多孔阵列阳极氧化铝膜润滑性能的Stribeck研究

为了研究阳极氧化铝膜的多孔结构对其润滑性能的影响,分别制备了光滑表面氧化铝膜,40 nm孔径、90 nm孔径多孔表面氧化铝膜.用接触角测试仪测试了水、机油与3种表面的接触角;在不同润滑条件下,用摩擦磨损试验机UMT-2测试了3种氧化铝膜与GCrl5钢面接触的润滑性能.结果表明:多孔结构氧化铝膜增强了材料的亲水性能和亲油性能,90 nm孔径氧化铝膜表现出超亲油特征;水润滑和机油润滑条件下,速度从0.016 m/s增至0.32 m/s过程中,光滑氧化铝表面只能形成边界润滑区域,多孔表面得到了包含边界润滑、混合润滑和流体润滑的完整的Stibeck曲线.机油润滑条件下,40 nm孔径的膜达到最小摩擦系数的临界速度为0.28 m/s,最小摩擦系数为0.083,90 nm孔径的膜达到最小摩擦系数的临界速度仅为0.2 m/s,最小摩擦系数减小为0.023;机油润滑条件下,90 nm孔径的氧化铝膜板的Stribeck曲线,谷底区域更宽.     

基于滑动摩擦的摩擦副表面织构优化分析

利用数值计算方法对织构化滑动摩擦副表面的动压润滑模型进行了求解,从理论上分析了表面织构不同截面类型和表面形状对摩擦副的润滑特性的影响,获得了特定工况下的最优织构参数和织构类型。结果表明：表面织构的不同截面类型和表面形状对摩擦副的摩擦系数和承载力有着非常大的影响;各类截面圆形凹坑都存在一个最优织构半径使得摩擦副摩擦系数最低;凹坑底面适当倾斜能够提高织构区域的承载能力和降低摩擦系数;各类典型表面形状中,底边靠近入口的倒三角形获得了最优的润滑性能;将凹坑底面合理倾斜与优化表面形状相结合可使得承载力得到大大提升。     

Comparison of Biotribology of Swine Compact Bone Against UHMWPE

A pin-on-disk tribometer was used, in a comparative test to observe the tribological behavior of the swine femoral bone against UHMWPE with dry friction, physiological water and human plasma lubrication. The wear mechanisms of swine bones and UHMWPE were investigated by SEM. The experimental results of these wear tests demonstrated that both the friction coefficient and wear rate of UHMWPE were the lowest when human plasma lubrication was used. The wear mechanism of the compact bone was mainly fatigue wear with dry friction, corrosive wear under physiological water lubrication and abrasive wear with human plasma lubrication. For UHMWPE, the wear mechanism was adhesive wear and plastic deformation with dry friction, serious ploughing and fatigue fracture wear under physiological water lubrication, fine ploughing and plastic deformation with human plasma lubrication. An analysis of nitrogen elements on the wear surface of UHMWPE indicated that the content of nitrogen in worn areas was 16 times higher than that in unworn areas, which proved that serum protein deposition occurred on worn areas.     

纳米填料增强UHMWPE–橡胶水润滑摩擦学性能

为了研究水润滑条件下试验载荷和速度对纳米填料（Nano-SiC）改性超高分子量聚乙烯（UHMWPE）/橡胶复合材料摩擦学性能的影响,通过高温混炼、热压成型制备Nano-SiC辅以聚四氟乙烯（PTFE）填充改性UHMWPE/橡胶复合材料。采用MRH-3型环-块摩擦实验机探究四种不同载荷条件下改性复合材料的摩擦磨损性能,采用光学显微镜（OM）、扫描电子显微镜（SEM）和非接触光学三维轮廓仪对试样微观磨损表面形貌分析,从微观层面探究改性复合材料的摩擦机理。试验结果表明：在定载变速条件下,速度由0.02m/s升到3.59m/s时,改性复合材料的动摩擦系数波动幅度与静摩擦系数均呈现大幅下降趋势,粘-滑现象（Stick-Slip Phenomenon）减弱,摩擦系数波动归于平稳;试验载荷和纳米粒子含量的变化与试样摩擦磨损程度呈负相关,在水润滑条件下,随着纳米粒子含量增加,摩擦系数与磨损率均出现明显降低,填充比例为5%的复合材料摩擦学性能最佳,摩擦系数整体较UHMWPE/橡胶材料降低35%,磨损率降低46.6%,磨损表面形貌也随之发生改变;随着载荷的增加,复合材料的磨损率从1.25×10-6mm3/(Nm)降至0.4×10-6mm3/(Nm)。Nano-SiC的含量与工况载荷压力对摩擦磨损均存在一定影响,即填充适量Nano-SiC的UHMWPE/橡胶复合材料与一定工况压力下的对偶钢环组成的摩擦配副能改善摩擦环境,减轻粘-滑现象,有利于减小材料的磨损。     

