Homogeneous Distribution Of SiC Particles Research Articles

Optimization of Stirring Speed and Time in Achieving Sound A356-Sic MMCs and its Effects on Microstructure and Mechanical Properties

Stirring is an essential and important factor in stir casting process of Liquid Metallurgy (LM) to achieve homogeneous dispersion of the reinforcements in the matrix. In the present study two important parameters of stirring, such as stirring time and speed were optimized for the preparation of sound A356-SiC Metal Matrix Composites (MMCs). The effect of stirring speed and time on microstructure of A356-10%SiC MMCs were analyzed using Scanning Electron Microscopy (SEM), Energy- dispersive X-Ray Spectroscopy (EDX) and X-Ray Diffractometry (XRD). The experiments were carried out for different stirring speed and time varying from 250, 350, and 450 rpm and 5, 7, and 9 minutes respectively. Initially stirring time was optimized and was found to be 7 minutes at a constant stirring speed of 350 rpm. And this optimized stirring time of 7 minutes is considered for further experiments while optimizing stirring speeds. Increase in the stirring speed and time from 5 minutes and 250 rpm resulted in homogeneous distribution of SiC particles in A356 matrix without having any agglomeration or segregation. Further, at the stirring speed of 350 rpm and stirring time of 7 Minutes a sound A356-SiC MMCs were obtained. Increases in stirring speed and time, on the other hand, resulted in the loss of microstructural characteristics. Finally, a stirring speed of 350 rpm and a stirring period of 7 minutes were discovered to be the ideal speed and time for achieving maximal tensile strength and hardness.

Effect of particle volume fraction on wear behavior in Al–SiC MMC coated on DIN AlZnMgCu1.5 alloy

Abstract In this study, DIN AlZnMgCu1.5 alloy surface (Al + SiC) was coated with metal matrix composite (MMC) by using hot press sintering method (HPSM). Al was used as matrix material and SiC powders were used as reinforcing material in the coating process on DIN AlZnMgCu1.5 alloy surface. Al/SiC MMC coating was produced at 600 °C under 120 MPa pressure and with varying SiC content (5, 10 and 15 vol.%). Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to examine the microstructure, elemental analysis and phase structure of both the coating zone and the transition zone between the substrate and the coating. The hardness was measured and a dry sliding linear reciprocating wear test was run to determine the mechanical properties of the coating layer. Consequently, the coefficient of friction (COF) and wear volume were determined. OM and SEM images showed a homogeneous distribution of SiC particles and a less porous structure. The hardness of the MMC coating increased with increasing SiC content. Also, the numerical analysis of the wear test simulation was done based on Archard’s law. The results of both wear tests showed that the volume loss values were consistent with each other and the amount of wear significantly reduced by increasing the rate of SiC reinforcement.

Effectuates of Direct Particle Injection Friction Stir Process tool for the Al/SiC surface coating fabrication

The Project is investigated the Direct Particle Injection Friction Stir Processing Tool (DPI-FSP) fabricating the Al/SiC Surface Coating (SC). The FSP using vertical milling machine which was performed the tool rotation speed 1000 rpm at traverse feed 20 mm/min.Peculiarity of the tool is the deletion of material preparation (Making grooves or Drill hole for filling the reinforcement particles) and continuously injected the reinforced particles during the process. The tool is fabricated the thin surface coating of Al/SiC. As a result, The micrograph is revealed that homogenous distribution of SiC particles and peneterated 340 µm thick on the surface matrix . The SC exhibited 55% of the increase in hardness as compared the base material. The X-ray diffraction results are showed that the no intermetallic was discovered besides the SiC particles. The SC wear test results is exhibited the superior frictional coefficient of 0.71 than the Empty Pass.

