Effect of sliding distance on the wear and friction behavior of as cast and heat-treated Al–SiCp composites

The present investigation aims to evaluate the effect of sliding distance on the wear and friction behavior of as cast and heat-treated Al–SiCp composites using pin-on-disc wear testing machine, giving emphasis on the parameters such as wear rate and coefficient of friction as a function of sliding distance (0–5000 m) at different applied pressures of 0.2, 0.6, 1.0 and 1.4 MPa, and at a fixed sliding speed of 3.35 m/s. Characterizing the alloy and composites in terms of microstructure, X-ray diffraction analysis, microhardness and wear surface analysis. The results revealed that the heat-treated composite exhibited superior wear properties than the base alloy, while the coefficient of friction followed an opposite trend. Moreover, the wear rate of the composite is noted to be invariant to the sliding distance and increased with applied pressures. Microstructure of composite shows fairly uniform distribution of SiC particles in the metallic matrix. The hardness value of heat-treated composite increased 20–30% by addition of SiC particles to the alloy, intermetallic phases like Al₂Mg₃ and Al₂CuMg, etc., were obtained from X-ray analysis. The wear mechanism of the investigated materials was studied through worn surfaces examination of the developed wear tracks.     

Preparation and properties of cast aluminium alloy–sillimanite particle composite

An attempt has been made to explore the possibility of using natural mineral namely sillimanite for synthesizing aluminium alloy composite through a solidification technique. The sillimanite particles were characterized in terms of X-ray, differential thermal analysis in order to examine their suitability for preparing the composite. An aluminium alloy (BS:LM6) was used as the matrix alloy. The sillimanite particles of mean size 140 μm (major axis) were used as reinforcement. The sillimanite particles were added into the matrix melt by creating a vortex with the help of a mechanical stirrer and the melt temperature was maintained between 750 and 800°C. The cast composite was characterized in terms of microstructural, mechanical and abrasive wear properties. It was noted that the sillimanite particles were reasonably uniformly distributed within the matrix and exhibited good mechanical bonding with the matrix. The strength of the composite was noted to be marginally lower than that of the base alloy but the hardness and the wear resistance of the composite were found to be significantly higher than those of the base alloy.     

Mechanical and tribological properties of LM13/TiO2/MoS2 hybrid metal matrix composite synthesized by stir casting

This paper involves the fabrication of LM13/TiO₂ (12?wt%)/MoS₂ (3?wt%) hybrid metal matrix composite and unreinforced alloy using liquid metallurgy route and evaluation of mechanical properties and adhesive wear characteristics. Microstructural investigation revealed homogeneous distribution of reinforcements in matrix. Hardness and tensile properties revealed that the composite had attained an improvement of 16.5 and 35%, respectively, over alloy. Wear characteristics were analyzed using pin-on-disk tribometer by varying load (10–40?N), sliding velocity (1–4?m/s), and sliding distance (500–2000?m). Statistical analysis was performed using response surface methodology to obtain the optimum wear process parameters for achieving maximum wear resistance. Results revealed that, with increasing load and sliding velocity, an increment in wear rate was observed for both alloy and composite, while a decline was observed with increasing sliding distance for composite and vice versa for alloy. Worn surface analysis revealed that load plays a prominent role in deciding wear rate, followed by sliding velocity. Sliding distance had less effect on wear rate of composite while it had significance on alloy. This hybrid composite can replace the conventional material used in automotive applications involving tribological importance.     

Reduced wear damage of carbon brushes via transfer layer upon W/Cu composite

An ultrafine (～100?nm) W particle-reinforced Cu matrix composite was fabricated by spark plasma sintering. The tribological properties of the fabricated W/Cu composite were tested by pin-on-disc sliding experiments and compared with those of brass alloy. The wear rate of the carbon brush when sliding against the W/Cu composite (0.102?mm?³s^?1) was much lower than that with brass (4.83?mm³?s^?1). Simultaneously, the W/Cu composite possessed higher conductivities and greater surface hardness than brass. The surface roughness of the W/Cu composite was found to play a critical role in improving the robustness of the tribofilm and reducing the volume loss of the carbon brush. The W/Cu composite has promising engineering applications for the long-term wear protection of self-lubricating materials.     

