Volume Fraction Of Silicon Carbide Research Articles

Investigation of Influence of Variations of Ageing Conditions on Aluminium-Silicon: Pathway to Tailored Mechanical Properties

This study focuses on the investigation of the influence of the variations of ageing conditions on the mechanical properties of ferrosilicon-silicon carbide reinforced Aluminium metal matrix composites. The ageing temperature, reinforcement percentage volume fractions and ageing time of the composite were systematically varied during fabrication stages by keeping the Aluminium and Ferrosilicon compositions constant while varying the percentage volume fractions of Silicon Carbide (SiC). The samples produced were machined into hardness, impact and tensile tests specimens. Then the specimens were subjected to laboratory based accelerated solution heat treatment, quenching and artificial ageing. Array of comprehensive mechanical properties examination and characterization in line with the appropriate specifications of the American Society for Testing and Materials Standard manuals were conducted to determine the influence of ageing on the material’s strength, hardness, impact toughness and stress-strain characteristics. The study revealed significant enhancement in the mechanical properties of the material and the findings would provide valuable insight into the ageing behaviour of Aluminium-Silicon, thus, enabling the optimization of the material’s performance for use in diverse engineering applications.

A Comparative Analysis of Low and High SiC Volume Fraction Additively Manufactured SiC/Ti6Al4V(ELI) Composites Based on the Best Process Parameters of Laser Power, Scanning Speed and Hatch Distance.

Silicon carbide (SiC) exhibits intriguing thermo-physical properties such as higher heat capacity and conductivity, as well as a lower density than Ti6Al4V(ELI). These properties make SiC a good candidate for the reinforcement of Ti6Al4V(ELI) with respect to its use as a heat shield in aero turbines to increase their efficiency. The traditional materials used in aircraft structures were required to have a combination of good mechanical properties such as strength, stiffness, and hardness and low weight, as well as low thermo-physical properties such as coefficient of thermal expansion (CTE) and thermal conductivity. The alloy Ti6Al4V(ELI) has a density of 4.45 g/cm3, which is lower than that of structural steel (7.4 g/cm3) and higher than that of aluminium (2.5 g/cm3). Lower density benefits light weighting. Aluminium is the lightest of the traditional materials used but has relatively low strength. The CTE of SiC of 4.6 × 10-6/K is lower than that of Ti6Al4V(ELI) of 8.6 × 10-6/K, while the density of SiC of 3.21 g/cm3 is lower than that of Ti6Al4V(ELI) of 4.45 g/cm3. Therefore, from the theory of composites, SiC/Ti6Al4V(ELI) composites are expected to have lower densities and CTEs than those of Ti6Al4V(ELI), thus providing for lightweighting and less thermal related buckling or separation at their joints with carbon/epoxy resin panels. The specific strength, stiffness, and Knoop hardness of SiC of 75-490 kNm/kg, 132 MNm/kg, and 600-3800 GPa, respectively, are generally larger than those of Ti6Al4V(ELI) of 211 KNm/kg, 24 MNm/kg, and 880 GPa, respectively. Therefore, investigating reinforcement of Ti6Al4V(ELI) with SiC particles is worthwhile as it will lead to the formation of composites that are stronger, stiffer, harder, and lighter, with lower values of CTE. For additive manufacturing, this requires initial studies to optimise the process parameters of laser power and scanning speed for single tracks. To print single tracks in the present work, different laser powers ranging from 100 W to 350 W and scanning speeds ranging from 0.3 m/s to 2.7 m/s were used for different SiC volume fraction values of values. To print single layers, different values of hatch distance were used together with the best values of laser power and scanning speed determined elsewhere by the authors for different volume fractions of SiC. Through optical microscopy, the built tracks and their cross sections were examined. By using laser power and scanning speeds of 200 W and 1.2 m/s, and 150 W and 0.8 m/s, respectively, the best tracks at 5% and 10% volume fractions were obtained, whereas the best tracks at 25% volume fraction were achieved using a laser power of 200 W and a scanning speed of 0.5 m/s. Furthermore, the results showed that the maximum SiC volume percentage of 30% resulted in limited or no penetration. Therefore, it is concluded from the study that parts with improved mechanical properties can be produced at SiC volume fractions ranging from 5% to 25%, while parts produced at the high volume fraction of 30% would have unacceptable mechanical qualities for the final part.