Effect of stirring speed and time on the mechanical properties of Al8011-SiC metal matrix composites

In this experimental research work, specimens were fabricated with three different stirring time periods and two different stirring speeds using the standard experimental setup to obtain Al 8011-SiC composites with the reinforcement of SiC by the stir casting method. Al8011 aluminum alloy is the latest explored material in the aluminum sequence which is used in the aerospace industries and heat exchangers. The stir casting method is the most broadly used in the liquid metallurgy technique to manufacture composites and to acquire uniform distribution of particles. Experiments are conducted with different experimental parameter ranges for the pure unreinforced metal alloy and Al8011-SiC composite specimens and results were observed and discussed. The highest hardness, yield strength, and tensile strength were observed in Al8011-SiC composites at the maximum stirring conditions and stirring time. Elongation was also observed to be highest for the same stirring conditions. The toughness of the composites remains the same for all stirring speeds and stirring times. Mechanical properties except the toughness value are gradually increased with the rise of stirring speed and time in the composite specimens because of the homogenous distribution of SiC particles in the Al8011 matrix at the maximum speed and timings.

Experimental Investigation of In-homogeneity in Particle Distribution During the Processing of Metal Matrix Composites

Particle reinforced metal matrix composites are skilled to fulfill the late needs of cutting edge designing applications, because of its tunable mechanical properties. Stir casting is one of the unmistakable and affordable strategies for preparing of particle reinforced metal matrix composites. However, complete investigation and evaluation of the vortex pressure and the homogenous distribution of particles are still an obstacle for the research community. In this method, vortex pressure and flow pattern are the important factors for the dispersion of particles in the liquid metal. Effectual flow pattern and vortex pressure can be attained by optimizing stir casting parameters such as volume concentration (5%, 10%), stirrer blade angle (45º, 90º), impeller position (20%, 40%) from the base, viscosity of Al melt (1.04 mPa-s, 1.24 mPa-s) and holding time (10 minutes, 15 minutes). In this research, computational fluid dynamics has been used to find the vortex pressure, which influences the particle distribution. A new photographic technique was implemented to find out the flow pattern of the reinforcement particles and the stir casting parameters are optimized using Taguchi method. Optimized parameters have been utilized for the production of PRMMCs. In addition, micro structural image and hardness test confirm the uniform particle distribution of the reinforcement particles. From the outcome of various experimentations, 10 minutes holding time of the stirrer blade with 45º angle which was kept 40% from the base and the viscosity of the Al melt (1.04 mPa-s) with 10% volume fraction of SiC particles shows effective flow pattern and optimum vortex pressure with homogenous distribution of SiC particles.

Effects of stir casting process parameters on dispersion of reinforcement particles during preparation of metal composites

Abstract The flow behavior of the liquid metal during the stir casting process significantly affects dispersion of reinforcement particles in Metal Matrix Composites (MMCs). Liquid metal processing is carried out in an opaque crucible, in which the flow patterns are invisible. Hence, numerical simulation is an apt tool to understand flow behavior and particle dispersion. Blade angle and stirring speed are two important factors ultimately resulting in the final quality of the composites. Thus, in the present investigation, simulation of stir casting process has been performed to optimize blade angle and stirring speed. In order to compare the results of simulation, MMCs were developed using a conventional stir casting technique. Microscopic investigation and porosity analysis has been incorporated to study dispersion of reinforcement inside molten matrix. Microstructural investigation unveiled the homogeneous distribution of SiC particles in the molten matrix and grain size of composite material is reduced by 10.5% as compared to matrix material.

A comparative study between friction stir processing and friction stir vibration processing to develop magnesium surface nanocomposites

