SiC Particle Reinforced Aluminum Matrix Research Articles

Cutting Simulations and Experiments of Milled SiC Particle-Reinforced Aluminum Matrix Composites

When SiC particles are added into aluminum, property of aluminum is greatly improved during a reinforcing phase to produce particle reinforced aluminum composites. However, cutting tools wear out quickly and it is difficult to meet machining accuracy and surface quality requirements due to the rough surface produced by the reinforcement process. This paper presents a simulation model of SiC particle-reinforced aluminum matrix composites is established considering particles, cohesive elements, and material matrix. Stress distribution and surface roughness are analyzed for SiC/Al matrix composites based on the cutting process. Experiments are performed to test the degree of surface roughness using different cutting parameters. The relationship of cutting depth, cutting velocity, and feed rate per tooth to surface roughness degree is obtained for SiC/Al matrix composites. The optimization of cutting process is performed based on simulation. The results lay a foundation on the optimization of machining processes for metal matrix composites.

Microstructure and Properties of SiC Particle Reinforced Aluminum Matrix Composites by Powder Metallurgy Method

The aim of this study is to investigate the effect of SiC particle pretreatment, aluminum matrix particle size and sintering temperature on relative density, hardness, microstructure and wear resistance to SiC particle einforced aluminum matrix composites. To this end, the amount of 16.7 wt.% SiC with average particle sizes 20μm was used along with pure aluminum of average particle size of 75 μm and 25μm. Powder metallurgy is a method used in the fabrication of this composite in which the powders were mixed using a planetary ball mill. By analyzing SEM micrograph and the Property test, it is concluded that SiC particle pretreatment has significant effect on the morphology of pecimens. pretreatment increase the interface adhesion, improve the wettability. SiC is uniformly distributed in the matrix, with good relation to the substrate, the maximum hardness is 51.1HB, the minimum wear rate is 0.1684%, while the density is 97.3%.For the same SiC content and particle size, the smaller the particle size of aluminum matrix is, the higher wear resistance of composite materials is on condition that others are same, the higher sintering temperature and the higher the wearability of composites, the wear resistance of the composite material is significantly improved after SiC pre-processing.The relative density increases with increasing aluminum matrix particle sizes under the same pressure and the holding time. The actual density of all samples reached the theoretical density over 96%, to a maximum of 98.9%.

Determination of Microstructure and Mechanical Behaviour of SiC Particle Reinforced Aluminum Matrix Ceramic Composites

The micro-structural changes and mechanical properties were investigated in an Al reinforced with SiC particles which synthesized using powder technology technique. Al/SiC composites containing four different weight percentages (40 wt.%, 50 wt.%, 60 wt.% and 70 wt.% of SiC) have been prepared. X-ray diffraction analysis was used to characterize and identify the phases formed at sintering process with different temperatures (800 °C, 1100 °C). The grain sizes of the SiC/Al are observed to increase with the increasing of the sintering temperature of samples. Hardness tests were conducted in the suitable Hardness Testing Apparatus choosing appropriate scales of loading and measurement. The test revealed a marked increase in the Vickers hardness with respect to the increasing of silicon carbide content and sintering temperature in the base composites. The best results have been obtained at 70 wt% of SiC particles at 1100 °C. The aim of this investigation is to obtain the fundamental understanding of the micro structural changes and mechanical properties of Al matrix composites reinforced with SiC particles.

Study of Transient Liquid-Phase Bonding of SiC Particle Reinforced Aluminum Matrix Composite

Transient liquid-phase(TLP) bonding of SiC particle reinforced aluminum matrix composite(SiCp/Al MMCs) ,using Cu film, Cu foil, Ni foil and Cu/Ni/Cu multilayer foil interlayer, was investigated. The effect of surface status, interlayer species and bolding time on bonding microstructure and properties were also estimated by metallographic microscope, scanning electron microscopy (SEM), X ray diffraction and tensile testing machine. The results show that adding holding time can improve shear strength of joint. Better strength of joint can be obtained due to without the effect of oxide with Cu film as interlayer, when bonding at 853K for 120min under 2MPa pressure, the shear strength of bonded joints can obtain 169.1MPa, about 81.7 percentage of the strength of base material. Best strength of joint can be obtained with Cu/Ni/Cu multilayer foil as interlayer, when bonding at 923K for 120min under 2MPa pressure, the of bonded joints can obtain 189.6MPa, about 84.6 percentage of the strength of base material.

