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.     

Two-body abrasion wear mechanism of super bainitic steel

The abrasion wear resistance and wear mechanism of super bainitic steel austempered at different temperatures and time have been investigated by two-body abrasion testings, scanning electron microscopy, X-ray diffraction, transformation electron microscopy and electron backscattering diffraction. The results show that the two-body abrasion wear mechanism is predominantly micro-ploughing abrasion, and the wear resistance is decreased with increasing isothermal temperature which is attributed to the decreased hardness caused by a higher retained austenite content and the coarsening of the microstructure. The sample austempered at 230°C for 2?h with the higher amount of retained austenite and lower carbon concentration exhibits excellent wear resistance, and the transformation induced plasticity effect is observed during wear process which is beneficial for the improving of hardness and wear resistance.     

Cu含量和烧结温度对Fe-Cu基粉末冶金复合材料摩擦磨损性能的影响

研究了铜含量和烧结温度对Fe-Cu基粉末冶金复合材料摩擦磨损性能影响。结果表明,Cu含量为20%~60%,随着Cu含量的提高耐磨性能先随之提高,Cu含量为40%时耐磨性能达到最优值,平均摩擦系数最小为0.172,磨损量为0.007 g;随着Cu含量的进一步提高耐磨性能反而降低。烧结温度为1096~1296℃时,随着烧结温度的提高耐磨性能随之提高,温度达到1196℃时耐磨性能达到最优,平均摩擦系数最小为0.123,磨损量为0.0018 g;烧结温度再提高耐磨性能反而降低。在最优工艺烧结过程中液相Al分别与Fe和Cu基体生成固溶体,使材料的密度和强度提高。MnS分解后,Mn与Fe基体生成固溶体,部分C也与Fe基体生成固溶体,两者促进了合金的固溶强化。其余的单质C,使合金的润滑性能提高。烧结后,Cu晶粒组织变得均匀细小,在Fe基中以网状形式存在。以上各组元的特殊作用使Fe-Cu基复合耐磨材料具有优异的耐磨性能。     

Effect of annealing temperature on the tribological behavior of ZnO films prepared by sol-gel method

The tribological behavior of zinc oxide (ZnO) films grown on glass and silicon (100) substrates by sol-gel method was investigated. Particularly, the as-coated films were post-annealed at different temperatures in air to investigate the effect of annealing temperature. Crystal structural and surface morphology of the films were measured by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). XRD patterns and AFM images indicated that the crystallinity and grain size of the films were enhanced and increased, respectively, with temperature. The tribological behavior of films was evaluated by sliding the ZnO films against a Si₃N₄ ball under 0.5 gf normal load using a reciprocating pin-on-plate tribo-tester. The wear tracks of the films were measured by AFM to quantify the wear resistance of the films. The results showed that the wear resistance of the films could be improved by the annealing process. The wear resistance of the films generally increased with annealing temperature. Specifically, the wear resistance of the films was significantly improved when the annealing temperature was higher than 550° C. The increase in the wear resistance is attributed to the increase in hardness and modulus of the film with annealing temperature.     

耐磨高熵合金制备工艺研究进展

耐磨高熵合金具有主元多、强度高、硬度大、磨损率低和耐高温等特征,应用前景广阔,是近几十年发展起来的一种新型耐磨材料。围绕耐磨高熵合金的主要制备工艺与耐磨性能的影响因素两方面,对近年来耐磨高熵合金的主要研究进展进行了综述。重点阐述了固、液、气态成型的耐磨高熵合金制备技术,总结了影响高熵合金耐磨性的因素,包括金属元素与非金属元素在内的多种元素对高熵合金耐磨性能的影响,说明了高熵合金及其碳氮化物涂层耐磨性能的研究进展。耐磨高熵合金的制备工艺较多,应根据合金形态成分的不同选择合适的制备方法;通过添加金属或非金属元素诱导硬质相析出仍是提高合金耐磨性能的主要手段;有些高熵合金或高熵合金涂层在高温、润滑等条件下也能够表现出优异的耐磨性能。     

Surface physical and chemical changes of pure iron after molybdenum ion implantation and their effects on the tribological behaviour II: Tribological behaviour

