Influence Of SiC Content Research Articles

Influence of SiC content on the properties of Al/SiC composites produced by powder metallurgical route

Influence of SiC content on the properties of Al/SiC composites produced by powder metallurgical route

Microstructure, Mechanical and Wear Properties of W-Si-C Composites Consolidated by Spark Plasma Sintering

W-Si-C composites with high relative densities and good mechanical and wear properties were successfully prepared by spark plasma sintering. The influence of SiC content on the relative density, microstructure, mechanical properties and wear characteristics was investigated. The results indicated that the reaction between SiC and W at their interface produced W2C and W5Si3. SiC also reacted with oxygen impurities at the W grain boundary to form SiO2. The purification of the grain boundaries of W was carried out by SiO2 synthesis. Reactive sintering reduces the free energy of the system and facilitates the densification process of W-Si-C composites. This results in a significant increase in the relative density of W-Si-C composites, which reaches a maximum of 98.12%, higher than the 94.32% of pure tungsten. The hardness significantly increases from 4.33 GPa to 8.40 GPa when the SiC content is 2 wt% compared to pure tungsten due to the generation of the hard ceramic phase and the increase in relative density. The wear resistance of the W-Si-C composites was significantly improved with little SiC addition. The wear rate significantly decreased from 313.27 × 10−3 mm3/N·m of pure tungsten to 5.71 × 10−3 mm3/N·m of W-0.5 wt% SiC. SEM analyses revealed that the dominant wear mechanism of pure tungsten was attributed to fatigue wear, while that of W-Si-C composites was due to abrasive wear.

Design and mechanical properties of SiC reinforced Gd2O3/6061Al neutron shielding composites

This paper presented a new type of neutron absorption material used in the storage and transportation of spent fuel in nuclear power plants as SiC/Gd2O3/6061Al composites (SGAC). The optimal component proportion of composites was designed by neutron shielding simulation with MCNP5 software and mechanical property simulation with LAMMPS software. The influence of SiC content on the neutron shielding performance and mechanical properties of the composites was explored by numerical simulation. SGAC with different content of SiC were prepared by SPS technology. The thermal neutron shielding properties, microstructure and mechanical properties for SGAC were analyzed by neutron shielding tests, XRD, typical SEM, TEM, and tensile tests. The neutron shielding test shows that the neutron shielding performance of (0 wt%-25 wt%) SiC/5 wt% Gd2O3/6061Al SGAC with a thickness of 5 mm all reach above 99.5%. Nanometer Gd2O3 particles and micron SiC particles play intragranular and intergranular reinforcement effects on Al matrix respectively. A new phase Al4SiC4 is generated at the interface of the two phases, facilitating the connection of interfaces. (15 wt% SiC+5 wt% Gd2O3)/6061Al shows superior mechanical properties with the tensile strength of 196 MPa and the elongation of 11%.

Influence of SiC Content on Microstructure and Mechanical Properties of SiCp/AlSi7Mg Composites Fabricated by Selective Laser Melting

Influence of SiC Content on Microstructure and Mechanical Properties of SiCp/AlSi7Mg Composites Fabricated by Selective Laser Melting

Influence of SiC reinforcement content and heat treatment on the corrosion behavior of pulsed electrodeposited Ni-W alloy metal matrix composite

The influence of SiC content and heat treatment on the corrosion behavior of pulsed electrodeposited Ni-W/SiC composite coatings was studied by electrochemical polarization and impedance spectroscopy in 0.6 M NaCl. Structural and compositional analysis was carried out using X-ray diffraction, differential scanning calorimetry, transmission electron microscopy and depth profiling XPS analysis. It was observed that as deposited composites coatings demonstrated better corrosion resistance than heat-treated coatings. A higher corrosion and passive current density in the heat treated composite coatings was attributed to the defective nature of the passive film as indicated by Mott-Schottky analysis. A suitable corrosion mechanism is proposed and the results are rationalized based on mixed potential theory and a point defect model. This study indicate that heat treatment of coatings does not always result in better corrosion resistance.

