玻璃纤维增强聚醚醚酮复合材料在水润滑下的摩擦学性能

利用球盘式摩擦磨损试验机考察了玻璃纤维(GF)增强聚醚醚酮(PEEK)复合材料在干摩擦和水润滑条件下的摩擦磨损性能,并探讨了其磨损机理。结果表明:在干摩擦和水润滑条件下,PEEK和GF/PEEK的摩擦因数和磨损率均随载荷和对磨时间的增加逐渐增大并趋于稳定,GF的加入可以显著降低GF/PEEK复合材料的摩擦因数和磨损率;在水润滑条件下,PEEK和GF/PEEK的摩擦因数和磨损率比干摩擦下显著降低。干摩擦下,PEEK以黏着磨损和磨粒磨损的混合磨损形式为主,水润滑条件下,磨损方式主要是以轻微的黏着磨损为主;干摩擦下,GF/PEEK磨损表面有大量的微观断裂裂纹和破碎,以磨粒磨损和疲劳磨损为主,水润滑条件下,磨损表面仅有微观切削的痕迹,磨损方式以轻微磨粒磨损为主。由于水的冷却和润滑作用,使得复合材料向对偶钢球的黏着转移明显减弱,同时阻止了对偶钢球上的Fe向复合材料磨损表面转移,从而减轻摩擦、降低摩擦表面温升,显著改善复合材料的摩擦磨损性能。     

载荷对重型车辆发动机活塞环-缸套摩擦学性能的影响

利用SRV实验机模拟重型车辆发动机活塞环-缸套摩擦副的工作状态,测试了静载荷和动载荷条件下摩擦副的摩擦学性能。采用扫描电镜、能谱仪分析了磨痕形貌和化学成分,研究了摩擦副的磨损机制。结果表明:随静载荷的增加,摩擦副的摩擦因数减小,总失重量增加。摩擦副的磨损机理以磨粒磨损为主,在400N条件下活塞环的磨损机理为综合的磨粒磨损和黏着磨损。在低强度和中等强度动载荷条件下,摩擦副的摩擦因数随载荷的变化而呈循环变化,磨损机理以磨粒磨损为主。在高强度动载荷条件下,摩擦副的摩擦因数保持稳定,活塞环的磨损机理是综合的磨粒磨损、黏着磨损、疲劳磨损,缸套的磨损机理是综合的磨粒磨损、黏着磨损。摩擦副的总失重量随动载荷强度的增大而增加。     

水/油润滑条件下PTFE复合材料的摩擦学性能

将碳纤维(CF)和锡青铜粉(Cu)分别添加到聚四氟乙烯(PTFE)中制备了两种PTFE复合材料,并将其与42CrMo钢环形成摩擦副,研究了两种PTFE复合材料在干摩擦、水润滑和油润滑条件下的摩擦学性能,并用扫描电子显微镜观察了两种复合材料的磨损表面形貌,分析了磨损机理。结果表明:在干摩擦和油润滑条件下,随着碳纤维含量的增加,CF/PTFE复合材料的摩擦因数增大,磨痕宽度减小;两种PTFE复合材料在干摩擦条件下的摩擦因数最大,油润滑条件下的摩擦因数最小;而且在油润滑条件下,两种PTFE复合材料的磨痕宽度最小;水润滑条件下的摩擦因数比干摩擦的的要小,但磨痕宽度比干摩擦时的要大;CF/PTFE复合材料的磨损机理主要为疲劳磨损,犁沟形貌不明显;Cu/PTFE复合材料的磨损机理主要为磨料磨损,犁沟形貌明显,伴有疲劳磨损。     