The components of tribological systems are all quite sensitive to the surface chemistry and microstructure of the tribological material which may be dramatically changed by ion implantation. This paper is aimed at studying the effect of surface physical and chemical changes caused by molybdenum ion implantation on the friction and wear behaviours of pure iron. For this purpose, the wear tests of unimplanted and implanted specimens were conducted on an SRV fretting wear machine in air, at room temperature and with or without lubrication. The surface morphology, composition and chemical state of the wear tracks were also examined using electron probe microanalysis, Auger electron spectroscopy and X-ray photoelectron spectroscopy. The experimental results indicate that the wear resistance of pure iron is largely improved by molybdenum ion implantation. Under dry friction conditions, the wear resistance of the specimen implanted with a dose of 3 × 10¹⁷ is increased to 2.8 times that of unimplanated pure iron since the anti-adhesion, anti-abrasion and anti-deformation abilities are improved as a result of the increase in microhardness. When liquid paraffin is used as a lubricant, the wear resistance of the implanted specimen is 4.8 times as high as that of the unimplanted one. This further increase in wear resistance compared with that for dry friction is mainly due to the boundary lubricating film provided by liquid paraffin, which reduces the adhesion between the wear counterpart and molybdenum atoms in the implanted specimen. When liquid paraffin plus sulphurized olefin is used as a lubricant, the wear resistance of the implanted specimen is 2.8 times as high as that of the unimplanted one. It can be seen that the increasing value of the wear resistance is lower than that of the sample lubricated with liquid paraffin. The reason is that the compounds FeS and FeSO₄ formed between the element of the wear specimen and the active elements of the lubricant in the wear process play an anti-wear role. However, the presence of a molybdenum element in the implanted specimen decreases the atomic ratio of iron, and thus decreases the amount of FeS and FeSO₄ and the wear resistance.     

Laser cladding of Zr-based coating on AZ91D magnesium alloy for improvement of wear and corrosion resistance

To improve the wear and corrosion resistance of AZ91D magnesium alloy, Zr-based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature. The corrosion resistance of the coating was tested in simulated body fluid. The results show that the coating mainly consists of Zr, zirconium oxides and Zr aluminides. The coating exhibits excellent wear resistance due to the high microhardness of the coating. The main wear mechanism of the coating and the AZ91D sample are different, the former is abrasive wear and the latter is adhesive wear. The coating compared to AZ91D magnesium alloy exhibits good corrosion resistance because of the good corrosion resistance of Zr, zirconium oxides and Zr aluminides in the coating.     

铜的表面含硅渗层的结构与性能

本文综述了利用ＳｉＨ４／Ｈ２混合气体在纯铜表面获得的含硅渗层的结构和性能。试验结果表明：通过纯铜表面气体渗硅这一新的化学热处理方法，其表面获得含硅渗层，可以改善铜的表面摩擦磨损、冲蚀磨损及耐高温腐蚀等表面性能     

Verschleißschutz für Titanbauteile

Wear Protection for Titanium Components The use of titanium and its alloys in the last decades keeps on increasing due to its material‐specific characteristics like high firmness, good corrosion characteristics and very high thermal maximum stress. However nowadays, the use of titanium components in systems where wear resistance is important is limited by titanium’s relatively low wear resistance. Surface wear is in principle a characteristic, conditioned by chemical and physical effects of the elements involved as well as collective stress. The necessity for new systems where good wear resistance and excellent mechanical properties are combined keeps on showing up. Due to titanium’s tendency to react with surrounding media, titanium alloys are difficult to be welded. Embrittlement by admission of hydrogen and oxygen can occur at high temperature processes or even changes on titanium’s microstructure may appear. Brazing techniques, which are actually applied to steel, have been modified and adapted for using them to titanium materials. Here, commercially available braze pastes and hard materials where combined and applied on titanium.     

