纳米碳酸钙颗粒作为钛基脂添加剂的摩擦学性能

采用四球摩擦磨损试验机研究纳米碳酸钙作为复合钛基脂添加剂的摩擦磨损性能，利用X射线光电子能谱仪分析试验后钢球磨斑表面主要元素的化学状态，用扫描电子显微镜观察钢球的磨斑表面形貌。结果表明：纳米碳酸钙作为复合钛基脂添加剂具有明显的减摩抗磨效果；其中纳米碳酸钙质量分数为时3%复合钛基脂具有佳的减摩抗磨效果，与纯钛基脂相比，可使平均摩擦因数降低14.9 %，磨斑直径降低35.1%。在添加纳米碳酸钙的复合钛基脂润滑下，钢球磨斑表面形成了由纳米碳酸钙分解生成的CaO、钛基脂分解生成的TiO2，以及Fe2O3、FeO等无机化合物成分组成的多孔状保护膜，这层保护膜阻止了摩擦表面的直接接触，起到了有效的减摩抗磨效果。     

高速铁路轴箱轴承纳米润滑脂摩擦学性能试验研究

以WS2和Si3N4纳米颗粒作为高速客车轴箱轴承润滑脂添加剂,依据完全析因试验方案,合成了高速客车轴箱轴承纳米润滑脂。采用四球摩擦磨损试验机对其抗磨减摩和抗极压性能进行了研究,使用扫描电子显微镜(SEM)分析了钢球磨斑表面形貌,运用双因素方差分析法探究了WS2-Si3N4复合纳米颗粒对纳米润滑脂润滑性能影响。研究表明:当WS2添加量为1.5%,Si3N4添加量为0.1%时,合成的纳米润滑脂PB值最大,摩擦因数最低,钢球磨斑形貌平整光滑;WS2和Si3N4纳米颗粒均可提高纳米润滑脂的润滑性能,对复合纳米润滑脂润滑性能的提高交互作用显著。     

含纳米CuO锂基润滑脂摩擦学性能研究

为改善锂基润滑脂摩擦学性能,制备不同添加量纳米CuO改性的锂基润滑脂。采用3H-2000PS2比表面及微孔分析仪对纳米CuO粒子进行表征,采用四球摩擦磨损试验机分析纳米CuO添加量对锂基润滑脂摩擦学性能的影响,采用扫描电镜(SEM)和三维形貌分析仪分析试验后钢球磨痕形貌。结果表明:纳米CuO质量分数为0.60%时锂基润滑脂具有最佳的抗磨减摩效果,摩擦因数和磨斑直径较基础脂分别降低24%和12%;一定添加量下,纳米CuO对磨损表面具有修复作用,含质量分数0.60%纳米氧化铜的润滑脂润滑时,磨损表面具有较低的表面粗糙度和较少的犁沟,表现出最佳的抗磨性能。     

含超细SiO_2/MoS_2粉锂基润滑脂摩擦学性能研究

采用四球摩擦磨损试验机研究了纳米SiO_2及超细MoS_2的粒径、添加量和载荷对2~#锂基脂摩擦学性能的影响,并研究了2种超细粉复配比例和载荷对2~#锂基脂摩擦学性能的影响。结果表明:单一纳米SiO_2和超细MoS_2的加入均能明显减小润滑脂的摩擦因数和钢球磨斑直径,纳米SiO_2和超细MoS_2的复配有助于进一步改善含超细粉锂基脂的摩擦学性能。当纳米SiO_2与MoS_2质量比为2∶8,总加入质量分数为2.0%时,润滑脂的摩擦因数和钢球磨斑直径较基础脂分别减小了77.1%和46.42%。利用SEM和EDS分析磨斑表面形貌及元素组成,初步探讨了含超细复合粉润滑脂的抗磨减摩机理。SEM和EDS分析表明:纳米SiO_2在摩擦过程中主要作用是填补磨痕沟壑,而超细MoS_2除填补沟壑外还对摩擦副表面有抛光研磨和形成减摩膜的作用,2种超细粉的协同使润滑脂具有自修复和抗磨、减摩作用。     