Prediction of particle-reinforced composite material properties based on an improved Halpin–Tsai model

This paper introduces an improved Halpin–Tsai model to predict the mechanical, thermal, and electrical properties of silicon-carbide-reinforced polypropylene composites. The model considers the influence of porosity and corresponding silicon-carbide volume fractions and derives relationships between material property shape factors and the aspect ratio, silicon-carbide volume fraction, and porosity. The improved model’s predictions exhibit errors of 4.00% for mechanical properties, 2.13% for thermal properties, and 2.24% for electrical properties when compared to finite element analysis. This study demonstrates that the improved Halpin–Tsai model can effectively predict the properties of silicon-carbide-reinforced polypropylene composites, aiding in the design and optimization of these materials.

Effect of Milling Time and Reinforcement Volume Fraction on Microstructure and Mechanical Properties of SiCp-Reinforced AA2017 Composite Powder Produced by High-Energy Ball Milling.

The influence of milling time and volume fraction of reinforcement on the morphology, microstructure, and mechanical behaviors of SiCp-reinforced AA2017 composite powder produced by high-energy ball milling (HEBM) was investigated. AA2017 + SiCp composite powder with different amounts of SiC particles (5, 10, and 15 vol%) was successfully prepared from gas-atomized AA2017 aluminum alloy powder with a particle size of <100 μm and silicon carbide (SiC) powder particles with an average particle size of <1 μm. An optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) were utilized to characterize the microstructure of the milled composite powder at different milling periods. The results indicated that the SiC particles were homogeneously distributed in the AA2017 matrix after 5 h of HEBM time. The morphology of the particles transformed from a laminar to a nearly spherical shape, and the size of the milled powder particles reduced with increasing the content of SiC particles. The XRD analysis was carried out to characterize the phase constituents, crystallite size, and lattice strain of the composite powders at different milling periods. It was found that with increasing milling time and SiC volume fraction, the crystallite size of the aluminum alloy matrix decreased while the lattice strain increased. The average crystallite sizes were reduced from >300 nm to 68 nm, 64 nm, and 64 nm after 5 h of milling, corresponding to SiC contents of 5, 10, and 15 vol%, respectively. As a result, the lattice strain increased from 0.15% to 0.5%, which is due to significant plastic deformation during the ball milling process. XRD results showed a rapid decrease in crystallite size during the early milling phase, and the minimum grain size was achieved at a higher volume fraction of SiC particles. Microhardness tests revealed that the milling time has a greater influence on the hardness than the amount of SiC reinforcements. Therefore, the composite powder milled for 5 h showed an average microhardness three times higher than that of the unmilled powder particles.

Optimization of Surface Roughness and Tool Wear during Machining of AMMC using Taguchi Technique

Metal matrix composite materials are used in several industrial applications due to its improved specifi c strength, capacity, good wear resistance, and high specifi c modulus and so on. In this work, the Aluminium alloy Al6061 is used as the matrix and 15% of volume fraction of silicon carbide is used as the reinforcing element to fabricate a MMC by stir casting process. The turning process parameters of Aluminium metal matrix composite (AMMC) considered in this work are cutting speed, feed, nozzle diameter and steam pressure and the responses surface roughness and tool wear. Taguchi technique is used in this research work to obtain optimum results and the S/N ratio is used as the quality characteristics and in this work L32 orthogonal array is used to conduct 32 experiments. It is observed that surface roughness of the AMMC is highly infl uenced by the nozzle diameter and it contributes to 19.87% and Tool wear of the AMMC is highly infl uenced by the steam pressure and it contributes to 7.12%.