A Study on Outstanding High-Temperature Wear Resistance of High-Entropy Alloys

Wear property is a main reason for failure, especially for those parts which are mechanically moving and interacting with each other in industrial utilization. High-entropy alloys (HEAs) are considered promising candidates to possess outstanding tribological factors of performance at high temperatures compared with conventional engineering alloys, which have drawn much attention from academic and industrial points of view. This study is performed to survey the influence of microstructure, grain size, precipitation, reinforcement, and elements addition on the wear resistance of HEAs over a wide temperature range. In this respect, the worn microstructure, wear rate, friction coefficient, hardness, wear track, and subsurface are precisely checked. This review also explores the high-temperature wear resistance of thermally sprayed and additively manufactured HEAs associated with emphasizing the dominant wear mechanisms through in a wide range of temperatures.     

纳米无溶剂环氧防锈漆的制备及性能

为了改善无溶剂环氧涂料的低温施工性及涂膜的耐磨性、柔韧性和耐蚀性,通过对主要组分材料的分析筛选,并采用在涂料A组分中配以复合防锈颜料并加入3%纳米氧化铝、B组分中加入10%二胺扩链剂的方法,制备了一种新型的纳米无溶剂环氧防锈漆;并对涂料低温施工性以及涂膜耐磨性、柔韧性、耐蚀性等性能进行测试评价。结果表明:在无溶剂环氧涂料体系中采用复合防锈颜料并引入纳米氧化铝及二胺扩链剂,涂料低温施工性改善,涂膜耐磨性、柔韧性及耐蚀性提高。     

Wear resistant carbon fiber reinforced Stellite alloy composites

Stellite alloys are a family of cobalt-based superalloys that are the main engineering materials used for severe corrosion, wear and high temperature environments. These alloys are strengthened by various carbides. However, the presence of carbides can cause many problems although they are main agents for wear resistance. This research attempts to develop a class of novel composite materials which substitute carbon of Stellite alloys with carbon fiber, aiming to minimize the disadvantageous effects of carbides in the alloys. Two types of carbon fiber, plain carbon fiber and nickel-coated carbon fiber, are employed in the composites. The new materials are fabricated using hot isostatic pressing (HIP) technique. The microstructures of these composites are analyzed to investigate if any carbides are induced due to incorporating carbon fibers. The tribological properties of these new composites are characterized on a pin-on-disk tribometer. The experimental results show that the developed composites exhibit better wear resistance than that of medium-carbon Stellite alloys and comparable wear resistance to that of high-carbon Stellite alloys.     

室温形变对20CrMnTi钢碳、氮共渗层抗磨损性能影响的研究

本文采用室温轧制形变量、碳一氮共渗温度、时间三因子二次旋转组合设计方法,着重研究了室温形变对20CrMnTi钢;碳、氮共渗层抗磨损性能的影响,并用微机进行数据的数学处理,推算出磨损失重量、室温形变量、共渗温度及时间关系的回归方程。结果表明:室温形变能明显提高共渗层的抗磨损性能,而且存在最佳形变量,对应最佳形变量磨损失重减小一半。本文还讨沦了适量室温形变改善和提高渗层抗磨损性能的原因。     

高温应用钼及钼合金表面改性研究进展

钼及钼合金因具有高熔点、高硬度、力学性能优异等优点,被广泛应用于军工、航空和航天等领域。但钼及钼合金在高温使用时存在抗氧化、抗烧蚀和耐磨损性能较差等缺陷,严重影响了钼及钼合金的高温使用性能。研究发现,通过表面改性能有效解决上述问题。首先提出了高温应用钼及钼合金表面改性涂层需满足的基本要求,系统地综述了改性涂层在改善高温应用钼及钼合金抗氧化、抗烧蚀和耐磨损性能方面的研究进展,介绍了常见改性涂层的制备方法,并指出了目前该研究领域存在的问题及今后的发展方向。     

Thermal stability of the phases formed in the near surface layers of unalloyed steels by nitrogen pulsed plasma treatment

Modification of the near surface layer of carbon steels using intense nitrogen plasma pulses leads to improvement of the hardness and wear resistance of the material surfaces, the main reason being the presence of the nitrogen expanded austenite formed during the process. A key factor influencing surface properties is the thermal stability of the identified phases, predominantly, the expanded austenite phases formed under the heat loading.Samples were characterized by nuclear reaction analysis (NRA), conversion electron Mössbauer spectroscopy (CEMS) and wear resistance measurements. The thermal stability of the modified samples has been investigated by annealing samples at increasing temperature in an argon atmosphere which showed phase transformation occurring at a characteristic temperature. The changes of the surface nitrogen concentration and wear resistance of the modified layer were investigated and discussed.     

