纳米颗粒增强摩擦材料摩擦学性能研究

以丁腈橡胶改性酚醛树脂为基体,芳纶纤维、玻璃纤维为增强纤维,选用不同类型的纳米颗粒作为填料设计摩擦材料组分配比,并通过热压烧结制备摩擦材料。通过摩擦磨损试验机测试其在干摩擦条件下的摩擦学性能,并用扫描电镜(SEM)对材料的磨损形貌进行观察分析,以研究不同类型的纳米颗粒对摩擦材料性能的影响。研究表明:在干摩擦条件下,经过纳米颗粒改性的摩擦材料摩擦系数、硬度比未改性的材料有不同程度的提高,同时磨损率有很大程度的降低;纳米颗粒改性的摩擦材料摩擦系数、磨损率变化趋势具有一致性,均随着实验载荷、滑动速度的增大而逐渐减小;纳米颗粒改性后的摩擦材料磨损机理表现为疲劳磨损与磨粒磨损并存,而未改性的材料磨损机理主要表现为疲劳磨损。     

旋流器磨损研究进展

介绍了旋流器磨损方面的研究进展,包括利用数值模拟、现场及实验室试验对水力旋流器壁面磨损位置、影响磨损的关键部位的结构参数和操作参数,以及为提高旋流器使用寿命对内衬材料和自身结构进行的改进,并对减缓旋流器壁面磨损的发展趋势作了简要分析。研究表明：旋流器不同位置的磨损率不同,可根据该情况设置耐磨层,在旋流器易磨损部位采用耐冲击磨损较佳的内衬材料,通过材料的差异化提高旋流器耐磨性能或者在旋流器靠近壁面位置引入其它结构而改变该区域流体流动情况,减缓旋流器壁面磨损。随着人们对旋流器壁面磨损的不断开发,其在石油、化工等行业得到了越来越广泛的应用,减缓旋流器壁面磨损,提高其耐磨性能,对工程应用具有实用意义。     

耐磨增韧改性聚甲醛的制备及性能研究

用双螺杆共混挤出法制备了不同比例的聚四氟乙烯(PTFE)纤维改性聚甲醛(POM),考察了PTFE纤维含量对POM摩擦磨损性能、力学性能和热稳定性的影响。在POM/PTFE耐磨体系中,创新性地引入聚氧化乙烯(PEO)作为相容剂,制备出耐磨性能和韧性俱佳的POM改性材料。对POM改性材料进行了耐磨性和力学性能分析,利用偏光显微镜进一步证实了PEO能促进PTFE纤维和POM的相容性。结果表明,随着PTFE纤维含量的增加,POM的摩擦磨损性能有所提高,但力学性能不理想。在8%PTFE+92%POM体系中引入PEO,改性材料的摩擦因数低至0.169,缺口冲击强度比POM提高了173%,得到了耐磨和增韧效果显著的POM改性材料。     

BF/黑宝石粉体增强EP基摩擦材料的摩擦磨损性能

以环氧树脂(EP)为基体,玄武岩纤维(BF)为增强材料,玄武岩水晶玻璃(黑宝石)粉体为摩擦性能调节剂制备BF/黑宝石粉体增强EP基摩擦材料,研究了黑宝石粉体对摩擦材料摩擦磨损性能和力学性能的影响,然后在添加质量分数为5%的黑宝石粉体的基础上,采用相同手段研究了BF含量对摩擦材料性能的影响。结果表明,黑宝石粉体可以极大地提高摩擦材料的摩擦系数,并进一步降低磨损率以及提高摩擦材料的力学性能。BF的加入在一定程度上降低了摩擦材料的摩擦系数,且当BF含量较低或较高时,摩擦材料的磨损率均会有所提升。当BF质量分数为6%时,摩擦材料的综合性能最优,其摩擦系数为0.534,与未加BF的摩擦材料相比仅降低了7.61%,磨损率为0.75%,较未加BF的摩擦材料降低了31.82%,拉伸强度和弯曲强度分别为55.568 MPa和92.750 MPa,与未加BF的摩擦材料相比,分别提高了148%和66.42%。     

Effect of Grain Boundary Impurities on the Mechanical and Tribological Properties of Zirconia Surfaces

