不同润滑介质下GCr15/45#钢摩擦磨损特性的研究

利用DELTALAB-NENEDS20型高精度液压式微动试验机在干摩擦、水润滑和油润滑等条件下，对GCr15／45#钢进行了微动磨损实验，研究了润滑条件对GCr15／45#钢对摩时的摩擦学性能的影响，并利用激光共焦显微镜对45#钢的磨损表面进行了观察和分析。结果表明润滑介质可以降低摩擦副摩擦因数和45#钢的磨损量；材料的磨损机制也随着润滑条件的不同发生了相应的变化。     

波箔气体轴承MoS2基润滑涂层的制备和性能研究

为了提高波箔轴承的耐磨减摩性能,采用喷涂法在平箔片和圆盘试样上制备MoS_2固体润滑涂层,并对圆盘试样涂层结合强度进行分析;采用自制球盘摩擦磨损试验机研究涂层圆盘试样的摩擦磨损性能,通过扫描电镜(SEM)测试涂层圆盘试样摩擦磨损前后表面、截面形貌,利用波箔轴承性能测试实验台探究涂层在实际工作中的耐磨减摩性能。研究结果表明:基体表面的粗糙度影响MoS_2涂层的结合强度,其中试样表面进行喷砂处理后与MoS_2涂层结合力最好;制备的MoS_2固体润滑涂层中各成分均匀分布,涂层的结合方式以机械结合为主;球盘摩擦磨损试验表明,制备的MoS_2涂层的耐磨减摩性能较好,其平均摩擦因数相比不锈钢基体降低了54.5%左右,磨损量相对减小了40.7%;波箔轴承台架试验表明,制备的MoS_2涂层减摩性能已接近商用PTFE涂层,但其耐磨性能较差。     

偶件表面粗糙度对PTFE密封材料摩擦磨损性能的影响

在干摩擦和油润滑条件下,采用MRH-3型高速环块摩擦磨损试验机研究不同粗糙度的45#钢环对PTFE摩擦副摩擦磨损性能的影响,借助白光干涉仪和SEM分析不同试环粗糙度下PTFE磨损后的表面形貌,结合油缸和密封件的工况分析油缸内壁粗糙度对密封材料磨损的原因和机制。结果表明:45#钢环表面粗糙度存在一个最佳的范围,在此范围内摩擦因数均较小;在干摩擦条件下,钢环表面粗糙度过高或过低时,PTFE磨损率均比较大,在油润滑条件下,PTFE磨损率一般随钢环表面粗糙度的增大而升高;粗糙度较大时,PTFE的损伤以犁沟损伤为主。     

在不同润滑油下齿轮锻造材料摩擦特性研究

采用销-盘摩擦副接触方式在不同流体润滑及载荷下,对齿轮锻造用SCr420H合金结构钢进行摩擦试验.采用齿轮油、石蜡油以及加工润滑油润滑.利用在不同润滑及载荷下随速度变化的摩擦因数变化曲线图分析摩擦材料表面摩擦特性.利用Stribeck曲线和摩擦表面形貌SEM照片分析在不同润滑油及载荷下的摩擦状态和摩擦行为.结果表明:SCr420H合金结构钢在最低动黏度的石蜡油润滑下摩擦因数最高,且随速度增大而减少;在齿轮油和加工润滑油润滑下,最低载荷时具有最高的摩擦因数,但摩擦因数随载荷增大而减少,速度对摩擦因数影响不大;在齿轮油和加工润滑油润滑下摩擦副处于流体润滑状态,在石蜡油润滑下显示临界润滑摩擦状态.     

一种水基切削液的电控摩擦性能

在改进的球盘式摩擦磨损试验机上，采用辅助电极的加压方法，考察了不同极性、不同幅值的电压对一种水基切削液润滑的GCr15／45钢副摩擦系统摩擦磨损性能的影响。结果表明该水基切削液具有较好的电控摩擦性能。外加电压的极性和幅值对摩擦副电摩擦性能有明显的影响，其作用效果主要取决于系统电化学反应形成的边界膜的性质。     