ZrB2–SiC composites for sliding wear contacts: Influence of SiC content and counterbody

In recent times, significant efforts have been put to develop wear-resistant ZrB2–SiC composites for aerospace and automotive applications. The present study details friction and wear of spark plasma sintered ZrB2-(10, 20, 30 vol %) SiC composites in dry unlubricated conditions of sliding against different counterbodies: SiC (120 W/m-K, 22 GPa), WC-Co (100 W/m-K, 15 GPa), Al2O3 (30 W/m-K, 18 GPa), ZrO2 (25 W/m-K, 12.5 GPa). The coefficient of friction (COF) varied in the range of 0.49–0.69 and wear volume in the range of 0.006–0.152 mm3 with varying SiC content in ZrB2–SiC composites and counterbody. Against a given counterbody, less friction and wear are found for the composites with large SiC content, owing to the high fracture toughness and hardness. Friction and wear of the composites are influenced by thermal conductivity of the counterbody. Worn surface analysis of the composites reveals mechanical aspects of fracture, pull-out, deformation as well as tribo-oxidation, while fracture and pull-out decreased with increased SiC content in the composites or thermal conductivity of the counterbody. Results from the present study recommend ZrB2-30 vol % SiC composites for the use in sliding contacts against SiC counterbody.

Influence of SiC Content on Microstructure, Dislocation Density and Mechanical Behavior of Cu/SiC Composite

The present investigation has examined the impact of micro-SiC on microstructure, dislocation and mechanical behavior of Cu/SiC composite. The micro-composite samples have been fabricated under a constant pressure (480 MPa) and sintered temperature (860oC) for 2 h. The sintering process was performed under argon gas. The microstructure examination was conducted using SEM/EDS and XRD diffraction. The SiC contents were 0, 5, 10,15,20,25 and 30 volume fraction. The outcomes showed that the density was significantly decreased with an increase of silicon carbide content. The relative densities of Cu and Cu/SiC composites was ranged from 91.24% to 83.56% for pure Cu and Cu/30 vol%SiC composites. The copper crystallite size was reduced with growing SiC content while the hardness, ultimate and yield compressive strength increased with increment of SiC volume fraction to 20% vol. The values of hardness, ultimate and yield compressive strength increased to 231 HV,343 and 176 N/mm2 , respectively for the composite sample containing 20% SiC particles with a percentage increase of 75%,26.6% and 57.2% compared with pure Cu.

Reverse analysis of constitutive properties of sintered silver particles from nanoindentations

Nanoindentation technology is an effective and convenient method for evaluating the mechanical properties of materials at micro and nano scales. Since the complete nanoindentation process is a typical non-linear mechanical behavior and the material deformation varies with the indentation depth, it is difficult to analytically obtain plastic parameters of constitutive models which are however important to describe the material properties in finite element simulations. In this study, nanoindentation experiments are carried out on the sintered silver nanoparticle (AgNP) which is one of the advanced die-attach materials for high-power electronic devices working in harsh environment. In order to further stabilize and enhance the thermal conductivity, different weight contents of SiC microparticles are incorporated in the AgNP paste before the sintering process. Finite element simulations are used to simulate the deformation and load resistance of materials in nanoindentation process. Plastic properties of materials are analyzed by proposing a reverse algorithm based on the measurements of nanoindentation responses. Essentially, the proposed reverse algorithm couples the dimensional analysis and trial-and-error fitting technique. The complete constitutive relationship of sintered AgNP with different SiC contents is obtained accordingly after examining the loading and unloading stages of nanoindentation responses. The influence of SiC content on the mechanical properties of sintered AgNP is also discussed by considering the material microstructure observed using a scanning electron microscopy. Finally, the uniqueness of constitutive curve from the proposed reverse algorithm is confirmed by the agreement of predicted and measured load-displacement responses using independent spherical indentations.

An investigation on D-gun sprayed Al2O3-SiC coatings

Mechanically blended Al2O3-SiC feedstock powder with varying SiC content (0%, 3%, 5%, 7%) is deposited on AISI 1020 steel substrates by Detonation gun technique. All the coatings are successfully deposited on the substrate without decomposing SiC in the coating. The influence of SiC content on the mechanical properties of the coating is thoroughly studied. Through XRD analysis and scanning electron microscopy (SEM) the phases and micro-structure of the coating are studied respectively. Quantitative phase analysis is performed by Rietveld refinement technique. Porosity of the coatings is estimated by image analysis technique. The wear behaviour of the coating is judged by ball-on-disc type tribometer. The micro-hardness and fracture toughness of the coatings are evaluated by using Vickers micro-hardness tester and scratch tester respectively. Among the four different coatings, Al2O3–3 wt% SiC coating is found to have the highest fracture toughness and micro-hardness values along with minimum porosity. Also, compared to the other three coatings Al2O3–3 wt% SiC has shown the highest wear resistant property. Adhesion induced spallation and brittle fracturing of lamellae are the two main wear mechanisms of the coatings. Phase stabilization of Al2O3 is found to happen while spraying with 3–5 wt% of SiC.