Simulations on various lubrication boundaries between diamond-like carbon films

Molecular dynamics (MD) simulations were used to study a sliding friction process between DLC films on various boundary conditions. The experimental results revealed that, in the absence of a lubricant, a transfer film between the DLC films was formed. In contrast, when the oil or water lubricants were added to lubricate between the DLC films, a boundary lubrication layer was found. The friction forces on the water and oil lubrication were almost the same, but the friction force in the absence of a lubricant was larger than those on the water and oil lubrication. The conclusions were in good agreement with the experiments.     

Friction properties of OTS SAMs and silicon surface under water lubrication

The friction and wear properties of silicon surface covered with octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) were investigated by a UMT-2 microtribometer with and without water as lubricant, and then compared with that of bare silicon surface. Dry friction measurement results show that OTS SAMs have a very low friction coefficient compared to bare silicon surface under lower sliding velocity and normal contact load. However, heavy wear occurs on OTS SAMs under higher contact stress and sliding velocity. Under water lubrication, OTS SAMs can prevent wear obviously and meanwhile present low coefficient of friction even under high velocities. The improved frictional and anti-wear property on OTS SAMs surface is attributed to the hydrophobic property of OTS and hydrodynamic effect of water. Furthermore, a wear critical phase diagram for OTS SAMs with and without water was proposed, which indicates that OTS SAMs working under water lubrication owns a wider range of available load and velocity to reduce friction and prevent wear. Funded by the National Natural Science Foundation of China (Nos. 50575123, 50275071, 50545035) and National Basic Research Program of China (“973” Program) (No. 2003CB716205)     

GCr15球-盘点接触摩擦副的滑滚摩擦磨损特性研究

选用GCr15钢盘和GCr15球作为摩擦副,在NGY‐6纳米润滑膜测量仪上开展球‐盘点接触摩擦副在润滑状态下的滑滚摩擦磨损实验,研究不同接触应力、钢球转速、滑滚比等参数对摩擦副的摩擦因数、磨损形貌的影响规律．结果表明：当接触应力和钢球转速一定时,摩擦因数随着滑滚比的增大而逐渐增加后达到稳定状态;当滑滚比一定时,摩擦因数随接触应力的增大而逐渐增大;当钢球转速低于300 r／min时,摩擦因数随着钢球转速的增大而减小;当钢球转速高于300 r／min、接触应力大于0．84 GPa时,摩擦因数随着钢球转速的增大而呈增大趋势．Stribeck曲线表明：当滑滚比为0．01时,摩擦副处于流体动压润滑状态;当滑滚比为0．03时,润滑状态随Sommerfield参数的增加而从边界润滑过渡到混合润滑;当滑滚比分别为0．05、0．1、0．3、0．5时,润滑状态为边界润滑．滑滚比较小时,磨损机制以疲劳磨损为主,随着滑滚比的增大,磨损机制转变为磨粒磨损．     

水环境下二硫化钼/聚四氟乙烯复合材料与石英玻璃的超润滑摩擦学特性

采用M-200型摩擦磨损试验机,对比研究了几种填充PTFE复合材料与石英玻璃对磨时,在水润滑、低速、较高载荷条件下的摩擦学特性。结果表明:在水润滑条件下,MoS2/PTFE复合材料与石英玻璃对磨时的摩擦系数可低于0.005,表现出超润滑摩擦特性,而且具有稳定的摩擦系数和很低的磨损率。石英玻璃所具有的优良表面特性和优异的亲水性是实现超润滑的关键。当添加高硬添料时,石英玻璃表面容易受到破坏,导致摩擦学性能下降。     