Effects of Al2O3 particle reinforcement on the lubricated sliding wear behavior of ZA-27 alloy composites

The present investigation deals with the effect of Al₂O₃ particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al₂O₃ particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that, effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions of higher load, lower sliding speeds and higher Al₂O₃ particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed by the SEM microphotographs.     

Influence of reinforcement volume fraction on sliding wear behaviour of SHS derived ferrous based metal matrix composite

Abstract

Steel matrix composites reinforced with (W,Ti)C particles were processed by directaddition of an innovative powder to molten 0.4 wt-%Clow alloy steel.Thispowder was producedusing a self-propagatinghightemperature synthesis(SHS) reaction and consisted of a dispersion of fine (W,Ti)C particles (5-10 μm) in an iron binder. Dry unidirectional sliding wear behaviour ofthe compositematerialanditsunreinforced counterpartwas investigated atroomtemperature against a white cast iron counterface. In situ monitoring of wear and friction, in conjunction with electron microscopy, has been used tointerpretwearscar microstructures observed intermsofwear mechanisms. Wear experimentswere performedat a sliding speed of 1.5 m s^-1 at different test loads. It was found that the wear resistance of the composite material was superior to that of their unreinforced counterparts over the entire range of loading employed during this investigation. The unreinforced base alloy exhibited a transition from mild to severe wear at a load of approximately 70 N. No such transition was found to occur for the composite materials. Instead, after a transient period of running in wear, steady state conditions were observed. At the highest level of carbide addition this transient period did not occur and the composite wore in a regime of mild wear over the full spectrum of loading utilised.     

Abrasive wear behaviour of zinc-aluminium alloy - 10% Al2O3 composite through factorial design of experiment

Two body abrasive wear behaviour of a zinc-aluminium alloy - 10% Al₂O₃ composite was studied at different loads (1–7 N) and abrasive sizes (20–275 m) as a function of sliding distance and compared with the matrix alloy. The wear rate of the composite and the matrix alloy has been expressed in terms of the applied load, abrasive size and sliding distance using linear factorial design approach. The study suggests that the wear rate of the alloy and composite follow the following relations:

Erosion-corrosion-abrasion characteristics in slurry of a zinc based alloy and its composite containing alumina particle dispersoid

Abstract

This study presents observations made pertaining to the slurry wear behaviour of a zinc based alloy and its composite containing dispersed alumina particles. The influence of varying the sand concentration in the medium and the traversal distance on the response of the specimens has also been investigated. Wear rate increased initially with traversal sliding distance, attained a peak, and then decreased thereafter at longer traversal distances. This trend was much more pronounced when tests were conducted in a liquid only medium than in liquid with sand. The presence of suspended sand particles in the test environment led to a considerably reduced wear rate of the specimens when compared with that of the liquid only medium. Furthermore, intermediate sand content caused the maximum wear rate within the slurries, although it was substantially less than that caused by the liquid only medium. A comparison of the wear response of the composite and the matrix alloy suggested a mixed trend in the liquid only medium and the slurry with 60 wt- sand. The composite exhibited a lower wear rate than the matrix alloy when tested in slurries with 20 and 40 wt- suspended sand particles. The observed wear response of the specimens has been discussed in terms of specific characteristics, such as susceptibility to corrosion and hardness of various phases, and the interfacial effects in the specimens. The changing nature of the medium, such as the corrosivity and impingingabrading efficiency, has also been discussed. Analysis of the affected surfaces and subsurface regions of typical specimens by SEM enabled the understanding of the operating wear mechanisms under specific test conditions and thereby it was possible to substantiate the observed wear characteristics of the specimens.     

