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...     

ZnOw填充铸型尼龙复合材料滚动摩擦磨损行为

研究ZnOw填充铸型尼龙(MC)复合材料的滚动摩擦学性能.结果表明,ZnOw/MC复合材料的拉伸强度随氧化锌晶须含量增加而升高,而断裂伸长率随氧化锌晶须含量的增加而降低;ZnOw/MC复合材料的摩擦因数和磨损率均随氧化锌晶须含量增加而降低;随着氧化锌晶须填充量的增加,磨损.ZnOw/MC复合材料的磨损机制由黏着磨损变为疲劳     

微米氧化铝/尼龙复合材料在不同条件下的滚滑摩擦磨损行为研究

以微米氧化铝(Al2O3)为增强剂,尼龙1010为基体,进行氧化铝/尼龙复合材料在干摩擦和水润滑条件下的滚滑动摩擦磨损实验。通过实验发现,水能降低氧化铝/尼龙复合材料的摩擦因数,但增大了磨损量。水润滑时,尼龙1010材料的摩擦因数为0.09,为干摩擦时的45%;氧化铝/尼龙复合材料的平均摩擦因数为0.1195,比尼龙增加了24.7%,是干摩擦时的42%。水润滑时尼龙1010的磨损量为干摩擦时的2.5倍,复合材料平均磨损量为干摩擦时2.8倍。     

Torsional Wear Behavior of MC Nylon Composites Reinforced with GF: Effect of Angular Displacement

The torsional wear behavior of monomer cast nylon (MC nylon) composites reinforced with glass fiber was studied with a self-made torsional friction tester. The worn surface of MC nylon composites was investigated with a scanning electron microscope. The worn surface of the steel disk was observed with a 3-D profiler. The experimental results indicated that the shape of torque–angular displacement (T–θ) curves changed from elliptic shape to quasi-parallelogram with the angular displacement increased from 5° to 30°. The serious wear characterized with a deep groove occurred at the position of about 1.5–4 mm radius of contact zone on the steel surface. The mass of MC nylon samples increased after torsional wear test. The torsional contact area can be divided into three zones: (a) a central stick zone, (b) an intermediate mixed-slipping annulus, and (c) a peripheral sliding annulus. The most serious wear occurred in the intermediate annulus because of the higher contact stress and mixed slip regime. The main wear mechanism of MC nylon samples was adhesive wear and abrasive wear. Plastic deformation of asperities was the character in the central zone. Slight adhesive wear was the main wear mechanism in the peripheral annulus.     

Comparison of tribological behavior of nylon composites filled with zinc oxide particles and whiskers

Mechanical properties and tribological behavior of nylon composites filled with zinc oxides were investigated in this paper. Different effects of ZnO particles and ZnO whiskers filling on the friction and wear behavior of nylon 1010 (PA1010) composites under dry friction condition were observed. The hardness, tensile strength and scratch coefficients of two kinds of nylon composites filled with the ZnO particles and whiskers were measured. Experimental results show that ZnO particles and ZnO whiskers improve the mechanical and tribological properties of nylon composites without affecting the crystallinity of nylon matrix. Hardness, tensile strength and scratch coefficient of composites are increased by the addition of ZnO particles and ZnO whiskers. Filler shape has little effect on the friction coefficients of nylon-based composites. These composites filled with particles and whiskers have nearly the same friction coefficients which locate between 0.4 and 0.45. The wear rates of composites are strongly dependent on filler shape and filler content. Particle-filled composites exhibit the lower wear rates than whisker-filled composites when the content of filler is lower than 10 wt.%. After that, the case is reversed. Ploughing and adhesion are the main wear mechanisms of composites with the addition of both ZnO particles and ZnO whiskers.     

Triboelectrification Electrostatic Potential of MC Nylon 6 under Point Contact Dry Sliding

The triboelectrification electrostatic potential of MC nylon 6 and its influence factors have not been investigated to date. Here, we report on our study of the interaction of tribological behaviors and triboelectrification electrostatic potential for the prevention or application of triboelectrification. The equipment we used to polymerize insulation materials and for instantaneously monitoring the dynamic variations of triboelectrification electrostatic potential, friction coefficient, and temperature at the tribo-interface was self-designed. The dynamic variations in the triboelectrification electrostatic potential of the polymer insulation materials under dry sliding were investigated using this equipment. An obvious influence on magnitude and change tendency of the triboelectrification electrostatic potential of MC nylon 6 could be produced only when the combined action of load (P) and speed (V) made PV values reach a certain degree. After MC nylon 6 rubbing against the bearing steel, the triboelectrification electrostatic potential of MC nylon 6 was not constant, and it could even abruptly drop from hundreds of volts to 0, especially under severe sliding conditions. A positive charge existed on the tribo-surface of MC nylon 6 and a negative charge existed on the tribo-surface of the counterpart steel. During the severe wear process, the experimental conditions, wear rate, the formation of transfer film, and the fraction of film on the counterpart as well as frictional heat were the most significant interaction effects on the abrupt change in the triboelectrification electrostatic potential among all factors studied. The interaction of tribological behaviors and triboelectrification electrostatic potential was clearly not a simple physical mechanism, which might be influenced by the external conditions and internal integration.     