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。     

溅射沉积MoS_2/Sb_2O_3复合润滑膜的摩擦磨损过程与失效分析

采用UMT-2型球-盘摩擦磨损试验机研究溅射沉积MoS2/Sb2O3复合固体润滑膜的滑动摩擦磨损寿命,采用显微镜分析球-盘摩擦副在不同磨损阶段的磨损形貌与磨损状况,并对磨痕位置S、Mo元素进行XPS分析。结果表明:在摩擦磨损寿命试验过程中,摩擦副的接触方式最开始的点接触逐步过渡到面接触;MoS2固体润滑膜对滑动摩擦副的延寿作用是基底材料表面的有效厚度润滑膜及MoS2对摩擦偶件(钢球)的转移;机械磨损的剪切剥离效应是润滑失效的主要原因,MoS2的氧化在一定程度上加剧了润滑失效的进程。     

聚氨酯和聚四氟乙烯的摩擦磨损性能试验研究

为提高现代密封行业中广泛应用的新型聚氨酯(PU)和聚四氟乙烯(PTFE)的密封性能,对其润湿性和摩擦磨损性能进行对比实验,并分析不同摩擦状态下的磨损性能,讨论接触压力和转速的影响。研究表明,聚氨酯的润湿性比聚四氟乙烯好;聚氨酯的耐磨性明显高于聚四氟乙烯,在干摩擦、滴油润滑和浸油润滑的试验条件下,聚氨酯都无明显磨损。干摩擦条件下,聚四氟乙烯的磨损主要受摩擦环转速的影响;滴油润滑条件下,摩擦环转速和接触压力对聚四氟乙烯的磨损都有一定影响;浸油润滑条件下,聚四氟乙烯的磨损主要受接触压力的影响。     

熔渗型宽温域复合固体润滑剂设计及其摩擦学性能研究

设计一种可用于300~800℃宽温度范围润滑的熔渗型Pb-Sn-Ag-RE复合固体润滑剂。基于润湿试验研究不同组分与配比对其润湿性能的影响;采用高频感应熔渗工艺,制备出熔渗型高温自润滑复合材料;利用XP-5型高温摩擦磨损试验机考察其摩擦磨损性能,运用扫描电子显微镜(SEM)和X射线衍射仪(XRD)分析磨损表面形貌、成分及结构。结果表明:不同组分组成对基体的润湿性有很大的影响,在Pb-Sn系固体润滑剂中添加Ag、RE既能提高其对母材的润湿性能,又能改善自润滑材料的摩擦磨损性能;熔渗Pb-Sn-Ag-RE复合固体润滑剂制备的复合材料具有良好的高温自润滑性能,其600℃下的平均摩擦因数约为0.28。     

船用内燃机轴瓦表面含MoS2的PAI/PTFE聚合物复合涂层制备及减摩抗磨研究

船用内燃机中轴瓦及曲轴工作时接触界面受力复杂，若润滑不当极易造成轴颈的黏着、擦伤、裂纹等。为改善船用内燃机轴瓦的使用寿命，在轴瓦表面制备聚酰胺酰亚胺和聚四氟乙烯（PAI/PTFE）聚合物涂层，并探讨MoS2颗粒对PAI/PTFE复合涂层摩擦性能的影响。通过喷涂-烧结法在轴瓦材料铝锡铜合金表面制备不同MoS2质量分数的复合涂层，并以轴承钢球作为摩擦配副，在3、4、5 N载荷以及干摩擦和油润滑下考察复合涂层的摩擦学性能。结果表明：在干摩擦下，MoS2质量分数为2%的复合涂层摩擦因数降低了80%以上，磨损降低了90%以上；油润滑下摩擦因数最大降低了67%。SEM和EDS分析表明，5 N载荷下，MoS2质量分数低于2%时，长时间摩擦会导致复合涂层破裂，进而产生大的摩擦磨损；而含有2% MoS2的涂层会在钢球接触表面上产生均匀的硫化物层，可以保护涂层提高其稳定性。通过对不同MoS2含量涂层的摩擦因数、磨损及磨痕形貌对比，得出较优的涂层配比。研究表明，适量的MoS2能够提高涂层摩擦膜的稳定性，减小摩擦磨损。     

Tribological performance of pullulan additives in water-based lubricant

Water can be used as an ecological lubricant base if the water-based additives are properly developed to modify its tribological properties. Additionally, those additives should be friend both to human and nature. Pullulan is a naturally occurring polysaccharide, which is biodegradable and non-toxic and widely used in food and nonfood applications. We focus here on understanding the lubrication properties of pullulan, in aqueous solution in absence and presence of sodium salts. Lubrication is studied using a ball-on-disk tribometer with steel–steel surfaces and the friction coefficient and wear are measured in the boundary lubrication regimes. The adsorption of pullulan molecules onto steel surface is determined by measuring wettability of friction couples. It was found that the addition of pullulan improves the lubricating properties of water. The lubricating performance of Pullulan solution could be further improved if sodium chloride or sodium fluoride is added. The tribological results obtained were correlated with the adsorption capacity of pullulan molecules onto steel surface.     

