The repeatability of friction and wear results obtained from unlubricated reciprocating sliding tests

Laboratory tests can help in the analysis of tribological failures of elements, and improve tribo‐systems by choosing appropriate materials. In order to characterise the friction and wear behaviour of candidate materials, various different test methods have been developed in the past and are still in use. One such method is the reciprocating sliding of a ball against a disc. In the work reported here, the repeatability of friction and wear results was evaluated with ten tests under identical conditions with a steel (100Cr6) or alumina (Al₂O₃) ball against a steel (100Cr6) disc under unlubricated conditions at room temperature. The influence of ambient humidity on friction and wear behaviour was determined in three additional tests in dry and in moist air, respectively. The repeatability of friction coefficient in normal air was better than 5% for alumina/100Cr6 and 12% for 100Cr6/100Cr6, while the repeatability of volumetric wear was slightly better than 10% for alumina/steel, and slightly worse than 10% for steel/steel. For both couples the coefficient of friction is lowest in moist air and about 50% higher in dry air. The coefficient of wear is also least in moist air and higher by a factor of 3(5) in dry air for tests with a 100Cr6 (alumina) ball.     

Tribological characterization of thin hard coatings by reciprocating sliding tests

Thin hard coatings on metal or ceramic surfaces offer a large spectrum of improvements of the friction and/or wear behaviour of tribosystems. The development of coatings and the tailoring of their properties require test methods providing information about their friction and wear behaviour. A new wear test standard (ASTM) is under development for the evaluation of friction and wear quantities for sliding motions using the reciprocating sliding mode. The applicability of this test method to coated specimens was checked by testing uncoated and coated steel specimens in contact with alumina balls, whereby lower loads were used than in the ASTM proposal for bulk materials. Additionally, the influence of the relative humidity of the surrounding air at room temperature on friction and wear results was examined.     

Al2O3增强粉末冶金铜基摩擦材料摩擦磨损性能研究

为提高铜基粉末冶金摩擦材料的耐磨性及制动效果,使用粉末冶金法（PM）制备氧化铝增强铜基摩擦材料,采用布氏硬度计、扫描电子显微镜（SEM）、能量色散光谱仪（EDS）等测试手段以及摩擦磨损实验,研究氧化铝的掺杂对摩擦材料微观组织和摩擦行为的影响。结果表明：在制备的铜基摩擦材料中,氧化铝硬质颗粒在铜基体中分布均匀,由于硬质相的存在所形成位错钉扎效应对复合材料的硬度有大幅的提升,而对材料的密度有一定的消极作用。摩擦实验结果显示,氧化铝可以提高材料的摩擦因数并增强其耐磨性;且随着载荷的增大Al2O3-Cu复合材料的摩擦因数较高且稳定性较好,磨损率有明显的降低,表明氧化铝的掺杂对铜基材料有显著的增强效果。通过光学显微镜以及EDS分析得出,Cu基材料的主要磨损机制为氧化磨损和黏着磨损,而Al2O3-Cu材料的磨损机制为氧化磨损和磨粒磨损组成的混合磨损。     

聚苯酯填充聚四氟乙烯基超声电机转子摩擦材料性能研究

制备聚苯酯填充聚四氟乙烯基超声电机转子摩擦材料,探讨聚苯酯含量对聚四氟乙烯基摩擦材料力学和摩擦学性能以及对应超声电机性能的影响。结果表明:聚苯酯能够提高PTFE复合材料的硬度和弹性模量;随着聚苯酯含量的增加,复合材料的摩擦因数和磨损量均先减小后增大,在本文研究范围内,当聚苯脂质量分数为5%时,复合材料的摩擦因数最小,磨损量最低,且使用该复合材料时超声电机的堵转力矩和空载转速均较高,综合性能较优。     

