双疏铝合金表面的水/油润滑摩擦学性能

利用激光加工在5083船用铝合金表面构建间距为100μm的点阵和网格微结构,将Si O2纳米粒子涂覆在微结构上构建微纳结构,制备出双疏铝合金表面。采用接触角测量仪测量其表面接触角和滚动角,采用多功能摩擦磨损试验机探讨其在水润滑和油润滑条件下的摩擦学性能。结果表明,网格表面的超疏水/疏油性能比点阵表面更强,水接触角达到159.9o,对十六烷的接触角达到147.0o。随表面疏水和疏油性能的提高,摩擦因数减小,磨痕深度变浅,宽度变窄。油润滑条件下的摩擦因数显著小于水润滑条件下的,且波动性更小,磨痕也更浅更窄。水润滑条件下,点阵表面的摩擦因数大于网格表面;而油润滑条件下,点阵表面的摩擦因数小于网格表面。     

环保型纳米润滑材料的研究

从环保角度,选择了两种纳米材料作为润滑油抗磨、极压添加剂。介绍了纳米材料的制备,根据亲水亲油平衡值(HLB)选择了合适的表面活性剂,并将其加入到含有单种或两种复合纳米粒子的润滑油中进行表面改性,采用四球摩擦磨损试验机测定含纳米粒子的润滑油的摩擦学性能。结果表明:含纳米粒子的润滑油具有良好的抗磨减摩性能,且含复合纳米粒子的润滑材料的抗磨减摩性能比单种纳米粒子的润滑材料的抗磨减摩性能好。这里还探讨了纳米润滑材料的抗磨减摩机理。     

沉积时间对MPTS自组装膜摩擦学性质的影响

利用分子自组装技术在羟基化后的单晶硅硅片表面制备(3-巯基丙基)三甲氧基硅烷(MPTS)自组装膜,用X射线光电子能谱仪(XPS)对薄膜的表面结构进行表征,用JGW-360a型接触角测量仪测量硅片表面的接触角,用UMT-200型微观摩擦磨损实验机测量硅片的摩擦因数,探讨沉积时间对自组装膜的摩擦学性能的影响。结果表明:MPTS自组装膜具有亲水疏水性能,其对水的接触角超过60°;硅片表面沉积MPTS可以大幅度降低硅片的摩擦因数,使硅基片表面的摩擦因数由无膜时的0.6降至0.25左右,且具有很好的耐磨性;沉积时间对硅表面自组装膜的摩擦学性能影响较大,在本实验条件下,0.5 h沉积时间所制备的MPTS-SAM硅片的耐磨性最佳,1 h沉积时间制得的硅片表面最为光滑。     

润滑介质对织构化表面摩擦学性能影响的实验研究

采用纳秒激光烧蚀技术在铍青铜盘试样表面加工3种不同参数圆形微凹坑织构,选用石油装备中常用的低黏度L-CKD150润滑油和高黏度复合锂基润滑脂为润滑介质,开展不同润滑环境下销-盘摩擦学实验,对比分析L-CKD150润滑油和复合锂基润滑脂对织构表面摩擦磨损性能的影响差异。实验结果表明:2种不同润滑环境下,合理参数织构均可有效提高表面润滑性能、减少摩擦磨损;润滑介质对织构表面摩擦磨损性能的影响差异与接触压力有关,接触压力较低时,L-CKD150润滑油润滑性能优于复合锂基润滑脂,接触压力较高时则复合锂基润滑脂润滑性能更优;相同工况下,相比于L-CKD150润滑油润滑,复合锂基润滑脂润滑时最优织构直径更大。     

微织构光固化填充h-BN的巴氏合金表面摩擦学性能

为了提高巴氏合金在油润滑条件下的摩擦学性能,在巴氏合金表面加工凹坑微织构并利用光固化填充方法填充六方氮化硼(h-BN)固体润滑剂,制备出h-BN与表面微织构相结合的复合润滑结构。研究复合润滑结构在油润滑条件下的摩擦学性能及其减摩润滑机制。结果表明：复合润滑结构的摩擦学性能远高于未织构面和纯织构面;当凹坑微织构直径较小时,织构密度为10%～20%时,复合润滑结构摩擦因数较小,而凹坑直径较大时,随着织构密度的增加,复合润滑结构摩擦因数逐渐减小;当织构密度小于20%时,凹坑直径较小的复合润滑结构摩擦因数小,当织构密度达到30%时,随着凹坑直径的增加,复合润滑结构摩擦因数减小。复合润滑结构能够改善巴氏合金表面摩擦学性能,是因为h-BN固体润滑剂的释放在巴氏合金表面形成了固体润滑薄膜,避免了润滑油膜较薄处的巴氏合金表面直接与45钢表面接触,且释放h-BN固体润滑剂后的微织构凹坑可以起到收集磨粒,储存润滑油的作用。     