Sliding velocity dependency of the friction coefficient of Si-containing diamond-like carbon film under oil lubricated condition

In this study we investigated the sliding velocity dependency of the coefficient of friction for a Si-containing diamond-like carbon (DLC-Si) film in an automatic transmission fluid (ATF) under a wide range of contact pressures. The DLC-Si film and a nitrided steel with a surface roughness, Rz_JIS, of around 3.0 μm were used as disk specimens. A high-carbon chromium steel (JIS-SUJ2) bearing ball was used as a ball specimen. Friction tests were conducted using a ball-on-disk friction apparatus under a wide range of sliding velocites (0.1-2.0 m/s) and contact pressures (P_max: 0.42-3.61 GPa) in ATF. The friction coefficients for the nitrided steel had a tendency to decrease with an increase in sliding veloicity under all the contact pressure conditions; however, the friction coefficients for the DLC-Si film were stable with respect to sliding velocities under all the contatct pressures. These results indicate that the DLC-Si film suppresses the stick-slip motion during sliding againt steel in ATF, which is a desired frictional characteristic for the electromagnetic clutch disks used under lubrication. Furthermore, the DLC-Si film showed a higher wear resistance and lower aggression on the steel ball specimen than the nitrided steel. There were less hydrodynamic effects on the friction coefficient for the DLC-Si film possibly due to maintenance of the initial surface roughness and its poorer wettability with the fluid. X-ray photoelectron spectroscopy (XPS) analysis of the sliding surfaces revealed that the adsorption film derived from the succinimide on the sliding surfaces of the DLC-Si film and the mating steel ball also contributed to the sufficient and less sliding-velocity-dependant friction coefficients.     

Friction Properties of Medical Metallic Alloys on Soft Tissue–Mimicking Poly(Vinyl Alcohol) Hydrogel Biomodel

In order to investigate the tribological behavior of medical devices in contact with tissue, friction tests for four kinds of medical metallic alloys (316L stainless steel, CoCr, NiTi and TiMoSn) on soft tissue–mimicking poly(vinyl alcohol) hydrogel (PVA-H) biomodel were carried out at low normal load. XPS analysis and wettability tests for them were prepared to understand the difference in friction. According to the surface oxide compositions, these alloys can be divided into two groups: “Fe/Cr-oxide-surface alloys” for 316L and CoCr, and “Ti-oxide-surface alloys” for NiTi and TiMoSn. From the wettability test, Fe/Cr-oxide-surface alloys show lower polar components of surface free energy than Ti-oxide-surface alloys. Fe/Cr-oxide-surface alloys show higher friction coefficients in the elastic friction domain than those of Ti-oxide-surface alloys, while there was no significant difference in the hydrodynamic lubrication. Since elastic friction is governed by the adsorption of hydrogel polymer on counterbody, the surface characteristic of alloys plays an important role in friction. A tentative explanation for this tendency is expressed by linking two different theories describing the adsorption force of hydrogel and wettability of countermaterial.     

Albumin and fibronectin protein adsorption on CO2-laser-modified biograde stainless steel

The surface properties of a biomaterial play an essential role in protein adsorption, which in turn determines the cellular response to the adsorbed surface. In order to obtain a surface that would yield favourable protein adsorption for successful cellular response, the surface properties of a biograde stainless steel were modified by CO2 laser treatment. An investigation of the CO2-laser-modified surface properties and the effects thereof on the adsorption of human serum albumin (no-cell adhesive) and human plasma fibronectin (cell adhesive) was conducted. It was found that the thickness of the adsorbed fibronectin layer increased with increasing CO2 laser power density, while the thickness of the adsorbed albumin layer decreased with increasing CO2 laser power density. The surface roughness and wettability characteristics contributed to the observed changes in protein adsorption. The wettability characteristics of the biograde stainless steel were found to be the predominant mechanism governing the observed change in protein adsorption. Since the wettability characteristics of the biograde stainless steel can be modified in an efficient and controllable way with the CO2 laser, it is believed that this work presents a demonstrable alternative to the techniques currently available for enhancing the biocompatibility of biograde stainless steels.     