聚四氟乙烯基超声电机转子摩擦材料性能研究

制备聚苯酯、碳化硅微粉及玻璃纤维填充聚四氟乙烯基超声电机转子摩擦材料,研究填充剂对复合材料力学、摩擦学性能及超声电机机械特性的影响。结果表明:POB、玻璃纤维、碳化硅微粉均能提高PTFE复合材料的硬度、弹性模量和耐磨性。在本文研究的范围内,质量分数20%玻璃纤维填充的聚四氟乙烯复合材料具有较低的摩擦因数和磨损率,使用该复合材料时超声电机具有较低的堵转力矩和较高的空载转速,且运行稳定,噪声较低。     

Tribological behaviour of DLC coatings compared to different materials used in hip joint prostheses

The goal of the study carried out in the laboratory was to quantify the wear and the friction of two materials used for the manufacturing of hip prostheses. Tests used had to obtain in a short time the tribological behaviour laws of the materials. Tests on a hip simulator have been excluded because their cost and their duration were too high for a program of preliminary development of new materials.

To amplify wear phenomena, dry friction tests were carried out for two configurations: ball-on-disc and pin-on-disc. The influence of the contact pressure at constant sliding velocity on the wear of materials has been clearly shown.

Results obtained with several different tested materials (stainless steel/UHMWPE, stainless steel+DLC coating/UHMWPE, stainless steel+DLC coating/stainless steel+DLC coating, titanium alloy+DLC coating/UHMWPE, titanium alloy+DLC coating/titanium alloy+DLC coating, zirconium dioxide/UHMWPE, alumina/UHMWPE, alumina/alumina) have shown the superiority of DLC coatings. Promising results obtained during this study are in the validation stage on a hip simulator.     

超声电机宽温域低损耗压电与摩擦功能材料

为了提高超声电机的环境适应性与能量转换效率,本文分析并制造了宽温域低损耗的新型压电材料与摩擦功能材料,提出了通过相结构调控、增加第三组元、引入偶极子缺陷钉扎畴壁等手段制备宽温域低损耗压电陶瓷材料的设计与制造方法;为了提高超声电机摩擦界面能量传递效率及环境适应性,设计了具有高摩擦系数、低磨损率且耐高温的聚酰亚胺复合材料。结果表明,与传统材料相比,新型压电陶瓷材料具有低介电损耗、高机械品质因数及高温度稳定性的优势,使超声电机的能量转换效率提高3.3%,而新型聚酰亚胺基摩擦材料在摩擦系数、耐磨性以及温度范围等指标上均有明显提高,使电机的最大效率提高了6.19%。综合两种新型材料后,超声电机的最大效率提升了13.6%,可靠工作温度从-40~70℃提升至-60~120℃。本文提出的压电与摩擦功能材料既增强了超声电机的环境适应性,也改善了电机输出性能,对超声电机在航空航天等高端装备中的应用具有重要的意义。     

Effect of Temperature on the Dry Sliding Friction and Wear of Rice Bran Ceramics against Different Counterpart Materials

In this study, we investigated the effect of temperature on the friction and wear of rice bran (RB) ceramics, a hard porous carbon material made from rice bran, sliding against alumina, stainless steel, and bearing steel balls under dry conditions. Friction tests were performed using a ball-on-disk-type friction tester wherein a ceramic heater was installed in the rotational stage. The surface temperature of the RB ceramic disk specimens was controlled at 20, 100, 150, or 200°C. The normal load was 1.96 N, sliding velocity was 0.1 m/s, and number of cycles was 20,000. The effect of surface temperature on the friction and wear of RB ceramics substantially differed among the ball material types. The friction coefficient for the RB ceramics sliding against an alumina ball decreased with increasing temperature and exhibited an extremely low value (0.045) at 200°C. The friction coefficient in the case of the RB ceramics sliding against a stainless steel ball exhibited a stable value as the temperature was increased to 150°C and slightly decreased as the temperature was increased further, reaching a low value of 0.122 at 200°C. The friction coefficient for the RB ceramics sliding against bearing steel ball drastically increased with increasing temperature, reaching 0.381 at 200°C. The specific wear rate of the RB ceramics increased with increasing temperature; it was lowest when sliding against alumina and highest when sliding against bearing steel. The wear of the alumina ball was the lowest and that of the bearing steel ball was the highest under all investigated temperature conditions. On the basis of these results, we concluded that alumina is a promising counterpart material for RB ceramics sliding at high temperatures (≤200°C).     

