Friction and Wear Behaviors of Nanostructured Metals

Nanostructured （ns） materials, i.e., polycrystalline materials with grain sizes in the nanometer regime （typically below 100 nm）, have drawn considerable attention in the past decades due to their unique properties such as high strength and hardness. Wear resistance of ns materials, one of the most important properties for engineering materials, has been extensively investigated in the past decades. Obvious differences have been identified in friction and wear behaviors Between the ns materials and their corresponding coarse-grained （cg） counterparts, consistently correlating with their unique structure characteristics and mechanical properties. On the other hand, the superior tribological properties of ns materials illustrate their potential applications under contact loads. The present overview will summarize the important progresses achieved on friction and wear behaviors of ns metallic materials, including ultrafine-grained （ufg） materials in recent years. Tribological properties and effects on friction and wear behaviors of ns materials will be discussed under different wear conditions including abrasive wear, sliding wear, and fretting wear. Their correlations with mechanical properties will be analyzed. Perspectives on development of this field will be highlighted as well.

Wear Studies on Metal Matrix Composites: a Taguchi Approach

An attempt has been made to study the influence of wear parameters like applied load, sliding speed, sliding distance and percentage of reinforcement on the dry sliding wear of the metal matrix composites. A plan of experiments, based on techniques of Taguchi, was performed to acquire data in controlled way. An orthogonal array and the analysis of variance were employed to investigate the influence of process parameters on the wear of composites. The objective is to establish a correlation between dry sliding wear of composites and wear parameters. These correlations were obtained by multiple regressions. Finally, confirmation tests were conducted to verify the experimental results foreseen from the mentioned correlations.

Microstructure and Wear Behavior of FeBSiNbCr Metallic Glass Coatings

In this paper, FeBSiNbCr metallic glass coatings were prepared onto AISI 1045 steel substrate by using wire arc spraying process. The phase and structure of the coating were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD） and scanning election microscopy （SEM） equipped with energy dispersive X-ray analysis （EDX）. The microstructure of the coating consists of full amorphous phase. The coating has high hardness and low porosity. Full density and little oxides are detected in the coating. The mechanical properties, especially wear resistance, were investigated. The relationship between wear behavior and structure of the coatings were analyzed in detail. The main failure mechanism of the metallic glass coating is brittle breaking and fracture. The results indicate that FeBSiNbCr metallic glass coating has excellent resistance to abrasive wear.

A View on Wear Mechanism of Metallic Card Clothing

The wear mechanism of metallic card clothing,used in textile industry,was analyzed.A fast wear test for metallic card clothing racks was developed,which was used as collecting the wear metal particles.The failure type of card clothing was analyzed by the mean of scanning electron microscopy(SEM)and ferro-spectrum technology.The results show that the main wear mechanism of metallic card clothing is low load and high repetition interval fatigue wear caused by friction force between fiber and metal wire teeth.The appropriate quenching microstructure,which improves the wear resistance of the metallic card clothing rack is also discussed.

Effect of Carbon Nanotube on the Oscillating Wear Behaviour of Metal-PTFE Multilayer Composites

Two kinds of metal-PTFE multilayer composites, which were composed of a steel backing, a middle layer of sintered porous bronze and a surface layer of polytetrafluoroethylene（PTFE） filled by carbon nanotubes（CNTs） or not, were prepared. The wear properties of metal-PTFE multilayer composites oscillating against 45 carbon steel under dry condition were evaluated on an oscillating wear tester, and the effect of CNTs on wear behaviour of metal-PTFE multilayer composites was studied. The results showed that the worn surface of metal-PTFE multilayer composites was characterized by adhesive wear, abrasive wear and fatigue wear. The CNTs greatly increased the adhesion strength of PTFE in the metal-PTFE composites and thereby greatly reduced puck, ploughing, and fatigue failure of PTFE during wearing. The PTFE filled with CNTs prevented direct contact between the mating surfaces and served as fine self-lubricating film, in which the oscillating wear mechanism of the composites was changed to a slightly adhesive wear. Therefore, the CNTs significantly decreased the weight loss and obviously increased the wear resistance of metal-PTFE multilayer composites.