It is desirable to establish a relationship between the processing of ceramics, their mechanical properties that can be rapidly measured, for instance by indentation (hardness and toughness), their abrasion and scratch resistance, and their tribological performance. This paper examines such relationships for transformation-toughened zirconia. Experiments were performed on two zirconium oxides of similar doping with yttria (3%), one of high purity and one containing grain boundary impurities. The results are compared with those of previous work, in which the composition of the zirconium oxide was changed, but the processing and grain boundary purity were constant. It is found that the relationship between mechanical properties and triboiogical performance is complex but understandable in terms of the scale of the material responses (plastic deformation and fracture) with respect to its microstructure. The yttria content of the zirconia has a large influence on the wear resistance of the material (which increases with the fourth power of toughness). At constant yttria content, impurities produce relatively small changes in mechanical properties and wear behavior. The impurities weaken the grain boundaries with the following consequences: zirconia with pure grain boundaries behaves much like a brittle continuum, the material is hard, and macroscopic cracks develop at the corners of indentations and underneath wear tracks. Grain boundary impurities lower the hardness and increase the apparent (macroscopic) toughness by crack diffusion. At low bearing load, wear occurs by microchipping, and grain boundary phases have no effect. In water, wear is increased by intergranular fracture and the presence of grain boundary phases increases the wear rate. At high loads (44.5N), macroscopic cracks underneath the wear track develop early in the pure material; these cracks are retarded by intergranular fissuration in the material with grin boundary impurities.     

Tribological Characteristics of α-Alumina at Elevated Temperatures

The tribological characteristics of a high-purity α-alumina sliding on a similar material under unlubricated conditions are divided into four distinct regimes. At low temperatures, T < 200°C, tribochemical reactions between the alumina surface and water vapor in the environment control the tribological performance. The coefficient of friction in this temperature range is approximately 0.40 and the wear coefficient is less than 10⁻⁶, independent of contact load. At intermediate temperatures, 200°C < T < 800°C, the wear behavior depends on the contact load. At low loads, wear occurs by plastic flow and plowing; the coefficient of friction is approximately 0.60 and the wear coefficient is less than 10⁻⁶. At loads larger than a threshold value, severe wear occurs by intergranular fracture. The coefficient of friction increases to 0.85 and the wear coefficient increases to a value greater than 10⁻⁴. At temperatures above 800°C, formation of a silicon-rich layer on the wear track by diffusion and viscous flow of the grain-boundary phase reduces the coefficient of friction to 0.40, and the wear coefficient is reduced to a value less than 10⁻⁶. The results of the wear tests and observations of the fundamental mechanisms controlling the tribological behavior of this material are consolidated in a simple wear transition diagram.     

新型密封件的研制

设计了采用高温接枝工艺制备三元尼龙改性丁腈橡胶密封材料的配方,考察了三元尼龙对材料性能的影响。研究结果表明:三元尼龙有效提高了密封材料的耐磨性、耐油性、耐热性以及材料的刚性等,且当主体材料NBR:PA为100:25时,材料具有较好的压缩变形和良好的综合力学性能,尤其是刚性。     

骨料种类与级配对路面混凝土耐磨性能的影响

提高路面混凝土耐磨性能对行车安全和道路服役寿命具有重要意义。本文通过优化普通砂石骨料架构提高道路混凝土的耐磨性能,研究了机制粗骨料级配、细骨料种类与用量、胶凝材料用量及水胶比对路面混凝土力学性能与耐磨性能的影响。结果表明,16~31.5 mm碎石由质量分数25%增加到70%时,混凝土磨损量降低了29%。与河砂混凝土相比,机制砂混凝土磨损量降低58.3%,同时适当增加砂率可提高耐磨性能。降低胶凝材料用量和水胶比可在保证混凝土强度的同时进一步提高耐磨性(磨损量仅为(0.320±0.070) kg/m²)。机制骨料表面粗糙,棱角较多,与水泥浆体机械咬合力增强,有利于骨料嵌锁架构的形成,路面混凝土耐磨性能改善机制的提出为优化设计高耐磨路面混凝土提供了理论依据与技术支撑。     

Mechanical properties and wear behaviour of plastics in relation to their use in prostheses

The mechanisms of wear in plastics are reviewed and the properties required for high wear resistance derived. The importance of determining relevant mechanical properties at meaningful temperatures and strain rates is discussed. The particular advantages of high molecular weight polyethylene for prostheses are outlined and a typical wear test on this material described.     

Ti3AlC2陶瓷的制备及其摩擦磨损性能

以钛、铝、碳粉为反应物原料,采用反应烧结技术制备了Ti3AlC2陶瓷,研究了各工艺参数对制备试样物理性能的影响,同时也对其摩擦磨损性能进行了分析。实验结果表明：按照摩尔比x（Ti）：y（Al）：z（C）=3.0：1.2：2.0的配比进行反应烧结,在1 300℃烧结0.5 h,能够制备出高纯致密的Ti3AlC2陶瓷,其质量含量高达94.6%,孔隙率为9.4%。当烧结温度过低时,得到的Ti3AlC2陶瓷含量较低,且杂质较多;当烧结温度过高时,会导致Ti3AlC2陶瓷发生分解反应。当载荷较小时,Ti3AlC2陶瓷磨损以磨损面的解理流变和粒子脱落造成的磨粒磨损为主;而载荷较大时,其磨损机理以轻微划痕和轻微黏着磨损为主。     

