Advanced Materials and Processes Research Institute
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Adsorption of cyanide from aqueous solutions at pyrophyllite surface
No full textThe adsorption of cyanide from aqueous solutions at pyrophyllite mineral surface has been studied by investigating the effect of initial concentration of adsorbate, amount of adsorbent, pH and temperature of test solutions. The adsorption efficiency is observed to be 99% in dilute solutions but decreases down to 40% with increase in cyanide concentration to 10 ppm. The adsorption is observed to be maximum from neutral solutions and is observed to increase with increase in temperature. The adsorption data have been fitted in Langmuir and Freundlich isotherms and the adsorption has been found to be endothermic in nature in the temperature range 30–60°
Optimization of processing para- meters for making pyrophyllite based ceramic tiles using di-sodium hydrogen phosphate binder
No full textThe processing parameters for making tiles using pyrophyllite with di-sodium hydrogen phosphate binder have been optimised. Infrared studies on sintered tiles prepared under optimised conditions indicate the presence of Si–O linkages and the formation of AlPO4. Using X-ray powder diffraction the various phases formed during sintering were identified as the tridymite form of aluminium phosphate (T-AlPO4), dehydroxylated pyrophyllite, and sodium silicate. Thermal changes taking place during sintering were studied using thermal analysis. Scanning electron micrographs revealed the presence of acicular T-AlPO4 crystals and dehydroxylated pyrophyllite with platelet morphology
Three-body abrasive wear mechanism for laser irradiated chopped glass fiber reinforced polyester composites.
No full textSurface microfibrillation of cellulose fibre was adopted as a facile method for improving cellulose fibre/phenolic resin interfacial adhesion in hybrid composites composed of sisal fibre and aramid fibre. Development of microfibrils and aggregates on the fibre surface significantly increased the interfacial adhesion between the sisal fibre and resin by providing a large contact area and by inhibiting the formation of spontaneous cracks in the composites. Consequently, the compression, tensile and internal bonding strengths, and wear resistance of the hybrid composites were remarkably improved. Surface microfibrillation of sisal fibre to a DM value of 24 °SR increased the tensile strength, internal bonding strength and wear resistance values of composites by 93%, 124% and 31%, respectively
Steady shear flow properties of organic fiber reinforced LLDPE
No full textThis paper reports the results of studies on the effect of aspect ratio of multiwall carbon nanotubes (CNT) on the shear and extensional rheological behavior of low density polyethylene (LDPE) nanocomposites. Up to a CNT loading of 2 wt%, as used in the present study, the shear rheological data suggest no network formation in the nanocomposites, irrespective of the aspect ratio of the nano filler. Dynamic shear viscosity η' increases with increase in loading and aspect ratio of CNT. However, at low CNT loadings (0.1 wt%) and with CNT of high aspect ratio, h. for the nanocomposites is found to be lower than that of neat polymer. Steady shear rheology results show negative values for the normal stress for the high aspect ratio CNT which is believed to be due to the tumbling of CNT with high aspect ratio. Results of extensional viscosity measurements show that extent of strain hardening is dependent on the CNT aspect ratio and follows the order, high aspect ratio > medium aspect ratio > short aspect ratio, while the time of break follows the reverse order. The effect of aspect ratio on critical extensional stress becomes prominent only at the high aspect ratio, but the stress increases with the increase in CNT loading, irrespective of the aspect ratio
Erosion- corrosion- abrasion characteristics in slurry of a zinc based alloy and its composite containing alumina particle dispersoid.
No full textThis study presents observations made pertaining to the slurry wear behaviour of a zinc based alloy and its composite containing dispersed alumina particles. The influence of varying the sand concentration in the medium and the traversal distance on the response of the specimens has also been investigated. Wear rate increased initially with traversal sliding distance, attained a peak, and then decreased thereafter at longer traversal distances. This trend was much more pronounced when tests were conducted in a liquid only medium than in liquid with sand. The presence of suspended sand particles in the test environment led to a considerably reduced wear rate of the specimens when compared with that of the liquid only medium. Furthermore, intermediate sand content caused the maximum wear rate within the slurries, although it was substantially less than that caused by the liquid only medium. A comparison of the wear response of the composite and the matrix alloy suggested a mixed trend in the liquid only medium and the slurry with 60 wt- sand. The composite exhibited a lower wear rate than the matrix alloy when tested in slurries with 20 and 40 wt- suspended sand particles. The observed wear response of the specimens has been discussed in terms of specific characteristics, such as susceptibility to corrosion and hardness of various phases, and the interfacial effects in the specimens. The changing nature of the medium, such as the corrosivity and impingingabrading efficiency, has also been discussed. Analysis of the affected surfaces and subsurface regions of typical specimens by SEM enabled the understanding of the operating wear mechanisms under specific test conditions and thereby it was possible to substantiate the observed wear characteristics of the specimens
Silicon nitride/SIAION ceramics - A review
No full textAdvanced ceramic materials such as Si3N4 and SiAlON are reviewed here with particular reference to their synthesis, properties, and applications in various sectors such as transport and defense. It is noticed that synthesis by the simultaneous carbothermic reduction and nitridation (CTR) is relatively easy and economical. The products thus obtained by CTR, have unusual combination of unique properties, viz., high strength at higher temperature, chemical inertness, wear resistance, etc. , and therefore they are very much useful in high-tech areas. In addition, some of the leading manufacturers of Si3N4/SiAlON are listed in this paper. Ceramic whisker growth mechanism and its importance in improving the mechanical properties of ceramic matrix composites (CMCs) are also discussed. This paper is mainly intended to cover important properties like structural, mechanical, oxidation/corrosion and wear resistance of Si3N4 and SiAlON
Two-body abrasion of a cast Al-Cu (2014 Al) alloy - Al2O3 particle composite : influence of heat treatment and abrasion test parameters.