不同温度下Fe-Al/Cr3C2复合涂层的摩擦学特性研究

使用THT07-135高温磨损实验机对不同温度下高速火焰喷涂Fe-Al/Cr3C2复合涂层进行滑动摩擦特性研究.运用扫描电镜及能谱仪对磨痕的形貌和不同区域的成分进行观察测试,运用透射电镜对涂层内部硬质相的存在状态进行观察分析.结果表明:高速火焰喷涂Fe-Al/Cr3C2复合涂层具有良好的抗摩擦磨损性能,随着滑动距离的增...     

硬质膜层耐磨性测试与表征

比较了测试硬质膜层耐磨性方法(如球-盘磨损试验方法、往复滑动磨损试验法、单向滑动磨损试验法)的各自特点和局限.从摩擦系数、磨损量及磨损机制方面对硬质膜层的耐磨性进行了详细讨论.指出,膜层的摩擦系数与试验参数(载荷、转速、温度等)之间并非简单的线性关系;与磨痕法相比,称重法在磨损量测量方面具有更高的精确度和更广泛的应用;硬质膜的磨损机理可以通过磨损后表面形貌、表面成分并结合摩擦系数和磨损量的变化规律综合分析得出.     

Fe3Al基摩擦材料的结构与摩擦磨损性能

采用热压烧结方法制备了一种适用于重载高速工况下的新型Fe3Al金属间化合物基摩擦材料,并对其微观结构、力学性能以及干滑动摩擦磨损性能进行了试验研究.结果表明,Fe3Al金属间化合物基摩擦材料密度低,强度高,摩擦系数高而稳定,高温耐磨性好.不同条件下摩擦磨损机制不同,轻载荷下主要是磨粒磨损和疲劳磨损,表现为微犁沟和凹坑;重载荷下摩擦初中期表现为严重塑性变形、裂纹扩展和疲劳断裂,摩擦后期以氧化磨损为主.     

激光熔覆原位生成Nb_2(C,N)及V_8C_7陶瓷粒子增强铁基金属涂层

采用5kW CO2激光设备,在42CrMo基体上制备出原位合成Nb2(C,N)及V8C7颗粒增强的铁基复合涂层,研究了熔覆层的组织及性能。结果表明:激光熔覆层主要组成相为α-Fe相、γ-Fe相、Nb2(C,N)及V8C7;增强相颗粒弥散分布在铁基复合涂层中,与母材相比,其磨损失重约为母材的1/8,显著提高了熔覆层的硬度和耐磨性。进一步的抗氧化性实验结果表明,氧化层结构连续致密,与42CrMo基体相比,在750℃/120h恒温氧化后的氧化层的厚度约为基体氧化层厚度的1/8。     

不同类型颗粒混合增强铁基复合材料的磨损性能

采用电流直加热动态热压烧结工艺制备陶瓷颗粒增强铁基复合材料,研究高体积分数(25%,30%,35%)下,单一类型颗粒(SiC,TiC,TiN)及混合类型颗粒(TiC+TiN,SiC+TiN,SiC+TiC)作为增强相对铁基复合材料磨损性能的影响。结果表明:单一类型粒子强化时,TiNP/Fe复合材料的耐磨性最好,TiCP/Fe次之,SiCp/Fe最差。混合粒子作为增强体时,(TiC+TiN)P/Fe复合材料磨损性能显著优于其对应的单一颗粒增强材料;其中粒子含量为30%时,(TiC+TiN)P/Fe复合材料磨损性能提高最大,其磨损量比TiCP/Fe降低了51.9%,比TiNp/Fe复合材料降低了44.1%,体现出可贵的混合增强价值。(SiC+TiC)_P/Fe和(SiC+TiN)P/Fe复合材料的磨损性能分别处于对应的两个单一颗粒增强材料之间。磨损表面观察表明,耐磨性好的(TiC+TiN)P/Fe复合材料的磨损机理为磨粒磨损,而(SiC+TiC)_P/Fe和(SiC+TiN)P/Fe复合材料除磨粒磨损外还存在明显的疲劳磨损现象。