氧化物润滑材料的研究进展

随着航空航天等高新技术装备的发展,要求相关运动部件在极高的温度下具有优异的摩擦学性能,因此开发适应极高温度的自润滑材料具有重大意义。综述了二元氧化物润滑材料和三元氧化物润滑材料用作高温固体润滑材料的研究与发展。重点介绍了含有Magnéli同源相的二元和三元氧化物润滑材料,在高温和宽温域环境下的摩擦学性能,同时也说明了通过控制材料的生长结构和缺陷形式,来生成具有高温润滑性的氧化物,成为实现材料高温润滑的一种潜在方法,并讨论了这些氧化物的结构、化学性能和电性能与其摩擦学性能的相关性。最后概括了氧化物润滑材料在工业中的应用前景,并提出了研发单一润滑材料实现室温至高温(25~1000℃)宽温域下的连续润滑成为未来的发展趋势。     

特种润滑材料研究进展简述

虽然有些情况下使用气体润滑,但一般认为润滑材料主要包括液体和固体润滑材料。根据使用环境和润滑材料特性,润滑材料可以划分为许多类。特种润滑材料顾名思义是指具有比常规润滑材料更为优异特性的润滑材料。通过分子结构、体相结构设计和复合提升润滑特性一直是制备新型润滑材料的主要途径。对于液体润滑剂和有机分子薄膜,常常将新型分子结构设计和摩擦化学机理探讨结合在一起以发展润滑材料。比如,作为可能的新型润滑剂,离子液体的评价主要通过考察不同官能团和摩擦过程中发生的摩擦化学机制,以指导合成新型离子液体。有机薄膜的摩擦学特性强烈依赖于薄膜分子结构和构造结构。对于经典固体润滑材料,常考虑体相结构设计和复合方法提高或调整摩擦磨损特性。类富勒烯结构的出现赋予类金刚石薄膜更高的弹性和更低的摩擦系数,而金属掺杂能够降低内应力并在有些情况下改善薄膜环境敏感度。由于合成新型聚合物润滑材料比较困难,因此,共混和无机纳米颗粒的添加成为制备良好力学性能和耐磨损特性聚合物润滑材料所采取的方法。高温润滑材料,特别是从室温到高温（1000℃及以上）均具有良好润滑特性的润滑材料的发展依然是一个大的挑战。具有高温稳定性的稀土和陶瓷填充金属是目前设计制备高温润滑材料的主流方法。通过摩擦磨损特性的考察可以获得对润滑材料的表观判断,而基于磨损表面反应物质的分析对摩擦过程中发生在表面的摩擦物理化学机制的探究则是了解润滑材料服役特性和机制的主要手段,也是设计制备新型润滑材料依赖的主要思想来源。     

添加Ni包覆MoS2的Ni-Cr高温固体自润滑材料的研究

通过硝酸镍分解-氢还原法制取镍涂覆二硫化钼粉末，加入到Ni-Cr基体合金中，以防止二硫化钼在高温制备过程及高温使用过程中的氧化分解。添加Ni包覆MoS2粉末，Ni-Cr25(w％)高温固体白润滑材料的机械性能优于未包覆材料，对(MoS2／Ni)20w％的高温固体白润滑材料的摩擦磨损性能分析表明：在室温和600℃下，材料有较低的摩擦系数。室温磨损率也很低，在高温下与未添加包覆材料相比前者具有很好的宽温带摩擦学性能。     

粉末冶金固体润滑轴承

固体润滑材料是指利用固体来减少两承载表面间的摩擦磨损作用,以降低摩擦与磨损的专用材料。固体润滑轴承是利用固体润滑剂的自润滑性能所制备的轴承,在使用过程中无需加润滑油维护。特别适用于无油、高温、高负载、防污、防蚀、防辐射以及在水中或真空溶液浸润而根本无法加润滑油的特殊工况条件下使用。常见的粉末冶金固体自润滑材料有铜基、铁基、铝基、镍基、钛基等。固体润滑轴承广泛应用于冶金轧钢设备、灌装设备、水轮机、气轮机、仪器仪表、矿山机械、船舶机械、纺织机械、船舶工业、航天航海等领域。     

板带钢卷取机摩擦衬板的镶嵌式固体润滑材料研究

介绍了板带钢卷取机卷筒棱锥轴与扇形块之间镶嵌式摩擦衬板固体润滑材料研究.根据板带钢卷取机卷筒的摩擦衬板的实际工况要求,选用聚四氟乙烯(PTFE)、二硫化钼和石墨作为固体润滑材料,通过正交试验法,确定了锡青铜摩擦衬板的镶嵌固体润滑材料的种类及组分配比.研究表明,镶嵌固体润滑材料的锡青铜摩擦衬板的摩擦系数明显降低,并使其耐磨性提高两个数量级以上,而且没有发生严重的磨损失效现象,完全可以满足卷取机的工作要求.     