Friction and wear properties of Kevlar pulp reinforced epoxy composites under dry sliding condition

In this work, the friction and wear properties of Kevlar pulp reinforced epoxy composites against GCr15 steel under dry sliding condition were evaluated on a reciprocating ball-on-block UMT-2MT tribometer. The effects of Kevlar pulp content on tribological properties of the composites were investigated. The worn surface morphologies of neat epoxy and its composites were examined by scanning electron microscopy (SEM) and the wear mechanisms discussed. The results show that the incorporation of Kevlar pulp into epoxy contributed to improve the friction and wear behavior considerably. The maximum wear reduction was obtained when the content of Kevlar pulp is 40 vol%. The friction coefficient of epoxy and its composites increased with load while increase in the sliding frequency induced a reverse effect. Fatigue wear and scuffing were notable for the neat epoxy. The fatigue cracks were greatly abated when the filler content was 40 vol%. The wear grooves appeared on the worn surface at higher filler content.     

Tribological behavior of natural fiber reinforced PLA composites

The application spectrum of natural fiber reinforced polymer composites is growing rapidly in various engineering fields. The present study explores the possibilities of reinforcing thermoplastic bio-polymer with locally available inexpensive plant fibers for developing a new tribo-material. Three different types of natural fibers (nettle, grewia optiva and sisal) were incorporated into PLA polymer to develop laminated composites using a hot compression technique. TGA analysis was carried out to investigate the thermal stability of developed composites. Wear and frictional characteristics of developed composites were investigated under dry contact condition at different operating parameters, such as applied load (10–30 N), sliding speed (1–3 m/s) and sliding distance (1000–3000 m). The experimental results indicate that incorporation of natural fiber mats into PLA matrix significantly improves the wear behavior of neat polymer. There was 10–44% reduction in friction coefficient and more than 70% reduction in specific wear rate of developed composites as compared to neat PLA. The worn surface morphology was studied using scanning electron microscope (SEM) to analyze the wear mechanism in different types of developed composites.     

Structure and Micromorphology of Wear Debris of MC Nylon 6 under Dry Sliding: Correlation with Wear Mechanisms

The structure and micromorphology of wear debris of MC nylon 6 under dry sliding were investigated by FTIR, XRD, DSC, and FESEM, and the 3D surface topographies of friction materials before and after the friction test were observed, which will be helpful in understanding the friction and wear processes. The primary crystalline phase of both the unworn MC nylon 6 and the wear debris were α crystal, but the crystallinity of the latter was higher than that of the former. The proportion of α ₂ (002 + 202) planes increased and the reflection from the α ₁ (200) planes was suppressed in the wear debris, indicating a preferential arrangement of α ₂ (002 + 202) on the surface of the wear debris. The transition in structure of the wear debris originated from the activation of the chain segments due to the thermodynamic effects. The thermodynamic effects and high chain segment mobility resulted in the hydrogen bonding whose interchain distance is a larger rupture or even chain scission. MC nylon 6 was severely worn due to the contribution of the tearing force that resulted from the combined action of the tribo-interface adhesion and the shearing effect during friction, whereas no damage happened on the worn surface of the counterpart steel pin even if under severe sliding conditions.     

Preparation and characterization of single-walled carbon nanotube/nylon 6, 6 nanocomposites

Morphological, thermal, mechanical, and solvent uptake was characterized for neat nylon 6, 6 and functionalized single-walled carbon nanotube/nylon 6, 6. Single-walled carbon nanotubes were functionalized by acid which introduced carboxyl groups on the nanotubes. Scanning electron micrographs of the fractured surfaces of the nanocomposites suggested that the functionalized single-walled carbon nanotubes were dispersed and embedded within the nylon 6, 6 polymer matrix. Polarized optical micrographs showed that the size of spherulites of the nanocomposites decreased, which may be due to nucleation of the carbon nanotubes. Thermogravimetric analysis showed that the stability of the functionalized single-walled carbon nanotubes/nylon 6, 6 nanocomposites was higher by 28–35°C than neat nylon 6, 6. The uptake of solvent by the functionalized single-walled carbon nanotube/nylon 6, 6 was lower than the neat nylon 6, 6, which may be due to the hydrophobic nature of functionalized single-walled carbon nanotubes and their interaction with the polymer.     