往复冲击对脂润滑成膜性能影响的试验研究

冲击现象广泛存在于工业链、滚动轴承等机械零部件中,严重的情况下会引起冲击磨损。为探究冲击载荷对脂润滑条件下成膜性能的影响,在点接触光干涉弹流试验台上对锂基脂润滑条件下的膜厚演化进行冲击试验研究。试验时钢球和玻璃盘的初始间隙设置为0,冲击载荷按三角波往复变化。结果发现：在第一个冲击周期内,接触区存在大块的增稠剂纤维团,该纤维团造成接触区内的脂膜凹陷;随着冲击周期的增加,接触区内的大块增稠剂纤维团消失,脂膜厚度逐渐降低,润滑状态进入到薄膜润滑状态,最后发生了表面损伤;在任何一个冲击周期内,中心膜厚和最小膜厚大部分的时间都呈现固定值;中心膜厚随着冲击周期数的增加而减小,最小膜厚在最初的100个周期内变化很小,此后逐渐降低,最后为0。     

The lubricant retaining effect of micro-dimples on the sliding surface of PDMS

The frictional behavior of elastomers is characterized by compliance of asperities, special surface chemistry, and wetting properties. The objective of this paper is to investigate the coupled influence of surface texture and wettability on the lubrication of an elastomer contact. Patterns of micro-dimples were fabricated on disks of a polymer material, PDMS. An oxygen plasma treatment was used to hydrophilize the disk surfaces. Friction tests of the disks sliding against a spherical pin of PDMS were carried out. The experimental results indicate that the effect of surface texture is different for PDMS with different wetting properties.     

A Theoretical Study of Vapor Lubrication for Heat Assisted Magnetic Recording

Heat assisted magnetic recording (HAMR) is a promising technique to overcome the superparamagnetic limit to further increase the areal recording density of hard disk drives. However, HAMR brings about serious problems to the slider-disk interface, such as lubricant depletion on disk surface caused by laser heating. It is proposed to overcome the lubricant depletion problem by using vapor lubrication. The lubricant film formation process on disk surface in vapor lubrication is studied theoretically based on fundamental adsorption and desorption theories. The controlling parameters of lubricant film thickness and film formation time are identified. It is found that the lubricant film thickness is controlled mainly by lubricant vapor pressure and molecular weight. The film formation time can be shortened by using low molecular weight lubricant and high temperature lubricant vapor.     

On the effort to discriminate the principal function of tribofilm on friction under the boundary lubrication condition

Friction coefficient under boundary lubrication conditions is affected by many factors. In order to study the friction characteristic of tribofilm, friction coefficient of tribofilm formed on steel disk under the boundary lubrication conditions was separately measured under dry condition using a laboratory-made micro-tribometer to eliminate the hydrodynamic lubrication action of fluid. This paper introduces the approaching method to understand the friction characteristic of tribofilm. In this paper, sliding speed dependency of friction exerted by tribofilm was observed that could not be interpreted by the classical boundary lubrication mechanisms. The additives having long alkyl chain showed strong sliding speed dependency of friction.     

Tribological properties of Fe7Mo6-based-alloy lubricated with poly-alpha-olefin containing PN additive

Tribological properties of Fe–Mo type disk specimens were investigated against ASTM 52100 steel balls under the lubrication of poly-alpha-olefin (PAO) and PAO containing 1.5 mass% alkyl-phosphonic acid-triazole-methanamine (PN additive). Both the Fe₇Mo₆-based alloy and Mo disk specimens exhibited lower friction and lower wear rates than the Fe and gray cast iron disk specimens under the lubrication of PAO. The friction coefficients of the Fe₇Mo₆-based alloy disk specimens were reduced to 0.07 by adding 1.5 mass% PN additive to PAO. No wear volume loss was observed on the Fe₇Mo₆-based alloy disk specimens when they were lubricated with PAO containing 1.5 mass% PN additive.     

Studying microprofile of surface of steel disc that operates in various friction units in a pair with MK-5 metal-ceramic frictional material

Results of studying the roughness of the working surface of a steel disk that operates in a pair with a copper-based metal-ceramic frictional layer under film lubrication are presented. The dependence of the root-mean-square roughness on the duration of operation in the steady wear mode is obtained. The microstructure of the 65G steel is identified at various values of the hardness and the dependence of the ultimate strength on the hardness is obtained. Recommendations on selecting rough surfaces and mechanical characteristics of the 65G steel for operation in a pair with the MK-5 metal-ceramic material are given.