Enhanced thermoelectric ZT in the tails of the Fermi distribution via electron filtering by nanoinclusions: Model electron transport in nanocomposites

Silicon carbide nanoparticles with diameters around 8 nm and narrow size distribution have been finely mixed with doped silicon nanopowders and sintered into bulk samples to investigate the influence of nanoinclusions on electrical and thermal transport properties. We have compared the thermoelectric properties of samples ranging from 0%--5% volume fraction of silicon carbide. The silicon carbide nanoinclusions lead to a significant improvement in the thermoelectric figure of merit ZT largely due to an enhancement of the Seebeck coefficient. A semiclassical Boltzmann transport equation is used to model the electrical transport properties of the Seebeck coefficient and electrical conductivity. The theoretical analysis confirms that the enhancements in the thermoelectric properties are consistent with the energy selective scattering of electrons induced by the offset between the silicon Fermi level and the carbide conduction band edge. This study proves that careful engineering of the energy-dependent electron scattering rate can provide a route towards relaxing long-standing constraints in the design of thermoelectric materials.

Effects of SiC content on the mechanical and thermophysical properties of 3D Cf/SiC–Al composites

3D Cf/SiC–Al composites were achieved through the pressure infiltration of liquid Al–Si alloy into porous 3D Cf/SiC preform, which was produced by different cycles of precursor infiltration and pyrolysis. The effect of silicon carbide volume fraction on the microstructure, anisotropic mechanical response, and thermophysical characteristics of the 3D Cf/SiC–Al composites was investigated. The results demonstrated that the initial microstructure of 3D Cf/SiC can be retained, and the obtained Cf/SiC–Al composites presented remarkable anisotropy characteristics. As the silicon carbide ceramics content increased from 12.5 vol% to 41.8 vol%, the thermal conductivity and thermal expansion coefficient of 3D Cf/SiC–Al composites decreased, whereas the bending strength initially increased and then decreased in the Z-direction. The bending strength perpendicular (Z) to the carbon cloth layer of 3D Cf/SiC–Al composites was higher than that of parallel (X–Y) to the carbon cloth layer. However, a significant anisotropy in the thermal conductivity values was the opposite. The 3D Cf/SiC–Al composite with 1ow ceramic content (17 vol%) had a higher thermal conductivity in the X–Y direction (64 W m−1 K−1) than in the Z-direction (34 W m−1 K−1). The thermal expansion coefficient of all the 3D Cf/SiC–Al composites along the X–Y direction also decreased initially and then increased in the range of 100–450 °C, which presents low expansion characteristics.

Топологическая оптимизация силового элемента отсека летательного аппарата из металломатричного композиционного материала

At present, in order to increase the weight efficiency of parts and structures of promising aircraft and rocket-space vehicles, various types of additive technologies and topological optimization methods are being actively introduced. Their purpose is a significant reduction in time and financial costs in the manufacture and creation of fundamentally new geometric solutions. The article considers approaches to selecting the geometric parameters of the strength elements of the flight vehicle body made of a metal-matrix composite material based on VT6 titanium alloy, reinforced with a finely dispersed silicon carbide powder, which is produced by direct laser growth technology. On the basis of numerical simulation, the dependences of the metal-matrix composite material physicomechanical and thermophysical characteristics on the volume fraction of silicon carbide have been determined. It was found that the use of a metal-matrix composite material and the optimization of geometric parameters with adaptation to the direct laser growth technology allows reducing the weight of the strength element of the flight vehicle body by more than 30% (depending on the overall dimensions).

Investigation of microstructure and mechanical characteristic of underwater friction stir welding for Aluminum 6061 alloy – Silicon carbide (SiC) metal matrix composite

Demand for metal matrix composites (MMCs) is expected to increase in these applications, such as ‎in the aerospace and automotive sectors. Adequate joining techniques, which are important for ‎structural materials, have not yet been developed for Metal Matrix Composite (MMCs), however. ‎This work aimed to demonstrate the feasibility of ‎friction stir welding (FSW) and ‎underwater friction stir welding (UFSW) for joining Al 6061/5, Al 6061/10, and Al ‎‎6061/18 wt. %SiC composites have been produced by utilizing reinforce stir casting technique. Two ‎rotational ‎speeds,1000and 1800 rpm, and traverse speed 10mm \ min were examined. Specimen ‎composite plates 10 mm thick have been successfully welded by FSW. For FSW and UFSW, a tool ‎made of high-speed steel (HSS) with a conical pin shape was used. The result revealed that the ‎ultimate tensile strength of the welded joint by FSW and UFSW at rotation speed 1800 rpm for (Al ‎‎6061/18 wt. ‎‎% SiC composites) was 195 MPa and 230 MPa respectively. The ultimate ‎tensile ‎strength of the welded joint by FSW and UFSW (Al 6061/18 wt.% SiCe composites) was 165 MPa ‎and 180 MPa at rotation speed ‎‎1000 rpm respectively. The microstructural assessment showed that due ‎to larger grain sizes at FSW and UFSW, most of the fractures are located in the thermal ‎mechanically affected zone (TMAZ) adjacent to the weld nugget zone (WNZ). It is observed that in ‎failure, most of the joints show ductile features. As the volume fraction of SiC (18 wt.%) increases, ‎the friction stir welded and underwater friction stir welded efficiency decreases.

