Effects of solid lubricants on friction and wear behaviors of the phenolic coating under different friction conditions

The phenolic coating filled with micro-MoS₂ or micro-graphite was prepared by spraying the coating precursors. The friction and wear behaviors of the unfilled and filled phenolic composite coating sliding against the steel ring were evaluated on an MHK-500 friction and wear tester under dry friction and under water lubrication conditions. The worn surfaces of the unfilled and filled phenolic coating and the transfer films formed on the surface of the steel ring were investigated using a scanning electron microscope (SEM) and an optical microscope (OM), respectively. FTIR analysis was performed to detect the chemical changes of the composite coating under different lubrication conditions. It was found that addition of graphite was effective in enhancing the wear life of the phenolic coating. Especially, the anti-wear ability of the phenolic coating was best when the content of graphite is 10 wt.%. However, the MoS₂ as filler was harmful to the friction and wear behaviors of the phenolic coating. The character of the fillers varied with the types of the solid lubricants and the transfer films of varied features formed on the counterpart steel ring, largely accounted for the different friction and wear behaviors of the unfilled and filled phenolic composite coating. Compared with under dry sliding, the phenolic composite coating filled with 10 wt.% MoS₂ or 10 wt.% graphite had lower friction coefficients and lower wear life under water lubrication. Since water hindered the formation of transferred films, and might penetrate and corrode the filler-matrix interface, the anti-wear ability of the phenolic composite coating reinforced with MoS₂ or graphite deteriorated under water lubrication.     

石墨增强聚酰亚胺在海水中的摩擦学性能

目的为石墨增强聚酰亚胺复合材料在海水环境下的摩擦学应用提供实验依据。方法利用SST-ST销/盘摩擦试验机,研究了质量分数为15%石墨增强聚酰亚胺复合材料与17-4PH不锈钢组成的摩擦副在海水介质中的摩擦学性能,并与干摩擦和纯水润滑条件下的摩擦学性能进行比较。结果聚酰亚胺复合材料在干摩擦下的摩擦系数和磨损体积最大,分别为0.134、1.930 mm~3。干摩擦条件下,聚酰亚胺复合材料的磨损表面存在较深的犁沟,在犁沟周围出现了材料塑性流动及粘着剥落现象,对偶件表面有聚酰亚胺复合材料转移。磨损机理主要表现为磨粒磨损、材料塑性变形以及粘着和剥落。在纯水润滑下,聚酰亚胺复合材料表面存在较多材料粘着撕裂现象,同时存在宽浅不一的犁沟,磨损机理主要为粘着磨损和磨粒磨损。在海水润滑下,复合材料的摩擦系数和磨损体积最小,分别为0.086、1.235 mm~3,材料磨损表面十分光滑,只有沿运动方向存在少量轻微犁沟,磨损机理主要表现为磨粒磨损。结论石墨增强聚酰亚胺复合材料在海水中的摩擦学性能优于干摩擦和纯水环境下的摩擦学性能。     

离子液体润滑下非晶碳膜的载流摩擦磨损行为

目的考察非晶碳膜(amorphous carbon film,a-C)在干摩擦和在离子液体(IL)润滑下的载流摩擦磨损行为特点。方法选取不锈钢、涂覆离子液体的不锈钢、a-C薄膜和涂覆离子液体的a-C薄膜(a-C-IL)分别与不锈钢小球对磨,在直流电流为0.2 A的条件下进行摩擦磨损测试,对比了各种试样的摩擦学行为。通过扫描电镜、表面三维轮廓仪和拉曼光谱对磨痕和磨斑进行分析表征,并讨论各种摩擦副的磨损机制。结果非晶碳膜与离子液体均能有效地降低钢-钢摩擦副在载流条件下的摩擦系数,使得稳定摩擦系数从～0.8分别降低到～0.2和～0.15。当a-C膜与IL进行复合后,进一步降低了a-C膜的载流摩擦系数(～0.1),但是a-C膜的耐磨性能降低。结论在载流摩擦磨损测试下,钢-钢摩擦副的摩擦系数大,磨损严重,伴随轻微的粘着磨损;离子液体可以明显减小摩擦副之间的粘着,降低钢-钢摩擦副的摩擦系数和磨损率。在钢基底上镀a-C薄膜,摩擦过程中a-C磨屑形成的转移膜发生了石墨化,能显著降低摩擦系数,减小磨损率。a-C-IL固液复合薄膜具有比a-C膜更低的载流摩擦系数,但其耐磨性能不如a-C膜。     

