Al_2O_3连续增强铝基复合材料的干摩擦磨损特性

通过摩擦磨损试验对比研究了含质量分数18%SiC颗粒和不含SiC颗粒的Al2O3连续增强铝基复合材料与NAO(无石棉有机材料)配副的干滑动摩擦磨损行为。结果表明:复合材料在较低的滑动速度(0.628m·s-1)下,最大启动摩擦因数随正压力的增大而降低;在较高的滑动速度(2.512m·s-1)下,最大启动摩擦因数随正压力的增大呈先减小后增大的趋势;正压力一定时,最大启动摩擦因数随滑动速度的增大先减小后增大;含SiC的Al2O3连续增强铝基复合材料比不含SiC的Al2O3连续增强铝基复合材料具有更高的摩擦因数和更好的耐磨性。     

纳米SiO2颗粒和玻璃微珠共混改性超高分子量聚乙烯复合材料的摩擦磨损性能

采用模压成型工艺制备了纳米SiO2颗粒和玻璃微珠共混改性的超高分子量聚乙烯复合材料;研究了相对滑动速度、载荷以及玻璃微珠含量对复合材料摩擦磨损性能的影响,并对磨损形貌和磨损机理进行了分析。结果表明:添加纳米SiO2颗粒和玻璃微珠可以提高复合材料的硬度、压缩弹性模量和摩擦磨损性能;相对滑动速度对复合材料摩擦因数和磨损率有很大的影响;载荷对复合材料的摩擦因数影响不明显,但磨损率随载荷的增加而增大;纳米SiO2颗粒和玻璃微珠混合改性后复合材料的磨损机理主要是粘着磨损和疲劳磨损。     

Ekonol/石墨/MoS2填料对PTFE力学和摩擦磨损性能的影响

研究了Ekonol含量对Ekonol／石墨／MoS2／P，PTFE复合材料的力学性能、摩擦磨损性能的影响，以及滑动速度、载荷对材料摩擦磨损性能的影响；用扫描电子显微镜观察了复合材料磨损后的表面形貌，并探讨了其磨损机制。结果表明：加入填料降低了材料的拉伸强度和弯曲强度，但提高了弯曲模量和硬度；同时填料能提高材料的磨损性能，但使摩擦因数升高了；当Ekonol含量较低时，磨损机制为粘着磨损，随着填料含量的增加，Ekonol分散到基体中，起到了承载作用，阻止了PTFE基体的带状破坏，磨损机制为疲劳磨损和轻微的粘着磨损；摩擦因数随载荷的增大而减小，随滑动速度的增大而增大，在相同的滑动时间内，磨痕宽度随载荷和滑动速度的增大而增大。     

Inconel718与硬质合金摩擦磨损特性的实验研究

利用UMT-2多功能摩擦磨损试验机对镍基合金Inconel 718与硬质合金刀具对偶时的摩擦磨损特性进行研究,揭示法向载荷和滑动速度对摩擦副摩擦因数的影响,通过SEM观察试样摩擦形貌并分析磨损机制.研究结果表明:摩擦副的摩擦因数随着法向载荷的增大而减小,随滑动速度的增大而增大;Inconel 718镍基合金与硬质合金对偶时的磨损机制主要为黏着磨损、磨粒磨损和氧化磨损.     

多绳摩擦提升机树脂基摩擦衬垫的摩擦学行为

采用CFT往复摩擦磨损试验机研究多绳摩擦提升机树脂基摩擦衬垫在干摩擦条件及不同载荷和滑动速度下摩擦因数的变化规律,采用扫描电镜(SEM)对摩擦衬垫试样的磨损形貌进行观察分析。试验结果表明：不同树脂基摩擦衬垫摩擦因数变化规律具有一致性,即摩擦因数随载荷与滑动速度的增加而减小;由于摩擦衬垫的成分不同,其摩擦因数的主要影响因素不同;磨损形式也由于材料的不同出现黏着磨损、疲劳磨损以及热磨损;载荷对摩擦衬垫磨损的影响比滑动速度更显著。     

