Advanced Materials and Processes Research Institute
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Properties of composites of 2014 aluminium alloy with Ni-Mo based metallic glass paricles.
No full textComposites of 2014 aluminium alloy containing dispersions of metallic glass particles (51.5wt% Ni, 38.0wt% Mo, 8.0wt% Cr and 1.5wt% B) have been prepared by a conventional powder metallurgy route involving powder mixing, compaction, sintering and heat treatment. Physical and mechanical properties of the composites, such as dimensional changes, hardness, electrical resistivity and corrosion behaviour, were studied. Dimensional growth up to a maximum of 6% in a linear direction was observed in all sintered composites. HardnessHv increased from 40 to 55kgmm−2 with the addition of 4vol% of dispersoid, followed by a gradual decrease with increasing additions of dispersoid. The decrease in hardness above 4vol% of dispersoid was attributed to the presence of increasing amounts of porosity. Electrical resistivity increased from 50nΩm (for 2014 aluminium alloy) to 180nΩm at 20vol% dispersoid. The corrosion rate in an artificial sea water environment decreased linearly with the volume fraction of dispersoid. Re-pressing and re-sintering (in an argon atmosphere) of composites containing 4vol% of metallic glass particles resulted in an increase inHv from 55 (argon sintering) to 83kgmm−2, and a decrease in electrical resistivity from 57 to 52nΩm due to the increase in density. The corrosion rate in an artificial sea water environment of composites containing 4vol% of metallic glass decreased from 70×10−3 to 50×10−3 mgdm−2 per day due to re-pressing and re-sintering
Mechanism of material removal during low stress abrasion of Al alloy Zircon particle composities.
No full text(Al11.8Si4.0Mg alloy)-zircon particle composites containing zircon particle (size, 100 μm) volume fractions of 0.15 and 0.35 have been prepared by liquid metallurgy techniques. The low stress abrasion resistance of these composites was tested using a rubber wheel abrasion test apparatus with American Foundrymen's Society 50–70 mesh rounded quartz abrasive. Scratch tests were performed on metallographic surfaces of composites using a fixed-depth scratch test apparatus in order to simulate the high stress pin-on-drum abrasion test.\ud
The results show that the low stress abrasive wear rate of the aluminum alloy was decreased by a factor of 5 as a result of the dispersion of the 0.35 volume fraction of zircon particles. The wear rate of the composite containing a zircon particle volume fraction of zircon 0.35 (a Vickers hardness of 144 HV) under the low stress condition was found to be equal to that of normalized AISI 1045 steel (197 HV). Scanning electron microscopy micrographs of the composite surfaces abraded under low stress conditions show that the zircon particles stand proud of the matrix without any particle pull-out or interfacial debonding. Material removal mechanisms during low stress abrasion of the composites appear to be governed by microfracture of zircon particles, leading to subsequent pit formation. There is a direct correlation between material removal mechanisms during fixed-depth scratch testing and high stress pin-on-drum abrasion. In both cases there was catastrophic fragmentation of the zircon particles.\u
Sunhemp fibre reinforced polyester.
No full textThis paper describes the tensile and impact behaviour of polyester composites reinforced with continuous unidirectional sunhemp fibres of plant origin. The tensile strength and Young's modulus of sunhemp fibre were found to be 389 MPa and 35.4 GPa, respectively. Tensile strength of composites containing up to 0.4 fibre volume fraction (V f) were found to increase linearly with (V f) and the results showed good agreement with the rule of mixtures. The work of fracture, as determined by Izod impact test, was also found to increase linearly with (V f) and the work of fracture for 0.24 (V f) composite was found to be approximately 21 kJ m−2. The analysis of various energy absorbing mechanisms during impact fracture showed that fibre pull out and interface fracture were the major contributions towards the high toughness of these composites. The results of this study indicate that sunhemp fibres have potential as reinforcing fillers in plastics in order to produce inexpensive materials with a high toughness
Liquid membrane phenomena in antiarrhythmic action
No full textAntiarrhythmic drugs have been shown to generate liquid membranes in series with a supporting membrane. Transport of sodium ions across the liquid membrane generated by these drugs has been studied. The data indicate that the transport of sodium ions is impeded in presence of the liquid membranes. Relevance of this observation to antiarrhythmic action has been discussed. Four structurally dissimilar antiarrhythmic drugs, namely quinidine, disopyramide, procainamide and propranolol, have been investigated