Advanced Materials and Processes Research Institute
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High-Stress Abrasive Wear Behaviour of a Zinc-Based Alloy and Its Composite Compared with a Cast Iron under Varying Track Radius and Load Conditions
No full textAn attempt has been made in this investigation to study the high-stress abrasive wear behaviour of a zinc-based alloy composite containing SiC particle reinforcement. The influence of the reinforcement phase on wear behaviour was investigated by characterizing the zinc-based matrix alloy under identical test conditions. A cast iron was also investigated on similar lines for comparison purposes. The effects of track radius, test duration and applied load on the wear response of the samples were studied. The wear properties studied were wear rate, friction coefficient and frictional heating. The zinc-based matrix alloy comprised of primary � dendrites, eutectoid � + � and ε phase. The composite revealed presence of SiC particles in addition to the features of the matrix alloy. The cast iron showed graphite in a matrix of pearlite and ferrite. The zinc-based matrix alloy attained maximum wear rate and frictional heating, while those for the composite were the least; the response\ud
of the cast iron was intermediate between the two in general. The trend observed by friction coefficient was somewhat different in the sense that it was the least for the cast iron while the maximum was still noted for the zinc-based matrix alloy, the composite revealing intermediate response. The wear rate and frictional heating increased with test duration while the friction coefficient was affected in an opposite manner. Increasing load and track radius caused the wear rate, frictional heating and friction coefficient to increase. The wear behaviour of the samples has been substantiated through the characteristics of wear surfaces, debris particles and the abrasive\ud
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Effects of Processing Parameters on he fabrication of near - net - shape fibre reinforced oxide ceramic matrix composites via sol - gel route
No full textThe sol infiltration technique was found to be very effective for the fabrication of near-net-shape mullite fibre reinforced ceramic matrix composites (CMCs). The infiltrated sol, in single- and bi-component oxide systems with equivalent molar compositions of Al2O3 (A), 60 Al2O3:40 SiO2 (AS), 87 Al2O3: 13 ZrO2 (AZ), and 94 ZrO2:06 Y2O3 (ZY), after drying and calcination, formed the matrix. The discontinuous mullite fibres (as preforms with 15 vol.% fibre content) acted as the reinforcement agents. The characteristics of the CMCs were found to be strongly dependent on the type of the sols (infiltrates) and their viscosity, presence of non-reactive fillers in the sol, number of infiltrations, intermediate and final sintering temperatures and in-situ deposition of carbon in the fabricated materials. The CMCs were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the three point bend test. SEM indicated fibre pull-out in the fracture surface of the CMCs. The pseudo-ductile character, developed in the CMCs, was evident from the load–elongation curve of the three-point bend test. The carbon-containing CMCs exhibited a modulus value of almost 51 GPa.\ud
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Influence of Heat Treatment Parameters on the Lubricated Sliding Wear Behaviour of a Zinc-Based Alloy
No full textThis investigation deals with the observations made pertaining to the influence of the duration of heat treatment (ageing) on the sliding wear response of a zinc-based alloy. The heat treatment comprised of solutionizing followed by artificial ageing for different durations. Partially lubricated sliding wear tests were carried out at a fixed applied pressure, speed and distance. The heat-treated samples attained less strength and hardness but more elongation over the as-cast one. The wear rate and frictional heating initially decreased with increasing ageing duration. This was followed by the attainment of the minimum and then a reversal in the trend at longer durations of ageing. The tensile strength and hardness decreased with increasing duration of ageing and became stable beyond certain ageing period while elongation followed a reverse trend. The response of the samples has been substantiated through the fractographic features and characteristics of wear surfaces, subsurface regions and debris
` Studies on Fluoride Removal Characteristics of Mineral (fluorapatite)'
No full textThe effectiveness of low grade fluorapatite bearing mineral on fluoride removal has not been examined earlier. For identification of such mineral, a preliminary assessment of performance of mineral is essential in order to know which aspect is necessary to carry out further research for development of mineral based defluoridation technology. In this study batch adsorption study was performed to evaluate the fluoride removal potential of low cost rock phosphate (fluroapatite) mineral at pH 4, 5 and 6. The optimum dose was determined to be 1.5, 2.5 and 3.5 g mineral at pH 4, 5 and 6, respectively. The first order adsorption rate constants derived by Lagergren equation at different pH, clearly indicates the fast removal kinetics at pH 4. The comparatively high solubility of mineral and an increase of calcium concentration at pH 4 appears to be the main reason for fast removal reaction. There was no effect of mineral quantity on fluoride removal after solution pH became alkaline. The various aspects of the study including recyclability of mineral are discussed
Study on the Fluoride removal characteristics of mineral (Fluorapatite)