Friction stir processing (FSP) can be used to improve surface composites. In this study, a modified method of FSP called friction stir vibration processing (FSVP) was applied to develop a surface composite on AZ91 magnesium alloy. In this technique, the workpiece is vibrated normal to the processing direction. The results illustrated that compared with the FSP method, the FSVP caused a better homogeneous distribution of SiC particles in the microstructure. The results also showed that matrix grains of friction stir vibration processed (FSV-processed) samples ((26.43 ± 2.00) µm) were finer than those of friction stir processed (FS-processed) specimens ((39.43 ± 2.00) µm). The results indicated that the ultimate tensile strength (UTS) of FSV-processed specimens (361.82 MPa) was higher than that of FS-processed specimens (324.97 MPa). The higher plastic strain in the material during FSVP, due to workpiece vibration, resulted in higher dynamic recrystallization, and consequently, finer grains were developed. The elongation and formability index of the FSV-processed specimen (16.88% and 6107.52 MPa%, respectively) were higher than those of the FS-processed sample (15.24% and 4952.54 MPa%, respectively). Moreover, the effects of FSVP were also found to intensify as the vibration frequency increased.

Air-isolated stir casting of homogeneous Al-SiC composite with no air entrapment and Al4C3

An air-isolated stir casting (AISC) technology was developed to solve the problems of air entrapment, inhomogeneous distribution of SiC particles and formation of weak compound Al4C3 in conventional stir casting of Al-SiC composite. To eliminate the air entrapment, a threaded cover screwed into the threaded crucible was used to evacuate the air in the crucible and a sealing plug on the cover was applied to isolate the Al-SiC slurry from the atmosphere. To realize the homogeneous distribution of SiC particles rapidly, a high-speed electromagnetic stirring was carried out to stir the Al-SiC slurry with the help of three uniform-distributed tilt blades on the crucible inner wall. Furthermore, the primary solid Al particles and the high viscosity of slurry were utilized to restrain the settling of SiC particles during casting. To avoid the formation of Al4C3 under short stirring time, the stirring temperature was dropped below 650 ℃. The theoretical analysis and the results of SEM, XRD, TEM and HRTEM show that the homogeneous Al-SiC composite with no air entrapment and Al4C3 can be processed by AISC technology. The mechanical and wear results and mechanism analysis show that the AISC Al-SiC composite possesses excellent performances.

Distribution of SiC particles in semisolid electromagnetic-mechanical stir-casting Al-SiC composite

The distribution of SiC particles in Al-SiC composite can greatly influence the mechanical performances of Al-SiC composite. To realize the homogeneous distribution of SiC particles in stir-casting Al-SiC composite, semisolid stir casting of Al-4.25vol.%SiC composite was conducted using a special electromagnetic-mechanical stirring equipment made by our team, in which there are three uniformly-distributed blades with a horizontal tilt angle of 25 ° to mechanically raise the SiC particles by creating an upward movement of slurry under electromagnetic stirring. The microstructure of the as-cast Al-SiC composites was observed by Scanning Electron Mcroscopy (SEM). The volume fraction of SiC particles was measured by image analysis using the Quantimet 520 Image Processing and Analysis System. The tensile strength of the Al-4.25vol.%SiC composites was measured by tensile testing. Results show that the Al-4.25vol.%SiC composites with the homogeneous distrbutin of SiC particles can be obtained by the electromagnetic-mechanical stirring casting with the speed of 300 and 600 r·min−1 at 620 °C. The differences between the volume fraction of SiC particles at the top of ingot and that at the bottom are both ~0.04vol.% with the stirring speed of 300 and 600 r·min−1, which are so small that the distribution of SiC particles can be seen as the homogeneous. The tensile strength of the Al matrix is enhanced by 51.2% due to the uniformly distributed SiC particles. The porosity of the composite mainly results from the solidification shrinkage of slurry and it is less than 0.04vol.%.

