Effect of the SiC particle size on the dry sliding wear behavior of SiC and SiC–Gr-reinforced Al6061 composites

The effect of size of silicon carbide particles on the dry sliding wear properties of composites with three different sized SiC particles (19, 93, and 146 μm) has been studied. Wear behavior of Al6061/10 vol% SiC and Al6061/10 vol% SiC/5 vol% graphite composites processed by in situ powder metallurgy technique has been investigated using a pin-on-disk wear tester. The debris and wear surfaces of samples were identified using SEM. It was found that the porosity content and hardness of Al/10SiC composites decreased by 5 vol% graphite addition. The increased SiC particle size reduced the porosity, hardness, volume loss, and coefficient of friction of both types of composites. Moreover, the hybrid composites exhibited lower coefficient of friction and wear rates. The wear mechanism changed from mostly adhesive and micro-cutting in the Al/10SiC composite containing fine SiC particles to the prominently abrasive and delamination wear by increasing of SiC particle size. While the main wear mechanism for the unreinforced alloy was adhesive wear, all the hybrid composites were worn mainly by abrasion and delamination mechanisms.     

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.     

Encapsulation and microwave hybrid processing of Al 6061–Graphene–SiC composites

The demand for new aluminum alloy–based metal matrix composites with combinations of novel reinforcements, processed through innovative methods are very much needed for critical engineering applications. With this perspective, the current research work is aimed at the development of Al 6061 composites reinforced with two-dimensional Graphene nanoflake-encapsulated SiC. Ultrasonic liquid processing method is used to disperse the Graphene flake and the mixture is ball milled by adding SiC to achieve the encapsulation. Subsequently, the Al 6061 powder is added to the milled mixture and consolidated through uniaxial vacuum hot press followed by microwave hybrid sintering. Scanning electron microscope (SEM) analysis, X-ray diffraction analysis, hardness, density, and microstructure analysis were carried out on developed composites. Raman analysis was carried out to analyze the distortion on Graphene physical structure during various processing stages. Further, effects on novel combination of material with combined processing approach on flexural and tribological behavior have been analyzed.     

Dry sliding wear of eutectic Al–Si

The wear of as-cast eutectic Al–Si was studied using pin-on-disk tribotests in two different environments, air and dry argon. The counterface in all tests was yttria-stabilized zirconia. It was found that wear of the Al–Si was reduced by about 60% by the removal of oxygen from the test environment. The zirconia counterfaces showed measurable wear after tests performed in air, while there was very little wear of the zirconia for tests conducted under argon. The near-surface regions of the Al–Si pins were examined using a transmission electron microscope (TEM), using specimens produced by focussed ion beam milling. The specimens that had been worn in air were characterized by a near-surface mechanically mixed layer containing a considerable amount of both aluminum oxide and zirconium oxide—the aluminum oxide particles had evidently acted as abrasive agents to remove material from the zirconia counterface. In contrast, TEM analysis of the Al–Si tested in argon showed little zirconium oxide in the near-surface regions.     

The effect of Al–8B grain refiner and heat treatment conditions on the microstructure,mechanical properties and dry sliding wear behavior of an Al–12Zn–3Mg–2.5Cu aluminum alloy

In this study the effect of Al–8B grain refiner on the structural and properties of Al–12Zn–3Mg–2.5Cu aluminum alloy were investigated. The optimum amount for B containing grain refiner was selected as 3.75 wt.%. The results showed that B containing grain refiner is more effective in reducing average grain size of the alloy. T6 heat treatment was applied for all specimens before tensile testing. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the heat treatment, the average tensile strength increased from 479 MPa to 537 MPa for sample refined with 3.75 wt.% Al–8B. The fractography of the fractured faces and microstructure evolution was characterized by scanning electron microscopy and optical microscopy.Dry sliding wear performance of the alloy was examined in normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu aluminum alloy to the dry sliding wear.     

Effect of Sn addition on microstructure and dry sliding wear behaviors of hypereutectic aluminum–silicon alloy A390

In this study, the effect of Sn addition on the microstructure and dry sliding wear behaviors of as-cast and heat-treated hypereutectic A390 alloys was investigated. The microstructural features of the alloys were characterized by means of optical microscope, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy techniques and their wear characteristics were evaluated at different loads. The worn morphologies of the wear surface were examined by SEM. The results show that the β-Sn in as-cast A390 alloy precipitates mainly in the form of particles within the Al₂Cu network on the interface of the eutectic silicon and α-Al phases and the grain boundaries of α-Al phase. The addition of Sn promotes the disintegrating and spheroidizing of both the eutectic and primary silicon of the A390 alloy during solid solution-aging treatment and β-Sn phase grains coalesces and grows, and some of them form the structure of Sn wrapping Si. The wear rates and friction factors of the as-cast and heat-treated A390 alloys with Sn are lower than those without Sn. At lower load, the addition of Sn changes the wear mechanism of as-cast A390 alloy from the combination of abrasive and adhesive wear without Sn into a single mild abrasion wear with Sn; at higher load, the wear of as-cast A390 alloy without Sn includes abrasion, adhesive, and fatigue one, while the addition of Sn effectively restrains the net-like cracks on the worn surface of the alloy and avoids the fatigue wear emerged.     