等离子喷涂NiCr合金基复合梯度润滑涂层的组织与力学性能研究

选取了具有优异的高温性能和一定的自润滑性能的高温镍基合金,作为复合涂层基体材料,润滑相则分别从高、中、低温固体润滑剂中选取了Ag、CaF2、石墨(C)、MoS2、BN为基本润滑组元;耐磨相则选用了在高温下具有良好的抗氧化性能及耐磨损性能的碳化铬(Cr3C2)硬质粒子,采用等离子喷涂技术制备了具有极佳相容性的高温润滑涂层.涂层的结合强度测定、硬度测定和扫描电镜分析均显示出涂层的梯度结构优于单层结构.梯度结构缓和了涂层内部的物理性能差异,不仅使涂层的硬度得到平缓过渡,而且使涂层的结合强度大大提高,有效改善了涂层的性能.     

类金刚石碳薄膜的高温摩擦学研究进展

现代工业的迅猛发展迫使愈来愈多的机械零部件需要在高温下运转,因此高温润滑材料的匹配发展至关重要。在摩擦表面沉积固体润滑薄膜是降低高温下机械装备的摩擦与磨损,提高其使用寿命和可靠性的有效手段。近年来,类金刚石碳(Diamond-like carbon,DLC)薄膜的高温摩擦学得到了广泛研究,并取得了一些重要的进展。大量研究表明,通过适当的元素掺杂可以显著提高DLC薄膜的高温摩擦学性能。首先分别综述了纯碳DLC薄膜、含氢DLC薄膜、Si掺杂DLC薄膜、金属元素掺杂DLC薄膜、元素共掺杂DLC薄膜的高温摩擦学研究进展。通过总结文献中的数据,绘制了各种DLC薄膜的摩擦系数随温度的变化曲线,进而确定了各种薄膜的有效润滑温域。在此基础上,提出了几种有望实现宽温域连续润滑的DLC薄膜新体系,并分析了DLC薄膜的高温润滑失效机理,强调了分子/原子的热扩散和薄膜的热应力在DLC薄膜高温润滑失效中的作用。最后,从提高DLC薄膜自身的高温摩擦学性能和提高DLC薄膜与基材的高温结合性能两个方面,对今后亟待开展的研究工作进行了展望。     

含银硬质涂层高温摩擦学性能的研究进展

贵金属银具有优异的固体润滑性能,常被用于关键机械零部件表面硬质防护涂层的摩擦学改性。近年来,航空、航天等技术的发展进一步促进了含银硬质涂层在高温工况下的大量应用。贵金属银在含银硬质涂层中主要以银单质和银的二元金属氧化物AgTMxOy等形式发挥作用。阐述了银单质和AgTMxOy在硬质涂层中的高温自润滑机理,分析了银类润滑材料和其他固体润滑剂之间的协同作用,归纳了金属银在硬质涂层中的几点优异特性,即较快的扩散速率、较好的热化学稳定性和较弱的Ag—O键等;展望了含银硬质涂层的未来研究方向。     

金属基固体自润滑复合涂层及其制备技术研究进展

金属基固体自润滑复合涂层具有强度高、耐高温、耐磨损以及易加工等特性,成为近来研究热点。首先综述了国内外金属基固体自润滑复合涂层的材料体系(即难熔金属基自润滑复合涂层、软金属基自润滑复合涂层、低温金属基自润滑复合涂层以及高温金属基自润滑复合涂层),随后分析了金属基固体自润滑复合涂层的润滑机理,指出润滑膜的低剪切特性是实现减磨润滑的关键。接着介绍了金属基固体自润滑复合涂层的制备技术,比较分析了烧结、电镀、化学镀、热喷涂、物理气相沉积(PVD)、化学气相沉积(CVD)、激光熔覆等技术,在制备金属基自润滑复合涂层方面的优点和不足。最后总结了目前在关于金属基固体自润滑复合涂层研究中存在的问题,进而探讨了相应的解决方案,提出应深入研究金属基体、固体润滑剂与环境三者之间的相互作用机理,并进一步指出研发新型固体润滑剂、改进现有制备技术、开发新工艺是未来重点发展的方向。     