钛基脂皂分子结构对其摩擦学性能的影响

采用实验室制脂釜制备出苯甲酸和癸二酸组分钛基脂,考察钛基脂的摩擦磨损性能及承载能力,分析皂分子结构和钛基脂摩擦学性能的关系。利用扫描电子显微镜(SEM)观察钢球的磨斑表面形貌,并用X射线光电子能谱(XPS)分析钢球磨斑表面元素含量,利用红外光谱分析表征钛基脂皂分子结构。结果表明:钛基脂摩擦学性能主要取决于钛基脂皂分子结构;含苯环结构苯甲酸组分钛基脂的抗磨特性优于癸二酸组分钛基脂,而他们的减摩特性和极压性能相同;2种钛基脂润滑下钢球主要的摩擦特征为黏着磨损。含苯环结构的苯甲酸组分钛基脂具有较好抗磨性能主要原因为在摩擦表面上生成了较厚含钛元素的化学沉积膜。     

聚四氟乙烯颗粒在复合钛基脂中的摩擦磨损性能研究

采用实验室制脂釜制备新戊基多元醇酯为基础油的钛基脂和含聚四氟乙烯颗粒的钛基脂,考察了复合钛基脂摩擦学特性,利用扫描电子显微镜和X射线电子能谱仪明察了钢球的磨斑表面形貌和主要元素的化学状态.结果表明,聚四氟乙烯降低了基础脂的摩擦系数和磨斑直径,但没有提高极压性能.钢球的磨损特征为轻微粘着磨损,其减摩抗磨机制为吸附膜和化学沉积膜协同作用的结果.     

纳米二氧化硅对锂基润滑脂摩擦学性能的影响

利用溶胶-凝胶法,以正硅酸乙酯为原料制备了纳米二氧化硅微粒,通过透射电子显微镜对其结构进行了表征,利用四球摩擦磨损试验机测定了添加不同含量纳米二氧化硅锂基润滑脂摩擦学性能,采用扫描电子显微镜观察磨损表面形貌。结果表明:制备的纳米二氧化硅是粒径为60 nm左右的球形微粒,具有很高的表面能和表面活性;纳米二氧化硅作为锂基润滑脂添加剂能够提高最大无卡咬负荷和烧结负荷,降低摩擦因数,添加量为2.0%(质量分数)时的润滑剂性能最好,相对应的钢球磨斑直径最小,摩擦因数最低。     

纳米石墨/聚丙烯酸乙酯复合乳液的合成及其润滑性能研究

采用自由基乳液聚合方法合成了纳米石墨／聚丙烯酸乙酯复合乳液，并用四球摩擦磨损试验机对其润滑性能进行了评估。结果表明，一定浓度的纳米石墨／聚丙烯酸乙酯复合乳液可有效提高水基液的承载能力，降低磨损量。采用IRMM对摩擦磨损试验后的钢球磨斑表面进行分析，结果表明：磨痕变浅，磨斑减小，有效降低了磨损。     

复合组分对复合磺酸钙基润滑脂摩擦磨损性能的影响

制备4种不同组分的复合磺酸钙基润滑脂,采用四球摩擦磨损机和SVR高频线性振动试验机,考察12-羟基硬脂酸钙、硼酸钙对复合磺酸钙基润滑脂摩擦磨损性能的影响,采用XPS分析钢球磨斑表面主要元素的化学状态。结果表明,复合磺酸钙基润滑脂优良的极压性主要来源于层状结构的方解型碳酸钙沉积膜,而不是FeS、CaS、Fe3C、CaC2反应膜;抗磨性归功于硼酸钙、12-羟基硬脂酸钙所形成的极性吸附膜。     

Ni-P-Nano PTFE镀层的制备及摩擦学性能研究

为提高轴承钢表面性能,提出一种化学复合镀工艺。采用“机械搅拌+化学分散”相结合的方式在轴承钢表面制备Ni-P-Nano PTFE镀层,利用UMT摩擦磨损试验机对比研究轴承钢、Ni-P镀层和Ni-P-Nano PTFE镀层的摩擦学性能,并研究不同载荷、不同频率条件下Ni-P-Nano PTFE镀层的摩擦学性能。结果表明：复合镀层表面均匀平整致密,且与基底结合强度高;与轴承钢相比,Ni-P-Nano PTFE镀层的摩擦因数降低了55%,磨损率降低了31.07%,对偶钢球的磨斑直径降低了34.19%;在载荷不高于20 N、频率不高于15 Hz条件下Ni-P-Nano PTFE镀层拥有较长的服役寿命,经过长时间的往复摩擦仍未失效。Ni-P-Nano PTFE镀层能够显著提高轴承钢的抗磨减摩性能,研究结果可以为航空、机械、化工等领域的材料表面设计提供一种新的思路。     