钢背UHMWPE纤维织物复合材料的摩擦学性能分析

纤维织物增强钢背复合材料因具备优异的力学与摩擦学性能在航空航海等领域备受关注,在无油或少油工况下具有较好的应用前景。使用改性处理的超高分子量聚乙烯(Ultra-high molecular weight polyethylene,UHMWPE)纤维织物作为增强材料,利用环氧树脂热压在不锈钢环上制备UHMWPE纤维织物增强钢背复合材料,研究其与45钢盘在环-环端面干摩擦状态下的摩擦学特性,考察纤维织物层数与摩擦转速对材料摩擦学性能的影响,对磨损前后复合材料厚度及45钢质量进行测取,利用表面轮廓仪与扫描电子显微镜对复合材料及对偶件磨损面进行观察与分析。结果表明,三种织物结构均能改善不锈钢的摩擦磨损特性,其中一层织物结构所表现的综合摩擦特性最好,在试验工况下摩擦因数与磨损率平均降低了77.7%与67.2%,在试验工况下主要发生磨粒磨损;二层与三层织物由于具备下层织物的支撑,故在较高转速下能保持材料自身良好的摩擦学特性,二层织物在试验工况下摩擦因数与磨损率平均降低了71.5%与65.7%,三层织物则为73.1%与60.3%,由于摩擦热量的积聚同时伴有树脂碎屑与破碎纤维的加入,其在高速下主要经历黏着磨损与疲劳磨损。试验表明,织物结构于干摩擦工况下表现出较优的摩擦特性与可靠性,能较好地胜任无油或少油作业。     

Tribological behavior of high specific strength PTFE-Al alloy composite

Solid lubricants lead to substantial weight savings relative to the use of liquid lubricant, especially in the weight-conscious aerospace industry. A new PTFE-Al alloy composite（A） containing 60% area proportion of PTFE composite was developed. Another type of common metal-plastics multilayer composite, also called DU, was selected for a comparative investigation. Friction and wear tests were carried out in an oscillating sliding tribotester in air at an oscillating frequency of 0.13 Hz and contact mean pressures from 10 to 80 MPa. The composites slid against a 38CrMoAlA steel shaft. The results show that the composite A exhibits low coefficient of dry sliding friction less than 0.1 and long wear life of 2 000 m. This is because the composite A can provide a sufficient solid lubrication during the whole tests. SEM examination of the transfer films for the composite A confirms that uniform, thin and coherent transfer films are prerequisites for low friction and good wear resistance.     

铸造铝基复合材料的滑动磨损行为

研究了用搅拌铸造法制备的ＳｉＣ颗粒增强铝基复合材料的滑动磨损行为。对载荷改变时，复合材料在干摩擦和油润滑条件下的耐磨性进行了较细致的分析，并对影响该复合材料滑动磨损行为的因素进行了讨论。结果表明：无论在干摩擦还是油润滑条件下，复合材料均比基体耐磨，但在油润滑条件下，尤其是高载时，复合材料的耐磨性能更突出地显示出来     

Tribological Behaviour and Cutting Performance of PVD-TiN Coating/Substrate System with Discontinuous Surface Architecture

TiN coating was deposited by arc evaporation PVD (physical vapor deposition) onto tool steel. A netted screen made of the stainless steel was placed between substrate and vaporizer in order to get discontinuous TiN coatings. Three kinds of surface condition (uncoated, continuous and discontinuous TiN coatings) were prepared and examined for their performance. Tribological behavior was investigated by means of dry and lubricated sliding tests at room temperature and 200 °C, on a disk-on-block and sphere-on-flat tribometer. The results show that the discontinuous TiN coating significantly decreases both the wear and the wearing speed of tool steel under sliding tests, and reduces friction under conditions of bidirectional sliding. In the three kinds of surface condition, the discontinuously coating has superiority for high speed cutting owing to its lifetime increasing compared with uncoated and continuously coated.     