纳米铜添加工艺对润滑油摩擦学性能的影响

探讨了纳米铜不同分散工艺和添加量对润滑油摩擦学性能的影响。分别采用超声分散和球磨分散工艺，将3种不同工艺制备的纳米铜材料溶于SF15W／40机油中，在T-11摩擦磨损试验机上进行摩擦学性能试验。结果表明，其中一种纳米铜能够提高基础油的减摩性能，采用超声分散比采用球磨分散的减摩性能好。随着纳米铜浓度的增加抗磨性能有明显的提高，分析认为纳米铜在摩擦表面的沉积有利于提高摩擦学性能。     

滚滑轴承滑块的油-气两相流润滑分析

为改善滚滑轴承的润滑,运用两相流理论对其滑块进行油气润滑设计,建立滑块的油-气两相流CFD模型,分析不同入口角度、进气速度、进油速度和润滑油黏度对流场油相分布的影响。结果表明:油-气混合润滑方式能在内外滚道接触区形成有效的润滑油膜;油气管道夹角影响油滴分布,角度过大时大量油滴会在滑块侧面上附着,角度过小时油滴会在外滚道入口处堆积,造成供油连续性不好,油膜稳定性下降;进气速度过大会降低油滴附着率,无法形成有效油膜,而进油速度过大会造成润滑油累积,出现搅油现象,因此选择合适的进气和进油速度,才能控制油滴的大小和保持润滑过程的连续性;润滑油黏度会影响油滴在滑块上的附着效果,合理地选择润滑油黏度,才能保证流场油相分布均匀。     

考虑润滑油供给条件的油环-缸套摩擦副润滑分析

内燃机油环-缸套摩擦副润滑分析,多采用富油条件或假定某种特殊边界条件,与油环-缸套摩擦副实际润滑油供给状况不相符。以某四行程内燃机为研究对象,研究油环-缸套间润滑油流动与供给,确定油环进口油膜厚度;在此基础上,根据流量平衡和压力平衡,确定油环上、下轨各段工作面边界条件,并分别对各段求解Reynolds方程,分析油环-缸套摩擦副在计及润滑油供给条件下的润滑性能,并与富油状况对比。研究结果表明,计及供油状况下,油环-缸套摩擦副在上、下行程的润滑性能不对称,最小油膜厚度、最大油膜压力、摩擦力及摩擦功耗与富油状况均有一定差异,特别是在上行程差别显著。可见,考虑进口润滑油供给条件分析内燃机油环润滑性能,将对活塞环-缸套摩擦副的设计信赖性产生积极影响。     

Al2O3-40%TiO2涂层/锡青铜的摩擦磨损性能研究

在室温下对Al2O3-40%TiO2涂层与锡青铜摩擦副进行了油润滑情况下的球盘式摩擦磨损试验。使用SEM分析了磨损表面形貌特性;同时采用EDAX进行了磨损微观区域的成分分析。结果表明:在FD-7主轴润滑油的条件下,A l2O3-40%TiO2涂层与锡青铜之间发生了明显的涂抹和擦伤现象,涂层摩擦磨损性能优异。     

空间光学调制器中轴承的润滑及密封研究

对空间紫外光谱仪中转动部件,即光学调制器系统支撑轴承的润滑及密封进行设计和研究。在真空环境下(10-3Pa),采用固体润滑和油润滑2种润滑方式进行轴承寿命试验。结果表明,当轴承采用MoS2固体膜润滑时,轴承转动到108转量级后,轴承动态摩擦力矩增大,转速急剧下降;采用扫描电子显微镜和能量色散谱(EDS)分析轴承工作表面,验证轴承工作表面有转移膜的形成。当轴承采用油润滑时,对轴承的润滑状态、机械密封结构及润滑油的泄漏量进行设计和计算表明,用非接触的组合式机械密封机构,能够降低油耗,减少润滑油对光学系统的污染,提高仪器的性能和指标,从而可以实现空间转动部件长时间工作的要求。     