柱塞泵柱塞密封摩擦副润滑状态分析

根据流体动压润滑理论,对柱塞泵柱塞密封摩擦副的润滑机理进行了理论分析,即在泵的排出行程由强制性润滑油润滑,泵的吸入行程由工作介质润滑;并利用最小油膜厚度的计算公式,对摩擦副的润滑状态进行了判断。模拟计算表明,在柱塞往复运动周期内,摩擦副处于干、混合摩擦状态,工作介质和强制润滑油可改善润滑状态,且润滑油的选择也是至关重要的。     

SF-1材料水润滑艉轴承摩擦性能研究

针对传统船舶艉轴承的应用现状与不足,在SSB-100型船舶艉轴试验机上对SF-1高分子石墨轴承进行水润滑条件下的摩擦性能试验,分析了载荷、线速度和润滑水温变化对摩擦系数的影响规律以及摩擦磨损性能。结果表明,SF-1材料具有优良的自润滑性能,摩擦系数低,承载压力高以及耐磨性好,在船舶行业具有广阔的应用前景。     

不同工况下丁腈橡胶的摩擦磨损机理

为了合理选择螺杆泵定子橡胶材料以提高螺杆泵的使用寿命,分析了不同工况下丁腈橡胶与金属配副的摩擦磨损机理.采用MPV-600环块式摩擦磨损试验机对不同炭黑质量分数的丁腈橡胶在变载荷情况下进行摩擦磨损试验,利用体视显微镜观察橡胶磨损后的表面形貌,使用红外光谱仪分析表面官能团变化.试验结果表明:干摩擦情况下,磨损量在一定炭黑质量分数范围内随其增加而减小,磨损机制为黏着磨损和磨粒磨损;水润滑情况下,由于水的润滑及冷却作用,炭黑质量分数适中的橡胶耐磨性最好,磨损机制为磨粒磨损;原油润滑低载荷情况下,磨损量几乎不受炭黑质量分数的影响,而高载荷情况下,炭黑质量分数越高,磨损量越小,其磨损机制以腐蚀磨损为主.     

MD simulation of nanometric cutting of copper with and without water lubrication

Three-dimensional molecular dynamics(MD)simulation was carried out to understand the mechanism of water lubrication in nanometric cutting.The water-lubricated cutting was compared with the dry cutting process in terms of lattice deformation,cutting force,heat and pressure distribution,and machined surface integrity.It was found that water molecules effectively reduce the friction between the tool and workpiece,the heat in the cutting zone and the pressure being generated on the tool surface,thus leading to prolonged tool life.Water molecules also enlarged the pressure-affected area,which decreased the roughness of the machined surface.     

刀具-岩石摩擦过程中的闪温分析

摩擦表面闪温对刀具材料性能产生着重要影响。针对刀具摩擦表面的微凸体建立了导热微分方程,系统分析了影响微凸体温度的影响因素。在提出摩擦表面接触系数的概念的基础上推导出了干摩擦条件下刀具闪温的解析计算模型并分析了水射流条件对闪温计算的影响。给出了基于均匀分布模型和概率分布模型的摩擦表面接触系数和水射流参与下满足动力润滑条件的摩擦系数等计算参数的确定方法。计算分析与红外测温实验的结果表明：刀具与岩石的摩擦闪温严重依赖两摩擦面的接触系数和各自表面微凸体分布情况;给出的摩擦面闪温计算模型比传统计算方法更接近实验测量值,更适用与工程中对材料安全性要求较高的场合应用。     

外加电对边界油润滑下摩擦系数的影响

利用外加电压实现对摩擦系数的主动控制是摩擦学者长期追求的目标之一．本实验应用球盘式摩擦试验机，针对150SN油润滑下的GCrl5／45″摩擦副，考察了外加直流电压极性、外加直流电流大小、以及外加交流电压的频率对其摩擦和润滑性能的影响，并对其作用机理进行了分析．实验结果表明，外加直流电压的极性对GCrl5／45″摩擦副间的摩擦系数和润滑状况有很大的影响；一定范围内的外加电流大小的影响只是程度上的不同而已；外加交流电压的影响则综合了由极性和幅值的变化所带来的影响，其变化频率也是重要的摩擦学性能影响参数．结合作者先前的工作及其他有关文献，对外加电压的影响机理进行了初步分析，认为外加电是通讨影响界面摩擦电化学反应所形成的表面氧化膜的性质和状态来影响摩擦和润滑性能的．     