激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层组织与耐磨性

以39Mo-35Ni-26Si(w％)合金粉末为原料，采用激光熔覆技术，在1Cr18Ni9Ti不锈钢基材表面翩得以Mo2Ni3Si金属硅化物为初生相，以Mo2Ni3Si／NiSi共晶相为基体的金属硅化物耐磨复合材料涂层。涂层的常温干滑动磨损试验结果表明，在磨损过程中，Mo2Ni3Si／NiSi共晶相轻微地优先磨损，Mo2Ni3Si金属硅化物微微凸出于磨损表面，起到抗磨的骨干作用。由于Mo2Ni3Si金属硅化物具有很高的硬度和很强的原子间键合力，在磨损过程中难于变形和粘着，激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层具有优异的耐磨性，与1Cr18Ni9Ti标样相比，涂层的耐磨性提高了56倍。     

TiN-Coating Effects on Stainless Steel Tribological Behavior Under Dry and Lubricated Conditions

The tribological properties of magnetron sputtered titanium nitride coating on 316L steel, sliding against Si₃N₄ ceramic ball under dry friction and synthetic perspiration lubrication, were investigated. The morphology of the worn surface and the elemental composition of the wear debris were examined by scanning electron microscopy and energy dispersive spectroscopy. TiN coatings and 316L stainless steel had better tribological properties under synthetic perspiration lubrication than under dry friction. Among the three tested materials (316L, 1.6 and 2.4 μm TiN coatings), 2.4 μm TiN coating exhibits the best wear resistance. The difference in wear damage of the three materials is essentially due to the wear mechanisms. For the TiN coating, the damage is attributed to abrasive wear under synthetic perspiration lubrication and the complex interactive mechanisms, including abrasive and adhesive wear, along with plastic deformation, under dry friction.     

Research of the Tribological Properties of the Surface on 16Mn Steel by Plasma Nitriding and S-N-C Plasmas Composite Treatment

Sulfide layer with certain thickness was made on the nitrided surface of 16Mn steel by means of plasma S-C-N composite treatment. Under half lubricated condition, friction coefficient and wear loss of LY12 aluminum alloy were measured in sliding against samples of 16Mn treated by cubrizing and sulphiding respectively; In order to avoid the transfer of aluminum to the steel that lead to the inaccurate measurement of wear loss of carburized samples, Grl5 steel was adopted as counterpart face to measure the wear loss of them. SEM and EDAX were used for the morphological and chemical characterization of the wear surface and longitudinal cross-sections beneath sliding surface of LY12 aluminum alloy cirque and the wear tacks of the carburized samples and sulphided samples. Results show: The surface roughness,wear rate, average friction coefficient and magnitude of friction fluctuations of LY12 aluminum alloy cirque sliding against sulphided sample were all lower than sliding against carburized sample; Compared with carburized layer, sulfide layer of 16Mn steel can not only efficiently prevent the occurrence of adhesion when sliding against LY12 aluminum alloy, but also greatly lower the wear loss when sliding against Gr15 steel.     

锡对铸造铝-石墨颗粒复合材料摩擦性能的影响

采用M-200摩擦磨损试验机,对加入固体润滑剂锡的铸造铝-3%石墨颗粒复合材料的摩擦性能进行试验研究,研究表明:锡和石墨具有优越的协同润滑效应,加锡可极大提高铝-石墨颗粒复合材料的减摩性能,使有润滑的摩擦系数达到0.004～0.005。同时锡和石墨的协同润滑作用存在最佳配合,在本试验条件下,加约7%的锡时,协同润滑效应最佳。加锡不能改善干摩擦时铝-3%石墨颗粒复合材料的耐磨性,但能极大提高有润滑时复合材料的耐磨性。并对加锡的铝-石墨颗粒复合材料的磨损机理进行了初步研究,其在干摩擦时的磨损机理为粘着迁移、粘着磨损和磨料磨损,在半干摩擦时的磨损机理为疲劳磨损和磨料磨损。     

Abrasion Mechanism of Stainless Steel/Carbon Fiber-Reinforced Polyether-Ether-Ketone (PEEK) Composites

A new type of composite material, stainless steel fiber and carbon fiber-reinforced polyether-ether-ketone (PEEK), was investigated to study its friction and wear properties and mechanisms. The friction materials containing 11 ingredients were hot-pressed and tested using a pad-on-disc type wear tester under unlubricated sliding friction and wear conditions at a constant sliding speed. The worn surface morphology was observed by Field-emission Scanning Electron Microscope (FE-SEM) and Atomic Force Microscope (AFM). The role of transfer film was studied using X-ray photoelectron spectroscopy (XPS) to investigate the thermal decomposition of the friction material. The fade ratio of the composites was only 4.8%, the recovery ratio 107%, and the total wear ratio was as low as 0.99 × 10⁻⁷ cm³(N m)⁻¹, showing the perfect properties of heat stability and recovery, as well as high antiwear ability of the composites. Adherence abrasion and particle abrasion take place at higher temperature. A transfer film is formed, which may improve abrasive resistant performance to get stable friction coefficient and low abrasion value for composite friction materials.     