干摩擦和水润滑条件下单晶硅的摩擦磨损性能研究

在UMT-2微摩擦试验机上,对单晶硅片进行了干摩擦和水润滑两种状态下的摩擦磨损试验,分析讨论了载荷和滑动速度对单晶硅片的摩擦因数和磨损率的影响规律;运用扫描电子显微镜,观察和分析了其磨损表面形貌。结果表明:干摩擦条件下的磨损机理主要表现为黏着磨损,水润滑条件下的磨损机理主要表现为机械控制化学作用下的原子/分子去除过程;水润滑条件下的摩擦因数和磨损量均较小,最小磨损率仅为10μm3/s;在水润滑条件下,载荷和滑动速度达到一定值时,硅片表面将发生摩擦化学反应,生成具有润滑作用的Si(OH)4膜,即机械作用在一定条件下对化学反应具有促进作用。     

On the behaviour of an oil lubricated fretting contact

Although many engineering situations involving fretting damage are lubricated, comparatively little has been reported on this aspect of fretting wear. The viscosity of the lubricating oil and its boundary layer performance are expected to influence fretting behaviour, in addition to the normal fretting parameters, such as stroke and contact force.

This paper examines the effect of lubrication regime, oil viscosity and stroke on the behaviour of a ball-against-flat specimen arrangement. Ball and flat specimens were both manufactured from a bearing steel (SUJ2). Polybutane oils, without additives, covering a range of viscosities from 1 to 10 000 cSt, and fretting strokes up to 35 μm were investigated. The lubricating oil was added to the fretting interface after 0, 3 and 2000 fretting cycles had been completed. Lubrication regime, oil viscosity and stroke were all found to affect fretting behaviour in terms of both coefficient of friction (or traction coefficient) and wear. For strokes less than 9 μm, i.e. for conditions approaching almost complete ‘stick’, coefficient of friction values under oil lubrication were well in excess of double those observed without it. These high values suggest that the oil was unable to penetrate into the fretting contact region, but did maintain a shield around it, so that metal-on-metal contact was maintained under oxygen deprived conditions. The lowest values of steady state coefficient of friction (≈ 0.2) were observed when oil lubrication was applied after 2000 cycles had been completed, indicating that surface roughening and the presence of oxide films and oxidised debris assisted penetration of the lubricant into the fretting contact zone.     

不同条件下不同尼龙的摩擦磨损性能

分别制备了MC尼龙、含5%(质量分数)润滑油的MC油尼龙及35%(体积分数)碳纤维增强的复合MC尼龙,研究了3种尼龙在干摩擦、洁净水、干砂、水砂条件下的摩擦磨损性能。结果表明:MC油尼龙表面由于存在润滑油膜,4种条件下的摩擦因数和磨损率均最小;干摩擦和水润滑条件下,复合MC尼龙表面的纤维凸起使其磨损率和摩擦因数均较MC尼龙的小;水润滑下的尼龙磨损程度均较干摩擦下的小;干砂和水砂条件下,石英砂的犁削作用使MC尼龙表面出现较多犁沟,M C油尼龙表面由于存在润滑油膜,仅出现少量犁沟。水砂条件下的尼龙磨损程度均较干砂条件下的小。     

304不锈钢表面离散圆形凹坑液相辅助激光制备及摩擦性能

为改善304不锈钢耐磨性及润湿性，在空气与液相2种介质下使用激光加工技术在304不锈钢表面制备离散型圆形凹坑织构。借助白光干涉仪、扫描电子显微镜及能谱、接触角测量仪对织构试样表面形貌、元素含量及润湿性进行了表征，并通过摩擦磨损试验考察了织构试样在干摩擦和油润滑下的摩擦学性能。结果表明：空气介质下激光加工增强了试样表面疏水性能，接触角为123.3°；液相辅助激光加工增强了试样表面润湿性，接触角为29.3°；液相辅助激光加工表面的微凹坑分布更加均匀，无明显的氧化及熔融物重铸现象，这是因为液相在激光加工时对试样起到了冷却及保护作用；液相辅助激光加工表面织构在2种摩擦工况下的摩擦因数均最小，且磨损有一定改善。液相辅助激光制备的织构表面较为均匀、无较大的微凸峰，且具有较好的润湿性能，有利于润滑油的存储及铺展，进而改善了界面摩擦行为。     

菜籽油润滑条件下TiN涂层摩擦学特性*

为探究TiN涂层在油润滑条件下的摩擦磨损性能,通过磁控溅射技术在AISI304不锈钢上制备TiN涂层,借助扫描电镜、纳米划痕仪、XRD和摩擦磨损试验机探究不同氮通比下TiN涂层的微观结构、力学性能及其在植物菜籽油润滑下的摩擦学性能。实验结果表明：在氮通比为0.45下制备的TiN涂层具有最致密的晶状结构,且力学性能最优;在菜籽油润滑下,随着氮通比的增大TiN涂层摩擦因数和磨损率呈现先降低后增加的趋势,在氮通比为0.45时两者均最小。XPS分析表明,TiN涂层表面存在的氧化层,增加了菜籽油在涂层表面的润湿性,从而更好地形成润滑膜而起到润滑特性。与橄榄油、聚α烯烃(PAO6)基础油、5W40润滑油3种润滑介质相比,TiN菜籽油润滑下涂层表现出更优的润滑性能。     