INVESTIGATION OF DRY SLIDING WEAR BEHAVIOR OF AL 7075–(SiC/TiC) HYBRID METAL MATRIX COMPOSITES

The main objective of present work focuses to investigate the tribological behavior of Al 7075 hybrid metal matrix composite. Al 7075 metal matrix composites has many potential applications especially in automotive and aerospace industries, due to their light weight to strength ratio and high wear resistance. The composite is fabricated using two step stir casting process by varying 5% to 15% volume fractions of Silicon Carbide and Titanium Carbide. Optical microstructure showed reinforcement distribution into Al 7075 matrix. The wear and frictional properties of the hybrid metal matrix composites was studied by performing dry sliding wear test using a pin-on-disc wear tester. Tribological behaviors were examined by applying different normal loads of 10[Formula: see text]N, 20[Formula: see text]N, 30[Formula: see text]N with different sliding velocities (1[Formula: see text]m/s, 2[Formula: see text]m/s, 3[Formula: see text]m/s) at room temperature without lubrication. Wear rate and coefficient of friction for different normal load and sliding velocities were plotted and studied. The micro hardness value of AST15 was higher by 18.8% than the AST0 Composites. The wear rate prediction indicated the wear rate for AST15 as [Formula: see text][Formula: see text]mm3/m as compared to AST0 which was [Formula: see text][Formula: see text]mm3/m. The wear rate increases with the increase in load and sliding velocities. Scanning electron microscopy micrographs of the worn surface are used to predict the nature of the wear mechanism.

Improving self-healing ability and flexural strength of ytterbium silicate-based nanocomposites with silicon carbide nanoparticulates and whiskers

In the emerging era of aircraft industry, silicon carbide (SiC) is regarded as an appropriate material for gas turbine engine blades. In order to protect this ceramic component against the oxidation and volatilization in hot steam environments, environmental barrier coating should be utilized. The composite of SiC/Yb2Si2O7–Yb2SiO5 with self-healing ability is a candidate for the top layer of this coating. In this study, the crack-healing behavior of SiC/Yb2Si2O7–Yb2SiO5 nanocomposites is investigated by pre-cracking followed by annealing in oxidizing environments. Comparing to previous studies, the healing time and healing temperature can be reduced to 15 min and 800 °C by increasing the volume fraction of SiC to 20 %. In addition, nanocomposites with both self-healing ability and superior strength were created in this research by combining two types of SiC filler (whiskers and nanoparticulates). The self-healing mechanism in these composites is the SiC oxidation and silicate transformation associated with their volume expansion, which is evidenced by X-ray diffraction and scanning electron microscope. According to the results, the best volume ratio between whisker and nanoparticulate is determined as 1/3.

Mechanical and Wear Properties of Aluminum-Based Nanocomposites Fabricated through Ultrasonic Assisted Stir Casting