Study On the Tribological Behavior of the Arc-added Glow Discharge Plasma Non-hydrogen Carburization On Titanium Alloy Surfaces

This paper introduces a new titanium alloys surface strengthening treatment by using the arc-added glow discharge plasmas non-hydrogen carburization technique. High purity and high strength graphite is selected as cooling cathode arc source for supplying carbon atoms and particle, which migrate to the titanium alloy(Ti6Al4V) surface and form modified layer. Thus, the hydrogen embrittlement is avoided while the tfibological behavior of the titanium alloy surface is improved in the respects of anti-friction and anti-wear ability.The tribological behavior of the modified layer under dry sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The results showed that the modified layer obtained a thickness of 30μm at 980℃, 30minutes. The microhardness of the Ti6Al4V alloy surface attained 936 HV, which was much larger than that of the Ti6AI4V alloy. The Ti6AI4V alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface modified layer experienced much abated adhesion wear and scuffing under the same testing condition. This could be attributed to the carbon dement with different modalities exists in the modified layer.The modified layer showed good friction-reducing and fair anti-wear ability in dry sliding against the steel. Using the SEM,XRD and XPS, the phase structure and morphology of the carburization modified layer was analyzed.     

高速滚动轴承用TiNi60合金的润滑性能及油气润滑两相流流型的数值计算(英文)

销-盘摩擦磨损实验研究表明:TiNi60合金在PAO油润滑下具有优异的摩擦学性能,稳定阶段的平均摩擦系数由干摩擦的0.6降低到油润滑下的0.1,而且非常稳定。从SEM磨损形貌图可知:油润滑下TiNi60合金的磨损表面光滑,粘着磨损明显减弱。在实际研究中,仿真计算是获得高速滚动轴承在油气润滑下各项工作性能数据的有效方法。采用FLUENT数值计算了油-气两相流在水平管子内的流型分布,得到了最佳油、气的进口速度,为高速滚动轴承用TiNi60合金在油气润滑下的使用提供了理论依据。仿真计算结果表明:当空气速度为10m/s和油速度为0.05m/s时,可以得到最佳的环状流型分布。     

Wear behavior of Al2O3-TiCN composite ceramic sliding on stainless steel

It is well known that austenitic stainless steel AISI302 is relatively difficult to cut. In order to investigate the wear behavior of Al₂O₃-TiCN composite ceramic when machining austenitic stainless steels, a blockon-ring tribometer was used to simulate a real machining process. The test results showed that the wear of both the ceramic and the stainless steel increased rapidly with increasing load and speed. The boundary lubrication actions of water and oil used in this test could not reduce the wear of the rubbing materials. Scanning electron microscopy and energy-dispersive x-ray spectroscopy analyses identified material transferred between the ceramic and the stainless steel surfaces in rubbing process. On the one hand, stainless steel transferred on the ceramic surface because of adhesion; on the other, some ceramic fragments caused by microfracture of the ceramic were found to be embedded in the worn stainless steel surface. The wear of Al₂O₃-TiCN ceramic sliding against stainless steel was caused primarily by adhesion between the rubbing surfaces and the microfracture of the ceramic.     

Tribological behavior of TSP reinforced WC matrix composites sliding against N80 casing steel lubricated by water-based drilling fluid

The friction and casing wear behavior of TSP composites sliding against N80 casing steels and lubricated by drilling fluids were investigated. It was found that the water-based drilling fluid reduced friction coefficient and casing wear effectively. The surface lubricating films with iron oxide grains formed on the surface of casings are all observed for the three hardbandings, while the discontinuous lubrication film of N3 alloy might account for the higher casing wear therewith. The lowest friction coefficient and casing wear was recorded for TSP composite under load of 10–130 N. This is dependent on the adsorbed lubricating liquid on the rubbing surface and the formation of height difference between the TSP part and the WC matrix part.     