Fabrication of light-weight Al LM13/TiS2 metal matrix composites and investigation of its wear characteristics

This paper aims to study the dry sliding wear characteristics of LM13 aluminum alloy matrix containing titanium disulfide (TiS₂) as the reinforcement (10?wt%, average size 37?µm) fabricated through liquid metallurgy route. Microstructural examination and Vickers hardness test were performed on the sample to investigate uniform distribution of the reinforcement particles in the composite. Energy Dispersive X-Ray Analysis and X-Ray Diffraction techniques were used to characterize the composite. The hardness test gave a result of 105.94 HV. The dry sliding wear experiments were designed by a five-level central composite design developed using response surface methodology. The factors considered were load, sliding distance, and velocity which were varied in the range of 10–30?N, 500–1500?m, and 1–3?m/s, respectively. The experiments were then performed at room temperature using a pin-on-disc tribometer for 20 combinations. The generated regression equation showed that the developed model established a proper relation between the process variables and the response. Load being the most influential factor showed increasing trends of wear rate in the surface plots against both velocity and sliding distance. The wear rate exhibited a nonlinear trend in the surface plots against sliding distance and velocity. Scanning electron microscopy results showed greater wear at higher loads due to higher surface damage. Thus, the fabricated Al/TiS₂ composite with the optimum wear process parameters can be well utilized for application where wear becomes a major consideration.     

Sliding wear of Al2O3P/6061 Al composite

The mild sliding wear behaviour of a 15 vol % Al₂O_3P/6061 Al composite has been investigated by using a pin-on-disc reciprocating sliding machine. The composite has been shown to exhibit an excellent wear resistance as compared to the unreinforced matrix alloy. The wear rate of the composite under dry wear conditions with a 12N load is approximately one tenth of that in the 6061 aluminium alloy. The wear rate of the composite under lubrication with 15W/40 gear oil under a 100N load is only one thousandth ofthat in the 6061 aluminium alloy.The dry wear resistance of an over-aged sample is shown here to be better than a peak aged or under-aged sample when the composite was aged at 160°C. The coefficient of friction of the composite was approximately 0.5–0.6 under dry conditions and 0.07 in lubricated wear experiments.In the initial stage, the worn surface of the composite under dry conditions is primarily composed of ploughed grooves and ductile tear. The composite makes a conducting contact with the steel pin. The worn surface is composed of compacted powder and the contact potential gradually increases when the period of the wear experiment goes beyond 2 h.     

Experimental correlations between wear rate and wear parameter of Al–Cu–Mg/bagasse ash particulate composite

The experimental correlations between wear rate and wear parameter of Al–Cu–Mg alloy composite reinforced with 10 wt.% bagasse ash particles produced by double stir casting method was developed in terms of applied load and sliding speed using the empirical linear regression and analysis of variance method. The wear behaviour of the specimen was investigated using pin-on-disc method. An empirical linear regression equation was used in predicting wear rate within a selected experimental domain. The predicted wear rate of the alloy and composite samples were found to lie close to that of the experimentally observed ones. The confirmation of experiments was conducted using analysis of variance (ANOVA) to verify the optimal testing parameters. The interactions of applied load and sliding speed of the composite had no significant effect, while the alloy had a significant effect on the wear rate.     

Dry sliding wear behavior of spray deposited AlCuMn alloy and AlCuMn/SiCp composite

The dry sliding wear behavior of spray-deposited Al-Cu-Mn alloy and its composite reinforced with 13 vol.% SiC particles have been studied in the applied load of 5–400 N (corresponding normal stress is 0.1–8 MPa). It showed that SiC particle-reinforced AlCuMn composite produced by spray deposition process exhibited an improved wear resistance at the entire applied load range in comparison to the monolithic alloy. However, this improvement was not significant in the overall load range. With increasing the applied load, the wear rate of the composite and the monolithic alloy exhibited four different regions, therefore the wear was dominated by different wear mechanism. The former three regions all belonged to mild wear. The transition from mild to severe wear occurred at the similar critical load for both the composite and the monolithic alloy. For both the composite and the monolithic alloy, with increasing applied load, the dominant wear mechanism exhibited successively: oxidative mechanism, delamination mechanism, subsurface-cracking-assisted adhesive mechanism and adhesive mechanism.     