Mechanical and tribological behaviour of nano scaled silicon carbide reinforced aluminium composites

ABSTRACTThis work assesses the impact of the presence of Nano scaled silicon carbide on the Mechanical & Tribological behavior of aluminium matrix composites. Aluminium matrix composites containing 0, 0.5, 1, 1.5, 2 and 2.5 wt.%-nano scaled silicon carbide was set up by a mechanical stirrer. The trial comes about to demonstrate that the inclusion of Nano silicon carbide brings about materials with progressively high elastic modulus and likewise brings about expanded brittle behavior, fundamentally lessening failure strain. Shear modulus and flexural shear modulus likewise increases with silicon carbide increase. The presence of Nano scaled silicon carbide in the aluminium matrix diminishes subsurface fatigue wear and increases wear resistance, because of silicon carbide lubricant activity. Wear testing, microstructure & morphological, density & void testing, hardness, flexural and tensile test of the readied composites were investigated and outcomes were analyzed which demonstrated that including nano-SiC in aluminum (Al) matrix increased wear resistance, tensile strength, and 2 wt. % of nano scaled SiC for Al MMC indicated maximum wear resistance, tensile strength, and an optimum balanced mix of both Tribological and Mechanical properties. Microstructural observation uncovered uniformand homogeneous distribution of SiC particles in the Al matrix.

Fabrication of Cu-SiC Composites using Powder Metallurgy Technique

Copper based metal matrix composites are gaining interest for multiple applications because of their good electrical, thermal and mechanical properties. In the present study, composite of Cu-SiC with different compositions are fabricated by using powder metallurgy technique. Three different volumetric fractional combination of composites are made namely Cu90%-SiC10%, Cu85%-SiC15% and Cu80%-SiC20% along with Cu100% sample. V-shape blender is used for blending the powder. Hydraulic press is used to compact the powder at a pressure of 250Mpa to achieve the solid structure. To obtain better results, sintering is performed at a temperature of 950°C and a holding time of 60 min. An attempt has been made to study the characteristics of fabricated copper based metal matrix composites. The study revealed that the addition of SiC as a reinforcement in Cu; improves the mechanical properties. Scanning Electron Microscope (SEM) is used to analyse the surface morphology of the sintered samples. Microstructural study of the metal matrix composite shows the homogeneous distribution of SiC particles in the metal matrix.

Scanning Electron Microscopic Studies of Microwave Sintered Al-SiC Nanocomposites and Their Properties.

Al-metal matrix composites (AMMCs) reinforced with diverse volume fraction of SiC nanoparticles were synthesized using microwave sintering process. The effects of the reinforcing SiC particles on physical, microstructure, mechanical, and electrical properties were studied. The phase, microstructural, and surface analyses of the composites were systematically conducted using X-ray diffraction (XRD), scanning electron microscope (SEM), and surface profilometer techniques, respectively. The microstructural examination revealed the homogeneous distribution of SiC particles in the Al matrix. Microhardness and compressive strength of nanocomposites were found to be increasing with the increasing volume fraction of SiC particles. Electrical conductivity of the nanocomposites decreases with increasing the SiC content.

Analysis of SiC nano-powder effects on friction stir welding of dissimilar Al-Mg alloy to A316L stainless steel

In this work, dissimilar friction stir welding (FSW) of an Al–Mg alloy (AA5083) to austenitic stainless steel (A316L) by using nano sized SiC reinforcement was examined. Two optimized traverse velocities of 16 and 20mm/min (and a constant rotational speed of 250rpm) with the intact joint appearance were considered for investigation the effect of number of passes on microstructural and mechanical properties. Microstructure of the single-pass FSWed specimens containing reinforcements indicated large steel fragments and agglomerated SiC particles within the stir zone (SZ). Further FSW passes led to more homogenous distribution of SiC particles and steel fragments. Field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the in situ reactions at the joint interface and stir zone of Al-Mg alloy. No marks demonstrating the formation of tunneling defects were revealed at the stir zone up to six passes. Furthermore, streaks of tiny intermetallic particles together with steel fragments aligned in the direction of material flow. Tensile tests indicated that after six passes of FSW at traverse velocity of 16mm/min, the joint strength ratio to the ultimate tensile strength (UTS) of the AA5083 base metal (BM) was boosted up to ∼94 %, with an elongation reduction to 3% and a Vickers hardness enhancement of 250% in the stir zone.

