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.     

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.     

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.     

Investigation on mechanical properties and tribological behaviour of stir cast LM13 aluminium alloy based particulate hybrid composites

LM13 aluminium alloy with boron carbide (0 wt.%–7.5 wt.%) and fly ash (2.5 wt.%) reinforced particulate hybrid composites were fabricated using liquid metallurgy route. Microstructure and mechanical properties viz., hardness, ultimate tensile strength and ductility were investigated. Wear behaviour of composites was tested by varying sliding distance and load. Fracture surface and worn surface of composites were examined using field emission scanning electron microscope. Microstructure of hybrid composites revealed uniform dispersion of particles in LM13 aluminium alloy. Hardness and tensile strength of composites increased with increasing wt.% of boron carbide and fly ash particles. Wear test results showed that addition of particles significantly decreased the weight loss and coefficient of friction. Also cumulative weight loss decreased up to 47.2 % for 10 wt.% of hybrid composites as compared to LM13 aluminium alloy. Fracture surface of composites showed dimples with particle cracking on the surface. Worn surface of LM13 aluminium alloy showed continuous grooves due to ploughing with delamination. However, worn surface of composites showed fine grooves due to the presence of hard reinforcements on the surface. Boron carbide and fly ash reinforced LM13 aluminium hybrid composites exhibited superior mechanical properties with excellent wear resistance as compared to LM13 aluminium alloy.     

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%.     

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.     

Experimental investigation and prediction of wear properties of Al/SiC metal matrix composites produced by thixomoulding method using Artificial Neural Networks

In this study, the wear properties of the SiC particle reinforced aluminium (A356) composite materials (MMCs), produced with thixomoulding method, were investigated both by experimental and Artificial Neural Network (ANN) model in order to determine the weight loss after the wear tests. Two different temperatures (590 °C and 600 °C) were used in production of the MMCs containing 5%, 10%, 15% and 20% SiC (vol%). The samples of MMC were tested at 2 ms⁻¹ constant sliding speed under 30 N and 60 N loads against four different sliding distances (500 m, 1000 m, 1500 m, and 2000 m). The results indicated that by increasing the production temperature increased the grain size of the MMCs was increased, but the hardness was decreased. The MMCs produced at 590 °C were found to have lower weight loss as compared with ones produced at 600 °C. In the theoretical prediction model of the MMCs, weight loss, SiC per cent, production temperature, applied weight and sliding distance were used as input values. After comparing the experimental results and the ANNs predicted data it was observed that R² was 0.9855. This shows that the developed prediction model has a high level of reliability.     

Dry sliding wear behavior of AM50B magnesium alloy

Wear behaviour of AM50B magnesium alloy was tested using pin-on-disc configuration with carbon steel discs as counterpart on dry-sliding conditions. Wear rates and friction coefficients were measured in a sliding velocity range of 0.1–1 m s⁻¹ and normal force range of 10–250 N. Worn surfaces were analysed using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectrometer (EDS) to define the main wear mechanisms. Abrasion, adhesion, delamination, oxidation, and plastic and severe plastic deformation were observed. Wear mechanism map was proposed. Oxidation and abrasion mechanisms dominated at the lowest sliding velocities and loads. Increasing load and speed led to a combination of oxidation, delamination and adhesion. Plastic deformation and severe plastic deformation were detected for the highest applied load and sliding speeds.     

The wear of aluminium-based journal bearing materials under lubrication

The aluminium-based alloys, nowadays, are developed to be used in high performance engine bearings. In this study, new Al-based bearing alloys, which are produced by metal mould casting, were developed; and tribologic properties of these alloys under lubrication were analyzed experimentally. Four different aluminium alloys were carried out on pin on disc wear tester for that purpose. SAE 1040 steel was used as the disc material in the wear tester. Friction tests were carried out at 0.231–1.036 N/mm² pressures and at 0.6–2.4 m/s sliding speeds. Wear tests were carried out at 1.8 m/s sliding speed and at 70 N normal load. Friction coefficients and weight losses of the samples were determined under various working conditions as a result of the experiments. The morphographies of the worn surfaces were analyzed. Hardness, surface roughness, and surface temperature of the samples were measured. The results showed that the friction and wear behaviors of the alloys have changed according to the sliding conditions. The effects of the elements except aluminium composing alloys on the tribologic properties were analyzed. Al8.5Si3.5Cu alloy has a lower friction coefficient value than other alloys. Al8.5Si3.5Cu and Al15Sn5Cu3Si alloys, on the other hand, have the highest wear resistance. Al15Pb3.7Cu1.5Si1.1Fe alloy is the most worn material; and Al15Pb3.7Cu1.5Si1.1Fe alloy has the highest wear rate. As a result of the evaluations conducted, Al–Sn and Al–Si alloys, which include Si and Sn, can be preferred, among the aluminium alloys that will work under lubrication, as the bearing material.     