弹性金属塑料复合材料的摩擦磨损特性研究

在MPX-2000摩擦磨损试验机上，用环盘摩擦副，结合扫描电镜分别评价了弹性金属塑料（EMP）复合材料与钢在油润滑和干摩擦条件下的摩擦磨损特性。结果表明：两种试验条件下，相同滑动速度的摩擦系数随载荷的升高而减小，当载荷为2000N，滑动速度小于3.52m/s时，摩擦系数基于趋于稳定，EMP磨损率随滑动速度和载荷的升高耐增加，但不同试验条件的增幅不高，油润滑下滑动速度小于3.52m/s和干摩擦条件下滑动速度小于1.96m/s时，EMP以微切削，塑性变形和梨沟磨损为主，并在摩擦副两表面形成转移物。     

高速摆动下PTFE编织复合材料干摩擦研究

利用高速摩擦试验机对PTFE编织复合材料进行干摩擦试验,研究不同条件(载荷、速度和湿度)下PTFE编织复合材料干摩擦磨损性能;并利用扫描电子显微镜对不同条件下的磨屑形貌进行分析。结果表明:单因素变化条件下,摩擦因数随载荷和相对湿度的增大而减小,随摩擦速度的增大而增大;磨损量随载荷和速度的增大而增大,但相对湿度的增加可降低磨损;载荷及速度的增加显著影响材料磨损状况。     

SiC颗粒增强铝基复合材料的摩擦磨损性能

制备了不同粒度和含量siC的铝基复合材料,与santana2000轿车用HFM605型非金属摩擦片材料配成摩擦副,于不同压力和速度条件下在MM-200型摩擦磨损试验机上进行干摩擦试验,研究了其摩擦磨损性能。结果表明:摩擦因数随摩擦压力的增大而下降;比较而言,在高速高压时摩擦因数最低;复合材料中SiC粒度和含量对摩擦因数影响不大;随着siC粒度减小、含量增大,复合材料的耐磨性能逐渐提高;热处理可以明显提高复合材料的摩擦因数和耐磨性能。     

Ni-Mo-P-Si3N4化学镀层的摩擦磨损性能研究

Q215碳素钢表面上制备一层Ni-Mo-P-Si3N4复合镀层,在MS-T3000摩擦磨损试验机上进行摩擦磨损试验,记录平均摩擦系数,测试磨痕宽度,计算磨损率,研究该化学镀层的摩擦磨损性能。分析结果表明:载荷不变时,平均摩擦系数和磨损率均随滑动速度的增大而增大;滑动速度不变时,平均摩擦系数和磨损率均随载荷的增大而增大;载荷和滑动速度不变时,平均摩擦系数和磨损率随镀层中Si3N4的体积分数先增大后减小。     

载流条件下黄铜/Al_2O_3/Cu复合材料摩擦副的摩擦磨损性能

采用内氧化法制备了Al2O3/Cu复合材料,以该复合材料为销试样,黄铜(H62)为盘试样进行载流条件下的干滑动摩擦磨损试验,并对销试样摩擦表面进行微观形貌分析.结果表明:磨损率随着电流、速度和载荷的增大而增加,摩擦因数随着电流的增大而增加,随着速度和载荷的增大而减小;电流较小时摩擦表面具有磨粒磨损和粘着磨损的共同特征,电流较大时以粘着磨损为主;在试验条件下,Al2O3/Cu复合材料的抗摩擦磨损性能显著优越于紫铜.     

Dry sliding friction and casing wear behavior of PCD reinforced WC matrix composites

The friction and casing wear properties of PCD reinforced WC matrix composites were investigated using a cylinder-on-ring wear-testing machine against N80 casing steel counterface under dry sliding conditions. The results indicate that the friction and casing wear rate of PCD reinforced WC matrix composites are the lowest among the materials. As the applied load and sliding speed steadily increase, the friction coefficients of PCD reinforced WC matrix composites decrease. In addition, the casing wear rates increase with increasing load, but decline with sliding velocity. The dominant wear mechanism of the PCD composite is the micro-cutting wear, accompanied by adhesive wear.     

