Advanced Materials and Processes Research Institute
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Thermal treatment of toxic metals of industrial hazardous wastes with fly ash and clay
No full textWaste generated from galvanizing and metal finishing processes is considered to be a hazardous due to the presence of toxic metals like Pb, Cu, Cr, Zn, etc. Thermal treatment of such types of wastes in the presence of clay and fly ash can immobilizes their toxic metals to a maximum level. After treatment solidified mass can be utilized in construction or disposed off through land fillings without susceptibility of re-mobilization of toxic metals. In the present investigation locally available clay and fly ash of particular thermal power plant were used as additives for thermal treatment of both of the wastes in their different proportions at 850, 900 and 950 °C. Observed results indicated that heating temperature to be a key factor in the immobilization of toxic metals of the waste. It was noticed that the leachability of metals of the waste reduces to a negligible level after heating at 950 °C. Thermally treated solidified specimen of 10% waste and remaining clay have shown comparatively a higher compressive strength than clay fired bricks used in building construction. Though, thermally heated specimens made of galvanizing waste have shown much better strength than specimen made of metal finishing waste. The lechability of toxic metals like Cr, Cu, Pb and Zn became far below from their regulatory threshold after heating at 950 °C. Addition of fly ash did not show any improvement either in engineering property or in leachability of metals from the solidified mass. X-ray diffraction (XRD) analysis of the solidified product confirmed the presence of mixed phases of oxides of metals.\u
The influence of alumina particle reinforcement 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 Al2O3 particle dispersion over a range of sliding speeds and applied pressures. The matrix alloy has been examined under identical test conditions inorder 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, and thermal stability of various microconstituents. The nature of predominance of one set of parameters (causing higher wear rate) over the other (producing a reverse effect) was thought to actually control the wear behaviour. Examinations of the characteristic of wear 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 to increased microcracking tendency of the composite than the matrix alloy. Reduced wear rate and higher seizure pressure experienced by the composite over that of the matrix alloy at the higher sliding speeds could be explained to be due to enhanced compatibility of matrix alloy with dispersoid phase and greater thermal stability of the composite in view of the presence of the dispersoid. The maximum 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 trend reversed at higher speeds. In general, the wear rate and temperature increased with applied pressure and speed. Seizure pressure reduced with increasing speed while the seizure resistance(pressure) of the matrix alloy was more adversely affected by speed than that of the composite
A noble binder free and energy efficient process for making ceramic tiles using red mud and sericitic pyrophyllite
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Effect of operating variables on shape of “fish-hook” curves in cyclones.
No full textExperiments have been carried out in a hydrocyclone and a Vorsyl separator using fine magnetite particles (less than 75 μm sizes). Although at all the experimental conditions “fish-hook” has been observed, the shape of the curves is found to be different. Therefore, in this paper a set of new nomenclature has been proposed to quantify the differences in various shapes. An attempt has also been made to describe the effects of variables on the shapes of “fish-hook” in terms of the proposed nomenclature. At a given operating condition, it is also shown that the shape of a “fish-hook” remains unchanged
A Novel Process for Making Radiopaque Materials Using Bauxite-Red Mud
No full textRed mud, which is an aluminum industry waste, has been utilized1 for making X-ray radiation-shielding materials. A novel method for making radiation shielding materials utilizing red mud and barium compound has been developed by ceramic processing route using phosphate bonding. The red mud based shielding materials (RMSM) are characterized for their X-ray attenuation characteristics. The shielding, i.e. half value thickness (HVT) for different energies of X-ray photons for RMSM have been computed and compared with conventionally used shielding materials namely concrete and lead, it is found that the (HVT) of the red mud based shielding materials, in comparison to concrete, is significantly very less for the various energies of X-ray photons.\ud
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The X-ray powder diffraction studies confirmed the presence of celsian, bafertiste and iron titanium oxide as the major shielding phases in the RMSM. Scanning electron microphotographs have revealed the compacted and continued integrated morphological characteristics of the various shielding phases in the matrix of shielding materials. The mechanical properties namely compressive strength and impact strength evaluation test showed that RMSM meets the standard specifications laid down for radiation shielding concrete and ceramic tiles. Based on the above studies, it is found that RMSM, can preferably be used for the construction of X-ray diagnostic and CT scanner room to provide adequate shielding against X-ray photons
Graphite Modified Cotton Fibre Reinforced Polyester Composites under Sliding Wear Conditions
No full textGraphite modified polyester–cotton composites were developed and studied for friction and sliding wear behaviour at different applied loads and graphite concentrations. Sliding wear tests were conducted using pin-on-disc apparatus. The composite pins were tested against EN-31 steel disc. The specific wear rate of polyester reduced on reinforcement of cotton and on addition of graphite. The coefficient of friction of polyester resin increased on cotton reinforcement and reduced significantly on addition of graphite in cotton–polyester composite. The temperature of contact surface reduced on addition of graphite in cotton–polyester composite. The reduction in wear rate of graphite modified polyester–cotton composite has been discussed with the help of scanning electron microscope (SEM) observations of worn surfaces, coefficient of friction and the temperature of contact surface
Microstructure and Mechanical Properties of Al Alloy and Al Alloy - SiCp Composite Foam
No full textAluminum alloy A356 filled with silicon carbide hollow spheres (SiCHS) is investigated for quasi-static (10-3\ud
s\ud
-1\ud
) and high \ud
strain rate (up to 1520 s-1\ud
) compressive properties. Such closed cell composite foams, called syntactic foams, are of interest in weight \ud
sensitive structural applications. The present work is focused on understanding the compressive failure mechanism and relating them \ud
with the material microstructure. The compressive and plateau strengths of syntactic foams with SiCHS are found to be 163 and 110 \ud
MPa, respectively. The measured properties are considerably higher than the existing fly ash cenosphere filled aluminum matrix \ud
syntactic foams. Compressive failure mechanisms are studied for A356/SiCHS syntactic foams and direct evidence of hollow sphere \ud
crushing at the end of the elastic regions is obtained. The predictions of compressive strength obtained from an existing model are \ud
validated with the experimental results. Extensive analysis of data on open and closed cell foams containing gas porosity and syntactic \ud
foams is presented. A clear advantage in terms of low density and high yield strength is observed in A356/SiCHS syntactic foams \ud
compared to other foams. Yield strength of aluminum foams may be different at high strain rate compression compared to quasi-static \ud
values but most of the foams do not show strong evidence of strain rate sensitivity within the high strain rate regime. \u
Effect of SiCp Addition on Age-Hardening of Aluminium Composite and Closed Cell Aluminium Composite Foam
No full textThe age hardening behavior of solid Al-alloy–SiCp composite and closed cell Al-alloy–SiCp composite cellular materials has been examined and compared. The peak aging period of these materials were also compared with that of the solid unreinforced alloy. The effect of SiCp content on the peak aging time has been examined. It was found that the composite aged faster than the alloy irrespective of SiCp content, wherein peak aging time was invariant to SiCp content. On the other hand, while the closed cell composite foam reached a peak aged condition faster than the alloy when SiCp content was less than 10 wt%, further increases in SiCp content delayed the age-hardening kinetics