Influence of SiC content on the oxidation of carbon fibre reinforced ZrB2/SiC composites at 1500 and 1650 °C in air

The microstructure and the oxidation resistance in air of continuous carbon fibre reinforced ZrB2–SiC ceramic composites were investigated. SiC content was varied between 5–20 vol.%, while maintaining fibre content at ∼40 vol.%. Short term oxidation tests in air were carried out at 1500 and 1650 °C in a bottom-up loading furnace. The thickness, composition and microstructure of the resulting oxide scale were analysed by SEM-EDS and X-Ray diffraction. The results show that contents above 15 vol.% SiC ensure the formation of a homogeneous protective borosilicate glass that covers the entire sample and minimizes fibre burnout. The scale thickness is ∼90 μm for the sample containing 5 vol.% SiC and decreases with increasing SiC content.

Corrosion behavior and microstructural evolution of BN–ZrO2–SiC composites in molten steel

AbstractThe influence of SiC content on corrosion resistance and microstructural evolution of BN–ZrO2–SiC composites after corrosion in molten steel at 1600°C has been investigated. The corrosion resistance of BN–ZrO2–SiC composite decreases with increasing the SiC content. When the SiC content is more than 15 vol%, the corrosion rate begins to accelerate sharply. A resintered ZrO2 bilayer structure with a distinctly reduced porosity in the corrosion layer contributes significantly to the enhanced corrosion resistance. Thus, optimizing the SiC content and tailoring the microstructural feature of residual corrosion layer are effective ways to improve the corrosion resistance of BN–ZrO2–SiC composite.

Influence of SiC Content and Heat Treatment on the Corrosion Resis-Tance and Oxidation Resistance of Ni-P-SiC Composite Coating

Ni-P alloy and SiC micron particles were codeposited on Q235 steel by electroless plating. The composition, microstructure, micro-hardness, corrosion resistance and oxidation resistance of the composite coating were studied. The results revealed that the deposited composite coating shows dispersed SiC particles and continuous Ni-P matrix. When the content of SiC was 8g/L and the heat treatment temperature was 300°C, the corrosion potential and corrosion current of Ni-P-SiC coating were-0.292V, and 8.2×10-7 A/cm2, respectively, while those of Ni-P composite coating were-0.501V, and 4.2×10-5 A/cm2, respectively. Ni-P-SiC composite coating with high content of SiC exhibits better oxidation resistance than Ni-P coating.

Searching for the superior solution to the population-based optimization problem: Processing of the wear resistant commercial AA6061 AMCs

In this present work, stir casting technique was used to fabricate aluminum matrix composites with varying weight percentages of SiC (5, 10 and 15) reinforcements. The proper selection of process parameter such as pouring temperature, stirring speed, stirring time and pre-heat temperature of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chemical reaction between reinforcement and matrix should be avoided. Optimization is an applied science which explores the best values of the parameters of a problem that may take under specified conditions. The execution of an optimized stir casting technique yields relatively homogenous and fine microstructure which improves the addition of reinforcement material in the molten metal. The influence of SiC content, SiC size and secondary mechanical processing with different rolling reductions on the dry sliding wear characteristics of Al matrix composites has been assessed using a pin-on-disc wear test. The porosity and hardness of the resultant composites were also examined.

A study on in-situ synthesis of TiB2–SiC ceramic composites by reactive hot pressing

TiB2–SiC ceramic composites with (10–20) wt% SiC were in-situ synthesized by the reactive hot pressing (RHP) process at 1700 °C under 32 MPa in vacuum. The influence of SiC content and sintering time on the microstructure and mechanical properties of the composites was investigated in detail. The fracture toughness increased while the flexural strength and hardness decreased as the content of SiC increased. Elongated TiB2 grains with a diameter of 1–2 μm and an aspect ratio of 3–6 were in-situ synthesized in the composites. The composite containing 15 wt% SiC had the optimum comprehensive mechanical properties with flexural strength of 704 MPa, fracture toughness of 5.6 MPa m1/2 and hardness of 19.8 GPa. The improved mechanical properties were attributed to the mixed fracture mode, the strengthening and toughening mechanisms of SiC particles and elongated TiB2 grains including crack bridging, crack deflection, crack branching, grain fracture and the interlocking structure. The fracture toughness and hardness increased due to the improved relative density and higher yield of elongated TiB2 grains as the sintering time increased. However, the abnormal grain growth deteriorated the flexural strength when the sintering time further increased.