Influencing the residual stresses in the surface layer by use of appropriate cutting parameters and tool geometries in turning of aluminium matrix composites

AbstractSurface properties of components often determine their proper functioning. More complex and increasing demands on operational systems require detailed understanding in the influence of machining on the surface layer. Besides surface structure, residual stresses are very important, especially for dynamically loaded boundary surfaces. But, for cutting of modern light weight construction materials like aluminium matrix composites there is insufficient information concerning residual stresses. On this account, experimental investigations in turning of SiC particle reinforced aluminium matrix composites with different cutting parameters and tool geometries are presented with the focus on residual stresses. They are determined by X‐ray diffraction analysis. The results show that in general the use of very small feeds, tools with a width of flank wear land of about 100 μm, or with a small corner radius cause high absolute values of the compressive residual stresses. In consequence, knowledge of the relation between machining and the residual stress state of the surface layer allows to selectively induce residual stresses in the surface layer. This can provide, for example, an increase of fatigue strength.

Investigation of Material Removal Rate in Mill-Grinding SiC Particle Reinforced Aluminum Matrix Composites

Particle reinforced metal matrix composites (SiCp/Al composites) have proved to be extremely difficult to machine with traditional cutting processes due to serious tool-wear and high machining cost, which lead to the low machining efficiency. This paper presents the results of an experimental research on mill-grinding of SiC particle reinforced aluminum matrix composites. Based on the Taguchi experimental design method, study on the material removal rate was carried out to gain the optimal processing parameters combination by using the analysis of S/N ratio. The detailed effect of wheel speed on material removal rate through single factor experiment was also studied. Though analysis of S/N ratio and variance, the depth of cut has greatest effect on the material removal rate, followed by feed rate. And grinding wheel speed has least effect on it. But the depth of cut and feed rate affect on the material removal rate nonlinearly. In the range of machining parameters applied, the optimal processing parameters combination gained is A2B3C3, namely, vs=11.77m/s, vw=100mm/min, ap=0.8mm. Material removal rate increased at first and then there was a decreasing trend with increasing wheel speed.

Fabrication of Oxidized SiC Particles Reinforced Aluminum Matrix Composite by Pressureless Infiltration Technique

The oxidation behavior of SiC particles in the temperature range from 1000℃ to 1200℃ was investi- gated. The dependence of weight gain and oxidation time was parabolic and the oxidation behavior was controlled by diffusion process, with a oxidation activation energy of 219 kJ/mol. Using oxidized SiC particles as reinforce- ment and aluminum alloy containing Si and Mg as matrix, a SiCp/Al composite was fabricated by pressureless infil- tration technique. The microstructure and interfacial morphology were analyzed and the pressureless infiltration mechanisms were discussed. The particles were distributed uniformly in the composite, without particles agglom- eration. Interfacial reactions were found in the composite and the product was identified as MgAl2O4, formed by the reactions between surface oxide layer of SiC particles and Mg, Al in the matrix. The interfacial reactions enhanced the wettability and promoted the spontaneous infiltration process.

