剑麻纤维的改性及其在摩擦材料中的应用

研究了不同改性处理工艺对剑麻纤维物化性能的影响, 确定了剑麻纤维最佳改性方案, 将剑麻纤维应用于制备摩擦制动复合材料。采用D-MS 定速摩擦实验机检测摩阻性能, 比较研究了经过改性处理和未经处理的剑麻纤维增强摩擦材料的特性, 并与无机矿物纤维/ 钢纤维混杂纤维增强摩擦材料进行了对比。研究结果表明,经过改性处理的剑麻纤维增强的摩擦材料摩擦系数适中, 随温度波动小, 是一种理想的石棉替代纤维。      

纤维增强摩阻材料中树脂含量的确定

选用碳纤维、钢纤维和FB酚醛树脂为主要成分制得纤维增强摩阻材料 ,研究了树脂含量对材料摩阻性能、力学性能的影响 ,确定了摩阻材料的最低树脂含量为 1 6% ,最佳树脂含量为 2 2 %     

剑麻纤维增强复合材料的研究进展

综述了剑麻纤维和剑麻纤维增强复合材料的结构和性能及其应用.对剑麻纤维的综述主要包括剑麻纤维概况及与其他纤维的比较、剑麻纤维的表面处理方法和表征;对剑麻纤维增强复合材料的综述主要包括剑麻纤维增强热塑性树脂、热固性树脂、橡胶、水泥和石膏等其他基体复合材料的研究.     

半金属摩阻材料中铜纤维摩擦磨损行为的研究

用扫描电子显微镜(SME)和X-射线能谱分析法(EDX)对铜纤维增强的半金属摩阻材料与灰铸铁对偶滑摩后的摩擦表面进行了分析,研究了摩阻材料中铜纤维的摩擦磨损行为.结果表明,在摩擦磨损过程中,摩阻材料摩擦表面上铜的分布更加弥散化,并且铜纤维具有集铁作用,因而摩阻材料摩擦表面上形成了富铁贫铜表面工作层;铜能从摩阻材料摩擦表面转移到对偶摩擦表面,故对偶摩擦面上分布一定量铜,这是摩擦副具有稳定摩擦系数和良好耐磨性的关键因素;铜纤维取向对摩阻材料摩擦磨损行为有显着影响.     

论我国发展无石棉摩阻复合材料的途径

本文分析了无石棉摩阻复合材料研究的必要性及国外研究动态后,对我国摩阻材料增强纤维采用的玻纤、碳纤维、有机纤维、kevlar纤维、钢纤维和矿纤维作了各种比较试验,并论述了采用的可能性及现实性,提出在现阶段应当采用软玻璃纤维、碳纤维预氧丝、混杂纤维来研制中国的无石棉摩阻复合材料。      

纳米表面改性纤维增强树脂基复合材料吸波性能及机理研究

用MEVVA源离子注入法对增强纤维进行表面处理,形成纳米表面改性层,用表面纳米改性的纤维制作树脂基复合材料,并对纳米表面改性纤维增强树脂基复合材料的电磁学性能和吸波特性进行研究,研究表明:对增强纤维进行纳米表面改性,可以有效改善纤维增强树脂基复合材料的吸波性能,用纳米表面改性法制备的纤维增强树脂基复合材料在8～18GHz内,反射率为-(2.6～6.1)dB,吸波曲线具有宽频带吸波特征,材料的质量增量趋近于0.     

