Sintering Environment Influence on the Properties of Alumina – Silicon Carbide Composites (original) (raw)
Related papers
It is traditionally thought to be challenging to incorporate tougher ceramic particles into a softer aluminium matrix. Powder metallurgy has emerged as a significant fabrication technology in this context. Silicon carbide (SiC) is reinforced to aluminium with varying reinforcement, i.e., 5, 10, and 15 %. The samples were sintered in a microwave sintering furnace at 550°C ± 5°C. The scanning electron microscope and the field emission scanning electron microscope (FESEM) were used to inspect the microstructure (structure/shape, dislocations, and grain distribution) of prepared powders and sintered composites. Water displacement methods were used to assess the density and porosity of prepared composites. X-ray diffraction (XRD) is used to assess the existence of intermetallic compounds (if any) and contaminations. Mechanical investigations were performed on aluminium and its composites, as well as the effect of particle size on the mechanical properties of Al/15 %SiC were studied and presented. Density and porosity found to incline with the increase in SiC content. Properties such as hardness, ultimate tensile strength (UTS) and yield strength (YS) of the reinforced composites (5, 10, and 15 %) were significantly improved, whereas elongation rapidly declined compared to pure aluminium. Also, the UTS and YS increases with the decrease in reinforcement particle size. The dominant mechanisms are ascertained to be dislocation density, refined grain size, and porosity.
Scanning, 2018
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.
Metal matrix composites with Aluminum as the base metal and with varying weight percentage of Silicon Carbide (SiC) as the reinforcement are being synthesized through powder metallurgy route. Sintering of the green compacts is carried out by using conventional and microwave heating. The variation in mechanical properties due to the different sintering processes both conventional and microwave processes are studied. The consolidation of the powder is done under different pressures. It has been observed that green compact density increases with increasing pressure and decreases with increase in weight percentage of SiC. The metal matrix composites (MMC) produced is tested for their hardness and their microstructure variation. Hardness of microwave sintered compacts is more than that of conventional sintered samples. Micro structural investigation shows softening of Al in conventional sintering, but not so in microwave sintering.
Advances in Materials Science and Engineering, 2021
Al2O3 with 10 wt.% of SiC ceramic composite is synthesized at 1500°C by electrical resistance heating sintering with a holding time of 5 hours and microwave sintering methods with a holding time of 15 minutes. The samples generated by the two methods are characterized using powder X-ray diffraction and field emission scanning electron microscopy (FESEM). Experiments with both samples showed that the existence of the α-Al2O3 and β-SiC phases in both samples was verified by the findings of XRD pattern on both samples. Microstructure study illustrates that the Al2O3 matrix particles have spherical-like shape and their average matrix particle size is 67 ± 5 nm for electrical resistance heating sintered sample and 38 ± 5 nm for microwave sintered sample. The lattice strain and crystallite size of Al2O3 matrix were measured using Williamson–Hall (W-H) methods, which were achieved via the use of XRD peak broadening, based on a diffraction pattern. Three modified W-H models were used to com...
Mechanical characteristics of microwave sintered silicon carbide
Bulletin of Materials Science, 2001
The present work deals with the sintering of SiC with a low melting additive by microwave technique. The mechanical characteristics of the products were compared with that of conventionally sintered products. The failure stress of the microwave sintered products, in biaxial flexure, was superior to that of the products made by conventional sintering route in ambient condition. In firing of products by conventionally sintered process, SiC grain gets oxidized producing SiO 2 (∼ ∼ 32 wt%) and deteriorates the quality of the product substantially. Partially sintered silicon carbide by such a method is a useful material for a varieties of applications ranging from kiln furniture to membrane material.
Advances in Materials Science and Engineering
This study was conducted to assess and compare the crack-healing ability of conventional electrical sintered and microwave sintered Al2O3/x wt. % SiC (x = 5, 10, 15, and 20) structural ceramic composites. The crack-healing ability of both conventional electrical sintered and microwave sintered specimens was studied by introducing a crack of ∼100 µm length by Vickers’s indentation and conducting a heat treatment at 1200°C for dwell time of 1 h in air. The flexural or bending strength of sintered, cracked, and crack-healed specimens was determined by three-point bending test, and the phase variations by X-ray diffraction and SEM micrographs before and after crack-healing of both the sintering methods were studied and compared. The results show that almost all the specimens recovered their strength after crack-healing, but the strength of microwave sintered Al2O3/SiC structural ceramic composites has been shown to be better than that of conventional electrical sintered Al2O3/SiC struct...