Synthesis,Characterization, and Tribological Behavior of Neopentyl Polyol Ester-Based and Mixed Oil-Based Titanium Complex Grease

Four types of titanium complex grease were synthesized using a 3-l reaction vessel, and their friction and wear behavior were evaluated using a four-ball tester in the presence of two base oils: neopentyl polyol ester and a mixture oil of neopentyl polyol ester, 650SN, and epoxidized soy bean oil (4.5:2.5:1), with two compositions: benzoic acid/stearic acid and sebacic acid/stearic acid. The results indicate that mixed oil-based titanium complex grease has excellent tribological properties. Moreover, compositions affect the physical characteristics of titanium complex grease but have little effect on the friction-reduction, antiwear, and load-carrying capability of the same types of oil-based titanium complex grease. In addition, base oils also affect the tribological property of titanium complex grease. Based on scanning electron microscopy and x-ray photoelectron spectrometer of the worn surfaces of steel balls lubricated with the different types of grease, synergistic boundary lubrication was proposed to illustrate the friction-reduction and antiwear properties of titanium complex grease.     

Experimental study of tribological properties of lithium-based grease with Cu nanoparticle additive

The tribological properties of lithium-based grease with nanometer Cu additive are studied in this paper. The feasibility of Cu nanoparticle as grease additive is evaluated by four ball friction tester. Both the bearing temperature rise and the vibration acceleration at different lubrication states are investigated using the bearing test machine. Results show that when the adding amount of nanometer Cu is 0.25% in grease, the friction coefficient and the wear scar diameter of the steel ball are the smallest. Moreover, the vibration acceleration and temperature rise of bearing in 1171-0.25 lithium-based grease are decreased and the bearing speed limit is improved because of the self-repair role of Cu nanoparticles on bearing rolling surfaces.     

Tribological behaviours of ultrafine Sn/heat treated serpentine powder in grease

Abstract

In order to improve the tribological performance of traditionally based lithium grease, ultrafine serpentine powder of 0·33 μm and Sn powder of 120 nm were prepared by ball mill and direct current arc plasma evaporation respectively. The milled serpentine powder was heat treated at 200, 500, 600 and 800°C in a muffle furnace separately with a four-ball wear test. Then, the tribological behaviours of lithium grease modified with complex powder with different ratios of ultrafine Sn/heat treated serpentine were investigated, and the effects of total concentration and load were discussed too. The optimal performance was achieved by the compound grease with 1 wt-% complex powder and 1∶1 Sn/serpentine powder (heated at 200°C). The friction coefficient and wear scar diameter decreased 25·5 and 42·5% respectively under 392 N compared with pure grease. The compound grease is much more suitable under high load rather than low load.     

碳纳米管基膨润土润滑脂的制备及摩擦学性能研究

为制备摩擦学性能优良的多壁碳纳米管基膨润土润滑脂,采用油酸对多壁碳纳米管(MWCNTs)进行修饰,在实验室自主设计的超声辅助球磨试验装置上,制备在PAO6中均匀稳定分散的多壁碳纳米管悬浮液,并以悬浮液为基础油制备MWCNTs增强的膨润土润滑脂。探讨不同分散方法(球磨分散、超声分散、超声和球磨分散)对多壁碳纳米管分散稳定性的影响,研究润滑脂的摩擦因数、磨斑直径随多壁碳纳米管质量分数的变化。实验结果表明:经油酸修饰的多壁碳纳米管在超声和球磨综合作用下分散稳定性最好;随多壁碳纳米管质量分数的增加,膨润土润滑脂的摩擦因数、磨斑直径先减小后增大,其中多壁碳纳米管质量分数为0.03%时,所制备的膨润土润滑脂摩擦学性能最佳,磨斑直径最小(0.690 mm),比美孚28号航空润滑脂(符合美国军方规格MIL-G81322C,磨斑直径0.807 mm)降低了14.5%。     