The influence of grain geometry and wear conditions on the material removal mechanism in silicon carbide grinding with single grain

High efficiency and precision grinding of brittle materials is challenging due to material physical and chemical properties. To understand the effect of grain geometry and wear conditions on the material removal mechanism in brittle material precision grinding, a single diamond grain grinding experiment was conducted on Silicon Carbide (SiC). The cutting edge radius and deflection angle were measured by confocal scanning. Under six different cutting edge radius and three maximum undeformed chip thickness, grinding force and ground surface were measured. Diamond grain wear was investigated by observing the grain morphology, wear rate, grinding force, and ground surface change over accumulative material removal volume. The result showed the existence of a critical cutting edge radius for improving SiC ground surface quality.. Normal grinding force increased with the cutting edge radius increase. Tangential grinding force increased with the cutting edge radius increase and reached the peak value at the critical cutting edge radius. Flank wear was the major wear mode in precision SiC grinding. The grain wear was associated with the grinding force and ground surface.     

大型全自动压滤机滤板的改进与耐磨强化

在分析大型压滤机改性聚丙烯滤板磨损失效原因的基础上,提出了磨损区域材料置换、涂布耐磨层和预铺阻力滤布等三种改进和耐磨性强化措施,工业实践表明:本改进和耐磨性强化措施效果明显,滤板使用寿命为原来的5倍以上。     

硅藻土/白炭黑复合填料的补强性研究

为拓展硅藻土在高分子复合材料中的应用,将硅藻土/白炭黑填充到天然橡胶/丁苯橡胶/顺丁橡胶中制备了复合材料。通过RPA2000和扫描电镜分析了复合填料的Payne效应和分散性,考察了硅藻土用量对复合材料工艺性能、力学性能、耐磨耗性能影响。结果表明:少量硅藻土的加入有利于白炭黑在橡胶中的分散,能降低复合材料的门尼粘度和Payne效应,提高复合材料的硫化速度,缩短硫化时间,复合填料的补强效果较好;随着硅藻土用量的增加,复合填料容易聚集,其力学性能呈下降趋势,而磨耗性能变化不大;当硅藻土用量10~20份时,复合材料的综合性能最好。     

PE-UHMW/PP共混物的流动、力学与耐磨损性能研究

将均聚型聚丙烯(PP)、耐磨助剂与超高分子量聚乙烯(PE-UHMW)共混,制备了PE-UHMW/PP共混物,研究了PP含量及耐磨助剂对PE-UHMW/PP共混物流动、力学与耐磨损性能的影响。结果表明,PP能有效地改善PE-UHMW的流动性能,PE-UHMW/PP共混物的维卡软化点和热变形温度均随PP含量的增加而增加;加入耐磨助剂后,当PP的质量分数为50%时,共混物的拉伸强度达到最大,但断裂伸长率最小,且随PP含量的增加,PE-UHMW/PP共混物的冲击性能降低;PP降低了PE-UHMW的耐磨损性能,加入耐磨助剂后保持了PE-UHMW的高耐磨损性能且对共混物的流动和力学性能影响不大。     

Improving tribocorrosion performance of chemically bonded ceramic phosphate coating reinforced by GO-ZnO

To enhance the tribocorrosion properties of chemically bonded phosphate ceramic coating (CBPCC), GO-ZnO was prepared and added into CBPCC. And the tribocorrosion behaviour of CBPCC was investigated. Results show that, with the introduction of GO-ZnO, the open circuit potential of CBPCC shifts in a positive direction and corrosion current density decreases. In addition, the total material loss, the total mechanical wear loss and the total electrochemical corrosion loss of CBPCC all decrease with the increase of GO-ZnO. The wear track of CBPCC after tribocorrosion without GO-ZnO is rough and porous, while the wear track becomes smooth and dense with the incorporation of GO-ZnO. The material in wear track is anchored by GO-ZnO due to the strong bond between GO-ZnO and CBPCC, which decreases the wear loss. Because of the extra force from the tribocorrosion experiment, the material anchored by GO-ZnO forms to a dense structure which prevents electrolyte diffusion into CBPCC. Moreover, GO-ZnO can block the electrolyte diffusion pathway and make it more tortuous. The resistance to the electrolyte diffusion decreases the corrosion current density and the increased wear loss due to electrochemical corrosion.     

