The sliding wear behavior of TiCp/AZ91 magnesium matrix composites

The AZ91 metal matrix composites (MMCs) reinforced with 5, 10 and 15 wt.% TiC particulates are fabricated by TiC_p–Al master alloy process combined with mechanical stirring. The effects of TiC particulate content, applied load and wearing time on the sliding wear behaviors of the composites were investigated using MM-200 wear testing apparatus. The results show that the wear resistance and friction coefficient of the composites increased and decreased with increase of the TiC particulate content, respectively. The wear volume loss and friction coefficient of the reinforced composites as well as the unreinforced AZ91 matrix alloy increased with increase of applied load or wearing time, but the increase rates of the reinforced composites in two performance is lower than those of the unreinforced AZ91 matrix alloy. Furthermore, the sliding wear behavior of the composites and the unreinforced AZ91 matrix alloy is characterized by ploughing, adhesion and oxidation abrasion.     

Relationship between thermal and sliding wear behavior of Al6061/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> metal matrix composites

Al6061 alloy and Al6061/Al₂O₃ metal matrix composites (MMCs) were fabricated by stir casting. The MMCs were prepared by addition of 5, 10 and 15 wt% Al₂O₃ particulates and the size of particulates was taken as 16 μm. The effect of Al₂O₃ particulate content, thermal properties and stir casting parameters on the dry sliding wear resistance of MMCs were investigated under 50–350 N loads. The dry sliding wear tests were performed to investigate the wear behavior of MMCs against a steel counterface (DIN 5401) in a block-on-ring apparatus. The wear tests were carried out in an incremental manner, i.e., 300 m per increment and 3,000 m in total. It was observed that, the increase in Al₂O₃ vol% decreased both thermal conductivity and friction coefficient and hence increased the transition load and transition temperature for mild to severe wear during dry sliding wear test.     

Dry wear properties of A356-SiC particle reinforced MMCs produced by two melting routes

SiC particle reinforced metal matrix composites (MMCs) were produced by a common liquid phase technique in two melting routes. In the first route, 5, 10, 15 and 20 vol% SiC reinforced A356-based MMCs were produced. In the second route, an Alcan A356 + 20 vol% SiC composite was diluted to obtain 5, 10, 15 and 20 vol% SiC MMCs. In both cases the average particle size was 12 μm. The composites that produced by two different routes were aimed to compare the dry wear resistance properties. A dry ball-on disk wear test was carried out for both groups of MMCs and their matrix materials. The tests were performed against a WC ball, 4.6 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40–60%. Sliding speed was chosen as 0.4 m/s and normal loads of 1, 2, 3 and 5 N were employed. The sliding distance was kept at 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. A complete wear microstructural characterization was carried out via scanning electron microscopy. The wear behaviors were recorded nearly similar for both groups of composites. Diluted samples showed lower friction coefficient values compared with the friction coefficient values of the vortex-produced composites. This was attributed poor bonding between matrix and particles in the vortex-produced composites associated with high porosities. But, in general, diluted Alcan composites showed slightly lower wear rate relationship with the particle volume percent and applied load when compared with vortex produced materials.     

外部因素对金属基复合材料磨损性能的影响

综述和分析了正载荷、滑动速度、滑动距离、环境温度等外部因素对金属基复合材料磨损性能的影响。与复合材料内部影响因素类似,外部因素通过影响复合材料磨损机制而影响复合材料磨损率。     

Tribological behavior and wear surface analysis of metal-matrix composites

This paper describes the results of dry sliding wear tests and wear surface analysis of boron-fibre-reinforced aluminium composites. The wear tests were conducted for normal and parallel orientations, rubbing against a rotating steel disc at different loads at speeds of 0.6 and 1.6 m s–1. In addition, the wear surface analysis of the aluminium-based composites was investigated by X-ray photoelectron spectroscopy (XPS). The metal–matrix composites showed excellent wear resistance compared with the unreinforced matrix. Fibre orientation had a small effect on wear rate: at low speed the normal orientation gave the lowest wear rate, with the performance of the parallel orientation being slightly worse, but this trend reversed at high speed. The XPS analysis revealed that there was no significant variation in the amount of oxide over the surface under the test conditions used. At low speed in the normal orientation boron oxide and iron boride were formed, while at high speed the proportions of these components were slightly different and showed alloyed material with more iron boride and aluminium but less boron in total.     