No full textAn Al–Cu (2014 Al) alloy reinforced with 10 vol.% Al2O3 particles (size: 75–150 μm), prepared by liquid metallurgy route, has been investigated under two-body (high stress) abrasive wear condition. The influence of varying load, abrasive size and sliding distance on the abrasive wear behaviour of the specimens was also studied. The base alloy prepared under similar condition has also been studied under identical test conditions in order to understand the influence of the dispersoid phase on the abrasive wear characteristics of the (base) alloy. In order to assess the role of matrix microstructure, the composite as well as the base alloy was subjected to abrasion in heat treated as well as in cast conditions.\ud
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The results indicate that the Al2O3 particle reinforced cast Al alloy composite was more wear resistant (less wear rate) than the (unreinforced) matrix alloy when tested against 20, 35 and 60 μm size abrasive particles over the entire range of loads and sliding distances due to protection provided by the Al2O3 particles to the alloy matrix. On the other hand, a reverse trend was observed when 100 μm size abrasive particle was used as the abrasive medium above 1 N load due to greater microcracking tendency followed by fragmentation of dispersoid/abrasive particles. Unlike cast composite, heat treated composite exhibited better wear resistance (lesser wear rate) than the matrix alloy even when the tests were conducted against 100 μm size abrasive particles over the entire range of loads and sliding distances. Matrix strengthening and the morphological changes of the precipitate particles caused lower wear rate of the heat treated base alloy and composite over the cast ones. Abrasive wear rates were observed to decrease with sliding distance because of the increased extent of clogging, capping, shelling and attrition of the abrasive particles as well as subsurface hardening of the matrix.\ud
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The wear behaviour of the specimens has been explained in terms of wear-induced subsurface work hardening, protection provided by the reinforced particles (in the case of composite) and degradation of the abrasive. Material removal mechanisms have also been studied through the examination of wear surfaces, subsurfaces, debris and abrasive particles
Erosion-Corrosion-Abrasion Characteristics of a Zinc-Based Alloy and Its Composite Containing Alumina Particle Dispersoid
No full textThree Body Abrasion of a Zinc-Aluminium Alloy: Effects of Alumina Dispersoid and Abrasive Medium
No full textThree-body abrasive wear characteristics of a cast zinc–aluminium alloy—10 wt.% alumina particle composite have been analysed in the present investigation. Silicon carbide, sand and zircon particles were used as the abrasive media. In order to see the influence of alumina dispersoid particles on the abrasive wear behaviour, the similarly processed matrix alloy was also tested under identical conditions.\ud
The composite exhibited less wear rate than the matrix alloy irrespective of the test conditions. This was attributed to the wear resistance offered by the hard dispersoid phase, thereby protecting the softer matrix. Further, the SiC abrasive caused maximum wear rate while the specimens experienced the minimum when abraded against zircon particles; sand particles led to intermediate wear response.Wear rate of the samples decreased progressively with distance until a steady-state value was attained. Abrasion-induced work hardening was thought to be responsible for the decreasing wear rate with distance. Increased hardness of the (subsurface) regions as compared to that of the bulk also supported the view. Further, the rate of reduction in wear rate with distance was relatively more for the matrix alloy than the composite. This behaviour was more clearly visible and, at the same time, the extent of reduction in the wear rate with distance was maximum in the case of the SiC abrasive. Sand was observed to be more damaging than zircon despite its less hardness (than the latter). This could be owing to the sharp/angular shape of the sand abrasive in comparison to the round shaped zircon particles suggesting the predominant effect of the particle shape over the hardness of the abrasive. More severe loading conditions led to larger wear rates because of the greater depth of cut and more surface/subsurface damage. Observed wear response of the samples has been supplemented with the features of wear surfaces and subsurface regions. The latter also enabled an understanding of the operating wear mechanisms