碳纤维增强尼龙1010复合材料的摩擦磨损性能及磨损机理研究

以注塑成型法制备了尼龙1010及碳纤维(CF)增强尼龙1010复合材料，研究了CF含量和载荷对材料摩擦学性能和磨损机制的影响。结果表明，CF的加入可显著改善尼龙的摩擦学性能，以体积分数为20％的CF增强尼龙1010复合材料的耐磨性能最好。较低的CF含量下复合材料磨损表面主要受到对偶钢环上微凸峰的切削和犁沟作用，较高载荷时发生了热疲劳剥层磨损；随着CF含量增加，复合材料表面在较高载荷时产生明显疲劳断裂，并使对偶钢环产生较剧烈磨损。     

氧化物/尼龙1010复合材料滚动疲劳行为研究

以我国自主研制的尼龙1010为基体，氧化铁（Fe3O4）和氧化铜（CuO）为增强剂，进行氧化物／尼龙复合材料的滚动疲劳实验，研究氧化物／尼龙复合材料的滚动疲劳机制。通过实验发现周期性应力导致在材料临界深处形成显微裂纹和显微空穴成核，裂纹扩展导致形成片晶形磨屑，显微裂纹和显微空穴成核是剥层磨损的主要因素。氧化物颗粒割裂了尼龙1010的基体，在接触应力和摩擦热的复合作用下，表面金属氧化物颗粒由于复合材料表面界面疲劳开裂而剥落，形成表面疲劳。30％CuO／尼龙1010复合材料的抗滚动疲劳磨损性能最好，疲劳磨损量只有尼龙的70％左右；10％Fe3O4／尼龙1010复合材料耐磨性能最差，滚动疲劳磨损量是尼龙的2．4倍。     

Tribological Investigation of MC PA6 Reinforced by Boron Nitride of Single Layer

Monomer casting polyamide 6 (MC PA6)/boron nitride of single layer (SBN) nanocomposites were successfully synthesized by in situ ring-opening polymerization. SBN was prepared by sonication assisted with solution beforehand. Studies on frictional and wear performance of the nanocomposites were carried out on a block-on-ring tester. The results showed that the nanocomposites had lower wear rates and friction coefficients in comparison with neat MC PA6. The incorporation of 0.25 wt% SBN into MC PA6 significantly reduced wear and friction under dry sliding; however, with further increasing the SBN loading, both wear rate and friction coefficient began to increase. The SEM micrographs of the worn surface revealed their friction and wear mechanisms. Pure MCPA6 was characterized by severe lamellar spalling with adhesive wear being the major wear form which caused high friction and wear. The wear modes of the nanocomposites became mainly abrasive wear with lower content of SBN and displayed fatigue wear with higher content of SBN. The morphology of a uniform transfer film on the counterpart ring and fine wear debris for the nanocomposites corresponded to the improved tribological performance.     

润滑油添加剂对聚合物材料摩擦磨损性能的影响研究

利用MM－200型磨损试验机考察了ZDDP对聚合物材料（PTFE、PI及MCPA）－GCr15轴承钢摩擦副摩擦磨损性能的影响。研究发现，液体石蜡及含ZDDP的液体石蜡润滑均可大幅度改善聚合物材料的摩擦磨损性能，且使其摩擦系数比干摩擦时降低一个数量级，摩擦副表面的ZDDP吸附膜均在不同程度上提高聚合物材料的耐磨性，但其对聚合物材料的摩擦性能影响不大。     

Friction and wear of highly stressed thermoplastic bearings under dry sliding conditions

The friction and wear behavior of sliding bearings made from high temperature thermoplastics was investigated to determine the possibility of dry sliding applications. A test apparatus for plain bearing testing was designed and built to enable load, speed, and temperature to be controlled and temperature, friction and wear to be continuously monitored.Bulk material bearings (polyaryletherketone-based composites and neat polybenzimidazole) and metal-thermoplastic compound bearings with a sliding layer of polyetheretherketone were investigated. Their suitability for dry sliding bearing applications was assessed using the values of friction coefficient, wear rate and friction induced temperature.In general, the operating performance is mainly influenced by the operating conditions and the precise construction of the bearing. A fiber reinforcement of the thermoplastic matrix is necessary at high loads, whereas it is unnecessary at low loads. A further increase of the operational limits is made possible by improving the heat conduction from the contact area, as comparison with results of pin-on-disk investigations indicates. The materials tested provide operation of dry sliding bearings to temperatures over 200°C.     