水润滑下316L不锈钢与聚醚醚酮摩擦磨损性能研究

为了寻找适合于水液压泵/马达的摩擦副材料,以316 L不锈钢与纯聚醚醚酮树脂、30%玻璃纤维增强PEEK(PEEKGF30)、30%碳纤维增强PEEK(PEEKCA30),PTFE和石墨及碳纤维填充PEEK(PEEKHPV)组成的摩擦副为研究对象,利用MMW-1立式万能摩擦磨损试验机测量摩擦副在水润滑下接触表面的摩擦因数和温度以及试样的磨损量,并通过激光共聚焦显微镜对试件表面磨损形貌进行分析。结果表明:316 L-PEEKHPV摩擦副的摩擦因数、摩擦温升、磨损量均小于其余3组摩擦副,适合作为水液压泵/马达的关键摩擦副材料。316 L不锈钢与PEEKGF30配对时,摩擦机制为涂抹和擦伤,磨损较为严重;与PEEKCA30配对时,摩擦机制为擦伤;与PEEKHPV配对时摩擦机制主要为划伤,磨损较为轻微。     

干摩擦工况下Si3N4/PTFE配副材料摩擦磨损特性与转移膜形成分析

为使全陶瓷轴承在干摩擦工况下可靠运转,选用四氟乙烯(PTFE)材质的保持架为全陶瓷轴承提供润滑.利用Rtec销/盘摩擦磨损试验机,以PTFE盘与氮化硅(Si3 N4)销为摩擦副,研究Si3 N4/PTFE在不同载荷和转速条件下的摩擦磨损性能,通过SEM对Si3 N4表面的转移膜形貌进行观察,分析转移膜形成原因.结果表明...     

Influence of test parameters on friction and wear results obtained in oscillating sliding tests with 100cr6 steel against sic‐based materials

In order to characterise materials for tribological applications, model tests with simple contact geometry are in widespread use. Friction and wear behaviour can be determined with high accuracy from this type of test. Tests with oscillating sliding motion have the advantage that only small‐sized specimens are required. However, the fact that the results of model tests are affected considerably by the choice of test parameters is often overlooked. In order to check the influence of test parameters on friction and wear results, tests were performed in which the relevant parameters (stroke, frequency, load, relative humidity of the surrounding air) were varied. Comparative studies with different SiC‐based materials (SiC, SiSiC, and SiC‐TiC) against steel (100Cr6) under unlubricated conditions at room temperature show that in all cases the relative humidity is an important parameter, influencing the friction and wear results substantially. Additionally, several parameters can modify friction and wear behaviour more or less significantly. The effects of test parameters on friction and wear are discussed here on the basis of the wear mechanism. Some of the consequences of this for planning test series and for the practical use of test results are noted.     

Influence of Temperature and Relative Humidity on the Friction and Wear of Unlubricated Reciprocating Sliding Steel/ Steel Couples

Many tribosystems are subjected to different conditions with respect to temperature and humidity. Reciprocating sliding tests with steel/steel couples were performed using a laboratory test rig in air with varying relative humidity and temperature. During each test the friction force, the total linear wear, the electrical contact resistance, and the acoustic emission were recorded. Tests with self‐mated couples of bearing steel (100r6) and of stainless steel (X10CrNiMoNb18‐10/X5CrNi18‐9) in a ball‐on‐disc arrangement revealed small effects of temperature and humidity on friction, but a strong effect of the water vapour content on the wear rate of the system. Attempts were made to correlate changes of wear behaviour with different wear mechanisms.     