Optimum Me-DLC coatings and hard coatings for tribological performance

In this study, hard coatings (TiN, TiCN, CrN, and CrCN) and Me-DLC coatings (Ti _x%-C:H and Cr _x%-C:H) were deposited on tungsten carbide (WC) substrate by multiarc physical vapor deposition (MAPVD) and unbalanced magnetron (UBM) sputtering, respectively. Counterbodies of the AISI 1045 steel cylinder and the AA7075T651 aluminum cylinder were used in the cylinder-on-disk, line-contact wear mode under dry condition; a counterbody of the AISI 52100 steel ball was used in the ball-on-disk, point-contact wear mode, under both dry and lubricated conditions. All wear tests were conducted with a reciprocating machine. After the tests, the most suitable coating for various counterbodies and test environments was selected. For the coating/1045 steel cylinder, the Ti_10%-C:H coating possesses excellent tribological characteristics. For the coating/7075T651 aluminum cylinder, hard coatings display excellent wear resistance. For the coating/steel ball, CrCN and CrN coatings display very little wear under both dry and lubricated conditions. On TiN and TiCN coatings, special wear mechanisms of material transfer, adhesion wear, and fatigue fracture occurred during initial tests under kerosene lubrication.     

生理盐水润滑下PEEK/WK复合材料的摩擦学性能

为研究生理盐水润滑条件下碳酸钙晶须含量、载荷大小、滑动速度因素对PEEK/CaCO3复合材料摩擦学性能的影响规律,并考察复合材料的摩擦学稳定性,在自制改性偶联剂处理晶须表面的基础上制备了PEEK/CaCO3复合材料,利用MMW1A立式万能摩擦磨损试验机对复合材料的摩擦学性能进行测试,用扫描电子显微镜(SEM)对磨损表面形貌进行扫描分析表征。结果表明,晶须含量对复合材料摩擦学性能影响明显,在0.9%的生理盐水润滑条件下PEEK/CaCO3复合材料随着晶须含量的增加,摩擦因数及比磨损率均呈现先减小后增大现象;当晶须质量分数为15%左右时,复合材料的摩擦因数达到最低值,同时比磨损量相对最低,复合材料与摩擦副的磨合过程相对平稳,具有较好的摩擦学性能,表现为粘着腐蚀磨损特征。外加载荷、滑动速度增大,材料的摩擦因数增大,比磨损率增加。     

Effect of porosity on wear resistance of SiCp/Cu composites prepared by pressureless infiltration

The influence of porosity on the wear behavior of high volume fraction （61%） SiCp/Cu composite produced by pressureless infiltration was studied using a sliding, reciprocating and vibrating（SRV） machine. SiCp/Cu composites slid against hardened GCr15 bearing steel ball in the load range of 40-200 N. The results show that the wear rate increases with increasing porosity. The composite containing low porosity shows excellent wear resistance, which is attributed to the presence of mechanically mixed layer on the worn surface. In this case, the dominant wear mechanism is oxidative wear. Comparatively, the composite containing high porosity exhibits inferior wear resistance. Fracture and spalling of the particles are considered as the main causes of severe wear. Third body abrasion is the controlling wear mechanism. In addition, porosity has more important influence on wear rate at high load than at low load. This is associated with the fact that the fracture and spalling of particles is a process of crack initiation and propagation. At lower load, the pores beneath the worn surface can not propagate significantly, while the pores become unstable and easily propagate under high load, which results in a higher wear rate.     

Friction and wear properties of ultra-high molecular mass polyethylene reinforced with Al2O3 nano-particle

The ultra-high molecular mass polyethylene (UHMMPE) as an artificial joint acetabular material was filled with nano-powder of Al2O3 of various mass fractions. The effect of Al2O3 mass fraction on the hardness, wetting property and tribological properties of the Al2O3-UHMMPE composites under dry friction sliding against both stainless steel and Ti-6Al-4V alloy was investigated. The morphologies of the worn surfaces of composites were observed with optical microscope. The results show that, wetting property and wear resistance of the composites are improved by filling Al2O3, while the friction coefficient is decreased largely under dry friction as compared with that of the unfilled UHMMPE. This is attributed to the reinforcing function of the nano-powder of Al2O3 in the composites. The wear of UHMMPE is dominated by plowing, plastic deformation and fatigue wear; while the Al2O3-UHMMPE composites are characterized by the mild fatigue wear.