配副材料对镍-磷-碳化硅化学复合镀层摩擦磨损性能的影响

利用化学复合镀技术制备了Ni-P-SiC复合镀层,研究了镀层的表面形貌、组织、显微硬度等性能,并对比研究了不同配副材料对Ni-P-SiC复合镀层和Ni-P镀层摩擦磨损性能的影响。结果表明,Ni-P-SiC复合镀层的显微硬度较Ni-P镀层有所提高;与GCr15钢球对磨时,Ni-P-SiC复合镀层发生严重的塑性变形和粘着磨损,但磨损率比Ni-P镀层稍有降低;与Si3N4陶瓷球对磨时,两者的磨损率相当,且均比与GCr15球对磨时小1个数量级,其主要磨损机理为磨粒磨损。配副材料的磨损率变化规律与镀层一致。在一定条件下,陶瓷材料与Ni-P镀层或Ni-P-SiC复合镀层是较匹配的摩擦副。     

Al2O3—TiB2陶瓷刀具材料的研制及其耐磨性能研究

本文研制成功了一种新型陶瓷刀具材料即Al_2O_3-Ti B_2陶瓷刀具材料。文中讨论了该材料的研制方法,力学性能和微观结构特点,并对该材料的磨损行为和磨损机理进行了研究。结果表明:Ti B_2粒子的弥散可以明显提高该材料的耐磨性。加工淬火钢时该材料的抗磨损能力明显优于Al_2O_3-TiC陶瓷刀具材料。Al_2O_3-Ti B_2陶瓷刀具材料的磨损过程主要受粘着、耕犁和微破损机制的控制。     

High wear-resistance characteristic of boron-doped nano-polycrystalline diamond on optical glass

Boron-doped nano-polycrystalline diamond (B-NPD) uniformly containing boron atoms in the diamond lattice has been successfully produced by direct conversion sintering under ultra-high pressure and high temperature using boron-doped graphite as a starting material, and its wear properties on optical glass materials have been investigated. The chemical wear of B-NPD sliding on glass was highly suppressed under sliding conditions where undoped NPD is worn considerably by chemical reaction with glass because the frictional resistance of NPD decreased and its sliding performance was improved by adding boron. In addition, because B-NPD has electrical conductivity, tribo-microplasma damages attributed to frictional electrification were not observed. Thus, the wear resistance of B-NPD on glass materials was improved greatly in comparison with that of undoped NPD. These results indicate that B-NPD has outstanding potential as a cutting tool material for high-performance and high-precision cutting on various types of glass, nonconductive ceramics and rigid plastics which are difficult to cut by conventional diamonds because of tribo-chemical wear or tribo-electrical wear.     

Properties of carbon fiber reinforced poly(vinylidene fluoride)‐based friction materials of ultrasonic motors

In order to improve output properties and anti‐irradiation capability of ultrasonic motors (USMs), which are driven by friction forces of friction material between the stator and rotor, a type of friction material is fabricated by composite materials consist of carbon fiber (CF) and polyvinylidene fluoride (PVDF). The effects of different contents of CF on the mechanical and tribological properties of PVDF‐based friction materials are studied, and the mechanical features of the relative USMs are measured. Further, the worn surface morphology of PVDF composites is observed by means of scanning electron microscope and the wear mechanisms are also discussed. In addition, the anti‐irradiation capability of the type of friction materials is measured by the γ‐ray irradiation at room temperature environment with the total radiation dose of 4.0X rad (Si). The experimental results show that the incorporation of CF into PVDF can effectively improve the friction and wear properties of the friction materials, and the mechanical properties of TRUM‐60 used by relative PVDF composites are also increased with the increase of CF. For TRUM‐60, both the no‐load speed and holding torque of the USMs were high, and the wear of friction material was lowest, when the CF content is 15 wt%. The experiment results also show that this PVDF‐based friction material has a good anti‐irradiation property. Therefore, the composite materials consist of CF and PVDF are beneficial for the applications in USMs, especially for some radiation environment. POLYM. COMPOS., 37:547–552, 2016. © 2014 Society of Plastics Engineers     

Influencing hardness and wear during the dynamic tempered microinjection molding process by considering isothermal holding time

For semicrystalline thermoplastic parts it is well known that increasing isothermal holding temperature can affect inner component properties, respectively, crystalline structure (e.g., morphology, degree of crystallization, crystal modification, etc.) and, therefore, resulting global component properties such as hardness and wear. Nevertheless, in literature there is no explicit focus on the effect of isothermal holding time during dynamically tempered injection molding process. In this article, semicrystalline microcomponents have been injection molded by varying isothermal holding time within the material's crystallization temperature area. As materials, POM‐C, as a material with relatively high crystallization kinetic, and PA 12, as a material with medium crystallization kinetic, were used. To evaluate the effects on hardness and wear, nanoindentation measurements as well as pin‐on‐disc wear tests were performed. Results show that for fast crystallizing POM‐C an isothermal holding step has no significant influence on inner component and resulting global component properties. For slower crystallizing PA 12, however, the morphology and the degree of crystallization could be influenced and, as a result, hardness could be increased by 21% while wear could be reduced by 30%. POLYM. ENG. SCI., 57:121–128, 2017. © 2016 Society of Plastics Engineers