丁腈橡胶在硬质颗粒环境下的摩擦磨损特性

采用销-盘接触方式考察丁腈橡胶/316L不锈钢配副的摩擦磨损性能,探讨有无Al2O3硬质颗粒及颗粒尺寸对其摩擦学行为的影响。通过扫描电子显微镜(SEM)和表面轮廓仪分析配副材料的磨痕表面形貌。结果表明:硬质颗粒参与磨损能降低接触副表面的摩擦因数;大尺寸颗粒会加速橡胶的磨损并能嵌入橡胶基体形成微切削效应,而随着颗粒尺寸减小至数十微米时,颗粒的存在反而能减缓橡胶的磨损;但颗粒的介入均会加剧配副金属的磨损、硬质颗粒的犁削作用使钢球磨损表面存在大量的犁沟;此外,无颗粒及不同尺寸颗粒环境下丁腈橡胶/不锈钢摩擦副表现出不同的损伤机制。     

5083铝合金/35CrMo钢线接触切向微动磨损行为

研究钢/铝配副的线接触微动磨损具有重要的理论意义和工程价值,过去对其报道不够。在电磁激振微动磨损试验机上,采用自调节式线接触夹具,对5083铝合金/35Cr Mo钢摩擦副进行线接触式切向微动磨损,研究了其在线接触条件下的切向微动磨损行为。结果表明:在线接触条件下,5083铝合金/35Cr Mo钢的微动运行区域存在部分滑移区、混合区和滑移区;部分滑移区摩擦系数较小,混合区摩擦系数峰值最大;部分滑移区损伤轻微,接触呈不连续特征,混合区和滑移区磨损严重;5083铝合金的磨损体积随着位移幅值的增加而增加,磨痕表层有微裂纹;5083铝合金/35Cr Mo合金钢的磨损机制主要为磨粒磨损和疲劳磨损。     

摩擦副类型对高速钢表面脉冲激光熔覆CrAlSiN薄膜摩擦性能的影响北大核心CSCD

以316不锈钢和TC11钛合金作为摩擦副类型,研究其对高速钢表面脉冲激光熔覆CrAlSiN薄膜表面摩擦磨损性能测试分析。研究结果表明:CrAlSiN薄膜表层部位存在许多针孔、凹坑和白色颗粒,并且颗粒尺寸都很大截面区域内生成了许多致密结构的组织,厚度2.5μm左右。薄膜硬度为2416 HV,和基体间的结合力等于53 N,达到良好综合性能。316不锈钢与CrAlSiN薄膜之间对磨后在薄膜表面生成了许多大尺寸磨痕,结合磨痕深度发生了轻微磨损;TC11钛合金与CrAlSiN薄膜进行对磨在薄膜上生成具有较大宽度磨痕,出现了轻度磨损。以不锈钢作为配副材料时,形成了较大的摩擦系数。以TC11钛合金作为配副材料时,发生了严重磨损的现象,跟316不锈钢对磨时形成了深度很大的磨痕。它们磨损机制相近,都是以磨粒磨损和粘着磨损为主。     

摩擦副类型对高速钢表面脉冲激光熔覆CrAlSiN薄膜摩擦性能的影响

以316不锈钢和TC11钛合金作为摩擦副类型,研究其对高速钢表面脉冲激光熔覆CrAlSiN薄膜表面摩擦磨损性能测试分析。研究结果表明:CrAlSiN薄膜表层部位存在许多针孔、凹坑和白色颗粒,并且颗粒尺寸都很大截面区域内生成了许多致密结构的组织,厚度2.5μm左右。薄膜硬度为2416 HV,和基体间的结合力等于53 N,达到良好综合性能。316不锈钢与CrAlSiN薄膜之间对磨后在薄膜表面生成了许多大尺寸磨痕,结合磨痕深度发生了轻微磨损;TC11钛合金与CrAlSiN薄膜进行对磨在薄膜上生成具有较大宽度磨痕,出现了轻度磨损。以不锈钢作为配副材料时,形成了较大的摩擦系数。以TC11钛合金作为配副材料时,发生了严重磨损的现象,跟316不锈钢对磨时形成了深度很大的磨痕。它们磨损机制相近,都是以磨粒磨损和粘着磨损为主。     

