Dependence of antifriction properties of multicomponent tribosystems on nature of secondary structures on friction surfaces

The dependences of the coefficients of friction, wear rates, and temperatures of the friction pair steel-polyurethane filled with powders of nonferrous metals on the friction path and load are studied. Polyurethane was filled with copper, tin bronze, zinc, and babbit powders. The tribological characteristics were investigated at different concentrations of the fillers in polyurethane and different particle sizes of the fillers. Secondary structures on the friction surfaces are examined and the relationship between the structure and composition of the secondary structures with the tribological characteristics is analyzed.     

再生聚四氟乙烯粉末填充聚甲醛复合材料的摩擦磨损特性研究

采用直接回收利用法,将废弃聚四氟乙烯(PTFE)再生成PTFE粉末后填充到聚甲醛(POM)中,机械共混后采用模压法制备出不同配方的POM复合材料,分别进行摩擦磨损实验,并用SEM观察试样的磨损表面。结果表明:填充POM复合材料与未填充POM相比,摩擦因数降低,耐磨性提高。因此,PTFE进行二次资源化是可行的。     

纳米SiO2包覆硅灰石填充改性尼龙1010的摩擦学性能

以硅灰石和水玻璃为主要原料,用无机化学沉积法制备纳米SiO2包覆硅灰石复合颗粒;利用扫描电镜和X射线衍射分析对包覆效果进行表征。将复合颗粒填充到尼龙1010中,对此复合材料进行拉伸、硬度和摩擦磨损实验,并与分别用硬脂酸改性硅灰石、未处理硅灰石填充的尼龙复合材料进行对比。结果表明,将纳米颗粒包覆硅灰石填充到尼龙1010中,可获得较好的结合界面,提高了尼龙复合材料的拉伸强度和硬度,比硬脂酸改性和未经处理的硅灰石更有效地改善了尼龙的摩擦学性能。     

A study on friction and wear characteristics of nanometer Al2O3 /PEEK composites under the dry sliding condition

The friction and wear properties of the polyetheretherketone (PEEK) based composites filled with 5 mass% nanometer or micron Al₂O₃ with or without 10 mass% polytetrafluroethylene (PTFE) against the medium carbon steel (AISI 1045 steel) ring under the dry sliding condition at Amsler wear tester were examined. A constant sliding velocity of 0.42 m s⁻¹ and a load of 196 N were used in all experiments. The average diameter 250 μm PEEK powders, the 15 or 90 nm Al₂O₃ nano-particles or 500 nm Al₂O₃ particles and/or the PTFE fine powders of diameter 50 μm were mechanically mixed in alcohol, and then the block composite specimens were prepared by the heat compression moulding. The homogeneously dispersion of the Al₂O₃ nano-particles in PEEK matrix of the prepared composites was analyzed by the atomic force microscopy (AFM). The wear testing results showed that nanometer and micron Al₂O₃ reduced the wear coefficient of PEEK composites without PTFE effectively, but not reduced the friction coefficient. The filling of 10 mass% PTFE into pure PEEK resulted in a decrease of the friction coefficient and the wear coefficient of the filled composite simultaneously. However, when 10 mass% PTFE was filled into Al₂O₃/ PEEK composites, the friction coefficient was decreased and the wear coefficient increased. The worn scars on the tested composite specimen surfaces and steel ring surfaces were observed by scanning electron microscopy (SEM). A thin, uniform, and tenacious transferred film on the surface of the steel rings against the PEEK composites filled with 5 mass% 15 nm Al₂O₃ particles but without PTFE was formed. The components of the transferred films were detected by energy dispersive spectrometry (EDS). The results indicated that the nanometer Al₂O₃ as the filler, together with PEEK matrix, transferred to the counterpart ring surface during the sliding friction and wear. Therefore, the ability of Al₂O₃ to improve the wear resistant behaviors is closely related to the ability to improve the characteristics of the transfer film.     