功能性填料改性聚合物材料的摩擦学研究进展

聚合物材料因其质轻、价廉、耐腐蚀以及优异的自润滑特性而广泛应用于工程机械润滑领域中。加入功能性减摩和增强填料复合改性聚合物树脂可以克服本征型高分子材料的一些固有缺陷,得到低摩擦因数、高耐磨性、高承载力以及耐高温等优异特性的摩擦学复合材料。本文综述了功能性填料如碳基材料、过渡金属硫化物、微胶囊、软金属、陶瓷纳米颗粒、矿物盐以及自润滑高分子对复合材料的减摩抗磨效果及机理。同时,力学性能是保证聚合物材料服役性能和使役寿命的关键参数,也会对材料的摩擦学性能带来显著影响。本文还重点论述了纳米颗粒和纤维等填料对复合材料的增强和增韧机理。最后,展望了功能性填料对力学性能与摩擦学性能的协效作用,以及计算机模拟在复合材料摩擦学中应用的发展趋势。     

高性能热塑性树脂基复合材料复合方法及成型工艺简介

芳香族聚合物一类新型热塑性工程塑料的出现,有可能代替某些热固性树脂基体制作长纤维增强复合材料。国外对热塑性工程塑料树脂基复合材料进行了大量的研究,已经成功地应用于航空航天事业。保证这种材料取代某些热固性树脂基复合材料的前提是预浸带制造方法和成型工艺技术的实施。本文将对热塑性树脂基复合材料的预浸带制备及成型方法作一简单分析介绍。      

剑麻纤维增强酚醛基摩擦材料的研制

以酚醛树脂为基体,以经过表面预处理的剑麻纤维为增强材料,研制出新型无石棉摩擦材料,其各项性能均达到汽车制动器衬片GB5763-1998的规定,且与市场产品的摩擦磨损性能处于同一范围,可作为目前常用石棉摩擦材料的更新换代产品.通过研究剑麻纤维的质量分数和表面状态对材料摩擦磨损性能的影响,发现剑麻纤维的最佳质量分数为10%～20%.研究结果表明,采用碱处理、偶联剂处理和阻燃剂处理后的剑麻纤维,可以较好地改善复合材料的摩擦磨损性能.     

高性能纤维增强树脂基复合材料湿热老化研究进展

高性能纤维增强树脂基复合材料具有卓越的结构整体性及抗分层等特性,在诸多工业领域中具有广泛适用性。在其储藏及使用时,制件强度会不可避免地因湿热老化造成降解和退化。探讨和揭示高性能纤维增强树脂基复合材料在不同湿热老化环境下的力学响应,对其结构件的耐久性、安全服役性能和寿命预估具有至关重要的意义。综述了国内外高性能纤维增强树脂基复合材料湿热老化方面的研究进展,介绍了其吸湿机理以及在湿热环境下的老化机理。梳理了湿热老化环境对于高性能纤维增强树脂基复合材料力学性能的影响,寿命预测模型等。最后指出了高性能纤维增强树脂基复合材料老化研究存在的问题、面临的挑战,对未来研究发展方向提出了展望。     

树脂基刹车片的改性研究进展

综述了树脂基刹车片的改性研究进展，主要介绍了树脂基体改性、增强纤维与摩擦调节剂的改变对刹车片的性能的影响。     

Effect of Short Fibre Reinforcement on the Friction and Wear Behaviour of Nylon 66

Use of thermoplastic composite material for load bearing components is increasing due to economical processing of complicated shapes in large quantities. Addition of fibre improves the strength and modulus of composites. Although the tribo-behaviour of thermoplastic composites were investigated, the friction and wear mechanisms are not yet fully understood. Friction and wear behaviour of injection unfilled Nylon 66, glass fibre reinforced Nylon 66 and carbon fibre reinforced Nylon 66 is investigated under dry sliding conditions. Tests were conducted at different normal loads and sliding velocities at room temperature. Coefficient of friction, wear loss and heat generation during the wear tests were quantified. Presence of fibre affects coefficient of friction and wear resistance of Nylon 66 matrix composites. The formation and stability of the transfer films affects the wear resistance. The rise in temperature during sliding was also calculated and also measured. The contact temperature rise is influenced by the composition which in turn influences the fibre adhesion and thereby the wear resistance. Glass fibre reinforced Nylon exhibited the lowest wear rate among the materials investigated. Both adhesive and abrasive wear mechanisms were observed in polymer matrix composites.     

