Advanced Materials and Processes Research Institute
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Effect of Addition of Talc Mineral on Sintering Characteristics of Pyrophyllite Based Ceramic Tiles Using a phosphjatic binder\ud
No full text
The Influence of Alumina Particle Dispersion and Test Parameters on Dry Sliding Wear Behaviour of Zinc-based Alloy.
No full textThe present investigation deals with dry sliding wear characteristics of a zinc-based alloy (ZA 37) with and without Al2\ud
O3\ud
particle\ud
dispersion over a range of sliding speeds and applied pressures. The matrix alloy has been examined under identical test conditions in\ud
order to examine the role played by the second phase alumina particles on wear behaviour. The observed wear behaviour of the samples\ud
has been explained in terms of specific characteristics like cracking tendency, lubricating, load bearing and deformability characteristics,\ud
and thermal stability of various microconstituents. The nature of predominance of one set of parameters (causing higher wear rate) over\ud
the other (producing a reverse effect) was thought to actually control the wear behaviour. Examinations of the characteristic of wear\ud
surfaces and subsurface regions also enabled to understand the operating wear mechanism and to substantiate the wear behaviour.\ud
At low sliding speed, significantly lower wear rate of the matrix alloy over that of the composite was noticed. This has been attributed\ud
to increased microcracking tendency of the composite than the matrix alloy. Reduced wear rate and higher seizure pressure experienced\ud
by the composite over that of the matrix alloy at the higher sliding speeds could be explained to be due to enhanced compatibility of\ud
matrix alloy with dispersoid phase and greater thermal stability of the composite in view of the presence of the dispersoid. The maximum\ud
temperature rise due to frictional heating has been observed to be low in the case of matrix alloy than composite at low speed while the\ud
trend reversed at higher speeds. In general, the wear rate and temperature increased with applied pressure and speed. Seizure pressure\ud
reduced with increasing speed while the seizure resistance (pressure) of the matrix alloy was more adversely affected by speed than that of\ud
the composite
Development and tribological behaviour of UHMWPE filled epoxy gradient composites
No full textIn this study, ultra high molecular weight polyethylene (UHMWPE) filled epoxy gradient composites have been developed. Samples were prepared for different centrifugation time periods. SEM and optical microstructures confirmed the graded dispersion of UHMWPE particles in the epoxy matrix. Quick estimation of gradient characteristics has been done by abrasive wear measurements. Sliding wear tests were conducted by using a pin-on-disc machine. The sliding wear rate of composites reduced on increasing centrifugation time. Reduction in sliding wear rate in UHMWPE filled epoxy gradient composites has been attributed to the reduction of tensile contact stresses as a result of the lubricating effect of UHMWPE's smooth surface and highly entangled chain structure of UHMWPE
Abrasive Wear Behaviour of Bamboo (Dendrocalamus Strictus) Powder Filled Polyester Composites
No full textAn experimental study was conducted to determine the abrasive wear behaviour of different weight percentage bamboo powder filled polyester composites under the multipass mode. The effect of bamboo powder concentration and sliding distance on the weight loss of composites has been analyzed. Worn surface have been analyzed to observe the mechanism of wear. The weight loss depends on bamboo powder concentration. The weight loss decreases with the increase of sliding distance. Samples having 20 weight percentage (wt%) of bamboo powder show the maximum weight loss during abrasion.\u
Shear Rate Dependence of Viscosity and First-Normal-Stress-Difference of LCP/PET Blends at Solid and Molten States of LCP
No full textThe liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) were blended in an elastic melt extruder to make samples having 20, 40, 60, 80, and 100 wt % of LCP. Morphology of these samples was studied using scanning electron microscopy. The steady state shear viscosity (η), dynamic complex viscosity (η*) and first normal stress difference (N1) were evaluated and compared at two temperatures: 265°C, at which LCP was in solid state, and 285°C, at which LCP was in molten state. The PET was in molten state at both the temperatures. The shear viscosity of the studied blends displayed its dependence on composition and shear rate. A maxima was observed in viscosity versus composition plot corresponding to 80/20 LCP/PET blend. The N1 increased with LCP loading in PET and with the increased asymmetry of LCP droplets. The N1 also varied with the shear stress in two stages; the first stage demonstrated elastic deformation, whereas second stage displayed dominant plastic deformation of LCP droplets. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2212–2218, 200
Investigation into sliding wear performance of zinc-based alloy reinforced with SiC particles in dry and lubricated conditions
