA与PCrNiMo配副的摩擦磨损特性。结果表明：材料的磨损率随着速度、载荷的增加而增大;摩擦因数随着载荷增加而减小;随着速度的改变磨损率的变化规律为：减小、增大、再减小;硬度对实验材料磨损率的影响与通常所用材料不同,磨损机理为磨粒磨损和粘着磨损。     

H13模具钢表面激光熔覆Co基合金涂层的组织和性能

采用CO2连续激光器在H13模具钢表面制备Co基合金涂层。利用扫描电镜(SEM)、能谱分析仪(EDS)、显微硬度计和摩擦磨损试验机等设备分析测试了熔覆层的微观组织和性能。结果表明:激光熔覆层与H13钢基材之间呈现良好的冶金结合特征。熔覆层与基材的结合区为粗大柱状晶和细小共晶组织,熔覆层中部呈典型亚共晶组织特征,表层为致密而细小的亚共晶组织。经过激光熔覆处理后,H13钢基材表面硬度和耐磨性得到了显著改善。     

Stress Distribution at PTFE Interface in Cylindrical Bearing

Two analytical methods capable of evaluating stresses at the curved polytetrafluoroethylene (PTFE) metal sliding interface in a cylindrical bearing subjected to combined vertical and horizontal loads are described. One method is based on a finite-element approach incorporating contact elements to model the sliding PTFE∕metal interface, while the other, referred to as the displacement method, is based on an approach that assumes all displacement in the bearing under load is confined to the PTFE. Both methods are shown to give similar results. Basic equations for the displacement method are derived assuming a bilinear stress-displacement relationship for the PTFE, and this method is used to produce design curves for cylindrical bearings, based on criteria relating to prevention of separation of the interface and limitation of maximum stress level in the PTFE under service load. The displacement model shows that the common design practice of assuming linear elastic material behavior and a plane surface is conservative. The design charts presented in this paper provide an effective tool for taking advantage of the extra horizontal load resistance resulting from the bilinear behavior of the PTFE and the curved interface of the bearing.     

GCr15轴承钢表面渗硼层生长动力学与机械性能

对GCr15轴承钢表面渗硼层的生长动力学与机械性能进行了研究.采用固体渗硼的方法,在1123、1173、1223和1323 K温度条件下,分别保温处理2、4、6和8 h,进行渗硼层制备.采用光学显微镜、扫描电镜、X射线衍射仪、维氏硬度计等对制备的渗硼层进行组织观察与性能分析,并通过试验数据对渗硼层的生长动力学特性进行了研究.研究结果表明:试样表面获得了均匀致密的渗硼层,渗硼层的相成分主要是FeB和Fe₂B;渗硼层的厚度随处理温度与保温时间的增加而增厚,变化范围为33.4~318.5 μm;渗硼层的表面硬度随处理温度及保温时间的增加而增大,主要是由于随着渗硼层厚度的增加,高硬度FeB相的含量上升,低硬度Fe₂B相的含量下降,表面硬度HV_0.1变化范围为1630~1950,与基体组织相比,提高了5~6倍;渗层截面硬度测试结果表明,渗层与基体之间有较宽的硬度梯度过渡;通过Arrhenius公式,对渗硼层的生长动力学方程进行了推导,可知B元素在GCr15轴承钢中的扩散激活能为188.595 kJ·mol-1,对推导的动力学方程进行了试验验证,结果表明最大误差仅4.93%,可有效的实现对渗层厚度的预测.      

Vacuum carburization of 12Cr2Ni4A low carbon alloy steel with lanthanum and cerium ion implantation

As bearing parts, 12 Cr2 Ni4 A is expected to have high hardness and excellent fatigue strength, so carburizing is employed to improve the inherit properties of 12 Cr2 Ni4 A. However, the traditional carburizing is limited by poor microstructure distribution and low rate of carburizing. The rare earth ion implantation is known to help improving the properties of tribology, corrosion resistance and oxidation resistance of metal. In this article, the RE implantation is employed to assist the carburizing. Lanthanum and cerium ion implantations are initially used to assist 12 Cr2 Ni4 A low pressure vacuum carburization.The microstructure, content of retained austenite, hardness, thickness of layer and carbon diffusion were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) and Rockwell/Vickers hardness tester, respectively. It was shown that lanthanum and cerium implantations can improve structure of the vacuum carburizing layer, and enhance the uniformity of carbon element distribution on the carburized surface. Meanwhile the RE implantation plays a positive role in promoting the surface hardness and carburized rate. The lanthanum element has more significant effect on surface hardness and content of retained austenite than cerium element. The surface hardness of lanthanum element implanted layer was 62.9 HRC with 9.6% content of retained austenite, while the carburizing rate of cerium implanted layer increased by 12.4%.     