纳米材料固体润滑干膜摩擦学性能研究

通过对纳米材料的筛选、预处理、并与普通固体润滑剂充分研磨、搅拌等一系列工艺措施,开发出纳米材料固体润滑干膜。进行了纳米材料固体润滑干膜的摩擦磨损实验,表明纳米Ａｌ２Ｏ３可以大幅度提高体润滑干膜的耐磨性,延长了固体润滑干膜的使用寿命,拓宽了固体润滑材料的应用范围,为纳米材料固体润滑干膜的广泛应用提供了有力依据。     

Experimental investigation to study the effect of solid lubricants on cutting forces and surface quality in end milling

Milling is a widely employed material removal process for different materials. It is characterized by high material removal rate. Machining leads to high friction between tool and workpiece, and can result in high temperatures, impairing the dimensional accuracy and the surface quality of products. Application of conventional cutting fluid may not effectively control the heat generation in milling. Besides, cutting fluids are a major source of pollution. Solid lubricant assisted machining is an environmental friendly clean technology for desirable control of cutting temperature. The present work investigates the role of solid lubricant assisted machining with graphite and molybdenum disulphide lubricants on surface quality, cutting forces and specific energy while machining AISI 1045 steel using cutting tools of different tool geometry (radial rake angle and nose radius). The performance of solid lubricant assisted machining has been studied in comparison with that of wet machining. The results indicate that there is a considerable improvement in the process performance with solid lubricant assisted machining as compared to that of machining with cutting fluids.     

Development of electrostatic solid lubrication system for improvement in machining process performance

Liquid lubricants have traditionally been used to control the high heat generation in machining; however, the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. Minimization or possible elimination of cutting fluids substituting their functions by some other means is emerging as a thrust area of research in machining. Solid lubricant assisted machining is a novel concept to control the machining zone temperature without polluting the environment. The focus of this study is to explore the possibility of application of graphite as a lubricating medium in drilling of AISI 4340 steel, as a means to reduce the heat generated due to friction, towards finding an alternative to conventional coolants. To this end, an optimized solid lubricant application method, electrostatic solid lubrication experimental setup has been envisaged for effective supply of solid lubricant mixture as a high velocity jet and at an extremely low flow rate to the machining zone, thus meeting environmental requirements. The process performance is judged in terms of thrust force, tool wear, chip thickness, hole diameter and surface finish of machined workpiece keeping the other conditions constant. A comparison with the results obtained in wet and dry machining is also provided. The results obtained from the experiments show the effectiveness of the use of the solid lubricant as a viable alternative to wet and dry machining through reduction in the cutting zone temperature and favourable change in chip–tool and work–tool interaction. The proper selection and application of solid lubricant can lead to low cost, and this concept could emerge as an effective alternative to conventional coolants.     

铝型材生产工艺润滑技术及润滑剂

阐述了我国近20年来铝型材挤压润滑技术和新型润滑剂的应用及发展前景．熔铸结晶器润滑剂,挤压固态润滑剂,高效分离剂,油性喷雾剂,模具润滑剂,型材锯切润滑剂等系列产品构成了中国铝型材挤压润滑技术的基础。     

激光微织构固体润滑表面高温摩擦学性能研究

目的 研究微织构纳米固体润滑剂及碳纳米管(CNTs)添加剂对微织构表面高温润滑性能的影响.方法 采用YLP-HP-1-100-100-100型光纤激光器在Cr4M04V高温轴承钢表面进行织构化处理,并填充二硫化钼(MoS2)-聚酰亚胺(PI)和不同碳纳米管添加含量的MoS2-PI-CNTs复合固体润滑剂.在环-盘接触的MMU-10G高温摩擦磨损试验机上进行了环境温度从室温到400℃的滑动摩擦性能试验.结果 填充含纳米MoS2的复合固体润滑剂的微织构表面的摩擦系数比填充含相同含量微米MoS2的低35％左右.微织构纳米MoS2-PI自润滑表面摩擦系数随碳纳米管含量的增加先减小后增大,当碳纳米管质量分数为6％时,其摩擦系数最小,且比无碳纳米管的低37％左右.在MoS2-PI纳米复合润滑剂中添加6％碳纳米管后,MoS2-PI-CNTs纳米复合润滑剂具有更高的使用温度和更低的摩擦系数.结论 纳米MoS2的润滑效果优于微米MoS2,碳纳米管有利于提高MoS2-PI复合固体润滑剂的耐热性能和润滑减摩性能.     