Fabrication and Characterization of Al-0.4%Si-0.5%Mg - SiCp Using Permanent Mould Casting Technique

Production of A6063/SiC composite with various weight fractions (3%, 6%, 9%) were prepared by using permanent mould casting was investigated. The preferred mean particle size of SiC is 60 μm. In addition, A6063 alloys were cast for comparison purposes. The alloys and composites were given a T6 heat treatment process (solution treatment at 520 °C, water quenching at room temperature and artificial ageing at 180 °C), Also Microstructure, hardness and tensile properties of these composites were evaluated and compared. In addition, tribological properties of these composites were evaluated using a Pin-on-Disc apparatus with various parameters (constant load of 10N and varying velocities as follows 0.5m/s, 1m/s, 1.5m/s, 2m/s) .The microstructure of the composites shows homogenous distribution of SiC particles in the Al matrix except in the A6063/9% SiC composite. The wear and mechanical properties of composites improve with increasing the weight fraction of SiC Wear morphology studies show that higher wear rate in case of unreinforced specimen compared to heat treated composites. Whereas with the increase in SiC content, the material tends to fail in brittle mode. The aim of present study is to evaluate the effect of heat treatment on the mechanical and tribological properties of aluminum alloy A6063 /SiC metal matrix composite.

Influence of Cold Working on Mechanical Properties of Al-SiC Composites

The main objective of this research was a study the simultaneous influence of cold working and particle reinforcement on mechanical properties of Al. The model composites were fabricated by cold pressing RAl1 aluminium and 5% and 10% SiC powders and hot extrusion with ratio 3.8 in isothermal conditions at 480°C with 90° die angle to 18 mm diameter. Some specimens were then cold drawn with linear velocity 1 m/min to 16% area reduction, and one specimen in 3 passes to 51% reduction in area. Mechanical properties of the near fully dense composites were determined by axial compression, bend tests and hardness measurement and their microstructures examined, showing near homogenous distribution of SiC particles in the aluminium matrix. The increase in Young’s modulus was from 67 to 74 GPa and to 82 GPa for 5% and 10% reinforcement, respectively. Drawing increased average yield strength from 70 to 100 MPa for Al, and from 74 to 110 MPa and from 80 to 115 MPa, for 5 and 10% reinforcement, respectively. The results indicate that there is a significant increase in E, in accord with the law of mixtures, through incorporation of SiC and a synergistic effect of SiC and plastic deformation during drawing on strength. An attempt is made to identify the various contributions to overall strengthening of Al by considering also Al-8.8Cu-6.3%Si-0.7Mg alloy. It appears that alloying and age-hardening have the greatest effect, but that contributions from hot, warm and cold working are not insignificant. As powder metallurgy processing is an important fabrication method, their incorporation into the processing schedule merits consideration.

Processing–structure–property correlation in nano-SiC-reinforced friction stir welded aluminum joints

In this work, friction stir welding (FSW) of AA5086-H34 aluminum with nano-sized SiC reinforcement is performed. The effects of traverse and rotational speeds and number of passes on microstructure, hardness, and tensile behavior of the FSWed joints are studied. Single-pass FSWed specimens containing reinforcements represented SiC particle-rich and SiC particle-free regions in grain refined Al-matrix within the stir zone (SZ), which could be affected by changing traverse and rotational speeds. Multi-pass FSW led to more grain refinement and homogenous distribution of SiC particles. Hardness measurement revealed that both single- and multi-pass FSW with SiC particles increased hardness values. Furthermore, tensile tests demonstrated that single-pass FSWed specimens with SiC possessed lower tensile strength and percentage of elongation in comparison to as-received aluminum and showed brittle fracture in the stir zone, while a remarkable increase in tensile properties was observed for multi-pass FSWed specimens with SiC particles and consequent ductile fracture in base metal.