Dry sliding wear of an Al2O3 continuous fibre reinforced Al-Cu alloy against steel counterface

The tribological properties of Al₂O₃ continuous fibre reinforced Al-4.43 wt %Cu alloy composites with a fibres' volume fraction of about 0.55 were measured for five types of fibre orientations under a dry sliding contact with a bearing steel. Fibres were in a plain perpendicular to wear surface and parallel to sliding direction, and had the angles 0°, 45°, 90°, or 135° with respect to the direction of motion of the counterface; or were anti-parallel the sliding direction. The results show obvious dependence of wear characteristics on fibres orientation: for the 45°, 90°, and 135° orientations, the larger the fibres' angle, the lower the volume loss; while the 0° orientation resulted in a higher steady-state wear rate than those of the 45°, 90°, and 135°, orientations, except that the anti-parallel orientation caused the highest volume loss at all sliding distances. The wear mechanism was inferred as a oxidation-microgrooving process through the analyses of worn surface and subsurface with the aid of optical microscope and scanning electron microscope. Also it was found that the fibres' broken and subsurface deformation had played an important role in causing wear anisotropy.     

The relationships between wear behavior and thermal conductivity of CuSn/M7C3–M23C6 composites at ambient and elevated temperatures

The effect of FeCr (M₇C₃–M₂₃C₆) particles on the wear resistance of a CuSn alloy was investigated under 125 N load, and 300–475 K temperature interval. Sliding tests were performed to investigate the wear behavior of FeCr_p-reinforced CuSn metal–matrix composites (MMCs) against DIN 5401 in a block-on-ring apparatus. The CuSn/FeCr_p MMCs, which were prepared by addition of 5, 10, 15 and 20 vol.% of FeCr_p, were produced by powder metallurgy and the size of the particles was taken as 16 μm. The powders were uniaxially cold compacted by increasing pressure up to 250 Mpa. The dry sliding wear tests were carried out in an incremental manner, i.e. 300 m per increment and 3500 m total sliding length. The wear-test results were used for investigation of the relationship between weight loss, microstructure, surface hardness, friction coefficient, particle content and thermal conductivity. Finally, it was observed that FeCr_p reinforcement is beneficial in increasing the wear resistance of CuSn MMCs. FeCr particles in MMCs also tend to reduce the extent of plastic deformation in the subsurface region of the matrix, thereby delaying the nucleation and propagation of subsurface microcracks     

Tribological Evaluations of Polyester Composites Considering Three Orientations of CSM Glass Fibres Using BOR Machine

In the current work, the effects of chopped strand mat (CSM) glass fibre 450 g/m² on tribo-properties of unsaturated polyester are evaluated. Experimental tests were performed by using Block on Ring (BOR) machine against polished stainless steel under dry contact condition. Three principle orientations of CSM glass fibre in the matrix were considered, i.e. namely Parallel (P-O), Anti-Parallel (AP-O) and Normal (N-O). Specific wear rate, friction coefficient and interface temperature were determined and presented as a function of applied load (30–100 N), and sliding distance (0–14 km) at two different sliding velocities (2.8 and 3.9 m/s). Scanning electron microscopy (SEM) was used to observe the damages features on the worn surfaces. The results showed that the orientations of CSM glass fibre significantly influenced the tribological performance of polyester composite. Better tribo performance were achieved when the polyester was reinforced with CSM glass fibre and tested at Parallel orientation. Moreover, specific wear rate and friction coefficient of polyester was reduced by 75%, and 55% at P-O of CGRP composite. The damage features were predominated by debonding of fibers, matrix deformation and polyester debris transfer.     

纤维取向对复合材料磨损性能影响的统计学研究

采用挤压铸造法制备了3Al₂O₃·2SiO_2f/ZL109复合材料.利用统计学方法研究了载荷为600N、滑动速度为1.05m/s的润滑滑动磨损条件下纤维取向对复合材料磨损性能的影响.研究结果表明:纤维平行取向与垂直取向复合材料的磨损体积均符合概率密度f(x)的同一总体的正态分布[式(1)],纤维取向对复合材料的耐磨性影响不大.通过磨面的SEM分析,发现两种纤维取向的复合材料的磨损均为纤维断裂与磨粒磨损.     