7A52铝合金微动磨损行为研究

利用微动磨损试验机研究7A52铝合金的微动磨损行为,分析不同载荷、振幅、循环次数等参数对摩擦因数和磨损体积的影响,观察分析不同振幅下的磨痕形貌,检测磨痕微区及磨粒的成分组成,探讨其磨损机制.结果表明:7A52铝合金的摩擦因数在不同振幅下的变化趋势不同,微动振幅较大时,实验初期摩擦因数迅速升高,而振幅较小时摩擦因数没有这种现象;磨损体积随着循环次数、振幅、载荷的增加而增加;振幅较小时微动磨损机制主要为磨粒磨损,振幅较大时磨损机制则以黏着磨损和磨粒磨损为主,随着振幅的进一步增加逐渐出现接触疲劳磨损.     

轧辊表面CrAlNx涂层的摩擦磨损性能研究

采用真空离子镀的方法在材料为45钢的轧辊表面涂覆Cr Al Nx涂层,优化制备了Cr Al Nx涂层的制备工艺,研究了Cr Al Nx涂层的摩擦性能。通过现代分析手段扫描电子的显微镜(SEM)等方法进行了涂层表面形貌、涂层厚度和磨痕形貌的测试分析,研究结果表明:在GCr15配副件条件下,Cr Al Nx涂层摩擦系数均随速度和载荷的增加而降低,随着加载载荷和滑动速度的增加,GCr15配副件条件下的磨损率增大,其磨损方式主要表现为黏着磨损和磨粒磨损的混合形式。     

阴极弧离子镀制备AlCrN涂层的高温摩擦磨损行为

采用阴极离子镀在TiC金属陶瓷刀具表面制备了AlCrN涂层,采用球/平面接触方式考察了900℃高温时不同载荷作下涂层的摩擦磨损行为。通过扫描电镜观察了磨痕轮廓和微观形貌,并用能量散射谱和X射线衍射分析了磨损后涂层表面化学元素和物相的变化,讨论了载荷对涂层摩擦因数和磨损性的影响。结果表明,经900℃高温氧化后,涂层中N元素全部释放,形成Al和Cr的氧化物,改善了润滑性能和磨损性能;在载荷600,800和1000 g作用下,涂层摩擦因数平均值分别为0.1455,0.3939,0.4188,在载荷600 g时表现出优良的摩擦特性,适用于精密切削加工;在高温下AlCrN涂层表现为氧化磨损,同时伴随着少量的磨粒磨损和黏着磨损。     

Analysis of friction between articular cartilage and polyvinyl alcohol hydrogel artificial cartilage

Many biomaterials are being used to repair damaged articular cartilage. In particular, poly vinyl alcohol hydrogel has similar mechanical properties to natural cartilage under compressive and shearing loading. Here, three-factor and two-level friction experiments and long-term tests were conducted to better evaluate its tribological properties. The friction coefficient between articular cartilage and the poly vinyl alcohol hydrogel depended primarily on the three factors of load, speed, and lubrication. When the speed increased from 10 to 20 mm/s under a load of 10 N, the friction coefficient increased from 0.12 to 0.147. When the lubricant was changed from Ringer’s solution to a hyaluronic acid solution, the friction coefficient decreased to 0.084 with loads as high as 22 N. The poly vinyl alcohol hydrogel was severely damaged and lost its top surface layers, which were transferred to the articular cartilage surface. Wear was observed in the surface morphologies, which indicated the occurrence of surface adhesion of bovine cartilage. Surface fatigue and adhesive wear was the dominant wear mechanism.     