Abstract The aluminum alloy AA6061 with 0.004, 0.008, 0.012, and 0.016 volume fractions of silicon carbide (SiCp) nanocomposites were fabricated using a semi-solid stirring assisted ultrasonic cavitation technique. Specimens are tested for morphology, density, mechanical, and wear properties. The density, strength, and microhardness of the nanocomposites increased with the increase of SiCp nano-reinforcement particles in the matrix. The yield strength of the SiCp-reinforced nanocomposites was evaluated by considering various strengthening mechanisms. It is found that the yield strength of the nanocomposites increased by 96 % for 0.004, 172 % for 0.008, 158 % for 0.012, and 206 % for 0.016 volume fractions of SiCp compared to the base alloy. The dislocation mismatch effect and Orowan strengthening effect are found to play a significant role in the SiCp-reinforced AA6061 nanocomposites. The dislocation mismatch effect increased with the reinforcement particles’ size reduction in the matrix. The Orowan strengthening effect increased up to 1.56 nm critical size of SiCp, and above that it decreased slightly. The experimental results are compared to predicted results obtained from various analytical models. The experimental results are observed to be in close agreement with the Mirza and Chen model. The wear loss of nanocomposites decreased with an increase in the nano-sized SiCp reinforcement quantity in the matrix. The amount of 0.004, 0.008, 0.012, and 0.016 volume fractions of nano-sized SiCp reinforcement additions to the AA6061 alloy matrix decreases the wear coefficient by 19.23 %, 38.46 %, 57.69 %, and 62.69 %, respectively. The worn surfaces were also analyzed using a scanning electron microscope and energy-dispersive X-rays.

A study on thermal conductivity enhancement of silicon carbide filler glass fiber epoxy resin hybrid composites

The silicon carbide filler glass fiber reinforced polymer composites have been prepared by using hand- lay- up technique compression molding machine. Thermal conductivity of silicon carbide filler glass fiber reinforced polymer composites at different volume fractions of glass fiber and silicon carbide is determined using Lee’s apparatus experimentally. The experimental results show that the thermal conductivity of the hybrid polymer composite increases with increase in silicon carbide percentage. Experimental results are compared with mathematical models Hashin formula, Maxwell model and Rule of mixture model to find the variation of the thermal conductivity with volume fraction of silicon carbide. All three mathematical models exhibited results close to each other at low percentage silicon content. From mathematical models and experimental results the difference between the two has been found to be small for 20% SiC content; for example, Maxwell model showed a difference 10.40%, Rule of mixtures 16.12% and Hashin formula 3.62% for 20% SiC content.

Microstructural Evolution and Strengthening Mechanism of SiC/Al Composites Fabricated by a Liquid-Pressing Process and Heat Treatment.

Aluminum alloy (Al7075) composites reinforced with a high volume fraction of silicon carbide (SiC) were produced by a liquid-pressing process. The characterization of their microstructure showed that SiC particles corresponding to a volume fraction greater than 60% were uniformly distributed in the composite, and Mg2Si precipitates were present at the interface between the matrix and the reinforcement. A superior compressive strength (1130 MPa) was obtained by an effective load transfer to the hard ceramic particles. After solution heat treatment and artificial aging, the Mg2Si precipitates decomposed from rod-shaped large particles to smaller spherical particles, which led to an increase of the compressive strength by more than 200 MPa. The strengthening mechanism is discussed on the basis of the observed microstructural evolution.

Influence of SiC Content on Microstructure and Tribological Properties of Friction Stir-Processed SiC/AA5083 Surface Composites

The present work aims to produce silicon carbide (SiC) particles-reinforced AA5083 surface composites through friction stir processing (FSP). The influence of SiC content on the microstructure and tribological properties of the friction stir-processed (FSPed) AA5083/SiC surface composites was investigated. The results reveal that the distribution of SiC particles within the stirred zone was homogeneous, irrespective of location, and SiC particle volume fraction. Good SiC/AA5083 interfacial bonding was obtained for all surface composites with refined grains. Electron backscattered diffraction results revealed that the stir zones comprised dynamically recrystallized, fine-grained, and equiaxed microstructures. Transmission electron microscopy revealed that dislocations rearranged to form high-angle grain boundaries upon dynamic recrystallization. The worn surface showed that an increase in SiC volume fraction transforms the wear from severe plowing, and delamination to light abrasive wear. The surface composites showed a substantial decrease in wear rate with an increase in SiC volume fraction due to the homogeneous distribution of SiC particles, grain refinement, and improved hardness. The wear debris of AA5083 alloy showed large flakes as a sign of severe plastic deformation whereas, surface composite samples comprised of fine wear debris.