Hierarchical composites reinforced with robust short sisal fibre preforms utilising bacterial cellulose as binder

A novel robust non-woven sisal fibre preform was manufactured using a papermaking process utilising nanosized bacterial cellulose (BC) as binder for the sisal fibres. It was found that BC provides significant mechanical strength to the sisal fibre preforms. This can be attributed to the high stiffness and strength of the BC network. Truly green non-woven fibre preform reinforced hierarchical composites were prepared by infusing the fibre preforms with acrylated epoxidised soybean oil (AESO) using vacuum assisted resin infusion, followed by thermal curing. Both the tensile and flexural properties of the hierarchical composites showed significant improvements over polyAESO and neat sisal fibre preform reinforced polyAESO. These results were corroborated by the thermo-mechanical behaviour of the (hierarchical) composites, which showed an increased storage modulus and enhanced fibre–matrix stress transfer. Micromechanical modelling was also performed on the (hierarchical) composites. By using BC as binder for short sisal fibres, added benefits such as the high Young’s modulus of BC, enhanced fibre–fibre and fibre–matrix stress transfer can be utilised in the resulting hierarchical composites.     

Friction and wear behavior of carbon fiber reinforced brake materials

A new composite brake material was fabricated with metallic powders, barium sulphate and modified phenolic resin as the matrix and carbon fiber as the reinforced material. The friction, wear and fade characteristics of this composite were determined using a D-MS friction material testing machine. The surface structure of carbon fiber reinforced friction materials was analyzed by scanning electronic microscopy (SEM). Glass fiberreinforced and asbestos fiber-reinforced composites with the same matrix were also fabricated for comparison. The carbon fiber-reinforced friction materials (CFRFM) shows lower wear rate than those of glass fiber- and asbestos fiber-reinforced composites in the temperature range of 100°C-300°C. It is interesting that the frictional coefficient of the carbon fiber-reinforced friction materials increases as frictional temperature increases from 100°C to 300°C, while the frictional coefficients of the other two composites decrease during the increasing temperatures. Based on the SEM observation, the wear mechanism of CFRFM at low temperatures included fiber thinning and pull-out. At high temperature, the phenolic matrix was degraded and more pull-out enhanced fiber was demonstrated. The properties of carbon fiber may be the main reason that the CFRFM possess excellent tribological performances.     

孔隙率对碳纤维增强纸基摩擦材料摩擦磨损性能的影响

碳纤维增强纸基摩擦材料是应用于汽车自动变速器中的一种新型湿式摩擦材料. 在固定原材料配比和含量的基础上, 通过改变摩擦材料厚度, 制备出几种孔隙率不同的碳纤维增强纸基摩擦材料. 采用液体渗透法测试摩擦材料的孔隙率. 利用扫描电镜观察试样形貌. 通过惯量试验机研究孔隙率对碳纤维增强纸基摩擦材料湿态摩擦磨损性能的影响. 试验结果表明: 短切碳纤维在树脂基体中均匀分散, 相互桥接, 形成了大小不一的贯穿性孔隙; 随着孔隙率的增大, 摩擦力矩曲线趋于平稳; 动摩擦系数升高, 静摩擦系数降低, 磨损率增大.     

The abrasive wear behaviour of continuous fibre polymer composites

The dry abrasive-dominant wear behaviour of several composite materials consisting of uni-directional continuous fibres and polymer matrices was investigated. Seven materials were examined: neat epoxy (3501-6), carbon fibre epoxy (AS4/3501-6), glass fibre/epoxy (E-glass/ 3501-6), aramid fibre/epoxy (K49/3501-6), neat polyetheretherketone (PEEK), carbon fibre/PEEK (APC2) and aramid fibre/PEEK (K49/PEEK). The wear behaviour of the materials was characterized by experimentally determining the friction coefficients and wear rates with a pin on-flat test apparatus. First, the effects of the operation variables apparent normal pressure, sliding velocity and apparent contact area were observed. The dimensionless wear rate increased linearly as the apparent normal pressure increased and decreased as the apparent contact area increased. Second, through microscopic observations of the worn surfaces and subsurface regions, basic wear mechanisms were identified as a function of fibre orientation. Observations of fibre-abrasive particle interactions allowed for the differentiation of the dominating wear mechanisms. Finally, a network of data was compiled on the wear behaviour in terms of the three material parameters: fibre orientation, fibre material and matrix material. This enabled the systematic selection of an ideal low wear composite material which would consist of a PEEK matrix reinforced with aramid fibres oriented normal to the contacting surface and carbon fibres oriented parallel to the contacting surface.     