TiCp/ZA-12复合材料磨损行为的研究

采用XD^TM与搅拌铸造技术相结合的工艺制备TiCp/ZA-12复合材料。利用MM－200摩擦磨损测试仪测试干摩擦条件下这种复合材料的磨损性能。研究了TiC颗粒含量、应用载荷和滑动距离对其磨损程度的影响。结果表明：复合材料的磨损率低于基体合金磨损率，且磨损率随TiC颗粒含量的增加而减小；增大应用载荷和滑动距离，并且复合材料和基体ZA－12合金的磨损程度均增加，但复合材料的增幅明显偏小。同时发现，在磨损过程中存在瞬变载荷，当应用载荷低于瞬变载荷时，磨损表现为微磨损，当高于瞬变载荷时为剧烈磨损，复合材料的瞬变载荷比基体合金高得多。最后分析了复合材料和基体合金的磨面形貌。     

飞灰颗粒增强铝基复合材料的摩擦与磨损特性

对挤压铸造制成的飞灰颗粒增强ZL109复合材料在不同条件下的摩擦磨损特性进行了研究。研究结果表明:在较低载荷和较低滑动速度下,该复合材料的耐磨性明显优越于基体铝合金,摩擦系数也稳定地低于基体铝合金,并且随飞灰含量的增加复合材料的耐磨性有所提高;在较高载荷和较高滑动速度下,同基体铝合金相比复合材料耐磨性的改善程度有所降低,但复合材料的摩擦系数仍可以保持较低的水平。这是由于随着载荷和滑动速度的变化,复合材料的磨损机制发生了转化。本文对该过程中的磨损机制的转化进行了初步分析。     

TIC/7075铝基复合材料的磨损实验研究

采用原位反应喷射沉积法制备TiC/7075铝基复合材料,并在销一盘式磨损机损上进行摩擦磨损实验研究.通过TEM观察原位TiC颗粒的分布与形貌,并利用SEM观察沉积态组织磨损表面形貌.结果表明:复合材料的耐磨性和TiC颗粒含量及载荷有关,在低载荷(8.9N)状态下,材料的耐磨性随TiC颗粒含量的增加而增强,在高载荷(26...     

Experimental investigation on mechanical properties and wear characterization of Al-Si12CulMg1 aluminium alloy reinforced with titanium diboride and boron carbide particulate hybrid composites using stir casting process

LM13 aluminium alloy (Al−Si12CulMg1) with titanium diboride (TiB₂) and boron carbide (B₄C) particulate hybrid composites have been prepared using stir casting process. Wt% of titanium diboride is varied from 0–10 and constant 5 wt% boron carbide particles have been used to reinforce LM13 aluminium alloy. Microstructure of the composites has been investigated and mechanical properties viz., hardness, the tensile strength of composites have been analyzed. Wear behavior of samples has been tested using a pin on disc apparatus under varying load (20 N–50 N) for a sliding distance of 2000 m. Fracture and wear on the surface of samples have been investigated. Microstructures of composites show uniform dispersion of particles in LM13 aluminium alloy. Hardness and tensile strength of composites increased with increasing wt % of reinforcements. Dry sliding wear test results reveal that weight loss of composites increased with increasing load and sliding distance. Fracture on the surface of composites reveals that the initiation of crack is at the interface of the matrix and reinforcement whereas dimples are observed for LM13 aluminium alloy. Worn surface of composites shows fine grooves and delamination is observed for the matrix.     

Influence of Fibre Orientation on Friction and Sliding Wear Behaviour of Jute Fibre Reinforced Polyester Composite

Jute fibre reinforced polyester composites were developed and characterized for friction and sliding wear properties. Effect of fibre orientation and applied load on tribological behaviour of jute fibre reinforced polyester composites were determined. It is found that wear resistance was maximum in TT sample, where fibres were normal to sliding direction. Wear rate under sliding mode follows this trend; W_TT < W_LT <W_LL LL sample showed higher capability to sustain the load whereas lowest wear resistance found in this case. The coefficient of friction found highest for TT sample and lowest for LT sample. The coefficient of friction decreased with increase of applied load. Worn surfaces were analysed and discussed with the help of SEM.     

Effect of in-situ TiC particulate on the wear resistance of spray-deposited 7075 Al matrix composite

TiC reinforced 7075 Al matrix composites have been fabricated by a melt in-situ reaction spray deposition. The microstructures of spray-deposited alloys were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding wear behavior of the alloys was investigated using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. It has been found that the wear behavior of the alloys was dependent on the TiC content in the microstructure and the applied load. At a lower load (8.9 N), with increasing TiC content, the wear rate of the alloy was decreased. At a higher loads (26.7, 35.6 N), a spray-deposited 7075 Al alloy exhibited superior wear resistance to the 7075/TiC composites.     