Investigations on dry sliding wear behavior of in situ casted AA7075–TiC metal matrix composites by using Taguchi technique

High strength 7075 aluminum matrix composites with 4 and 8 wt.% of TiC particulate reinforcement was synthesized by reactive in situ casting technique. X-ray diffraction analysis and scanning electron microscopy were used to confirm the presence of TiC particles and its uniform distribution over the aluminum matrix. The dry sliding wear behavior of the as-casted composites was investigated based on Taguchi L₂₇ orthogonal array experimental design to examine the significance of reinforcement quantity, load, sliding velocity and sliding distance on wear rate. The combination of 4 wt.% of TiC, 9.81 N load, 3 m/s sliding velocity and 1500 m sliding distance was identified as the optimum blend for minimum wear rate using the main effect plot. Load and sliding velocity were identified as the highly contributing significant parameters on the wear rate using ANOVA analysis. Further a confirmation test was also conducted with the optimum parameter combination for validation of the Taguchi results.     

Investigation of the effect of Al-8B master alloy and strain-induced melt activation process on dry sliding wear behavior of an Al–Zn–Mg–Cu alloy

This study was undertaken to investigate the influence of Al–8B master alloy and modified strain-induced melt activation process on the structural characteristics and dry sliding wear behavior of Al–12Zn–3Mg–2.5Cu aluminum alloy. The optimum amount of B containing master alloy for proper grain refining was selected as 3.75 wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The optimum temperature and time in strain-induced melt activation process are 590 °C and 10 min, respectively. T6 heat treatment was applied for all specimens before wear testing. Significant improvements in wear properties were obtained with the addition of grain refiner combined with T6 heat treatment. Dry sliding wear performance of the alloy was examined in normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3 Mg–2.5Cu aluminum alloy to the dry sliding wear. The results showed that dry sliding wear performance of globular microstructure specimens was a lower value than that of B-refined specimens without strain-induced melt activation process.     

Influence of coated SiC particulates on the mechanical and magnetic behaviour of Fe–Co alloy composites

Near-equiatomic Fe–Co alloy composites containing 0, 5 and 10 vol% of uncoated and coated SiC particles were prepared by applying a uniaxial pressure of 80 MPa at 900 °C for 5 min in a spark plasma sintering furnace. The SiC particles used in this study were coarse, with an average particle size of 20 μm and their surfaces were coated with four different types of coatings, namely Ni–P, Cu, Co and duplex Cu and Ni–P by an electroless plating method. Quasi D.C. magnetic, bending and hardness tests were performed on the composites. The influence of particulate coatings on the magnetic and mechanical behaviour of the composites was investigated by correlating their properties with their microstructures as observed using scanning electron microscopy and optical microscopy and crystallographic information as obtained using X-ray diffraction. The cobalt coated particles were found to exhibit the best wettability with the matrix without the formation of deleterious intermetallic compounds at the interface. Because of the better interfacial bonding in the composites with Co coated particles, there was an enhancement in flexural strength and permeability compared to the uncoated and other coated particulate composites studied. In addition, inclusion of cobalt coated SiC particulates produced an increase in hardness and a decrease in coercivity compared to the monolithic material.     

Hybrid composites – Metallic and ceramic reinforcements influence on mechanical and wear behavior

This experimental study is concerned with the influence of metallic (Ti) and ceramic (SiC) reinforcements in an aluminumfsilicon (AlSi) alloy, when regarding tensile properties and wear behavior. Several micron sized particulate reinforced composites were produced by hot-pressing technique: AlSi–SiC and AlSi–Ti composites and AlSi-(Ti–SiC) hybrid composites.Regarding tensile properties, all composites presented higher ultimate tensile strength (UTS) than the AlSi matrix, with the highest UTS being attained by a hybrid composite (AlSi-11.25%Ti–5%SiC).Regarding wear behavior, reciprocating pin-on-plate wear tests were performed for unreinforced AlSi; AlSi–Ti composites and AlSi-(Ti–SiC) hybrid composite against a gray cast iron (GCI) counterface. The wear mechanisms for all the tested tribopairs are presented and discussed. It was observed that the wear behavior of the AlSi–Ti/GCI and also AlSi-(Ti–SiC)/GCI tribopairs are improved when compared with the AlSi/GCI system. AlSi-11.25%Ti-5%SiC hybrid composite exhibited the highest improvement in wear rate.     