Interphase region effect on the biaxial yielding envelope of SiC fiber-reinforced Ti matrix composites

The objective of this paper is to investigate the coupled effects of interphase and thermal residual stress on the biaxial initial yield surfaces of metal matrix composites using the simplified unit cell micromechanical model. The representative volume element of the composite consists of three phases, including unidirectional silicon carbide (SiC) fiber, titanium (Ti) matrix, and the interphase region between the fiber and matrix. It is found that the interphase slightly affects the initial yield surfaces of metal matrix composites without thermal residual stress. However, the results reveal that as the thermal residual stress is considered in the micromechanical modeling, the effect of interphase on the response of metal matrix composites becomes much more significant. The effects of the SiC volume fraction, interphase parameters including thickness and material properties on the yielding behavior of the metal matrix composites are examined. To demonstrate the validity of the model, comparisons are carried out between the results of the present model and other micromechanical methods as well as experiment. The extracted results could be useful to guide the modeling and design of a wide range of multiphase metal matrix composites.

Thermal shock resistance of refractory composites with Zirconia and Silicon-Carbide inclusions and alumina binder

With the goal of designing a castable refractory for an aerospace application with optimum resistance to thermal shock, three different particle-reinforced ceramic composites are designed and compared. Different volume fractions of Silicon Carbide (SiC) particles, Zirconia (ZrO2) bubbles, and Zirconia solid particles dispersed in an alumina (Al2O3) matrix are used in the fabrication of these castables. Destructive and nondestructive testing procedures are implemented to evaluate their thermomechanical properties, both before and after a custom designed thermal shock cycle. After demonstrating the applicability of thermal shock indices, the variation of these indices due to thermal shock is measured experimentally and utilized as a design tool. Multiple micro-scale damage mechanisms were observed, all of which are various forms of structural deformation.

Numerical Simulation Analysis of High-precision Dispensing Needles for Solid-liquid Two-phase Grinding

In order to investigate the effect of abrasive flow polishing surface variable diameter pipe parts, with high precision dispensing needles as the research object, the numerical simulation of the process of polishing high precision dispensing needle was carried out. Analysis of different volume fraction conditions, the distribution of the dynamic pressure and the turbulence viscosity of the abrasive flow field in the high precision dispensing needle, through comparative analysis, the effectiveness of the abrasive grain polishing high precision dispensing needle was studied, controlling the volume fraction of silicon carbide can change the viscosity characteristics of the abrasive flow during the polishing process, so that the polishing quality of the abrasive grains can be controlled.

Aluminum Silicon Carbide Particulate Metal Matrix Composite Development Via Stir Casting Processing

In this paper, conventional simple methods of producing MMC with attained properties through the dispersion of silicon carbide in the matrix are investigated. To achieve these objectives a two-step mixing method of stir casting technique was employed. Aluminum (99.66 %C.P) and SiC (320 and 1200 grits) were chosen as matrix and reinforcement materials respectively. Experiments were conducted by varying the weight fraction of SiC for 2.5 %, 5.0 %, 7.5 % and 10 %. The result indicated that the stir casting method was quite successful to obtain uniform dispersion of reinforcement in the matrix. This was evident by the improvement of properties of composites over the base metal. Reinforced Aluminum Silicon Carbide (ASC) showed an increase in Young’s modulus (E) and hardness above the unreinforced case and marginal reduction of electrical conductivity was recorded for the composites. The silicon carbide of 1200 grits (3 μm) showed increased Young’s modulus (E) and hardness of 1517.6 Mpa and 26.1 Hv values at 7.5% volume fraction silicon carbide; when compared with the silicon carbide 320 grit (29 μm). Also; the electrical conductivity properties of the two grit sizes of the silicon carbides were less than the base metal for all the volume fractions of silicon carbide.

Novel microwave composite casting process: Theory, feasibility and characterization

In the present work, the feasibility of high temperature melting and casting of metallic powders through microwave hybrid heating has been successfully attempted. The castings of nickel based powder reinforced with varying volume fraction of silicon carbide were successfully developed using microwave energy. The theory of microwave-metal interactions and the mechanism involved in the processing of composites through microwaves has been illustrated and discussed. The microstructure study of developed castings revealed uniform nearly equiaxed grain growth with uniform dispersion of reinforcements. Microwave heating allowed lower processing time and energy savings with the benefit of trifling pollution. The present work reports the successful applications of microwave processing towards cleaner manufacturing sector in the form of melting and casting of metallic powders.