制备工艺对PTFE复合材料硬度的影响

采用溶剂蒸发法和固体纳米粉末混合法制备两种工艺制备了PTFE复合材料。结果表明：在填料含量相同时，溶剂蒸发法制备的PTFE复合材料的硬度显著高于固体纳米粉末混合法制备的PTFE复合材料的硬度；使用纳米颗粒作填料时，用偶联剂处理表面对硬度没有显著影响。其作用机理为：当用固体纳米粉末填料时，由于纳米粉末的团聚作用，丧失了部分纳米颗粒的表面特性，界面结合较差，硬度较低；而使用液体纳米硅溶胶制备PTFE复合材料时，纳米颗粒在搅拌蒸发的过程中被PTFE大分子包裹，可以有效防止团聚的发生。     

The effect of gamma radiation on the tribological behavior of polyethylene terephthalate-based antifrictional material

Tribological behavior and strength characteristics of radiated polyethylene terephthalate materials filled by fine dispersed graphite and polytetrafluoroethylene powders are studied. The composite material treated by 150 kGr-dosed gamma radiation shows a low coefficient of friction and high wear resistance. It is recommended for usage as antifrictional material in friction units operating under increased radiation.     

Influence of counter surface topography on the tribological behavior of carbon-filled PPS composites in water

This study is aimed at investigating the influence of counter surfaces׳ topography on tribological behavior of several carbon-filled polyphenylene sulfide (PPS) composites in water lubricated contacts. The results of this study showed significant increase in wear rate of pure, graphite and/or multi-walled carbon nanotubes filled PPS composites with increase in mean slope of profile along the sliding direction (Δα_y). This is while SCF filled PPS composites exhibited 1–3 orders of magnitude lower wear rate with little dependence on counter surface roughness characteristics. Among the roughness parameters studied, R_pk and lay orientation played a more significant role in friction, and R_pk and Δα_y were found to correlate best with the wear rate of the composites not containing SCF in their matrices.     

Composites with improved absorption of noise and vibration

The development of composites based on thermosetting resins with improved vibration and noise absorption is considered. Mathematical and topological models are proposed to describe the influence of the composition on the vibration and noise absorption and elastic properties of the composites. The composition of filled epoxy, polyester, and polyurethane vibration-absorbing composites is optimized in terms of their loading, dynamic, and economic characteristics.     

PTFE复合材料的摩擦磨损性能研究

用机械共混、冷压成型烧结的方法制备了纳米SiO2/石墨/玻璃纤维/PTFE复合材料试样。用MM-200型磨损试验机测试了在干摩擦条件下不同载荷时各试样的摩擦磨损性能;用扫描电镜对磨损后试件表面进行观察和分析。研究结果表明：纳米SiO2和玻璃纤维有效提高了PTFE的承载能力,石墨的加入起到了减小摩擦的作用;在本试验条件下,在摩擦过程中三元混合填充PTFE复合材料在偶件表面形成了转移膜,减少了复合材料与偶件的直接接触,因而表现出优异的抗磨性。     

纳米和微米SiO2颗粒对PPESK复合材料摩擦学性能的影响

用热压成型法制备了纳米、微米SiO2填充聚醚砜酮(PPESK)复合材料,考察了复合材料的硬度和抗弯强度,并研究了干摩擦条件下纳米、微米SiO2颗粒对复合材料摩擦磨损性能的影响,用扫描电镜观察分析了复合材料磨损表面形貌及磨损机理。结果表明：干摩擦条件下,纳米SiO2填充PPESK主要是轻微的磨粒磨损;而微米SiO2填充PPESK主要是严重的磨粒磨损。     

青铜粉对聚四氟乙烯基复合材料摩擦学性能影响的研究

通过向聚四氟乙烯材料加入不同质量比的青铜粉和氧化铅制备了3种自润滑复合材料,并与不加青铜粉的填充氧化铅的聚四氟乙烯材料进行实验研究,研究了青铜粉及其含量对聚四氟乙烯基复合材料摩擦学性能的影响,并探讨了填料的减磨机理。结果表明:在干摩擦条件下,在一定范围内,随着青铜粉含量的增加,填充氧化铅的PTFE基材料的摩擦磨损性能有所降低;在油润滑条件下,填充氧化铅的PTFE基材料的摩擦磨损性能相对干摩擦有所提高,且在一定范围内,随着青铜粉含量的增加,填充氧化铅的PTFE基材料的摩擦磨损性能有所提高;填料的减磨机理与“第三体”有关,而“第三体”又与材料的基体组分有关。     