Effects of Hardness of Counterface on Dry Sliding Wear of Aluminum Matrix Composites against Steels

The effect of the hardness of a counterface on the sliding wear behavior of SiC whisker or of SiC particle reinforced aluminum matrix composites (designated as MMCw, MMCp) was investigated by pin-on-disk tests. The counterface materials were 0.45% carbon steel and tool steel with a hardness range (HV=180-1000) obtained by different heat treatment. When the MMCw (Vf=29%) and MMCp (Vf=10%, d=5 µm) pins were rubbed against steel disks, their wear rates took constant values below the hardness of the worn surfaces, but the wear rates varied inversely proportional with increasing hardness of the steel counterface. The wear rates of the steel disks varied inversely with their hardness. On the other hand, when a MMC disk was rubbed against a steel pin, the wear rates of MMCp showed an almost constant value regardless of the counterface hardness. The wear rates of MMCw increased slightly for high hardness of the counterface. The wear rates of the steel counterfaces were remarkably small. These phenomena are discussed depending on the characteristics of worn surfaces, the wear debris and tribo-induced layers on the counterface. The findings obtained in this study contribute to the evaluation of tribological properties of aluminum alloys as well as their matrix composites based on a large variety of experimental data obtained with different wear test methods.

Investigation on Joining Mechanism of SiC Particle Reinforced Aluminum Matrix Composite (Al/SiCp-MMC) by Resistance Spot Welding

The present study had investigated the joining performance of SiC particle reinforced aluminum metal matrix composite (Al/SiCp-MMC) having 1.0mm thickness by resistance spot welding processes. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zone. In addition both scanning electron microscopy (SEM) and optical microscopy (OM) were conducted to investigate the micro structural and micro hardness’s changes of the welded joints. The results reveal that: the maximum tensile-shear strength value of welded joint was obtained in these optimum welding parameters as in 17.5kA welding current for 60 periods welding. The electrode pressure was 3.5kN. It was favorable to select relatively high welding current and short welding time for improving mechanical properties of spot welded SiCp/LY12 composite joint. In this base, the welding mechanism of resistance spot welding SiCp/LY12 composite has also been discussed in detail.

Fabrication and Thermal Physical Properties of SiC<sub>p</sub>/Al Composite upon Powder Metallurgy Followed by Hot Extrusion

In this study, SiC particles reinforced aluminum matrix composite was successfully fabricated using powder metallurgy technique followed by hot extrusion. The phases were identified by XRD and the microstructures were observed by SEM. The results showed that only Al and SiC phases existed in the composite, SiC particulates were well distributed in the aluminum matrix and the interface between Al and SiC was clean and well combined. Meanwhile, thermal conductivity and coefficient of thermal expansion of the composite were investigated, the research showed that thermal conductivity decreased as SiCp content increased because of poor thermal conductivity of SiCp and increased crystal defects forming during the fabrication process. And the same to thermal conductivity, coefficient of thermal expansion of the composite decreased as SiCp content increased because SiCp can acted as obstacles to the motion of dislocations, which can hinder the hot movement of electronics.

Experimental Study on the Surface Roughness with Mill-Grinding SiC Particle Reinforced Aluminum Matrix Composites

In view of the present machining status of SiC particle reinforced aluminum matrix composites, the electroplated diamond wheel (80# diamond grit) was used for mill-grinding the SiC particle reinforced aluminum matrix composites and the effect of speed ratio (q) and material removal rate (MRR) on surface roughness was studied based on experiments. The experimental results show that surface roughness almost increases with the increase of speed ratio. At the same material removal rate, surface roughness increases when raising material removal rate by raising feed rate singlely or raising depth of mill-grinding singlely; surface roughness has decreasing trend with raising material removal rate by increasing feed rate and depth of mill-grinding at the same time.

Fabrication and Cutting Performance of Ultrafine Grain Composite Diamond Coated Drills

Ultrafine grain composite diamond films are deposited on the WC-Co-based drills using a bias-enhanced hot filament CVD system. During the deposition, the spiral hot filaments and novel two-step pretreatment method for complicated shape tools are adopted. The composite structure is achieved by regulating the concentration of Ar in a mixture of acetone and a hydrogen gases at different stages. The surface morphologies and composition of the first fabricated microcrystalline diamond film and the ultrafine grain diamond film grown later are observed with different techniques. The composite films have the advantages of good adhesive strength and low surface roughness. The cutting performance of the composite diamond-coated drills is investigated by drilling SiC particles reinforced aluminum matrix composites. The drilling life is improved greatly compared with those of uncoated drills and microcrystalline diamond coated drills.