Fabrication and abrasive wear properties of metal matrix composites reinforced with three-dimensional network structure

Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-porosity and super-strong skeleton. The aluminum magnesium matrix composites reinforced with three-dimensional network structure were prepared using the infiltration technique by pressure assisting and vacuum driving. Light interfacial reactions have played a profitable role in most of the ceramic-metal systems. The metal matrix composites interpenetrated with the ceramic phase have a higher wear resistance than the metal matrix phase. The volume fraction of ceramic reinforcement has a significant effect on the abrasive wear, and the wear rate can be decreased with the increase of the volume fraction of reinforcement.

Impact Wear Properties of Metal-Plastic Multilayer Composites Filled with Glass Fiber Treated with Rare Earth Element Surface Modifier

The friction and wear properties of metal-plastic multilayer composites filled with glass fiber, which is treated with rare earth element surface modifier, under impact load and dry friction conditions were investigated. Experimental results show that the metal-plastic multilayer composite filled with glass fiber exhibits excellent friction and impact wear properties when using rare earth elements as surface modifier for the surface treatment of glass fiber.

Effect of Rare Earths-Treated Glass Fiber on Impact Wear-Resistance of Metal-Plastic Multilayer Composites

The friction and wear properties under impact load and dry friction conditions of metal-plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear-resistance.

Optimization of Wear Factors of Aluminium Hybrid Metal Matrix Composites Using Taguchi Method

Hybrid metal matrix composites (Hmmc) are found to be more superior than the conventional composite materials because of their improved mechanical properties, which can be suited for an extensive range of engineering applications. Automobile and aerospace industries widely make use of hybrid composites as they possess excellent corrosion, wear resistance, low density, and high strength. This paper displays the strategy to build the hybrid composite utilizing Stir casting Method. Present investigation includes the creation of composites utilizing boron carbide (2%, 4%, 6% volume) and Red mud (2% volume) as the reinforcements and Structural aluminium as the matrix. Experimental investigation of wear analysis of the composites was carried out according to the L9 Taguchi method. The designated number of experiments was accomplished to probe the impact of control factors on the specific wear rate (SWR) of the developed composites. ANOVA was carried out and Wt%. Reinforcement was found to be the decisive factor on the SWR of the developed hybrid composite. The Confirmatory test was successfully carried out and the computed error was found to be varying from 0.878% to 2.58%.

Wear Behaviour of Al-SiCp Metal Matrix Composites and Optimization Using Taguchi Method and Grey Relational Analysis

Aluminium metal matrix composite is a relatively new material that has proved its position in automobile, aerospace and other engineering design applications due to its wear resistance and substantial hardness. Need for improved tribological performance has led to the design and selection of newer variants of the composite. The present investigation deals with the study of wear behaviour of Al-SiCp metal matrix composite for varying reinforcement content, applied load, sliding speed and time. Aluminium metal matrix composites reinforced with SiC particles are prepared by liquid metallurgy route using LM6 aluminium alloy and silicon carbide particles (size ~ 37 μm) by varying the weight fraction of SiC in the range of 5% - 10%. The material is synthesized by stir casting process in an electric melting furnace. The materials are then subjected to wear testing in a multitribotester using block on roller configuration. A plan of experiments based on L27 Taguchi orthogonal array is used to acquire the wear data in a controlled way. An analysis of variance is employed to investigate the influence of four controlling parameters, viz., SiC content, normal load, sliding speed and sliding time on dry sliding wear of the composites. It is observed that SiC content, sliding speed and normal load significantly affect the dry sliding wear. The optimal combination of the four controlling parameters is also obtained for minimum wear. The microstructure study of worn surfaces indicates nature of wear to be mostly abrasive.

Optimization of Friction and Wear Behaviour in Hybrid Metal Matrix Composites Using Taguchi Technique

Al-7075 alloy-base matrix, reinforced with mixtures of silicon carbide (SiC) and boron carbide (B4C) particles, know as hybrid composites have been fabricated by stir casting technique (liquid metallurgy route) and optimized at different parameters like sliding speed, applied load, sliding time, and percentage of reinforcement by Taguchi method. The specimens were examined by Rockwell hardness test machine, Pin on Disc, Scanning Electron Microscope (SEM) and Optical Microscope. A plan of experiment generated through Taguchi’s technique is used to conduct experiments based on L27 orthogonal array. The developed ANOVA and the regression equations were used to find the optimum wear as well as co-efficient of friction under the influence of sliding speed, applied load, sliding time and percentage of reinforcement. The dry sliding wear resistance was analyzed on the basis of “smaller the best”. Finally, confirmation tests were carried out to verify the experimental results.