The influence of Strontium addition on wear properties of Al–20 wt% Si alloys under dry reciprocating sliding condition

The modification response of Al–20 wt% Si alloys was studied with different Sr addition levels. The wear properties of Al–Si alloys modified by Sr were investigated by using a UMT-3 reciprocating wear machine over a range of normal loads, i.e., 2, 5, 8 N, at the frequency of 50 Hz. The worn morphologies of the wear surface were examined by scanning electron microscopy (SEM). The results show that the primary Si and the interdendritic eutectic matrix are obviously changed after the Sr modification. The frictional coefficient greatly changes at a low load and mains unnoticeably at a high load. In addition, the frictional coefficients of the unmodified alloys decrease with increasing of the load, but those of the modified alloys increase when Sr addition level exceeds 0.04 wt%. The wear volumes of Al–Si alloys are inversely proportional to the hardness. The wear behaviors are optimal in the range of 0.04–0.06 wt% Sr. Adhesive wear is the main mechanism for the unmodified alloys, whereas abrasion wear characterizes in the modified alloys.     

Isothermal aging effect on the microstructure and dry sliding wear behavior of Co–28Cr–5Mo–0.3C alloy

In this study, an attempt to investigate the role of isothermal aging on the microstructure and dry sliding wear behavior of Co–28Cr–5Mo–0.3C alloy was made. Regarding the results, it is clear that isothermal aging at 850 °C for 8 and 16 h contributed to the formation of lamellar type carbides (γ-fcc + M₂₃C₆) at the grain boundary regions. Moreover, at higher aging times (24 h), the lamellar type carbides decreased whereas severe precipitation of carbides was found to occur on the stacking faults. Furthermore, according to X-ray diffraction results, 24 h isothermal aging of solution treated specimens did not lead to complete fcc → hcp transformation. The wear properties of as-cast and heat treated samples were determined at 0.5 ms⁻¹ speed several under normal applied loads such as 50, 80, and 110 N. At the lowest load applied (50 N), isothermally aged specimens for 8 and 16 h have higher wear resistance probably due to more volume fraction of lamellar-type carbides when compared to as-cast for both 4 and 24 h aged specimens. But, at higher applied loads (80 and 110 N) due to the formation of adhesive oxide layer on the as-cast specimen surface, the wear rate of as-cast samples is lower compared with all heat treated specimens.     

Heat treatment effect on the microstructure,tensile properties and dry sliding wear behavior of A356–10%B4C cast composites

In present paper, an attempt was made to examine the influence of T6 heat treatment (solution treatment at 540 °C for 5 h, quenching in hot water and artificial aging at 170 °C for 8 h) on the microstructure, tensile properties and dry sliding wear behavior of A356–10%B₄C cast composites. The composite ingots were made by stir casting process. In this work, the matrix alloy and composite were characterized by optical microscope, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, tensile tests and conventional pin-on-disk experiment.     

Effect of Al and C on structure and mechanical properties of Fe–Al–C alloys

Abstract

Effect of aluminium and carbon content on the microstructure and mechanical properties of Fe–Al–C alloys has been investigated. Alloys were prepared by combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot forged and hot rolled at 1373 K. As rolled alloys were examined using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to understand the microstructure of these alloys. The ternary Fe–Al–C alloys containing 10·5 and 13 wt-%Al showed the presence of three phases: FeAl with disordered bcc structure, Fe₃Al with ordered DO₃ structure and Fe₃AlC_0·5 precipitates with L′1₂ structure. Addition of high concentration of carbon to these alloys resulted in excellent hot workability and superior tensile at room temperature as well as tensile and creep properties at 873 K. An increase in Al content from 9 to 13 wt-% in Fe–Al–C alloys containing the same levels of carbon has no significant influence on strength and creep properties at 873 K, however resulted in significant improvement in room temperature strength accompanied by a reduction in room temperature ductility.     

