M.K. Surappa

Fabrication and characterisation of pure magnesium-30 vol.% SiCP particle composite

Pure magnesium-30 Vol.% SiC particle composite are fabricated by melt stir technique without the use of a flux or protective inert gas atmosphere. After hot extrusion with an extrusion ratio of 13, Mg-30 vol.%

Fabrication and characterization of SiC/MoSi2 composites

SiC_P

The machinability of a cast aluminium alloy-graphite particle composite

composites have been evaluated for their tensile properties at room and elevated temperatures (up to 400°C). Composites in the as-cast conditions do not show any change in dendrite arm spacing:cell size compared to unreinforced pure magnesium. However, in the extruded conditions average grain size of the composites is 20 mm compared to 50 mm in the pure magnesium. Microstructure shows no evidence of reaction product at particle:matrix interface. At room temperature, stiffness and UTS of the extruded composites are 40 and 30% higher compared to unreinforced pure magnesium, signifying significant strengthening due to the presence of the SiC particles. Further, up to temperatures of 400°C, composites exhibit higher UTS compared to pure magnesium. Mg composites show a wear rate lower by two orders of magnitude compared to pure Mg, when tested against steel disc using pin-on disc machine.

Microstructure and interface structure studies of SiCp-reinforced Al (6061) metal-matrix composites

Abstract In the present study, SiC particle reinforced molybdenum–disilicide (MoSi 2 ) matrix composites have been fabricated by hot press sintering and in situ reaction sintering process successfully. Hot pressed SiCp/MoSi 2 composite has a phase constituent with about 20 vol.% α -SiC and less Mo 5 Si 3 in MoSi 2 matrix. In situ SiC/MoSi 2 composite contains about 24.5 vol.% β -SiC and a small amount of Mo 5 Si 3 in MoSi 2 matrix. Two types of SiC/MoSi 2 composites have been improved in their hardness, flexural strength and fracture toughness. Compressive yield strength of SiC/MoSi 2 composites at 1200 and 1400°C has also been enhanced obviously. Wear behavior test abraded on Al 2 O 3 and SiC grind wheel has shown very excellent wear resistance of SiC/MoSi 2 composites compared with monolithic MoSi 2 .

Dry sliding wear of fly ash particle reinforced A356 Al composites

The microstructure of a cast Al---Si alloy-graphite particle composite is examined using optical and analytical scanning electron microscopy. Specimens containing different percentages of graphite were machined by orthogonal planning with 25° and 45° rake angle tools at both 6.5 and 13.2 m min−1. The machining forces are reported and the chip-rake-face friction coefficients and shear flow stresses are calculated. It is shown that the reduction in machining forces with increasing graphite content is due mostly to a decrease in the shear flow stress rather than to lower chip-rake-face friction. Both the polished and the machined surfaces of the composite are rougher than those of the simple alloy, apparently owing to the greater porosity, the tearing out of graphite particles, or the opening of cracks at the graphite particles in the wake of the tool.

Synthesis of fly ash particle reinforced A356 Al composites and their characterization

The microstructure and interface structure of the particle reinforced 6061-Al metal-matrix composites have been studied by optical microscopy, transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and energy dispersive X-ray spectroscopy (EDX). The SiC particles are uniformly distributed in the matrix. The constituent phase observed in the matrix is Al-15(Mn,Fe,Cu)(3)Si-2. It has a BCC structure with lattice parameter a=1.28 nm. The SiC reinforcements are found to contain hexagonal alpha-SiC (including 6H alpha-SiC and 4H alpha-SiC) and cubic beta-SiC. Stacking faults are observed in the SiC particles. SIC reinforcements are well bonded with the matrix. In most cases, the interface between the SiC particles and the matrix is clean and no reaction product was observed. However, certain amount of oxygen and magnesium elements have been found at the interface. The reaction products at the interface are identified to be MgAl2O4, and MgO. The size of these particles are found to be of several nanometers