Wear of hard-turned AISI 52100 steel

High-precision machining such as hard turning changes the surface and the material properties of steel alloys. The near-surface material properties have been predicted from the known hard-turning cutting conditions. The effect of the predicted hard-turned surface and material properties on wear performance was analyzed in detail to develop a process-performance model. A sliding block-on-cylinder wear tester was used for the purpose of testing the wear performance of AISI 52100 bearing steel. The microstructure, surface roughness, residual-stress field, and loading conditions from each wear test were used to develop the process-performance model. The effect of microstructure on the wear performance of hard-turned steel showed that the white layer and overtempered martensite (OTM) had a higher wear resistance than martensite. The wear-mechanism dependence on the surface hardness was attributed to this increase in wear performance. The near-surface residual stress of the material was shown to become more compressive as the material wore down. The applied normal loads affected the surface roughness, residual stresses, and, in turn, the wear performance of the material. A process-performance model was developed to predict the wear performance of hard-turned steels, which considers the machining process and the operating conditions in sliding wear.     

Effect of Fluorides and Cerium Dioxide Additives onEP and Antiwear Performance of Grease

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Tensile Properties of Surface-Treated Glass Fiber Reinforced PTFE Composite with Rare Earth Elements

The optimum amount of rare earth elements (RE) for treating glass fiber surface and its effect on the tensile properties of glass fiber reinforced polytetrafluoroethylene (GF/PTFE) composites were investigated. The tensile properties of GF/PTFE composites with different surface treatment conditions were measured. The fracture surface morphologies were observed and analyzed by SEM. The results indicate that rare earth elements can effectively promote the interfacial adhesion between the glass fiber and PTFE, owing to the effects of rare earth elements on the compatibility. The tensile properties of GF/PTFE composites can be improved considerably when the content of RE in surface modifier is 0.2%-0.4%,and the optimum performance of GF/PTFE composites is obtained at 0.3 % RE content.     

渗硼剂粒径对钛合金渗硼层组织和性能的影响

采用不同粒径的碳化硼作为硼源,以氧化铈作为催渗剂,在非惰性气氛保护下对TC4钛合金表面进行固体渗硼。利用场发射扫描电镜(FESEM)、背散射电子成像(EBSD)、X射线衍射(XRD)、UMT摩擦磨损试验机对渗硼层的微观组织结构和摩擦学性能进行研究。结果表明,TC4钛合金表面渗硼层为双相硼化物;随着碳化硼粒径的增加,Ti B层厚度与渗层总厚度减少,渗层硬度约为60(HR30N),硼化物层摩擦系数约为0.2,碳化硼的杂质组成对渗层有较大影响。     

Effect of heat treatment process on impact wear property and mechanism of SKD11 steel

The microstructure, mechanical property, phase of SKD11 steel after vacuum heat treatmentor deep cryogenic heat treatment were studied by means of OM, hardness tester, impact tester and XRD.The impact wear properties of SKD11 steel under the two heat treatments were tested by MLD- 10 dynamic load- bearing wear tester. The impact wear mechanism was also analyzed. The results show that the microstructures of SKD11 steel after the two heat treatmentsare composed of tempering martensite, retained austenite and carbide. The hardness after cryogenic treatment is 1HRC higher than that of the vacuum treatment and impact toughness decreases lightly. Under impact wear conditions, the weight loss of the sample during deep cryogenic treatment is lower than that of the vacuum treatment, which shows better wear resistance. In the studied wear time, the wear mechanism of the sample after vacuum treatment is high stress surface fatigue and abrasive wear, and the wear mechanism of the sample after cryogenic treatment is slight abrasive wear.     

M50NiL钢磨削表面完整性特征及变质层厚度表征方法

通过透射电子显微镜确定了M50NiL钢渗碳后磨削表面变质层厚度,同时利用扫描电子显微镜、原子力显微镜、显微维氏硬度计、X射线残余应力测定仪等设备表征了M50NiL钢磨削表面完整性特征.结果表明:磨削在渗碳硬化层表面构建了一个表面变质层,该变质层组织的基本特征是晶粒细化和变形,在选区电子衍射图上显示为拉长模糊的多晶环;变质层厚度约0.5μm,残余压应力和硬度略有升高,表面应力集中系数较低.