氧化锌晶须增强尼龙复合材料蠕滑特性

使用自制牵引滚动摩擦试验机测试氧化锌晶须(ZnOw)增强尼龙(Polyamide,PA)复合材料的滑移率—牵引力系数特性曲线,采用赫兹理论分析复合材料45钢的接触特性,并根据复合材料的粘弹性模型分析粘弹性对牵引力系数的影响。结果表明,ZnOw/PA复合材料的牵引力系数随滑移率先线性增大,在滑移率为5%～15%范围内,牵引力系数增至最大,然后则随滑移率增加逐渐减小并趋于稳定。牵引滚动特性受ZnOw的质量分数和试验正压力的影响。复合材料的粘弹性特性对复合材料的牵引力系数影响较小。复合材料的牵引力系数主要取决于其与45钢之间的粘着摩擦,牵引力系数符合大滑移率条件下牵引力系数的数学模型。     

Solid particle erosion of unidirectional fibre reinforced thermoplastic composites

In the present study, the solid particle erosion behaviour of neat PEEK matrix and unidirectional glass fibre (GF) and carbon fibre (CF) reinforced polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) composites has been studied. The erosion experiments have been carried out by using silica sand particles (200 ± 50 μm) as an erodent. Steady state erosion rates of these composites have been evaluated at different impact angles and impact velocities. The neat PEEK exhibited peak erosion rate at 30° impingement angle whereas the composites exhibited a semi-ductile behaviour with peak erosion rate at 60° impact angle. The erosion rate of the glass fibre reinforced composites was higher than that of the carbon fibre reinforced composites. The results show that the fibre orientation has a significant influence on erosion rate only at lower impact angles. The erosion rate of the composites was higher when the particles impact perpendicular to the fibre direction than parallel to the fibres. The morphology of eroded surfaces was observed under scanning electron microscope and damage mechanisms were discussed.     

纳米SiO2对火焰喷涂尼龙1010涂层干摩擦磨损性能的影响

为了探讨纳米SiO2(n-SiO2)对火焰喷涂尼龙(PA)1010涂层干摩擦磨损性能的影响,采用MRH-3型环-块摩擦磨损试验机对不同n-SiO2含量的尼龙1010涂层的干摩擦磨损性能进行了测试;并利用扫描电子显微镜(SEM)对复合涂层的磨损表面进行观察,以探讨n-S iO2对火焰喷涂尼龙1010涂层摩擦磨损性能的影响机制。结果表明:n-SiO2的加入能明显提高尼龙涂层的耐磨性,降低摩擦因数,疲劳磨损、粘附磨损及犁切现象明显减轻;当n-SiO2含量为1.5%(质量分数)时,复合涂层摩擦磨损性能最佳,试验条件下磨损量降低近4倍,摩擦因数降低23%,跑合期降低44%,复合涂层与GCr15钢环对磨时的磨损机制主要为疲劳磨损和轻微的粘附磨损。     

聚丙烯、炭黑和碳纤维共混填充超高分子量聚乙烯复合材料的力学和摩擦磨损性能

采用模压成型的方式制备超高分子量聚乙烯(UHMWPE)复合材料,通过AG-1型电子万能实验机和MM-200型摩擦磨损试验机分别研究填料对复合材料力学性能和摩擦磨损性能的影响,采用光学显微镜分析复合材料磨损表面的形貌。结果表明:聚丙烯(PP)和无机填料炭黑(CB)或CB与碳纤维(CF)混杂填料的加入使UHMWPE复合材料的拉伸强度降低,弯曲模量和硬度增加,其中UHMWPE/PP/CB/CF复合材料的弯曲模量和硬度增幅大于UHM-WPE/PP/CB复合材料。填料的加入可改善UHMWPE复合材料的摩擦磨损性能,当填料的质量分数为5%时,UHMWPE复合材料的摩擦磨损性能最好,且UHMWPE/PP/CB/CF复合材料的耐磨性能优于UHMWPE/PP/CB复合材料。与UHM-WPE相比,UHMWPE/PP/CB/CF复合材料的摩擦因数和磨痕宽度分别下降了10%和44%,UHMWPE/PP/CB复合材料则分别下降了12%和42%。光学显微镜观察表明填料的加入大大改善了UHMWPE的磨粒磨损,复合材料表面以较浅的犁沟磨损为主要特征。     

前混合磨料水射流系统流化器密封套筒的选材

为了保证流化器高压切换阀的正常工作,需要加工与其相配套的密封套筒,以起到保证系统压力恒定不变,在高压下平稳切换磨料罐的作用。为选择合适的密封套筒材料,确保流化器切换阀的密封性和耐磨性,分别在干摩擦、水润滑和油润滑条件下对含不同质量分数短玻璃纤维的复合尼龙材料进行了摩擦学试验。结果表明,在油润滑条件下,含玻璃纤维33%左右的尼龙复合材料具有最佳的抗磨性和较小的摩擦阻力。并根据制备的复合材料,成功研制出符合系统要求的密封套筒。