Materials challenges for solid-oxide fuel cells

Solid-oxide fuel cells (SOFCs) can be used for efficient energy conversion with a variety of fuels. The fuel tolerance of SOFCs is due primarily to the high operating temperature, which accelerates reactions in the fuel. However, the high temperature accelerates unwanted reactions and creates materials challenges, so intermediate-temperature SOFCs are being developed. Reduction of the operating temperature requires solid electrolyte materials with higher conductivities, which can create new compatibility issues. In this paper, materials challenges in the development of SOFCs will be discussed.     

Tribological coatings for lubrication over multiple thermal cycles

Nanocomposite materials demonstrating multiple temperature-adaptive mechanisms including diffusion, oxidation and/or catalysis mechanisms to yield low friction coefficients of < 0.2 from room temperature to 700 °C were combined with diffusion barrier layers in coatings with different architectures (e.g., layer thicknesses, number of layers, etc.) to examine adaptation of contact surface chemistry and morphology over multiple thermal cycles. Multilayered coatings consisting of ceramic-metal nanocomposite adaptive lubricant layers separated by diffusion barriers allowed adaptation to occur only upon exposure of the lubricant layer by wear, which resulted in prolonged wear life at static and cycled temperatures. It was also observed that a relationship between the number of adaptive lubricant layers and the number of thermal cycles existed, where one thermal cycle consumed two adaptive lubricant layers. The thickness of the adaptive coating layers was also important because diffusion- and oxidation-based adaptation in these particular coatings required a minimum volume of solid lubricant material. The surface roughness of the adaptive coating materials played a significant role in their performance within multilayered coatings, where rough coatings (> 100 nm R_a) failed after relatively few sliding cycles. The utility and application of adaptive coatings materials providing lubrication over multiple thermal cycles is discussed.     

镁合金板料数控热渐进成形时的摩擦和润滑性能

利用数控实验机床和摩擦实验研究AZ31镁合金板料数控热渐进成形时的摩擦和润滑机理。结果表明:镁合金薄板在加热条件下可以实现单点渐进成形;固体润滑膜可分为粘结型和吸附陶瓷型两种;固体石墨和MoS2润滑剂的初始摩擦因数均小于0.12,均可保证热渐进成形件获得良好的内外表面质量,没有任何划痕和裂纹等缺陷;吸附多孔陶瓷型固体润滑膜具有润滑和自润滑作用,固体润滑剂颗粒大小对初始摩擦因数有一定影响;固体BN粉末没有起到润滑作用,不能单独作为热渐进成形用固体润滑剂;当温度小于500℃时,固体石墨和MoS2粉末按一定比例配置的润滑复合喷剂的初始摩擦因数均小于为0.2,且表现出一定的协同作用。     

An investigation on solid lubricant moulded grinding wheels

The conventional flood coolants employed in grinding suffer many limitations in performing their functions. They cannot be recommended in the light of ecological and economic manufacture. Application of solid lubricant in grinding has proved to be a feasible alternative to the fluid coolants, if it could be applied in a proper way. Towards finding out an improved method of application of solid lubricant, attempts on development of solid lubricant moulded grinding wheels with various bonding and lubricants have been reported here. Such wheels with resin bonding were successfully made and improved process results were obtained. But the wheel wear depended on the type of the lubricant used.     

Improved wear performance by the incorporation of solid lubricants during thermal spraying

For components that are required to function in sliding or rubbing contact with other parts, degradation often occurs through wear due to friction between the two contacting surfaces. Depending on the nature of the materials being used, the addition of water as a lubricant may introduce corrosion and accelerate the degradation process. To improve the performance and increase the life of these components, coatings may be applied to the regions subject to the greatest wear. These coatings may be engineered to provide internal pockets of solid lubricant in order to improve the tribological performance. In the present study, coatings containing a solid lubricant were produced by thermal spraying feedstock powders consisting of a blend of tungsten carbide-metal and a fluorinated ethylene-propylene (FEP) copolymer-based material. The volume content of this teflon-based material in the feedstock ranged from 3.5 to 36%. These feedstocks were deposited using a high velocity oxy-fuel (HVOF) system to produce coatings having a level of porosity below 2%. Sliding wear tests in which coated rotors were tested in contact with stationary carbon-graphite disks identified an optimum level of teflon-based material in the feedstock formulation required to produce coatings exhibiting minimum wear. This optimum level was in the range of 7 to 17% by volume and depended on the composition of the cermet constituent. Reductions in mass loss for the couples on the order of 50% (an improvement in performance by a factor of approximately 2) were obtained for the best performing compositions, as compared to couples in which the coating contained no solid lubricant.