Wear behavior of laser metal deposited 17-4 PH SS-W composite at varied tungsten powder flow rate

This research studies the wear behavior of laser metal deposition of 17-4 PH SS-W composite using a 6 mm alumina-stainless steel ball under a load of 10 N, for 16 minutes, 40 seconds and with acquisition rate of 100 Hz conducted at 25 °C. The effect of laser power of between 2600 W and 1500 W; and powder flow rate of between 0.5 min⁻¹ and 2.0 min⁻¹ on wear resistance is investigated. Other processing parameters are constant throughout the experiments. The results show that the 17-4 PH SS-W composite produced at a high laser power of 2600 W exhibits a higher wear resistance as compared to the 17-4 PH SS-W composite samples produced at low laser power of 1500 W. The 17-4 PH SS-W composite sample produced at high laser power of 2600 W with tungsten powder flow rate of 2.0 min⁻¹ has the highest wear resistance with wear volume of 0.0276 mm³ and wear rate of 8.8 ⋅ 10⁻⁵ mm³/N m while the 17-4 PH SS-W composite sample produced at a low laser power of 1500 W with tungsten powder flow rate of 1.0 min⁻¹ has the wear volume of 0.02834 mm³ and wear rate of 9.0 ⋅ 10⁻⁵ mm³/N m.     

Mechanical-contact-induced transformation from the amorphous to the partially crystalline state in metallic glass

Sliding friction and wear experiments and electron microscopy and diffraction studies were conducted to examine the metallurgical microstructure of a metallic glass surface strained in sliding contact. Friction and wear experiments were conducted with aluminium oxide spheres 3.2 and 6.4 mm in diameter sliding, in reciprocating motion, on a metallic foil with a composition of Fe₆₇Co₁₈B₁₄Si₁ at a sliding velocity of 1.5 mm s^-1 (frictional heating is negligible) with a load of 2.5 N at room temperature and in a laboratory air atmosphere.The results of the investigation indicate that the amorphous alloy (metallic glass) can be crystallized during mechanical contact. Crystallites with a size range of 10–150 nm are produced on the wear surface of the amorphous alloy. A diffused honeycomb-shaped structure formed by dark gray bands is also produced during sliding. Considerable plastic flow occurs on an amorphous alloy surface with sliding and the flow film of the alloy transfers to the aluminium oxide pin surface. Multiple slip bands due to shear deformation are observed on the side of the wear track. Two distinct types of wear debris were observed as a result of sliding: an alloy wear debris and/or powdery and whiskery oxide debris. The wear rate of Fe₆₇Co₁₈B₁₄Si₁ was 5 × 10^-9 mm³ N^-1.     

Investigation of the abrasive wear behaviour of ZA-27 alloy and CuSn10 bronze

In this study, abrasive wear behaviours of ZA-27 alloy and CuSn10 bronze were investigated using a purpose-built wear tester. The ZA-27 alloy was produced by permanent mould casting. The abrasive SiC particles having 63 μm grit size was added to the lubricant oil. The wear rate and friction coefficient of alloys were determined at the different test conditions such as sliding distance, applied load, linear velocity and percentage SiC weight content. The wear surfaces of alloys were examined using SEM and EDS analysis. The results showed that the wear rate of alloys decreased with the increasing of applied load and increased with the increasing linear velocity and abrasive SiC content. It was found that the SiC particle fracture was an important mechanism determining the friction and the wear rate of alloys. CuSn10 bronze showed higher wear resistance than ZA-27 alloy under abrasive test conditions except at high linear velocities.     