Friction and wear behavior of Ni-P coated Si3N4 reinforced Al6061 composites

Al6061 matrix composite reinforced with nickel coated silicon nitride particles were manufactured by liquid metallurgy route. Microstructure and tribological properties of both matrix alloy and developed composites have been evaluated. Dry sliding friction and wear tests were carried out using pin on disk type machine over a load range of 20-100 N and sliding velocities of range 0.31-1.57 m/s. Results revealed that, nickel coated silicon nitride particles are uniformly distributed through out the matrix alloy. Al6061-Ni-P-Si₃N₄ composite exhibited lower coefficient of friction and wear rate compared to matrix alloy. The coefficient of friction of both matrix alloy and developed composite decreased with increase in load up to 80 N. Beyond this, with further increase in the load, the coefficient of friction increased slightly. However, with increase in sliding velocity coefficient of friction of both matrix alloy and developed composite increases continuously. Wear rates of both matrix alloy and developed composites increased with increase in both load and sliding velocity. Worn surfaces and wear debris was examined using scanning electron microscopy (SEM) for possible wear mechanisms. Energy dispersive spectroscope (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) techniques were used to identify the oxides formed on the worn surfaces and wear debris.     

Sliding wear behavior of planar random zinc-alloy matrix composites

The friction and wear behavior of planar random zinc-alloy matrix composites reinforced by discontinuous carbon fibres under dry sliding and lubricated sliding conditions has been investigated using a block-on-ring apparatus. The effects of fibre volume fractions and loads on the sliding wear resistance of the zinc-alloy matrix composites were studied. Experiments were performed within a load range of 50–300 N at a constant sliding velocity of 0.8 m s⁻¹. The composites with different volume fractions of carbon fibres (0–30%) were used as the block specimens, and a medium-carbon steel used as the ring specimen. Increasing the carbon fibre volume fraction significantly decreased the coefficient of friction and wear rates of both the composites and the medium-carbon steel under dry sliding conditions. Under lubricated sliding conditions, however, increasing the carbon fibre volume fraction substantially increased the coefficient of friction, and slightly increased the wear of the medium-carbon steel, while reducing the wear of the composite.Under dry sliding conditions, an increasing load increased not only the wear rates of both the composite and the unreinforced zinc alloy, but also those of their corresponding steel rings. However, the rate of increase of wear with increasing load for both the composite and its corresponding steel ring was much smaller than for the unreinforced zinc alloy and its corresponding steel ring. The coefficient of friction under dry sliding conditions appeared to be constant as load increased within a load range of 50–150 N for both the composite and the unreinforced zinc alloy, but increased at the higher loads. Under any load the coefficient of friction of the composite was lower than half that of the unreinforced zinc alloy under dry sliding conditions.     

Tribological studies of polymer based ceramic–metal composites processed at ambient temperature

Use of composite material is increasing due to economical processing of complicated shapes in large quantities. Addition of fiber/particulates improves the composite strength. In the current study, the tribological characterization of polymer based particulate composites which are processed at room temperature are investigated. The friction and wear behavior of polystyrene reinforced with steel powder (polymer–metal), alumina powder (polymer–ceramic) and a mix of steel and alumina powders (polymer–metal–ceramic) have been investigated under dry sliding conditions using a pin-on-disc tribometer. Tests were conducted at different normal loads and sliding velocities at room temperature. Coefficient of friction and wear loss during the wear tests are determined. Presence of metal and ceramic particulates affects the tribological behavior of the composite. The rise in temperature of the pin during sliding was measured. The rise in contact temperature is influenced by the composition which in turn influences the wear behaviour. The polymer–ceramic composite exhibits the lowest wear rate among the materials investigated.     

Replacing of glass fibres with seed oil palm fibres for tribopolymeric composites