No full textThe effectiveness of low grade fluorapatite bearing mineral on fluoride removal has not been examined earlier. For identification of such mineral, a preliminary assessment of performance of mineral is essential in order to know which aspect is necessary to carry out further research for development of mineral based defluoridation technology. In this study batch adsorption study was performed to evaluate the fluoride removal potential of low cost rock phosphate (fluroapatite) mineral at pH 4, 5 and 6. The optimum dose was determined to be 1.5, 2.5 and 3.5 g mineral at pH 4, 5 and 6, respectively. The first order adsorption rate constants derived by Lagergren equation at different pH, clearly indicates the fast removal kinetics at pH 4. The comparatively high solubility of mineral and an increase of calcium concentration at pH 4 appears to be the main reason for fast removal reaction. There was no effect of mineral quantity on fluoride removal after solution pH became alkaline. The various aspects of the study including recyclability of mineral are discussed
Effect of Sand Concentration in the Medium and Traversal Distance and Speed on the Slurry Wear Response of a Zinc-Based Alloy Alumina Particle Composite
No full textStudies on sintering behavior of pyrophyllite based ceramic tiles using Di-potassium phosphatic binder
No full textIn the present studies the effect of di-potassium hydrogen phosphate binder on sintering behaviour of pyrophyllite mineral has been investigated with a view to develop pyrophyllite based ceramic tiles. The various process parameters namely effect of binder content, particle size of pyrophyllite powder, compaction pressure and sintering temperatures have been optimized to make tiles possessing properties as per the requirement of Indian Standard specification. The formation of different phases formed on sintering of optimised composition has been investigated using X-ray powder diffraction technique. The thermal analysis of optimised composition has been studied with a view to understand the various thermal changes and various phase transformations taking place up to 1200°C temperature. The molecular bonding of aluminum phosphate and silica linkages have been studied by recording IR- spectra of optimised composition sintered at different temperatures. The morphology of aluminium phosphate and dehydroxylated has also been studied using scanning electron microscopy. The results of these studies are presented in this paper
Sorption Mechanism of Some Divalent Metal Ions Onto Low-Cost Mineral Adsorbent
No full textThis paper investigates the underlying mechanism of uptake from aqueous solution of divalent metal cations (Pb2+, Cu2+, and Zn2+) by a low-cost mineral adsorbent. Batch adsorption studies were carried out for the concentration ranges of 24.1−2410 μmol/L for lead, 78.65−7865 μmol/L for copper, and 76.45−7645 μmol/L for zinc solutions under natural conditions. Two simple kinetic models, that is, pseudo-first-order and pseudo-second-order models, were tested to investigate the adsorption mechanism. All of the parameters of these models were calculated and are discussed. Rate constants were found to be nearly constant at all metal concentrations for the first-order model, whereas they gradually decreased with increasing metal concentration in the order Pb2+ > Cu2+ > Zn2+ for the second-order model. The sorption kinetics appears to be mainly controlled by liquid-film diffusion. External-diffusion and film-diffusion models were tested to evaluate mass-transfer coefficients and film-transfer constants at different initial concentrations of solute (metal cation). Both mass-transfer and film-transfer constants were noticed to be affected by the initial metal concentration. They gradually decreased with increasing initial concentration of metal cation in the order Pb2+ > Cu2+ > Zn2+. The film-diffusion model was found not to be applicable for the adsorption of lower concentrations of divalent cations. The equilibrium data were described to a lesser extent by Freundlich model, and the Langmuir model seemed to be more appropriate, giving maximum fixation capacities for Pb2+, Cu2+, and Zn2+ of 90.9, 270.2, and 250.0 μmol/g, respectively. The crystallographic dimensions of the treated mineral adsorbent samples were measured by X-ray diffraction (XRD), which revealed appreciable expansion of the crystal size as a result of the incorporation of divalent cations in the place of exchangeable cations of the adsorbent. The affinity order for the adsorption of cations by the mineral adsorbent is validated by ionic radius theory. Cation exchange along with complexation were found to be the most probable mechanisms for the sorption of divalent cations. An attempt was made to quantify the ion-exchange and complexation mechanisms
Wear Response of a Zinc-Based Alloy Containing Silicon as Influenced by Material Microstructure and Test Conditions.
No full textThis paper describes observations pertaining to the sliding wear response of a zinc-based alloy comprising silicon.Wear tests were performed in oil lubricated condition over a range of applied pressures and sliding speeds. The influence of microstructural changes (brought about through heat treatment) on mechanical properties and wear characteristics of the samples has also been investigated. The study indicates that microstructural alterations brought about through heat treatment could be beneficial in terms of improved wear response of the zinc-based alloy despite a reduction in hardness and tensile strength. However, the extent of improvement depends on test conditions like sliding speed and pressure. Factors like hardness, strength, cracking tendency, thermal stability, morphology and mode of distribution of various microconstituents in the alloy microstructure were noted to be responsible for specific wear behaviour in different test conditions. Different slopes exhibited by the data plots could be explained in terms of changing mode of predominance of operating wear mechanisms. The observed wear behaviour of the alloy was substantiated further through the features of wear surfaces, subsurface regions and debris particles