Development of durable cementitious composites using sisal and flax fabrics for reinforcement of masonry structures

Natural fibres are one of the most studied materials. However, the use of these fibres as reinforcements in composite materials for structural applications, especially for existing or historical masonry structures, remains a challenge. In this study, efforts were made to develop sustainable composites using cementitious matrices reinforced with untreated bi-directional fabrics of natural fibres, namely, flax and sisal fibres. The fibres were mechanically characterised by tensile tests performed on both single yarns and fabric strips. Ageing effects due to fibre mineralisation in alkaline cement paste environments may cause a reduction in the tensile strength of natural fibres. The matrices used to study fibre durability were a natural hydraulic lime-based mortar (NLM) mix with a low content of water-soluble salts and a lime-based grouting (NLG) mix containing natural pozzolans and carbonated filler. Tensile tests on impregnated single yarns subjected to wetting and drying cycles by exposure to external weathering were conducted at different ages to quantify these problems. Composite specimens were manufactured by the hand lay-up moulding technique using untreated fibre strips and an NLG matrix. The mechanical response of natural fibre reinforced cementitious (NFRC) composites was measured under tension, and the effect of the matrix thickness was also addressed. Both sisal and flax fibres showed good adhesion with the NLG matrix, making them capable of producing composites with ductile behaviour and suitable mechanical performance for strengthening applications in masonry structures.     

Mechanical properties of natural fibre reinforced polymer composites

During the last few years, natural fibres have received much more attention than ever before from the research community all over the world. These natural fibres offer a number of advantages over traditional synthetic fibres. In the present communication, a study on the synthesis and mechanical properties of new series of green composites involving Hibiscus sabdariffa fibre as a reinforcing material in urea-formaldehyde (UF) resin based polymer matrix has been reported. Static mechanical properties of randomly oriented intimately mixed Hibiscus sabdariffa fibre reinforced polymer composites such as tensile, compressive and wear properties were investigated as a function of fibre loading. Initially urea-formaldehyde resin prepared was subjected to evaluation of its optimum mechanical properties. Then reinforcing of the resin with Hibiscus sabdariffa fibre was accomplished in three different forms: particle size, short fibre and long fibre by employing optimized resin. Present work reveals that mechanical properties such as tensile strength, compressive strength and wear resistance etc of the urea-formaldehyde resin increases to considerable extent when reinforced with the fibre. Thermal (TGA/DTA/DTG) and morphological studies (SEM) of the resin and biocomposites have also been carried out.     

Fabrication and characterization of <Emphasis Type="Italic">S. cilliare</Emphasis> fibre reinforced polymer composites

In the recent times, there has been an ever-increasing interest in green composite materials for its applications in the field of industries, aerospace, sports, household etc and in many other fields. In this paper, fabrication of Saccharum cilliare fibre reinforced green polymer composites using resorcinol formaldehyde (RF) as a novel matrix has been reported. A systematic approach for processing of polymer is presented. Effect of fibre loading on mechanical properties like flexural, tensile, compressive and wear resistances has also been determined. Reinforcing of the RF resin with Saccharum cilliare (SC) fibre was done in the form of particle size (200 micron). Present work reveals that mechanical properties of the RF resin have been found to increase up to 30% fibre loading and then decreases. Morphological and thermal studies of the resin, fibre and particle reinforced (P-Rnf) green composites have also been studied.