多因素影响的格莱圈材料摩擦磨损试验研究*

格莱圈由聚四氟乙烯(PTFE)矩形滑环和丁腈橡胶(NBR)O形圈组成。为了研究不同因素对于格莱圈密封材料摩擦磨损性能的影响,利用UMT-3多功能摩擦磨损试验机,通过改变往复频率、粗糙度、润滑状态研究格莱圈材料与45钢配副时的摩擦磨损性能,利用SEM对试块试验前后表面形貌进行观测,并对摩擦磨损机制进行分析。试验结果表明:在干摩擦和滴油润滑条件下PTFE材料相比NBR材料具有更为优异的摩擦磨损性能;NBR材料表面粗糙度过高或过低都会导致摩擦因数升高,表面粗糙度对具有自润滑性能的PTFE材料的摩擦因数影响不大;高往复频率会使NBR材料摩擦因数降低,过高或过低的往复频率都会使PTFE材料摩擦因数降低;NBR材料的磨损形式以磨粒磨损和黏着磨损为主,PTFE材料以黏着磨损和疲劳磨损为主。     

超声振动对不同黏度润滑油摩擦学性能的影响

研究GCr15/45#钢摩擦副在4种不同黏度的润滑油润滑时,有和无超声振动下的摩擦磨损性能,采用扫描电子显微镜分析磨痕表面形貌,探讨在不同黏度润滑油作用下,超声振动对润滑油摩擦学性能的影响机制。结果表明:超声振动对不同黏度润滑油摩擦学性能的影响是不同的;超声振动可以提高低黏度润滑油润滑的减摩抗磨性能,如在6#白油润滑时施加超声振动后,摩擦副间的摩擦因数和磨损体积分别减小了13.6%和17.5%;高黏度润滑油润滑时,超声振动会加剧摩擦副的摩擦磨损,如在150BS润滑时施加超声振动后,摩擦副间的摩擦因数和磨损体积分别增加了10.4%和50%。     

对偶材料对树脂基摩擦材料摩擦磨损性能的影响

分别以45#钢、铍青铜、碳化硅颗粒基体改性铍青铜、氧化铝涂层为对偶材料与同一种树脂基摩擦材料在MM1000-II型摩擦磨损试验机上进行干式摩擦磨损试验,研究对偶材料对树脂基摩擦材料摩擦磨损性能的影响;利用偏光显微镜观察材料磨损后的表面微观形貌。结果表明:氧化铝涂层对偶材料的磨损率最低,摩擦因数适中,但摩擦因数稳定性较差;对偶材料为45#钢时摩擦因数较低,但摩擦因数的稳定系最好;对偶材料为铍青铜时摩擦磨损性能最佳,摩擦因数较高且稳定性较好,铍青铜本身和与之匹配的摩擦材料的磨损率都很低,且摩擦表面均没有形成孔洞和犁沟;改性铍青铜在各方面都表现出较差的性能。     

TiN/Ti涂层在波箔轴承中的摩擦磨损性能

采用真空离子镀的方法在304不锈钢基体上喷涂厚度为3μm的TiN/Ti薄层,利用硬度计、三维形貌仪、划痕试验仪对涂层基本力学性能进行分析,通过球盘试验机分析涂层试样的摩擦磨损性能,根据波箔轴承性能测试实验台的测试结果:研究TiN/Ti涂层对基体表面耐磨减摩性能的影响。研究结果表明:TiN涂层硬度可达HV1500,是基材硬度的5.5倍;TiN/Ti涂层平均摩擦因数为0.23,相对不锈钢304基材的平均摩擦因数0.71,降低了68%,磨损量也仅为基材的18.75%;GCr15与PTFE对磨的最大摩擦力矩可达2.4 N·mm,而TiN/Ti与PTFE对磨的最大摩擦力矩仅为1 N·mm,仅为GCr15的41.7%。TiN/Ti涂层表现出了优异的承载能力和耐磨减摩性能。     