The effect of strontium on the microstructure and wear properties of A356–10%B4C cast composites

This study was undertaken to investigate the effect of strontium (0.5%) as a modifier on the microstructure and dry sliding wear behavior of A356–10%B₄C particulate metal matrix composite (PMMC). The composite ingots were made by stir casting process. In this work, composite were characterized by scanning electron microscope equipped with energy dispersive spectrometer (EDS), and dry sliding wear experiment were performed in a pin-on-disc wear tester against a DIN 100Cr6 steel disc at speed of 0.5 ms⁻¹ and normal loads of 20, 40 and 60 N. The obtained results showed that 0.5%Sr was needed to modify of silicon eutectic in A356–10%B₄C cast composite. Also, the wear results showed that the addition of strontium to MMCs can lead to reduction of wear rate through strong bonding (between B₄C and matrix) and silicon particle modification. Formation of compact transfer layer has been identified on the entire surface of the pins at the applied load of 60 N. It is suggested that the transfer layer which was formed under an applied load of 60 N can act as a protective layer and helps to reduce wear rate.     

Microstructural, mechanical and wear behavior of A390/graphite and A390/Al2O3 surface composites fabricated using FSP

In the present investigation, A390/graphite and A390/Al₂O₃ surface composite (SC) layers were fabricated using friction stir processing (FSP). The effect of tool rotational and traverse speeds on the microstructural, mechanical and wear characteristics of the surface layers was studied. The results revealed that increasing the tool rotational speed increases the hardness of the composite layers. The traverse speed has less significant influence on the hardness of the composite layer than the tool rotational speed. The A390/Al₂O₃ surface composites exhibited higher hardness than the A390/graphite surface composites. The surface composites exhibited better wear resistance than the matrix alloy. The A390/Al₂O₃ surface composites exhibited lower wear rates than the A390/graphite surface composites. Increasing the tool rotational reduces the wear rate of both A390/Al₂O₃ and A390/graphite surface composites.     

铝/石墨复合材料高速高温下的摩擦磨损特性

本文研究了用中间法新工艺制造的铝石墨复合材料在高速高温下的摩擦磨损特性。试验在销盘式试验机上进行。滑动线速度最高达9.4米/秒。在2米/秒干摩擦时,所有测试的复合材料磨损量均小于基体合金。200℃时,含石墨2～5%的复合材料磨损量也此基体合金小。在9.4米/秒干摩擦时,含石墨2%的复合材料耐磨性能最好。以前曾有报导:滑动线速度大于1米/秒,铝石墨复合材料的磨损量大于基体合金[12,13]。本文认为新工艺制造的复合材料在9.4米/秒的高速摩擦时摩擦系数和磨损量下降是由于石墨与基体界面结合良好。      

The effect of fibre orientation of the dry sliding wear of borsic-reinforced 2014 aluminium alloy

The effect of fibre orientation on the dry sliding wear of continuous B(SiC) fibre reinforced aluminium alloy composites was investigated using a pin-on-disc wear testing machine. The metal-matrix composites (MMC) samples were tested in the normal (N), parallel (P) and antiparallel (AP) orientations sliding against a steel counter disc at a fixed speed of 1 m s^–1 under loads of from 12 to 60 N.The results showed that for the matrix alloy and MMCs, the average wear increased linearly with load. Wear of the MMCs was insensitive to fibre content but for composites with fibre contents at or above the minimum of 16 vol% used for this work, the wear rate was about 18% of that of the unreinforced matrix. Fibre orientation had a minor effect on wear rate; the N orientation gave the lowest wear rate with the AP orientation slightly higher and the P orientation significantly higher.The average coefficients of friction of the MMCs in N and AP orientations decreased linearly with increased wear rate and non-linearly with increased load, but the P orientation was insensitive to either variable.It was concluded from these results and a metallographic examination that the mechanism of wear of MMCs was essentially oxidative wear of the matrix. The hard fibres modified this to slightly different degrees depending on their orientation relative to the wear surface and sliding direction.     