No full textThe objective of the present investigation was to assess the influence of SiC particle dispersion in the alloy matrix, applied load, and the presence of oil and oil plus graphite lubricants on the wear behaviour of a zinc-based alloy. Sliding wear performance of the zinc-based alloy and its composite containing SiC particles has been investigated in dry and lubricated conditions. Base oil or mixtures of the base oil with different percentages of graphite were used for creating the lubricated conditions. Results show a large improvement in wear resistance of the zinc-based alloy after reinforcement with SiC particles. The lubrication improved the wear resistance and friction behaviour of both the reinforced and base alloys. It was also observed that there exists an optimum concentration of graphite particles in the lubricant mixture that leads to the best wear performance. The composite experienced higher frictional heating and friction coefficient than the matrix alloy in all the cases except oil lubricated conditions; a mixed trend was noticed in the latter case. The wear rate and frictional heating increased with load while friction coefficient was affected in an opposite manner. Test duration influenced the frictional heating and friction coefficient of the samples in a mixed manner.\ud
\ud
Examination of worn surfaces revealed a change of predominating wear mechanisms from severe ploughing and/or abrasive wear for base alloy to delamination wear for the reinforced material under dry sliding conditions. The presence of the lubricant increased the contribution of adhesive wear component while reducing the severity of abrasion. This was attributed to the generation of more stable lubricant films on the contacting surfaces. Cross-sections of worn surfaces indicated substantial wear-induced plastic deformation, thereby suggesting adhesive wear to be a predominant wear mechanism in this study. The debris particles revealed deformed flakes and machining chips signifying the involvement of adhesion and abrasion modes of wear respectively
On the accuracy of ductile fracture assessment of through-wall cracked pipes
No full textDuctile fracture assessments of circumferentially through-wall cracked piping components performed on the basis of the elastic–plastic J - integral concepts are discussed with particular interest in its ability and accuracy to predict actual experimental loads corresponding to initiation\ud
of stable crack growth and failure stages. Possible source of uncertainty in the modeling of material behaviour is treated separately, comparing results with each other and with experimental data. Especially J estimation schemes for evaluating applied J -integral are checked against 3D\ud
non-linear finite element analysis (FEM) using the advanced fracture analysis code WARP3D. The influence of stress–strain curve used as an input to the FEM analysis on the predicted results of crack initiation and maximum loads is examined in circumferentially through-wall cracked pipes. The elastic–plastic fracture mechanics based J -integral combined with J–T analysis is found to give an accurate and complete description of component behaviour. An approximation of material stress–strain curve is given based on the interpretation of experimental result
Modeling the sorption kinetics of divalent metal ions onto mineral adsorbent using integral method.
No full textA mathematical model has been developed that could predict kinetic parameters for the adsorption of divalent cations (lead, copper and zinc) onto low-grade rock phosphate using experimental data. The experiments were conducted with the initial concentrations of metal ions ranging from 10 to 100 mg/L. The mathematical model is based on application of Freundlich isotherm to mass transfer across the film surrounding the adsorbent. A code in C programming is used to numerically integrate the model equation, and to obtain the best simulated values of Freundlich constants K, N, order of reaction n, and film transfer coefficient, α. It is observed that the adsorption of metal ions on rock phosphate is more sensitive to N,n, and α in comparison to K, and lead is adsorbed more favorably than copper and zinc
CFD simulation and experimental validation studies on hydrocyclone.
No full textHydrocyclone is a key unit operation in mineral process industry and simulation of which using CFD techniques is gaining popularity in process design and optimization. The success of the simulation methodology depends primarily on how best the results are matching with the experimental values and the computational time it requires for obtaining such results. In the present investigation, attempts are made to develop a methodology for simulating the performance of hydrocyclone. Initial work included comparison of experimental and simulated results generated using different turbulence models i.e., standard k–ε, k–ε RNG and RSM in terms of water throughput and split with the help of suitably designed experiments. Among the three modeling methods, predictions using RSM model were found better in agreement with experimental results with a marginal error between 4% and 8%. Parametric studies have indicated that a decrease in the spigot opening increased the upward vertical velocity of water more compared to a decrease in the downward vertical velocity. An increase in the inlet pressure has increased the axial velocities of water in both the upward and downward directions and increased the mass flow rates through the cyclone. An increase in the inlet pressure has also increased the static pressure differential along the radius within the cyclone body and hence more water split into overflow. Further, an increase in the inlet pressure has also increased the tangential velocities and reduced the cyclone cut size. The simulated particle distribution values generated using the particle injection technique are found matching with the experimental results while achieving cut sizes between 4.9 and 14.0 μm