Effect of Microwave and Conventional Heating on Sintering Behavior of Cu-10vol.%SiC Nanocomposites

Effect of heating mode and sintering temperature on sinterability of ex-situ Cu-10vol.%SiC composites was investigated. The Cu and SiC powder mixture were mechanically alloyed for 5 hours at 100 rpm in a planetary ball mill under argon atmosphere. The as-milled powders of Cu-10vol.%SiC were compacted and sintered in conventional tube furnace and microwave furnace at 700°C, 800°C, and 900°C. Microwave reduces the processing time significantly along with higher heating rates when compared to conventional tube furnace. Based on XRD result, the average Cu crystallite size is 80.49 nm after milling and its value remained under 100 nm after sintering. Microwave gave relatively smaller crystallite size than tube furnace. SEM revealed the homogeneous distribution of SiC particles in the Cu matrix in both heating mode. Relatively higher densification parameter was obtained by microwave furnace sintered at 900°C. This temperature was defined as an optimum sintering temperature and microwave sintering was claimed to exhibit much better sinterability than conventional tube furnace sintering.

Deformation behavior of AA2017–SiCp in warm and hot deformation regions

Abstract In this work, the flow stress behavior of a metal matrix composite AA2017–10% SiCp was studied by means of the uni-axial compression test. The composite was first produced by stir casting technique and then, hot extrusion with the ratio of 18:1 was carried out to achieve a microstructure with a homogeneous distribution of SiC particles. In the next stage, the isothermal compression tests were conducted on the cylindrical specimens up to the true strain of 0.6. The experiments were performed at temperatures between room temperature to 400 °C and strain rates of 0.003, 0.03 and 0.3 s−1. Negative strain rate sensitivity was observed in the temperatures less than 250 °C indicating the occurrence of dynamic strain aging. However, at higher temperatures a regular hot deformation behavior associated with dynamic recovery as the main restoration mechanism was detected while the apparent activation energy for hot deformation was calculated about 303 kJ/mole.

Carbon-bonded carbon fiber composites containing uniformly distributed silicon carbide

Carbon-bonded carbon fiber composites (CBCFs) containing SiC particles with uniform microstructure were produced using an innovative dispersion and flocculent approach. The mixed phenolic (Pf), SiC particles and chopped carbon fibers (Cf) were blended uniformly using polyethyleneimine (PEI) as a dispersant and polyacrylamide (PAM) as a flocculating agent. A homogeneous distribution of SiC particles coated CBCFs was obtained with the addition of 0.6 wt% PEI and 0.8 wt% PAM. The effect of PEI and PAM content on the microstructure, slurry dispersibility and stability of SiC-modified CBCFs was investigated. The compressive strength and compression modulus of the SiC-modified CBCFs were improved compared with unmodified CBCFs. This simple and versatile approach can be used to prepare large-scale and modified CBCFs.

Mechanical properties improvement of cast AZ80 Mg alloy/nano-particles composite via thermomechanical processing

Three different nano-composites with cast AZ80 magnesium alloy matrix and nano-particles reinforcement, including Al2O3, TiO2 and SiC, have been prepared via stir casting method. In order to refine the microstructure and improve the mechanical properties, the monolithic AZ80 as well as AZ80/nano-particles composites were thermomechanically processed employing forward extrusion at 200°C. The obtained microstructures of extruded nano-composites materials indicated significant grain refinement due to the progression of dynamic recrystallization (DRX); however, the extruded monolithic material depicts a typical necklace structure with limited DRX grain. To evaluate the mechanical properties, micro-hardness and tensile tests were conducted. The results showed a remarkable increase in hardness of extruded nano-composites because of adding harder particles along with outstanding grain refinement. Furthermore, tensile tests results indicated a remarkable improvement in yield and ultimate strength as well as room temperature ductility for extruded composites compared with cast AZ80 Mg alloy. Finally, it is concluded that adding SiC nano-particles to the cast AZ80 Mg alloy resulted in the best combination of strength and ductility in comparison with Al2O3 and TiO2 particles. This may be attributed to the homogenous distribution of SiC particles and the lowest level of agglomeration during the extrusion process.