Friction and wear behaviors of B4C/6061Al composite

The friction and wear behaviors of B₄C/6061Al composite were studied by considering the effect of sliding time, applied load, sliding velocity and heat treatment. The results show that, when the sliding time, applied load and sliding velocity reach critical values (namely 120 min, 30 N and 240 r min⁻¹, respectively), the mass loss and friction coefficient (COF) increase significantly. Severe delamination wear is the main wear mechanism after sliding for 120 min and under an applied load of 30 N. While fretting wear happens at a sliding velocity of 240 r min⁻¹. After solution-treated at 550 °C for 1 h and then aged at 180 °C for 15 h, the composite shows the highest wear resistance owing to the precipitation of β″ (Mg₂Si) phases in the matrix and the strong interface bonding between B₄C particles and the matrix alloy.     

Effects of surface preparation on the friction and wear behaviour of silicon nitride/silicon carbide sliding pairs

Silicon carbide and silicon nitride specimens were fabricated to provide three different surface finishes. They were subjected to sphere-on-flat (pin-on-disc) testing in order to determine the interaction of load, velocity, disc surface finish, and material effects on unlubricated friction and wear. Tests were conducted in air using applied loads of 1 and 10N, velocities of 0.1 and 0.5 ms^–1, and surface preparations of 150-grit grinding, 220-grit grinding and fine polishing. The test duration was kept constant at 1000m of sliding distance for the pin specimen. In half the tests silicon nitride was the pin material and silicon carbide was the disc material. For the other half, the pin and slider materials were reversed. There was a much greater effect of normal force on steady-state friction coefficient than of either surface finish or material pairing. Increasing the sliding velocity raised the friction coefficient for both material pairings and for all surface roughnesses. Higher wear resulted when the velocity increased, but the effect of surface finish on wear ranged from none in some cases to about a factor of 10 in other cases. A trend of increasing run-in period duration with increasing smoothness was observed. The results are interpreted in terms of material properties, the Lim and Ashby model, and the friction force-velocity product.     

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 behaviour of fly ash particles reinforced AA 2024 composites

AA 2024 alloy has been melted and cast in a permanent cast iron mould in the form of 18 mm ?? fingers. The synthesis of AA2024 alloy ? 5wt.% fly ash composite was made by stir cast technique. A uniform distribution of fly ash particles in the matrix phase was obtained. Good bonding between the matrix and reinforcement was also achieved. Dry sliding wear behavior of the alloy and the composite has been investigated using a pin-on-disc wear tester. The investigation was carried out at a fixed sliding velocity of 2.0 m/s, track diameter of 60 mm and load ranging from 0.5 kgf to 1.5 kgf (4.9?C14.7 N). SEM studies were carried out to assess the wear behavior of the alloy and the composite. The composite showed better wear resistance than the base alloy for the lower loads. However, for the higher loads and longer sliding distances, the wear in the composite was extensive due to the existence of fractured and dislodged fly ash particles in the alloy matrix.     

Comparative study of wear performance of particulate and fiber-reinforced nano-ZnO/ultra-high molecular weight polyethylene hybrid composites using response surface methodology

The effects of two types of filler reinforcements i.e. particulate (talc particles) and fiber (Glass Fiber (GF)) as secondary reinforcements in ultra-high molecular weight polyethylene (UHMWPE)-based composites on the wear and friction properties were discussed in this paper. These UHMWPE hybrid composites were fabricated by the addition of 10 wt% of talc and glass fiber at a fixed nano-ZnO loading of 10 wt% using a hot compression moulding technique. The wear and friction properties of these hybrid composites were investigated using a pin-on-disc tester with different operating conditions of applied loads, sliding speeds and sliding distances based on response surface Box–Behnken design. Response Surface Methodology (RSM) was applied to model the effects of various variables of applied load, sliding speed and distance on the wear volume loss and average coefficient of friction (COF) of UHMWPE hybrid composites. The mathematical regression models of the wear volume and average COF were derived from the analysis of variance (ANOVA). Optimization of the independent variables to minimize the wear and friction responses of both UHMWPE composites was estimated using RSM. The mathematical models showed that applied load, sliding speed and distance have significant effects on the wear and friction properties of both UHMWPE composites in the tested range of variables. The most significant, in order of the variables that affect the volume loss and friction of UHMWPE composites is load, followed by sliding distance and speed. In addition, the combined effects of load and distance indicate the highest significance on volume loss and average COF for both UHMWPE hybrid composites as compared to other variable interactions. GF/ZnO/UHMWPE exhibited better wear performance compared to talc/ZnO/UHMWPE hybrid composites. The severity of worn surfaces of the GF/ZnO/UHMWPE was less than that of talc/ZnO/UHMWPE. The GF/ZnO/UHMWPE produced transfer films that were more uniform and had better coverage compared to talc/ZnO/UHMWPE.     