Nanowear of a Zr Based Bulk Metallic Glass/Nanocrystalline Alloy

The hardness, elastic modulus, nano-scratch resistance and wear depth for a bulk metallic glass of and its partial crystallization alloys have been measured by using nanoindentation method. The results showed that partial crystallization did not influence the reduced elastic modulus but increased the hardness, and then increased the scratch coefficient. The scratch coefficient increased linearly with increasing the hardness H but decreases when W>6.2GPa. Partial crystallization decreased evidently the wear depth, and when the load was large the wear depth decreased with increasing the hardness.

Dry Sliding Wear Behaviour of SiC Particles Reinforced Zinc-Aluminium (ZA43) Alloy Metal Matrix Composites

The present paper reveals the wear behaviour of Zinc - Aluminium alloy reinforced with SiC particulate metal matrix composite. The composite is prepared using liquid metallurgy technique. The unlubricated pin-on disc wear test is conducted to find the wear behaviour of the ZA43 alloy based composite. The sliding wear test is conducted for different load, speed and time. The result reveals that wear rates of composite is reduced as reinforcement increases. For the same working conditions wear rate increases with increasing load and with increasing speed. The tested samples are examined by taking micro structure photos and analyzed for the type of wear. Dominating wear types observed are delamination and abrasion.

Research on Wheel Rail Wear for a 140 t Open Type Hot Metal Car

To maintain the safety of an open-type hot-metal car and to reduce wheel-rail wear during transportation, simulation models of the main components of such car were built using Pro/E software and then tested. In particular, the Pro/E models were imported into ADAMS/Rail for assembly and then used to construct a complete hot-metal car dynamic model. Locomotive wheel-rail attack angle, wheel-rail lateral force, and wear index were used as evaluation parameters during the simulation to analyze the effects of bogie parameter, rail parameter, and speed of the hot-metal car on wheel-rail wear. An improvement scheme for reducing wheel-rail wear was proposed based on the result of the dynamic simulation, wherein wheel-rail wear and curving performance were analyzed and compared. The simulation provided an important reference for evaluating and improving the dynamic performance of the hot-metal car. The applied effect showed that the improvement scheme is effective.

激光熔覆WC/316L复合涂层结构及磨损性能

为改善激光熔覆过程中WC增强金属基复合涂层分解与分布不均匀的问题,采用激光熔覆技术制备了50%WC含量的WC/316L复合涂层,分别采用扫描电子显微镜(SEM)、显微维氏硬度计、摩擦磨损试验机表征了熔敷层的组织形貌、硬度与摩擦磨损性能。结果显示,低热输入量可以防止WC颗粒下沉,提升熔覆层厚度方向上的WC颗粒分布均匀性;但WC的平面分布均匀性较差,同时低热输入导致WC颗粒结合较弱,易发生脱落;熔覆过程中,粉末中15%的WC发生分解。研究表明,通过降低激光热输入量,可以制备WC厚度方向较为均匀的复合涂层,提升熔覆层耐磨性,但是需要优化WC平面分布均匀性与WC颗粒结合性能。

基于金属电化学腐蚀的单晶SiC表面腐蚀和磨损性能研究

针对化学机械抛光中抛光液的环境污染,提出一种基于金属电化学腐蚀的单晶SiC化学机械抛光方法.通过腐蚀实验和摩擦磨损实验,研究了电化学腐蚀单晶SiC的Si面腐蚀性能和磨损性能.通过对比Al、Cu、Fe金属在Na_(2)SO_(4)电解质溶液中对Si面的腐蚀性能,发现Al在Si面产生明显的腐蚀层,EDS和XPS检测证实该腐蚀产物为SiO_(2).采用摩擦磨损实验研究溶液组分对SiC的Si面磨损影响规律.结果表明,提高Na_(2)SO_(4)电解质溶液浓度能获得更大的磨损量,当Na_(2)SO_(4)电解质溶液浓度为1.00 mol/L时,得到最大为7.19µm^(2)的磨损量;在酸性的金属电化学腐蚀溶液中,Si面具有更好的材料去除性能,在pH=3时磨损量达到11.97µm^(2).单晶SiC的金属电化学腐蚀材料去除机制为阴极的Al金属发生电偶腐蚀反应产生腐蚀电流,促使阳极SiC表面氧化生成SiO_(2)氧化层,进而去除材料.