Preparation and characterization of SiCp/2024Al composite foams by powder metallurgy

SiCp/2024Al composite foams were manufactured by powder metallurgical methods using foaming agent CaCO3 in order to enrich the foam fabrication process and promote its development and extensive application. The effects of CaCO3 and SiC volume fractions on the foaming behaviours were investigated by means of SEM and Magiscan-2A image analysis technique. The influence of SiC content on the compressive behaviour was analyzed using Gleeble 1500 thermal simulation testing machine. The experimental results show that with increasing the foaming agent, the porosity and pore dimension increase first and decrease later. With increasing the reinforcement content, the porosity and pore dimension decrease. The compressive curves reveal that the introduction of SiC particles can improve compressive yield strength and energy absorption capacity. Meanwhile, it is found that SiCp/2024Al composite foams are the brittle foam materials.

Hot-Pressing Sintering Behavior and Properties of AlON/SiC Composites

AlON/SiC composites were synthesized by hot-pressing sintering technology using SiC and prepared AlON powder as raw materials. The influence of SiC content on relative density, hardness, bend strength and microstructure of multiphase material was studied by several testing methods, such as XRD and SEM. The strengthening mechanism of SiC was also explored in this paper. The experimental results indicated that with the addition of SiC, the bend strength of the multiphase material was obviously enhanced, comparing with AlON single phase material, and ultimately it reached 310 MPa. The best adding mass content of SiC was 8% and its strengthening mechanism was mainly thermal expansion mismatch and fine grain strengthening. As the adding mass content of SiC increased, the hardness of AlON/SiC ceramic matrix composite was increased gradually, the bend strength firstly increased and then decreased, and the main fracture way of composite was changed from intergranular fracture to transgranular fracture and finally both of the two modes of fracture occurred. This research had positive significance on deep popularization and application of AlON ceramic material.

Fabrication of hot-pressed ZrC-based composites

In this work, ZrC-based composites reinforced with SiC particles were processed using the hot-pressing route. The influence of SiC content on the microstructure and mechanical properties of the hot-pressed composites was investigated. In all composites with different SiC contents, the highest relative density was obtained for ZrC-based composite containing 20 vol% SiC, having a value of 97 per cent. The flexural strength of ZrC-based composites increased modestly from 390 to 452 MPa as the SiC content increased from 10 to 20 vol%. The increase in strength was attributed to a decrease in grain size and improvement of the relative density. But the strength did not show great variation when the content of the SiC particles increased to 30 vol%, which may be because of the inhomogeneous microstructure and the low relative density. In contrast, toughness and hardness did not vary significantly with SiC content.

Oxidation of ZrB2–SiC: Influence of SiC Content on Solid and Liquid Oxide Phase Formation

The effect of SiC concentration on the liquid and solid oxide phases formed during oxidation of ZrB2–SiC composites is investigated. Oxide‐scale features called convection cells are formed from liquid and solid oxide reaction products upon oxidation of the ZrB2–SiC composites. These convection cells form in the outermost borosilicate oxide film of the oxide scale formed on the ZrB2–SiC during oxidation at high temperatures (≥1500°C). In this study, three ZrB2–SiC composites with different amounts of SiC were tested at 1550°C for various durations of time to study the effect of the SiC concentration particularly on the formation of the convection cell features. A calculated ternary phase diagram of a ZrO2–SiO2–B2O3 (BSZ) system was used for interpretation of the results. The convection cells formed during oxidation were fewer and less uniformly distributed for composites with a higher SiC concentration. This is because the convection cells are formed from ZrO2 precipitates from a BSZ oxide liquid that forms upon oxidation of the composite at 1550°C. Higher SiC‐containing composites will have less dissolved ZrO2 because they have less B2O3, which results in a smaller amount of precipitated ZrO2 and consequently fewer convection cells.

Thermal shock behaviour of Si 3N 4/SiC composites

In the present study the thermal shock behaviour of Si 3N 4 SiC composites with and without Y 2O 3 as additive was investigated using the KFA electron beam test facility JUDITH at energy densities of up to 9 MJ m −2, which is designed for disruption simulations of materials for the first wall of a fusion reactor. The influence of SiC content, microstructure, additive and density on thermal shock behaviour and mass loss is discussed. Composites with additive have a slightly higher mass loss rate, but show no catastrophical thermal shock behaviour as do the composites without additives. Samples with lower density in the system with additive revealed no visible difference in mass loss and fracture behaviour.

SI 3N 4/SIC composites using conventional and nanosized powders

In the present study mixtures of conventional α-Si 3N 4 (450nm) with 5, 10, 15, 20wt% β-SiC(500nm) or nanosized β-SiC(20nm) and ternary Si-C-N (15nm) powders (25, 40wt%SiC) were used as starting materials. Hot isostatic pressing (HIP) of these powders using quartz capsules at temperatures above 1800° C and pressures of 200MPa resulted in compacts with densities higher than 98% theoretical density. The influence of SiC content and of the different types of starting powders on density, phase transformation, microstructure, hardness and fracture toughness is discussed.