以乳化液润滑时灰铸铁/Si3N4间配副的摩擦磨损行为

研究了以乳化液和蒸馏水作润滑剂时Si     

GF增强尼龙1010复合材料的磨擦学性能研究

制备了玻璃纤维（GF）增强尼龙1010复合材料,在环一块磨损试验机上研究了复合材料的摩擦学性能。结果表明：GF含量对复合材料的摩擦学性能有显著影响,GF质量分数为35％时增强效果较好;随着滑速的增加,GF增强尼龙1010复合材料的摩擦系数和磨损量持续上升。干摩擦下的复合材料磨损以疲劳断裂和粘着为主,且纤维出现磨损、断裂及从基体中剥落的现象。在油润滑下材料向对偶产生轻微的转移,与干摩擦相比复合材料的摩擦系数和磨损量大为降低;水润滑下的尼龙以化学腐蚀磨损和磨粒磨损为主,此时复合材料摩擦系数也有较大程度的降低,但磨损量较干摩擦增大。     

流体润滑下微小凹痕图案的摩擦特性研究

采用销-盘摩擦副接触方式在常温常压及液体润滑下,对不同密度的50μm和110μm大小的微小凹痕图案表面进行摩擦试验,探讨接触压力及滑动速度对不同大小以及密度的微小凹痕图案的摩擦性能影响,并利用Stribeck曲线分析在不同试验条件下不同密度的50μm和110μm大小的微小凹痕图案表面的摩擦特性.结果表明:降低摩擦中,不同的微小凹痕图案表面具有最佳的密度含量.即大小为50μm的微小凹痕图案中,密度为32.4%的微小凹痕图案表面的摩擦系数最低;大小为110μm的微小凹痕图案中,密度为19.8%的微小凹痕图案表面的摩擦系数最低.     

High temperature tribological behaviors of nano-diamond as oil additive

The tribological behaviors of the nano-diamond particles including the nano-diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy (XPS). The results show that nano-diamond particles can obviously improve the antiwear and friction reducing properties of the base oil at high temperature and the high load. The friction coefficient of the nano-diamond is very low at 200 °C when the test load is not more than 20 N. This tribological behaviors should attributed to the similarly to “ball bearing” lubrication action of the nano-diamond particles, so the movement between tribological pairs become sliding/rolling. The nano-diamond modified by dimer ester possesses excellent antiwear and friction reducing performance at 500 °C and load 500 N. The tribochemical reaction film between the nano-diamond particles and the renascent wear surface plays dominating lubrication role and the presence of the dimer ester on the rubbing surface can be propitious to form lubrication film containing nano-diamond on the worn surface at high temperature and high load. Foundation item: Project (51489020605JS9105) supported by National Key Laboratory for Remanufacturing     

Tribological properties of CrN coating deposited on 20CrMo against tin bronze

A CrN coating was deposited on the piston pin material 20CrMo. The tribological properties of 20CrMo and CrN coating against tin bronze QSn7-0.2 were compared by pin-on-disk tests under dry friction and oil lubrication, respectively. The cross-sectional morphologies and structures of the coating were characterized through scanning electron microscopy and X-ray diffraction. The hardness, elastic modulus, and adhesion strength of the coating were tested through nano-hardness and scratch tests. The wear tracks were tested with an optical profilometer, and wear volume was calculated. Under dry friction conditions, the CrN coating exhibited a significantly stable friction coefficient and a relatively lower wear rate against QSn7-0.2 at various temperatures compared with 20CrMo. The wear rate decreased by 98.5% at 700°C. Under poly-alpha-olefine lubrication, the CrN coating reduced the load effect on the friction coefficient. Under engine oil 5 W40 lubrication, the CrN coating improved the tribological properties under high speed and heavy load conditions. Simultaneously, the CrN coating changed the friction and heat flow with increasing temperature.     

分子膜剂在岩石表面上的吸附及减阻性能研究

分子膜降压增注技术是将分子膜剂注入到石油储层微孔道中来改变孔壁润湿性及微结构特性, 达到 降低注水压力或提高注水量的目的。研究了分子膜 - 壁的微观引力与水 - 壁微观引力的对比, 认为分子膜在竞争吸附 中占优势, 能够突破并赶走水化层, 最终牢固吸附在孔壁上, 形成分子膜层; 并探索了分子膜剂应用条件, 对分子膜 剂吸附量的变化规律进行了研究, 同时从降低边界层效应和注水摩阻两方面揭示了分子膜剂减阻机理, 最后进行了 分子膜剂减阻性能研究。