刮板输送机中部槽金属对磨试验分析

本文设计对磨试验,探究不同工况对刮板输送机中部槽金属耐磨情况的影响。对磨实验采用控制变量法,使用16Mn、NM400和HD400三种钢材料制作了试样,将试样置于万能摩擦磨损试验机中,分别探究了磨损行程、加载压力、滑动速度等变量对于中部槽试样磨损量的影响。结果表明,磨损行程与磨损量呈正相关;在低压低速工况下HD400的耐磨性较好,在高压高速时HD400的耐磨性较好,任意工况下16Mn的耐磨性最差。由此可得,应根据刮板输送机的运行工况选择合适材质的中部槽金属,并且在满足采煤运煤需要的前提下,科学设置刮板输送机的加载压力、滑动速度等参数,对延长中部槽金属使用寿命有积极作用。

Si含量对Fe-Cr-Si合金高温耐磨性能的影响

为研究Si含量对Fe-Cr-Si合金高温耐磨性能的影响,改善Fe-Cr-Si合金在高温环境下的耐磨性能,采用真空电弧熔炼制备了4种不同Si含量(原子分数5%、10%、15%、20%)的Fe-Cr-Si合金,研究了Si含量变化对其高温耐磨性能的影响。结果表明,4种Fe-Cr-Si合金均由单相组织构成,Si含量的增加使得合金硬度逐渐升高,并且促进了金属硅化物Fe_(3)Si的形成。随着Si含量的增加,Fe-Cr-Si合金的摩擦系数和磨损率逐渐减小,磨损机制由剥落磨损转变为氧化磨损、磨粒磨损和黏着磨损。

含硅烷偶联剂有机金属涂层的制备及性能研究

硅烷偶联剂涂覆是金属表面改性最常用的手段之一,而为了获得与金属基体结合良好的有机涂层,需要进行涂覆材料选择、表面预处理、涂覆工艺选择等多因素考虑。对于硅烷偶联剂对金属表面改性的作用机理进行阐述,对含硅烷偶联剂有机金属涂层的制备最近研究现状进行介绍,并提出一种用于镁合金的耐磨环氧涂层的制备方法。

Cu含量对激光选区熔化CoCrMoCu合金微观组织及表面摩擦磨损性能的影响

目的阐明不同Cu含量对激光选区熔化(Selective Laser Melting,SLM)制备的CoCrMoCu合金微观组织的影响及其在表面摩擦磨损和腐蚀性能使役行为方面的作用。方法采用CoCrMo合金粉和纯Cu粉通过行星球磨机进行机械混合,制备了Cu质量分数为2%、4%、6%的CoCrMo/Cu混合粉末,并通过SLM技术制备相应的试样。对不同Cu含量的SLM CoCrMoCu的相组成、微观结构、硬度、摩擦磨损和腐蚀性能进行检测和分析。结果Cu含量对SLM CoCrMoCu的相组成和微观组织没有明显影响,在不同Cu含量的试样中,试样的微观组织均主要为胞状等轴晶。在力学性能方面,随着Cu含量的升高,试样的硬度先提升后降低,在含2%Cu的情况下达到最大值(429.2HV0.2),在含6%Cu的情况下达到最小值(367.7HV0.2)。CoCrMoCu的摩擦因数和磨损率随着Cu含量的升高而降低,在4%时摩擦因数和磨损率达到最低(2.7×10^(-5)mm^(3)/(N·m)),摩擦磨损性能最好。随着Cu质量分数进一步增加到6%,由于硬度降低,磨损性能下降,试样表面出现沟壑,影响Cu自润滑层的附着,磨损机制由黏着磨损向磨粒磨损转变,导致摩擦因数和磨损率增加。在腐蚀性能方面,腐蚀电位随着Cu含量的升高而升高,而腐蚀电流随着Cu含量的升高呈现先下降后上升的趋势,在4%时达到最佳的腐蚀性能。结论Cu的引入在一定范围内(2%~4%)可以有效提高CoCrMoCu合金的硬度和腐蚀性能。结合Cu的自润滑效应和类钝化效应,实现CoCrMo合金耐磨性能和腐蚀性能的协同提升。