SiC颗粒增强PTFE基复合材料磨损图的研究

研究了SiC颗粒增强PTFE基复合材料(PTFE／SiCp)在干摩擦条件下的磨损特性。对磨损表面进行了观察分析，建立了复合材料磨损机制转变图，对在不同磨损条件下的磨损机制进行了概括。结果表明，SiC颗粒增强PTFE基复合材料发生轻微磨损的主要机制是显微切削，发生严重磨损的主要机制是粘着磨损。     

Effect of Particle Size on the Wear Resistance of Alumina-Filled PTFE Micro- and Nanocomposites

It was long supposed that the ability of hard particle fillers to reduce the wear rate of unfilled PTFE (typically ～ 10^{? 3} mm ³ /Nm) by an order of magnitude or more was limited to fillers of microscale or greater, as nano-fillers would likely be encapsulated within the large microscale PTFE wear debris rather than disrupting the wear mechanism. Recent studies have demonstrated that nano-fillers can be more effective than microscale fillers in reducing wear rate while maintaining a low coefficient of friction. This study attempts to further elucidate the mechanisms leading to improved wear resistance via a thorough study of the effects of particle size. When filled to a 5% mass fraction, 40- and 80-nm alumina particles reduced the PTFE wear rate to a ～ 10^?7 mm ³ /Nm level, two orders of magnitude better than the ～ 10^?5 mm ³ /Nm level with alumina micro-fillers at sizes ranging from 0.5 to 20 μm. Composites with alumina filler in the form of nanoparticles were less abrasive to the mating steel (stainless 304) countersurfaces than those with microparticles, despite the filler being of the same material. In PTFE containing a mixture of both nano- and micro-fillers, the higher wear rate microcomposite behavior predominated, likely the result of the continued presence of micro-fillers and their abrasion of the countersurface as well as any overlying beneficial transfer films. Despite demonstrating such a large effect on the wear rate, the variation of alumina filler size did not demonstrate any significant effect on the friction coefficient, with values for all composites tested additionally falling near the μ = 0.18 measured for unfilled PTFE at this study's 0.01 m/s sliding speed.     

Influence from humidity on the alumina friction drive system of an ultrasonic motor

Miniaturized ultrasonic motors, based on piezoelectric movement, are rapidly developing and the number of commercial applications is steadily growing. The details of the friction drive system of these motors still need systematic studies to fully utilize the potential of the technique. The friction drive system transfers the high frequency oscillatory movement from the stator to a drive rail. The friction force should be maximized and stabilized to achieve the best motor performance, while maintaining a low wear rate.The mating parts of a friction drive system typically consist of alumina which is selected due to its relatively low wear rate and relatively high coefficient of friction. With increasing relative humidity, the friction coefficients of alumina ceramics generally decrease.This work examines how water and humidity affect a friction drive system with respect to coefficient of friction and wear of the mating surfaces. Ball-on-disc experiments were used to evaluate the tribological properties. The worn surfaces were studied by scanning electron microscopy.The coefficient of friction was found to be relatively low but stable with water on the surface but higher and more fluctuating in dryer conditions. The character of the worn surfaces did not clearly correlate to the friction behaviour.     

玻璃陶瓷材料与轴承钢表面摩擦磨损的试验研究

在盘销式摩擦磨损试验机上考察了氟金云母玻璃陶瓷与轴承钢的摩擦磨损性能,在不同载荷条件下,测试了摩擦因数和玻璃陶瓷的磨损率,用金相显微镜观察和分析磨损表面形貌,并探讨了玻璃陶瓷材料的磨损机制。结果表明：在低载荷条件下,摩擦因数较低;随着载荷的增加,摩擦副的摩擦因数比较稳定,氟金云母玻璃陶瓷与轴承钢的平均摩擦因数为0.095。玻璃陶瓷和轴承钢的磨损率存在波动,其对磨过程以磨料磨损为主。