表面改性硅灰石纤维填充PTFE复合材料的摩擦学性能

用KH550硅烷偶联剂表面改性的硅灰石纤维(WF)填充PTFE,在MPX-2000型磨损试验机上研究复合材料的摩擦磨损性能,并与经典的炭纤维(CF)填充PTFE复合材料进行比较。采用SEM对磨损面和对偶面进行分析。结果表明:较高载荷(200和300 N)下复合材料摩擦因数随WF含量变化的幅度不大,较稳定地维持在较低值;细小尺寸WF填充PTFE复合材料的耐磨性能较好,在WF质量分数为10%时,复合材料的磨损量只有相同含量CF填充PT-FE复合材料的81%;细小尺寸WF填充PTFE复合材料的磨损面较为平整,存在轻微黏着磨损,其对偶面转移膜平整光滑、结构致密;而CF/PTFE复合材料磨损面存在许多裸露和碎断的CF,犁削和磨粒磨损是主要的磨损形式。     

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.     

A comparison of the microstructure of silicon nitride-silicon carbide composites made with and without deoxidized starting material

Two different types of silicon carbide (SiC) matrix composites, with either 10 wt% or 20 wt% silicon nitride (Si₃N₄) reinforcement, were fabricated to investigate the effect of pretreatment on the resulting composite micro-structure. The first type of composite was prepared from as-received α-SiC and α-Si₃N₄ powders, while the second type was prepared from powder compacts that had been deoxidized to eliminate surface silica on the powder particles. The composites were hot isostatically pressed in tantalum cans at 2373 K for 1h under a pressure of 200 MPa. Density measurements showed that full theoretical density was achieved for the composites prepared from the as-received powders, while much lower densities were obtained for the composites prepared from the deoxidized green compacts. Almost all of the α-SiC transformed into β-SiC, and almost all the α-Si₃N₄ transformed into α-Si₃N₄ in the composites made from the as-received powders, while in the composites made from the deoxidized material the α-SiC remained untransformed and both α-Si₃N₄ and β-Si₃N₄ phases were present in significant quantities. High-resolution transmission electron microscopy and Fresnel fringe imaging were used to identify the grain boundary and interphase boundary structure. Most interfaces were found to be covered with ? 1 nm thick amorphous intergranular films in the composites prepared from as-received powders, whereas most interfaces were found to be free of such amorphous intergranular films in the composites prepared from the deoxidized material. Taken together, the presence of intergranular films at the interfaces and the results from density measurements are consistent with the densification and reverse α → β-SiC transformation taking place in the composites made from as-received powders by a liquid-phase sintering route. An incomplete liquid-phase sintering mechanism is also able to explain the microstructure observed in the composites made from the deoxidized material.     

聚酰亚胺填充丁腈橡胶复合材料的研究

研究了聚酰亚胺对丁腈橡胶的填充改性，对聚酰亚胺填充的丁腈橡胶复合材料的物理机构性能进行了研究，利用栓－盘式摩擦磨损试验机考察了复合材料的摩擦学特性。结果表明，聚酰亚胺的填充可明显提高丁腈橡胶胶复合材料的物理机械性能，并且显著改善其摩擦学性能，聚酰亚胺的填充存在一最佳值。     

Development and tribological behaviour of UHMWPE filled epoxy gradient composites

In this study, ultra high molecular weight polyethylene (UHMWPE) filled epoxy gradient composites have been developed. Samples were prepared for different centrifugation time periods. SEM and optical microstructures confirmed the graded dispersion of UHMWPE particles in the epoxy matrix. Quick estimation of gradient characteristics has been done by abrasive wear measurements. Sliding wear tests were conducted by using a pin-on-disc machine. The sliding wear rate of composites reduced on increasing centrifugation time. Reduction in sliding wear rate in UHMWPE filled epoxy gradient composites has been attributed to the reduction of tensile contact stresses as a result of the lubricating effect of UHMWPE's smooth surface and highly entangled chain structure of UHMWPE.     