含Nb高碳钢的组织及耐磨性能

采用金相显微镜、扫描电镜表征了含Nb高碳钢的显微组织,并采用MFT-3000型摩擦磨损试验机,在室温下研究了摩擦载荷、滑动速度及滑动时间对铸态高碳钢的摩擦性能的影响。结果表明,铸钢组织由莱氏体和珠光体组成,洛氏硬度为37.3HRC。随施加载荷、滑动速度的增加,磨损失重量增加;摩擦系数随载荷增加而降低,随滑动速度增加而增加,随滑动时间的延长先增加后趋于稳定。磨损机制是以粘着磨损为主的粘着与磨粒磨损的混合磨损,高速、长时间滑动时,还存在明显的氧化磨损。     

复合材料在传动过程中的摩擦磨损行为

采用化学气相渗透法(CVI)制备了二维碳纤维增强碳化硅(C/SiC)陶瓷基复合材料. 基于耦合应力等效模拟系统的开发, 采用摩擦扭矩的变化表征传动过程的摩擦磨损性能. 研究了以传动为背景的高载荷、低转速摩擦磨损行为及机理. C/SiC复合材料以其较低的摩擦扭矩、低的磨损率特别是在高载荷下的较小变形验证了良好的耐磨特性以及承载能力. 相同条件下其磨损率只有Ti合金的1/10～1/20. 低转速下磨损机理以磨粒磨损为主, 高载荷没有引起表面热裂纹.     

Microstructure and Tribological Properties of Plasma Nitriding Cast CoCrMo Alloy

A medical cast CoCrMo alloy was coated by plasma nitriding process to enhance the wear resistance.The microstructures,phases and micro-hardness of nitrided layers were investigated by atomic force microscopy(AFM),scanning electron microscopy(SEM),X-ray diffraction(XRD) and micro-hardness.Tribological properties were investigated on a pin-on-disc wear tester under 25% bovine serum solutions.The experimental results showed that plasma nitriding was a promising process to produce thick,hard and wear resistant layers on the surface of CoCrMo alloy.The harder CrN and Cr2N phases formed on the plasma nitrided layer with the compact nano-crystalline structure.Compared with the untreated sample,all nitrided samples showed the lower wear rates and higher wear resistance at different applied loads and nitriding temperatures.It was concluded that the improvement of wear resistance could be ascribed to the formation of thicker and harder nitrided layers with the specific microstructures on nitrided surfaces.     

Effects of temperature and normal load on tribological behavior of nickel-based high temperature self-lubricating wear-resistant composite coating

NiCr/Cr₃C₂–WS₂–CaF₂ mixed powders were designed and aimed to fabricate high temperature self-lubricating wear-resistant composite coating by laser cladding. The friction and wear properties of the coating were investigated under different temperatures and loads against Si₃N₄ ceramic ball. Results show that friction coefficient decreases with the increasing temperature while the wear rate firstly decreases and then increases with the increasing temperature. Both the friction coefficient and wear rate firstly decreases and then slightly increases with the increasing normal load. The coating exhibits relatively excellent tribological behavior under moderate temperature and moderate normal load.     

Effects of potassium titanate whiskers and carbon fibers on the wear behavior of polyetheretherketone composite under water lubricated condition

The tribological behaviors of polyetheretherketone (PEEK) composite reinforced by carbon fiber (CF) and potassium titanate whiskers (PTW) have been investigated using the pin-on-disk configuration at different applied loads under water lubricated condition. The effects of micrometer carbon fiber and sub-micrometer PTW on the wear properties of the hybrid composite have been discussed. It was found that the PEEK/PTW/CF composite showed excellent tribological performance in water condition. High wear resistance and low friction coefficient were achieved under a wide range of loads. It was revealed that the two fillers worked synergetically to enhance the wear resistance of the hybrid reinforced PEEK composite. The carbon fiber carried the main load between the contact surfaces and protected the matrix from further severe abrasion of the counterpart. At the same time, the exposed PTW out of the polymer matrix around the fiber inhibited the direct scraping between the fiber edge and counterpart tip in some degree, so that the fibers could be less directly impacted during the subsequent sliding process and they were protected from severe damage. In addition, the reinforcement effect of PTW on PEEK could reduce the stress concentration on the carbon fiber-matrix interface, and thereby reduce the CF failure/damage. The reinforcement effect of PTW on PEEK might also restrict the crack initiation and propagation on the surface and subsurface of the composite, and therefore to protect the matrix from fatigue failure during the sliding process.     