Metal matrix composites with Aluminum as the base metal and with varying weight percentage (wt. %) of Silicon Carbide (Sic) as the reinforcement is being synthesized through powder metallurgy route.The consolidation of the powder is done under different pressures. It's been observed that green compact density increases with increasing pressure and decreases with increase in weight percentage of Sic. Sintering of the green compacts produced is carried out by using both conventional and microwave technique. The composites produced are tested for their hardness and their microstructure is studied. The properties of conventional and microwave sintered composites are compared. Microstructural investigation shows that precipitation of Sic particles occurs in conventional sintering but homogeneous distribution in case of microwave sintering.
Microstructure and Properties of Al2O3–SiC Nanomaterials
The relationship between densification, microstructure and mechanical properties of Silicon carbide reinforced Alumina matrix were investigated. The composites were prepared from nano-powders in an attempt to produce composites with nanostructured grains and as a result improved hardness and fracture toughness values. The composite powders were sintered using a Spark Plasma Sintering (SPS) furnace which allows for high heating and cooling rates to be implemented. For the Al 2 O 3-SiC composites it was evident that the densification of the materials containing 30% and 50% (by volume) of the reinforcing component was below 97%, whereas for the lower additions of the reinforcing components full densification was observed. The oxygen content of the starting powder was seen to strongly affect the densification behaviour of the Al 2 O 3-SiC nano-composites and is also assumed to have resulted in deterioration of the mechanical properties in the Al 2 O 3-SiC composites. The hardness values of the Al 2 O 3-SiC nano-composite materials were up to 20.7GPa, while the fracture toughness was up to 4.7MPa.m 0.5 .
Materials & Design, 2012
In this study Al 2 O 3-SiC micro/nanocomposites have been fabricated by mixing alumina nanopowders and silicon carbide micro/nanopowders, followed by hot pressing at 1550, 1600, 1650 and 1700°C. The density, mechanical properties and fracture mode of Al 2 O 3-SiC composites containing different volume fractions (2.5%, 5%, 7.5%, 10% and 15%) of micro/nanoscale SiC particles were investigated and compared with those of alumina. The relative density of composites could reach values very close to theoretical density, especially after sintering at 1700°C. However, relative density declined by increasing the SiC fraction at the same sintering temperature. The flexural strength of composites was best for sintering temperature of 1700°C and showed a maximum of 545 MPa for Alumina-10%SiC sintered at 1700°C. Hardness showed a remarkable increase by adding SiC and reached a pick of 22.6 GPa for Alumina-15%SiC. Fracture toughness and fracture mode of alumina and composites with 5%, 10% and 15% SiC sintered at 1700°C were also investigated. Composites were tougher than alumina and the scanning electron microscopy observations showed that fracture mode changes from intergranular for alumina to transgranular for composites. Finally X-ray diffraction analysis could not detect any chemical reactions between Al 2 O 3 and SiC particles.
Crystals
Aluminum hybrid metal matrix nanocomposites (Al/SiC/TiO2) were synthesized through a microwave-assisted powder metallurgy process, and their evolved microstructure and mechanical properties were investigated. The Al/SiC/TiO2 hybrid nanocomposites were prepared by reinforcing aluminum (Al) matrix with a fixed amount of silicon carbide (SiC) nanoparticles (5 wt.%) and varying concentrations of titanium dioxide (TiO2) nanoparticles (3, 6, and 9 wt.%). The morphology results revealeda uniform distribution of SiC and TiO2 reinforcements in the aluminum matrix. An increase in the hardness and compressive strength of the Al/SiC/TiO2 hybrid nanocomposites was noticed with the increasein TiO2 nanoparticles. The Al/SiC/TiO2 hybrid nanocomposites that had an optimum amount of TiO2 nanoparticles (9 wt.%) showcased the best mechanical properties, with maximum increments of approximately 124%, 90%, and 23% of microhardness (83 ± 3 HV), respectively, yield strength (139 ± 8 MPa), and ultimate comp...