Reciprocating Sliding Wear Performance of Hard Coating on Modified Titanium Alloy Surfaces

The high strength, low weight, and outstanding corrosion resistance properties possessed by titanium alloys have led to a wide range of successful applications in aerospace, automotive, and chemical industries and in power generation. Titanium alloys are characterized by poor wear resistance properties and their utilization has been excessive in nontribological applications. Surface texturing is a well-known and effective means of surface modification to improve the tribological properties of sliding surfaces. In the present work, modification of titanium alloy surfaces (Ti6Al4V) was done by lapping and laser surface texturing. The wear-resistant coating, AlCrN, was applied over the modified titanium alloy surfaces, with and without a chromium interlayer. Linear reciprocating sliding wear tests were performed with ball-on-flat contact geometry to evaluate the tribological performance of the coated alloy. The tests were performed under different normal loads for a period of 105 cycles at a frequency of 5 Hz. The friction force between the contact pair and displacement of the ball were simultaneously observed using a force transducer and laser displacement sensor. Optical microscopy was used to quantify the wear volume by measuring the wear scar diameter on both the specimen and the counterbody. Scanning electron microscopy (SEM) was employed to study the morphology of the wear scar. The characteristic behavior of the AlCrN coating such as bonding strength, wear volume, wear rate, and coefficient of friction with the chromium interlayer was evaluated and compared with the coating directly applied over the substrate. The coating on the textured surface, with the chromium interlayer showed better tribological performance.     

The Effect of FeS Solid Lubricant on the Tribological Properties of Bearing Steel under Grease Lubrication

In order to improve the tribological properties of 52100 steel under grease lubrication, FeS solid lubricant was used in two ways. Low-temperature ion-sulfurization technology was utilized to prepare solid lubricant iron sulfide (FeS) films on the surface of 52100 steel, and FeS particles were mixed into the lithium grease as additive. The friction and wear properties were examined systematically on a “ball-on-disc” testing machine. The results showed that the tribological properties of bearing steel under grease lubrication can be improved either by using ion-sulfurization technique or by adding FeS microparticles into the grease. The tribological performance of sulfurized surface lubricated by grease is better than that of a plain surface lubricated by grease containing FeS microparticles at lower load and speed. The plain surface lubricated by the grease containing FeS micropaticles possesses better antiwear property under harsher conditions. The mechanism of the experimental results is discussed in detail.     

Synthetic aluminium complex grease: A tribological evaluation using a four‐ball test

This paper describes the preparation and performance evaluation of a synthetic aluminium complex grease. The aluminium complex grease was prepared in situ by reacting stearic acid and benzoic acid in the presence of a synthetic base oil, polyalphaolefin. The preparation of the soap (aluminium benzoate stearate hydroxide) was monitored using Fourier transform infrared. Two different extreme‐pressure additives blended with the prepared aluminium complex grease were evaluated for their extreme‐pressure activity in four‐ball and Timken tests. These greases exhibited higher Timken OK loads (60 lb), lower values of wear‐scar diameter at higher loads, and higher values of weld load in the four‐ball test than the aluminium complex grease without additive. The blended greases were also found to pass rust and corrosion, oxidation‐stability, and shear‐stability tests. The topography of the specimens after four‐ball testing was studied with scanning electron microscopy.     

单胺基双巯基三嗪衍生物的合成及摩擦学性能研究

为改善锂基脂极压抗磨性能使其适应于更为苛刻的工矿条件,合成了一系列单胺基双巯基三嗪衍生物,使用四球机考察了添加剂在锂基脂中的极压、抗磨、减摩性能。结果表明,此类添加剂均能改善锂基脂的极压、抗磨、减摩性能,碳链最短的2-二正丁胺基-4,6-二巯基-1,3,5-均三嗪(DBAT)的极压性能表现最佳,能够使锂基脂的pB值提高约50%,在不同负荷或不同质量分数的条件下DBAT表现出了最好的抗磨效果。使用SEM与XPS分析钢球表面典型元素的分布情况与化学态,发现由无机硫酸盐、硫化亚铁及有机含氮化合物所组成的保护膜可能是摩擦学性能提高的主要原因。