Sliding wear behaviour of aluminum syntactic foam: A comparison with Al–10 wt% SiC composites

The sliding wear behaviour of cenosphere-filled aluminum syntactic foam (ASF) has been studied in comparison with that of 10 wt% SiC particle reinforced aluminum matrix composite (AMC) at a load of 3 kg and varying sliding speeds under dry and lubricated conditions using a pin-on disc test apparatus. The tribological responses such as the wear rate, the coefficient of friction and the frictional heating were investigated. The wear surfaces and subsurfaces were studied for understanding the wear mechanism. It was noted that the coefficient of friction, the wear rate, and the temperature rise for ASF are less than that for AMC in both dry and lubricated conditions. The craters (vis-à-vis exposed cenospheres) play an important role in the wear mechanism for ASF.

Diamond Tool Wear Mechanism in Ultra-Precision Turning of SiC<sub>p</sub>/Al Composites

The wear pattern and its mechanisms of Single Crystal Diamond (SCD) tool has been investigated experimentally and theoretically during ultra-precision turning of SiC particle-reinforced aluminum matrix composite. The results showed that micro wear, chipping, peeling, abrasive wear and chemical wear were the dominating wear patterns of SCD tools. Coupled with XRD analysis on the machined surface and Raman studies on the flank wear land of SCD tool, it was pointed that the combined effects of abrasive wear of SiC particles and catalysis of copper in the aluminum matrix have caused the severe graphitization.

Predicting Interfacial Strengthening Behaviour of Particulate-Reinforced MMC — A Micro-mechanistic Approach

The fracture properties of particulate-reinforced metal matrix composites (MMCs) are influenced by several factors, such as particle size, inter-particle spacing and volume fraction of the reinforcement. In addition, complex microstructural mechanisms, such as precipitation hardening induced by heat treatment processing, affect the fracture toughness of MMCs. Precipitates that are formed at the particle/matrix interface region, lead to improvement of the interfacial strength, and hence enhancement of the macroscopic strength properties of the composite material. In this paper, a micro-mechanics model, based on thermodynamics principles, is proposed to determine the fracture strength of the interface at a segregated state in MMCs. This model uses energy considerations to express the fracture toughness of the interface in terms of interfacial critical strain energy release rate and elastic modulus. The interfacial fracture toughness is further expressed as a function of the macroscopic fracture toughness and mechanical properties of the composite, using a toughening mechanism model based on crack deflection and interface cracking. Mechanical testing is also performed to obtain macroscopic data, such as the fracture strength, elastic modulus and fracture toughness of the composite, which are used as input to the model. Based on the experimental data and the analysis, the interfacial strength is determined for SiC particle-reinforced aluminium matrix composites subjected to different heat treatment processing conditions.

Heat Treatment and Interface Effects on the Mechanical Behavior of SiC-Particle Reinforced Aluminium Matrix Composites

Abstract The interface plays a vital role in composites. Strengthening behavior of SiC-particle reinforced aluminium matrix composites relies on load transfer behavior across the interface, whereas toughness is influenced by crack deflection at the boundary between matrix and reinforcement and ductility is affected by relaxation of peak stresses near the interface. In general, metal matrix composites often behave asymmetrically in tension and in compression and have higher ultimate tensile strength, yet lower proportional limits, than monolithic alloys. Such behavior of composites lies with the factors governing matrix plasticity, which can be divided into two areas: those affecting the stress rate of the matrix, and those which alter the flow properties of the matrix through changes in microstructure induced by inclusion of the reinforcement. This work focuses on the characterization of the mechanical response of the interface to stresses arising from an applied load in SiC-particle reinforced aluminium matrix composites. The composites have been studied in the as-received (T1) and in the T6 and modified T6 (HT1) conditions. In the nonequilibrium heat treatment processing of the composites, nonequilibrium segregation arises due to imbalances in point defect concentrations set up around interfaces. Mechanical properties, including microhardness and stress-strain behavior, of aluminum matrix composites containing various percentages of SiC particulate reinforcement have been investigated. The elastic modulus, the yield/tensile strengths, and ductility of the composites were controlled primarily by the volume percentage of SiC reinforcement, the temper condition, and the precipitation hardening.