Investigations on the influence of graphite filler on dry sliding wear and abrasive wear behaviour of carbon fabric reinforced epoxy composites

In this experimental study, the dry sliding wear and two-body abrasive wear behaviour of graphite filled carbon fabric reinforced epoxy composites were investigated. Carbon fabric reinforced epoxy composite was used as a reference material. Sliding wear experiments were conducted using a pin-on-disc wear tester under dry contact condition. Mass loss was determined as a function of sliding velocity for loads of 25, 50, 75, and 100 N at a constant sliding distance of 6000 m. Two-body abrasive wear experiments were performed under multi-pass condition using silicon carbide (SiC) of 150 and 320 grit abrasive papers. The effects of abrading distance and different loads have been studied. Abrasive wear volume and specific wear rate as a function of applied normal load and abrading distance were also determined.The results show that in dry sliding wear situations, for increased load and sliding velocity, higher wear loss was recorded. The excellent wear characteristics were obtained with carbon-epoxy containing graphite as filler. Especially, 10 wt.% of graphite in carbon-epoxy gave a low wear rate. A graphite surface film formed on the counterface was confirmed to be effective in improving the wear characteristics of graphite filled carbon-epoxy composites. In case of two-body abrasive wear, the wear volume increases with increasing load/abrading distance. Experimental results showed the type of counterface (hardened steel disc and SiC paper) material greatly influences the wear behaviour of the composites. Wear mechanisms of the composites were investigated using scanning electron microscopy. Wear of carbon-epoxy composite was found to be mainly due to a microcracking and fiber fracture mechanisms. It was found that the microcracking mechanism had been caused by progressive surface damage. Further, it was also noticed that carbon-epoxy composite wear is reduced to a greater extent by addition of the graphite filler, in which wear was dominated by microplowing/microcutting mechanisms instead of microcracking.     

铜包裹氧化铝粉体增强铝基复合材料的研究

用非匀相沉淀的方法制备出了纳米铜颗粒包裹Al2O3的复合粉体,并制备出铝基复合材料,对包裹粉体的形貌、铝基复合材料的微观结构和性能进行了分析研究.结果表明：包裹层铜颗粒呈球形,团聚少,尺寸在10～20 nm左右,铝基复合材料当中包裹粉体位于晶界处,分布均匀;铝基复合材料的密度和显微硬度都有一定提高,耐磨性能也比较高.     

Local Stress–Strain State of Tribocomposites with Spherical Microcapsules Filled with Liquid Lubricant

A method for predicting the local elastic characteristics of multicomponent matrix-assisted tribocomposites with spherical microcapsules filled with a liquid lubricant is proposed. These characteristics are defined by the operators (tensors) of the stress and strain concentration. This method is based on a generalized singular approximation of the theory of random fields and allows taking into consideration the inherent size of microcapsules (the ratio of the shell thickness to the radius of the liquid filler) and the volume fraction of the tribocomposite components. The local elastic characteristics are numerically modelled for the composites based on phenylon with disperse inclusions of alkali-free glass and microcapsules, which are spherical kapton shells filled with glycerin. The dependences of the local elastic properties of the tribocomposites on the inherent size of the microcapsules at fixed volume fractions of the heterogeneity elements are studied.     

特种配方填充聚四氟乙烯复合材料在大型石化设备中的应用

概述了聚四氟乙烯材料的性能特点及常用的改性填充材料,根据大型石化设备的工况使用要求,设计制造了特种配方填充聚四氟乙烯复合材料的相关产品,并分析说明了该类复合材料的性能参数特点及相关产品（楔形密封条、填料密封环等）在丙烯压缩机和高温风机上的应用情况。