多孔PEEK自润滑材料的制备与摩擦磨损性能

采用模压-滤取和高温真空熔渍工艺制备了多孔聚醚醚酮(PEEK)发汗式自润滑材料,并分别考察了成型压力、造孔剂含量和润滑油脂种类对PEEK多孔自润滑材料的摩擦磨损性能的影响。结果表明,压力为100MPa,NaCl的质量分数为30%,采用通用锂基脂时,所得多孔PEEK自润滑材料的磨损率最低,200N下磨损率为2.73×10-16m3/(N.m),与纯PEEK干摩擦相比耐磨性提高了1245倍,其耐磨性较经典的炭纤维增强PEEK复合材料还提高了32倍。研究表明,多孔结构能够储存润滑油,在摩擦过程中能通过发汗作用在对偶面上形成稳定连续的油膜而起到良好的润滑作用,从而大幅降低复合材料的摩擦系数和磨损率。     

聚醚醚酮摩擦磨损行为和机理的研究

本工作通过摩擦过程中聚醚醚酮(PEEK)结构(包括材料与磨屑结构)的变化研究了PEEK的摩擦磨损机理。结果表明,低负载下,材料的摩擦表面不熔融,但表层的凝聚态结构发生了变化,摩擦状态不变,磨损是由于摩擦对偶的连续作用下产生疲劳而脱落。高负载下,材料表面熔融并发生氧化交联,摩擦状态改变,材料外形结构与内层凝集态结构发生变化,磨损是熔融了的表面层粘附于对偶上经进一步的交联反应后,受剪切力作用而脱落。材料在摩擦磨损过程中的表面状态决定了其摩擦磨损机理,并导致了材料摩擦磨损行为对负载的特殊依赖性。     

(Mg2B2O5w+ND)/ZK60镁基复合材料的摩擦磨损性能研究

在湿球磨条件下以600 r/min高能球磨混粉,并将球磨后的粉末经过热压烧结-热挤压成型制备(Mg2B2O5w+ND)/ZK60镁基复合材料。研究了(Mg2B2O5w+ND)/ZK60镁基复合材料在不同载荷和转速下的干摩擦磨损性能。结果表明:干摩擦条件下,材料的摩擦系数随着滑动距离的增加会经历跑和阶段和稳定阶段;材料的质量磨损率随着转速的增大而降低,随着载荷的增大而增大,且基体镁合金的质量磨损率始终低于复合材料。随着摩擦载荷和转速的增加,材料的摩擦系数减小,然后逐渐趋于平稳。混杂增强的镁基复合材料相比基体合金具有更低的摩擦系数。     

Hybrid effect of nanoparticles with carbon fibers on the mechanical and wear properties of polymer composites

Polyetheretherketone (PEEK) composites reinforced with carbon fibers (CFs) and nano-ZrO₂ particles were prepared by incorporating nanoparticles into PEEK/CF composites via twin-screw extrusion. The effects of nanoparticles on the mechanical and wear properties of the PEEK/CF composites were studied. The results showed that the incorporation of nano-ZrO₂ particles with carbon fiber could effectively enhance the tensile properties of the composites. The tensile strength and Young’s modulus of the composites increased with the increasing nano-ZrO₂ content. The enhancement effect of the particle was more significant in the hybrid reinforced composites. The compounding of the two fillers also remarkably improved the wear resistance of the composites under water condition especially under high pressures. It was revealed that the excellent wear resistance of the PEEK/CF/ZrO₂ composites was due to a synergy effect between the nano-ZrO₂ particles and CF. CF carried the majority of load during sliding process and prevented severe wear to the matrix. The incorporation of nano-ZrO₂ effectively inhibited the CF failures through reducing the stress concentration on the carbon fibers interface and the shear stress between two sliding surfaces. It was also indicated that the wear rates of the hybrid composites decreased with the increasing applied load and sliding distance under water lubrication. And low friction coefficient and low wear rate could be achieved at high sliding velocity.