Mechanical and dry sliding wear characterization of epoxy–TiO2 particulate filled functionally graded composites materials using Taguchi design of experiment

Titania (TiO₂) reinforced homogeneous and functionally graded epoxy composites are developed by simple mechanical stirring and vertical centrifugal casting technique respectively. Investigations on mechanical and wear characteristics of TiO₂ reinforced homogeneous epoxy composites and its functionally graded composite materials developed for tribological applications are presented. The effect of various operational variables, material parameters and their interactive influences on specific wear behaviour of these composites has been studied systematically. A series of test are conducted on a pin-on-disc machine with three sliding velocities of 105, 209 and 314 cm/s under three different normal loading of 20 N, 30 N and 40 N. Out of all samples 20 wt.% epoxy–TiO₂ epoxy graded composites exhibited lowest specific wear rate TiO₂ particle additions on epoxy graded composites have a dramatic effect on the flexural strength, tensile modulus and impact strength in comparison to homogeneous composites. Scanning electron microscope (SEM) observations also indicate that in homogeneous composites TiO₂ particles are peeled off from the matrix to form holes while in graded composite materials under same experimental conditions the TiO₂ particles remain quite intact to the matrix.     

Investigation of corrosion and mechanical properties of Al–Cu–SiC–xNi composite alloys

In this study, dry sliding wear behavior and corrosion resistance of Al–Cu–SiC–xNi (x: 0, 0.5, 1, 1.5 wt.%) composites were investigated. Effect of nickel content on the microstructure and hardness of the alloys was also studied. Wear tests were conducted using a ball on disc wear test device. Corrosion behavior of Al–Cu–SiC–xNi composite alloys in 3.5% NaCl solution was investigated by using potentiodynamic polarization, impedance spectroscopy and cronoamperometric methods. The results showed that the hardness of the composite alloy increases with increasing nickel content. Maximum wear resistance is reported with the addition of 1 wt.%Ni. It was determined that corrosion resistance of Al–Cu–SiC composite alloys improved with increasing nickel content in the alloy.     

Investigation of the effect of Al–5Ti–1B grain refiner on dry sliding wear behavior of an Al–Zn–Mg–Cu alloy formed by strain-induced melt activation process

This study was undertaken to investigate the influence of Al–5Ti–1B master alloy and modified strain-induced melt activation process on the structural characteristics, mechanical properties and dry sliding wear behavior of Al–12Zn–3Mg–2.5Cu aluminum alloy. The optimum amount of Ti containing master alloy for proper grain refining was selected as 2 wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The optimum temperature and time in strain-induced melt activation process are 575 °C and 20 min, respectively. T6 heat treatment was applied for all specimens before tensile testing. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 MPa and 252 MPa to 564 MPa for samples refined with 2 wt.% Al–5Ti–1B before and after strain-induced melt activation process, respectively. Dry sliding wear performance of the alloy was examined in normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu aluminum alloy to the dry sliding wear.The results showed that ultimate strength and dry sliding wear performance of globular microstructure specimens was a lower value than that of Ti-refined specimens without strain-induced melt activation process.     

Microstructure and mechanical properties of in situ Al–Mg2Si composites

Abstract

In situ metal matrix composites (MMCs) with Mg₂Si particulate reinforcement have been developed recently as ultralight materials. In this paper, a brief overview of the physical and mechanical properties of Mg₂Si and the current status of research on Mg₂Si reinforced MMCs is presented, followed by more detailed information on recent progress in the research group of the present authors. The effects of element additions and processing parameters on the microstructure of the composites obtained by gravity casting are discussed, together with some mechanical property data.     

Experimental optimization of dry sliding wear behavior of in situ AlB2/Al composite based on Taguchi’s method

A wear rate prediction model for aluminum based composites reinforced with 10 and 30 wt.% in situ aluminum diboride (AlB₂) flakes was developed using Taguchi’s method by considering the parameters of sliding velocity, normal load, sliding distance and reinforcement ratio. Having produced the in situ reinforced bulk of composite, the final shape of the test samples was given through squeeze casting method. The wear behavior of the specimen was investigated using pin-on-disk rig where the samples sliding against a steel disk under different conditions. The orthogonal array, signal-to-noise ratio (S/N) and analysis of variance (ANOVA) were employed to study the optimal testing parameters on composite samples. The experimental results demonstrate that the normal load and reinforcement ratio were the major parameters influencing the specific wear rate for all samples, followed by sliding velocity. The sliding distance, however, was found to have a negligible effect on the specific wear rate. Moreover, the optimal combination of the testing parameters has been predicted. The predicted specific wear rates for all the test samples were found to lie close to that of the experimentally observed ones.     

Influence of MgO addition on mechanical and ablation characteristics of ZrB2–SiC composites developed through microwave sintering

Journal of Materials Science - Zirconium diboride (ZrB2) is a credible candidate for hypersonic aerospace applications owing to magnificent characteristics such as higher melting point temperature,...