Influence of Processing Conditions on the Micro-Mechanical Properties of Particulate-Reinforced Aluminium Matrix Composites

During processing, metal matrix attempts to deform and this deformation plays the key role in the microstructural events of segregation and precipitation at the matrix-reinforcement interface. The important aspect of this behaviour is to identify the strengthening micro-characteristics which enhance the material's interphasial reactions in order to improve the bonding properties of the matrix-reinforcement interface. This work focuses on the non-equilibrium segregation which arises due to imbalances in point defect concentrations set up around interfaces during non-equilibrium heat treatment processing of SiC particle reinforced aluminium matrix composites. The important factors affecting the heat treatment process are the temperature, the cooling rate, the concentration of solute atoms and the binding energy between solute atoms and vacancies. Aluminium – silicon – magnesium alloy matrix reinforced with varying amounts of silicon carbide particles were used in this study. Samples in the as-received and heat treated condition were examined by microstructural and microhardness analyses. Based on the analysis, it has been observed that the macroscopic mechanical behaviour of the composite is influenced by several factors including the manufacturing process, the processing conditions, the inter-particle distance, as well as the mean size and the percentage of reinforcement.

Friction and Wear Properties of Aluminum Matrix Composites and its Application

Friction and wear properties of aluminum matrix composites are studied, including brake speed, brake pressure, and surface temperature etc. A conclusion can be drawn that SiC particle reinforced aluminum matrix composites are of stable friction coefficient, high thermal conductivity, and excellent wear-resistance. Hubs of motorcycle with brake rings of Al/SiC composites were manufactured and exhibited an excellent braking performance.

Effect of Particle Diameter and Volume Fraction on Wear Behaviour of SiC-Particle Reinforced Aluminum Matrix Composites

The wear behavior of SiC-particle reinforced aluminum matrix composites (MMCp) was investigated by pin-on-disk tests under atmosphic conditions. The matrix material was 2024 aluminum alloy. The SiC particles were between 2 and 10 μm in diameter (d) with volume fractions (Vf) between 2 and 10%. The MMCp of the disk were rubbed against the 0.45% carbon steel of the pin witha load of 10N at a sliding velocity of 0.1m/s. The steady-state wear rate of MMCp decreased with increasing d and Vf, On the other hand, the wear rate of the steel counterface increased with increasing d and Vf. The wear rate was affected by two factors; one is the effect of reinforced particles against adhesive wear, and the other is the abrasive action of reinforcements. As a result, it was concluded that d=5μm, Vf=5, 10% provide the highest wear resistance for MMCp in this study.

Microstructure Characteristics of SiC Particle-Reinforced Aluminum Matrix Composites by Plasma Spraying

Aluminum with 55 and 75 vol.% SiC powders were ball milled as plasma spray feedstock. The feedstock was deposited onto a graphite substrate to form a freestanding composite by air plasma spraying. The microstructure characteristics of the sprayed composite were investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The SiC volume fraction and porosity in the sprayed composites depend on plasma spray conditions. The silicon phase was formed in the sprayed composites in some plasma spray conditions, and its amount was related to the input of electrical power into the plasma spray. The mechanism of silicon formation was studied. In the sprayed composites, no reaction products could be observed in the Al/SiC interface. Impurity materials from ball media, stainless steel, and ZrO2 reacted with aluminum and silicon to form complex compounds during plasma spray deposition.