磨屑对润滑油摩擦性能的影响

通过实验和模拟研究磨粒对润滑油摩擦性能的影响。首先通过微纳米压/划痕试验测量含磨屑润滑油的摩擦因数。同时,建立边界润滑体系模型,采用分子动力学方法模拟含磨屑润滑油膜在不同载荷下沿膜厚方向的压缩率和密度分布;对体系的上下固体壁面施加方向相反的剪切速度,计算出壁面原子的应力、摩擦力、正压力和摩擦因数;分析不同粒径磨屑的动态行为特征;通过减少润滑油分子数量,探究乏油工况下含磨屑润滑体系的摩擦性能。结果表明,润滑体系摩擦因数的模拟值与试验值一致;磨屑的存在会降低油膜的压缩率,同时在高载下磨屑的存在会对油膜的分层产生破坏,影响磨屑附近的密度分布;含小粒径磨屑的润滑体系的摩擦因数比含大粒径磨屑的润滑体系的小,表明磨粒聚集长大现象会恶化润滑油的润滑性能;磨屑在剪切过程中同时存在滚动和滑动,含小粒径磨屑的润滑体系剪切过程中表现出波动幅度更大的角速度;随着载荷的增大,磨屑角速度减小,波动幅度降低;在乏油工况下,磨屑会在剪切过程中出现变形破碎现象。     

Tribological Performance of Attapulgite Nano-fiber/Spherical Nano-Ni as Lubricant Additive

Tribological properties of attapulgite, Ni and their composite nanoparticles suspended in mineral lubricating oil for a steel–steel contact were investigated with an optimal SRV-IV oscillating friction and wear tester. Results demonstrated that the composite nanoparticles exhibit better friction-reduction and anti-wear properties than the single additives. The oil containing a composite powder of 0.5 % attapulgite and 0.1 % Ni owns the best friction-reduction and anti-wear properties. Under the lubrication of oil containing composite nanoparticles, a smooth and compact tribofilm mainly composed of iron oxides, Ni, NiO and silicon oxide was formed on the rubbing surface.     

石墨含量对铜基石墨自润滑复合材料摩擦过程中石墨润滑膜的影响

为研究石墨含量对铜基石墨自润滑复合材料摩擦过程中形成石墨润滑膜的影响,采用粉末冶金法制备了不同石墨含量的铜基石墨自润滑复合材料,测试了复合材料的力学性能,用自制环-块摩擦试验机测试评估了材料的耐磨性能,用光学显微镜实时原位观察了摩擦表面组织形貌的变化,用扫描电镜对磨痕进行观察和分析,通过能谱仪成分扫描分析接触面石墨润滑膜的覆盖率。结果表明:随着复合材料中石墨含量的增加,材料的力学性能逐渐降低,石墨润滑膜的覆盖率先升高后降低,磨损量先减小后增大;当石墨体积分数为14%时,石墨润滑膜的覆盖率最高,磨损量最小,耐磨性能最好。     

Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

In this study, we investigated the effects of composite nano-Cu/WS₂ lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS₂ lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS₂ lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

     

Silicon Nitride Boundary Lubrication: Effect of Oxygenates

A ball-on-three-flat (BTF) wear tester was used to investigate the boundary lubricating characteristics of oxygenates on a commercial silicon nitride. A wide variety of oxygen-containing compounds were tested neat and/or at 1% by weight in a paraffin oil. Compounds containing hydroxyl functional groups were more effective compared to a base case of neat paraffin oil. Decreases of up to 58% in friction coefficient, and 95% in wear were obtained. In most cases, films were observed in and around the wear scar, suggesting chemical reactions had taken place in the contact.

Additional wear tests, conducted using neat shorter-chain linear primary alcohols, i.e., 6–10 carbons, demonstrated boundary lubrication protection, with longer chain length providing better antiwear performance. A study of several C₈ compounds with specific oxygen-containing functional groups (primary alcohol, secondary alcohols, acid, aldehyde, and ketone) demonstrated that the primary alcohol had the strongest boundary lubricating effect. Varying the amount of water in the alcohols had little effect on friction and wear, suggesting that the boundary lubrication effects observed were not merely due to dissolved water in these fluids, but some characteristic chemical interaction with the hydroxyl functional group of the alcohols and acids.