Dry sliding wear behavior of stir cast aluminium base short steel fiber reinforced composites

Dry sliding wears behavior of die cast aluminium alloy composites reinforced with copper-coated short steel fibers were investigated using a pin-on-disk wear-testing machine. The composites were prepared by liquid metal route using vortex method. The weight percentage of copper-coated steel fibers was varied from 2.5 to 10. The density and hardness of the composite increased linearly with increasing wt% of steel fibers. The wear rate decreased by 40% with addition of 10% weight percentage of fibers. A linear dependence of wear rate on fiber content and hardness of MMC is observed. The unreinforced aluminium and composites containing upto 5-wt% of fibers exhibited a sliding distance dependent transition from severe to mild wear. However, composites containing 10-wt% fiber showed only mild wear for all sliding distance. It was also observed that with increase in the fiber content to 10-wt% the coefficient of friction decreased by 22%. The duration of occurrence of the severe wear regime and the wear rate decreased with increasing fiber content. For the composite the wear rate in the mild wear regime decreased with increase in fiber content reaching a minimum. From the analysis of wear data and detail examination of (a) wear surface and (b) wear debris two modes of wear have been identified to be operative, in these materials. These are (i) adhesive wear in the case of unreinforced matrix and in MMC with low wt% (upto 5-wt%) fibers (ii) abrasive wear in case of MMC with high wt% of fibers.     

Sliding wear behaviour of Al-Si-Cu composites reinforced with SiC particles

Abstract

The sliding wear behaviours of an unreinforced monolithic Al-Si-Cu alloy and SiC particles reinforced composites containing 5, 13, 38 and 50 vol.-% with diameters of 5.5, 11.5 and 57μm were investigated. The results showed that the wear resistance of the composites is much higher than the monolithic alloy, and the larger and the more SiC particles, the higher the enhancement of the wear resistance. Metallographic examinations revealed that the subsurface of worn composites was composed of both fragmented particles and deformed matrix alloy. The depth of the particle fracture zone in the subsurface varied in the range of 20-35 μm at a sliding distance of 1.8 km, while the plastic deformation zone of the worn subsurface on monolithic alloy was more than 100 μm. Scanning electron microanalyses of the worn surface, subsurface microstructure and debris suggested that the depth of the particle fracture zone became smaller as the diameter of SiC particles increased. Increasing the hardness and decreasing the applied wear stress changed the debris morphology from flake to very small lumps.     

Effect of matrix alloy and influence of SiC particle on the sliding wear characteristics of aluminium alloy composites

This article presents an effect of matrix alloy and influence of SiC particle on the sliding wear characteristics of high strength aluminium alloys AA7010, AA7009 and AA2024, composites was examined under varying applied pressure and a fixed sliding speed of 3.35 m/s. The results revealed that the wear resistance of the composite was noted to be significantly higher than that of the alloy and is suppressed further due to addition of SiC particles. The overall observation among the matrix alloys, AA7010 alloy shows maximum wear resistance than that of the other, and can withstand the seizure pressure up to 2.6 MPa. The wear mechanism was studied through worn surfaces and microscopic examination of the developed wear tracks. The wear mechanism strongly dictated by the formation and stability of oxide layer, mechanically mixed layer (MML) and subsurface deformation and cracking. The overall results indicate that the high strength aluminium alloys and composite could be considered as an excellent material where high strength and wear resistance components are prime importance especially designing for structural applications in aerospace and general engineering sectors.     

Dry sliding wear behaviour at ambient and elevated temperatures of plasma transferred arc deposited aluminium composite coatings

Abstract

Plasma transferred arc (PTA) surfacing is a surface engineering process in which a coating is deposited on the substrate by the injection of metal powders and/or ceramic particles into the weld pool created by the formation of a plasma plume. The present work involved the tribological evaluation of metal matrix composite (MMC) coatings deposited onto an aluminium alloy using the PTA technique. Coatings were fabricated by the deposition of an Al–Ni powder containing either Al₂O₃ or SiC particles. Dry sliding wear behaviour of the coatings was evaluated at ambient and elevated temperatures. Under sliding conditions of low applied stress and ambient temperature, reinforcement properties such as interfacial structure and fracture toughness have a significant influence on wear resistance. The SiC particles, which exhibit high interfacial bonding and toughness, support the matrix by acting as load bearing elements, thereby delaying the transition in wear mechanism as applied stress increases. As applied stresses exceed the fracture strength of the SiC and Al₂O₃ particles, these particles suffer fragmentation and/or debonding and no longer support the matrix. At higher stresses and elevated temperature, matrix properties such as flow stress and the tribolayer formation play more important roles in determining wear resistance.