Abstract

In the current study, the possibility of replacing woven glass fibres (WGFs) with seed oil palm fibres (SOPFs) as reinforcements for tribopolymeric composites is investigated. Mainly, two different polyester composites based on woven glass reinforced polyester (WGRP) and seed oil palm reinforced polyester (SOPRP) are developed. Different volume fractions (25, 35, and 45 vol.-%) of SOPFs were considered. The experiments were performed using a block on disc (BOD) machine and the tests were conducted under dry contact condition against smooth stainless steel counterface at 2˙8 m s^–1 sliding velocity, 20 N applied load for different sliding distances (up to 5 km). The wear mechanism was categorised using a Scanning Electron Microscope (SEM). The results revealed that the steady state was reached after 4 km sliding distance for both WGRP and SOPRP composites. Seed oil palm reinforced polyester composites showed very high friction coefficient compared to WGRP. 35 vol.-% SOPRP composite exhibited a promising wear result, i.e. SOPFs are possible to replace WGFs in polymeric composites reinforcements whereas the wear resistance of the synthetic and natural composite were almost the same. The wear mechanisms for SOPRP composites were predominated by microcracks, deformation and pulledout of fibres while in the WGRP composite, abrasive nature was observed.     

Friction and wear scar analysis of carbon nanofiber-reinforced polymeric composite coatings on alumina/aluminum composite

Alumina/aluminum based composites with excellent physical and mechanical properties offer great potential for lightweight, wear resistant, and high temperature applications. The objective of the present research was to investigate a suitable coating material to provide a low coefficient of friction (COF) during sliding contact. The friction behavior of carbon nanofiber-reinforced aerospace polymer coatings prepared by the spin coating technique were investigated. Polymethylmethacrylate (PMMA), bis A polycarbonate, and two biphenyl endcapped poly(arylene ether phosphine oxide) compositions, namely BPETPP-E and 6FETPP-E, were used as the matrices. Pin-on-disc experiments were performed between 440C stainless steel balls and disc samples of coated alumina/aluminum interpenetrating phase composites at 0.2 m/s sliding velocity, in air, at room temperature under 0.25 and 0.74 N normal load. In all cases, formation of a lubricious carbon layer and its transfer to the steel counterface was observed to result in lower COF (∼0.2–0.3). Higher levels of fiber content (40 and 60 wt.% fibers) contributed to a faster formation of this layer. Wear scar analysis showed the dual roles of the carbon nanofibers, serving as solid lubricants and as reinforcement in the coatings. The amount of debris generated and the coverage of the lubricious carbon-rich film on the scar surface was dependent on the matrix material used. Adherent and uniform coverage of a lubricious carbon-rich film at the wear contact with the least amount of debris fragments was obtained only for composite coatings using BPETPP-E and 6FETPP-E matrices.     

A relation between wear volume and sliding time for composite materials

Friction and wear experiments on two graphite fiber-aluminum matrix composites and two commercially pure metals (aluminum and copper) were conducted on a brake-type friction machine. The counterface material was graphitic cast iron. The composite samples were tested with the graphite fibers perpendicular to the counterface; the load varied from 5 to 100 N. The initial sliding velocity varied from 2.0 to 11.4 m s^?1. The wear resistance of the HM-Al 1100 graphite fiber-aluminum matrix composite was found to be more than one order of magnitude better than that of the unreinforced matrix material. With aluminum and copper, the wear volume per braking cycle is proportional to the product of load and sliding distance in accord with both the adhesion and delamination theories of wear. For the two composite materials studied, the wear volume per braking cycle is proportional to the product of load and sliding time which cannot be explained by either of the two wear models. Thus the wear mechanism of composites might be fundamentally different from that of pure metals.     

Wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material

The effect of load range of 30-100 N and speed range of 3-12 m/s on the wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material was investigated. Dry sliding frictional and wear behavior were investigated in a pin-on-disc type apparatus. Automobile friction material was used as pin, while the A359-20 vol% SiC particle composites formed the rotating disc. For comparison, the wear and friction behavior of commercially used cast iron brake rotor were studied. The results showed that the wear rate of the composite disc decreased with increasing the applied load from 30 to 50 N and increased with increasing the load from 50 to100 N. However, the wear rate of the composite disc decreased with increasing the sliding speed at all levels of load applied in the present work. For all sliding speeds, the friction coefficient of the composite disc decreased with applied load. The worn surfaces as well as wear debris were studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyzer and X-ray diffraction (XRD) technique. At load of 50 N and speed range of 3-12 m/s, the worn surface of the composite disc showed a dark adherent layer, which mostly consisted of constituents of the friction material. This layer acted as a protective coating and lubricant, resulting in an improvement in the wear resistance of the composite.