Wear behaviour of aluminium matrix composite materials

Wear behaviour of aluminium matrix composites is characterized by the dry spindle wear test under various conditions (volume fractions of reinforcements, sliding distances and speeds). Wear resistance of composites is improved due to the presence of reinforcements, but no noticeable improvements are observed in the wear resistance with more than 20% addition of reinforcements. To analyse wear mechanisms, wear surfaces are examined by scanning electron microscopy (SEM). The major wear mechanisms of discontinuous metal matrix composites (MMC)s are strongly dependent on sliding speeds. Dominant mechanism is the adhesive-abrasive wear at low and intermediate sliding speeds, and melt wear at high sliding speeds. Weight loss is linearly increased with the sliding distance. The effect of reinforcements' orientations on wear behaviours is also discussed.     

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.     

Optimization of reinforcement content and sliding distance for AlSi7Mg/SiCp composites using response surface methodology

Extruded AlSi7 Mg alloy based SiC_p reinforced (AlSi7 Mg/SiC_p) composites and the matrix alloy were wear tested on a pin on disk type tester. The work was planned so that some response surface (RS) models can be used to examine the wear behaviour of composite samples. The effects of friction load, sliding distance and reinforcement content on the wear rate and weight loss of AlSi7 Mg/SiC_p composites were evaluated by using RS optimization procedure. In the applications of RS models to engineering problems, the estimated RS models usually have a maximum or a minimum point. Through this article the RS optimization procedure was employed to optimize the reinforcement content and sliding distance for the minimization of wear rate and weight loss of tested composites. During the tests, the values of reinforcement content, friction load and sliding distance were changed on the intervals (0%, 20%), (49 N, 169 N), (100 m, 1000 m), respectively. It was shown that there exists some optimum values of reinforcement content and some optimum values of sliding distance which minimize the wear rates also weight losses of tested composites for some fixed values of friction load in the experimental region. In this concern, the average value of optimum reinforcement contents and the average value of optimum sliding distances of AlSi7 Mg/SiC_p composites minimizing the wear rate were found as 13% and 595 m, respectively. Also the average value of optimum reinforcement content minimizing the weight loss was found as 13%.     

Effect of testing conditions and microstructure on the sliding wear of graphite fibre/PEEK matrix composites

The sliding friction and wear behaviour of unreinforced polyetheretherketone (PEEK) matrix and its unidirectional continuous and two-dimensional woven graphite fibre-reinforced composites were investigated. The operating wear mechanisms, as evinced by scanning electron microscopy of the worn surfaces, and the coefficients of friction and the wear rates changed considerably with the fibre reinforcement form and orientation. Sliding wear rates, on account of their extreme sensitivity to the microstructure of the interacting surfaces at the sliding interface, were found to be a function of not only the surface roughness, but also of the sliding time. Complex interactions arising due to the effects of the testing parameters such as fibre orientation, sliding velocity, contact pressure and interface temperature were characterized for the neat matrix and the two composite systems. The wear rates of the two-dimensional woven composites were almost an order of magnitude lower than those of the unidirectional fibre composite or the unreinforced matrix.     

Wear behavior of WC<Subscript>P</Subscript>/Fe–C composites under high-speed dry sliding

WC_P/Fe–C composites are manufactured by centrifugal casting method. Dry sliding wear behaviors of the composites containing about 70 vol.% of WC_P were investigated at room temperature against 3Cr2W8V die steel counter face. And wear experiments were performed under loads of 50, 100, 150, and 200 N and sliding velocities of 20, 40, 60, and 80 m/s. Results showed that at the low load of 50 N, the composites, under different sliding velocities, all displayed significantly superior wear resistance. Meanwhile the results also showed that the variation of wear weight loss and wear rate of the composites was almost linear with sliding velocity when the sliding velocity and the load were below 60 m/s and 100 N. But as the sliding velocity and the load exceed 60 m/s and 100 N, the weight loss and wear rate of the composites increased rapidly. But the effect of the load applied on wear weight loss and wear rate was larger than that of the sliding velocity. Finally, the mechanism of the dry sliding wear is discussed in the article.