Study on friction and sliding wear behavior of woven S-glass fiber reinforced vinylester composites manufactured with different comonomers

The effect of variations in sliding velocity and applied normal load on the friction and sliding wear behavior of glass–vinylester composite (G–V) is studied by measuring the weight change and observing the surface features of worn specimens using scanning electron microscopy (SEM). The G–V composites were manufactured with Bi-directional woven S-glass fibers (65 wt%) reinforced with vinylester resin with different comonomers. Friction and wear experiments were carried at ambient conditions on a Pin on disc machine arrangement. The wear in the experiment was determined from the weight loss measured after running against steel disc at sliding velocities of 1, 2, 3, and 4 m/s and applied normal load of 10, 20, 30, and 40 N. The experimental findings show increase in specific wear rate with increase the applied load. Specific wear rate was maximum for the sample A (Styrene as Comonomer), intermediate for sample B (Methyl acrylate as comonomer), and least for sample C (Butyl acrylate as comonomer). It was also observed that increasing normal load and sliding velocity the coefficient of friction decreases. The scanning pictures show features like tendency for the matrix to adhere towards the fiber, debris formation, network of cracks, agglomeration of debris, and broken fibers depending on the load and velocity employed.     

The investigation of the effect of particle size on wear performance of AA7075/Al2O3 composites using statistical analysis and different machine learning methods

In this study, 7075 - Al₂O₃ (5 wt%) composites with a particle size of 0.3 µm, 2 µm, and 15 µm were developed by hot pressing. The dry sliding wear performance of the specimens was evaluated under loads of 5 N, 10 N, 20 N, 30 N, and at sliding speeds of 80 mm/s, 110 mm/s, 140 mm/s by reciprocating wear tests. The wear tests showed that 7075 - 5Al₂O₃ (15 µm) exhibited the best wear performance. The volume loss of 7075 - 5Al₂O₃ (15 µm) under load of 30 N for sliding speed of 140 mm/s was 37.1% lower than the unreinforced 7075 alloy. The volume loss (mm³) of composites reinforced with the particle size of 0.3 µm, 2 µm, and 15 µm was 11.62, 9.87, and 8.07, respectively, for load of 30 N and sliding speed of 140 mm/s. An increase in the applied load and sliding speed increased the wear severity by changing the wear mechanism from abrasion to delamination. The analysis of variance (ANOVA) showed that the load was the most significant parameter on the volume loss. The linear regression (LR), support vector regression (SVR), artificial neural network (ANN), and extreme learning machine (ELM) were used for the prediction of volume loss. The determination coefficient (R²) of the LR, SVR, ANN, and ELM was 0.814, 0.976, 0.935, and 0.989, respectively. The ELM model has the highest success. Thus, the ELM model has significant potential for the prediction of wear behaviour for Al matrix composites.     

Improving the specific wear rate and coefficient of friction of polyamide 6 polymer and its composite by adding wax under self-operation conditions

Polyamide polymers are widely used in tribological areas in a wide range of industries. The purpose of this study is to extend the tribological life of this material. For this purpose, composite materials were produced by adding solid lubricants such as graphite and wax to the polyamide 6 (PA6) matrix at different rates, and the synergistic effect of these composites on tribological behavior was investigated. Tribological experiments were carried out under dry sliding conditions and on themselves. The polyamide 6/graphite/wax composites were first produced in the form of granules in a twin-screw extruder, and then test samples were molded using the injection molding technique. Wear tests were performed using a pin-on-disc wear device. Tribological tests were carried out at a sliding speed of 0.5 m s⁻¹ and under loads ranging from 10 N to 250 N. Following the experiments, the friction coefficient, specific wear rate, and surface wear were determined under the condition of the materials working on each other. The results showed that the lowest specific wear rate and friction coefficient were obtained for the polyamide 6 composites containing 6 % wax and 15 % glass fiber working on each other.