Advanced Materials and Processes Research Institute
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Optimisation of processing parameters 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
`Detoxification of aqueous Zinc using fluorapatite bearing rock phosphate’.\ud
No full textDetoxification of aqueous zinc was studied using the adsorption technique by application of fluorapatite bearing low grade phosphate as a sorbent. The effects of particle size of adsorbent, contact time, initial concentration of zinc and temperature on the adsorption process were studied. Initial rate of adsorption of zinc increases with time up to 30 min and thereafter it reaches equilibrium. Percent adsorption is adversely affected by increase in initial concentration of zinc and increase in particle size of sorbent. Adsorption processes follow first order kinetics and are found to be exothermic
A comparative study of corrosion behavior of Al/SiCp composite with cast iron.
No full textThe Erosion–corrosion behavior of a SiC particle reinforced Al–Si alloy has been studied in two different environments, namely saline and acidic, to simulate sea water and mining atmospheres, respectively. These studies were performed at different sand concentrations (20–40 wt%) and varying rotational speeds (700–900 rpm). It is noted from the present study that the composite exhibited better wear resistance than the alloy in marine and acidic atmospheres irrespective of sand content and speed. It is also noted that the wear rates increased with increasing sand content and speed irrespective of material due to increase in the severity of erosive/abrasive attacks. However, the wear rates decreased at higher speeds (e.g., 1100 rpm) due to increased intercollisions and rebounding and also the decrease in the mobility of the erodant particles. It is observed that erosion is the dominant mode of material removal in these two media. Corrosive attack was more predominant in the acidic media than in the NaCl media at lower sand concentrations (0–20 wt%). However, at higher sand concentrations (30–40 wt%) corrosive attack was more severe in the NaCl medium. Scanning electron microscopic (SEM) observation shows that Al/Si interfaces act as predominant sites for corrosion attack rather than the Al/SiC interfaces. Formation and removal of the passive layer, preferential attack at the Al/Si interfaces, fragmentation and wear of SiC particles were observed as mechanisms of material removal in marine and acidic media. SEM studies of the eroded–corroded surfaces indicated that an increase in the sand content of the slurry and in the rotational speed of the slurry increased resulted in greater damage to the SiC particles and matrix, resulting in an increase in wear rates
Influence of protective agents on metal induced respiratory distress in labeo rohita (Ham)
No full textThe short term effects of waterborne cadmium (Cd+2) on the levels of serum parameters related to bone metabolism including calcium (Ca), inorganic phosphorus (Pi) and alkaline phosphatase (ALP) in common carp fish (Cyprinus carpio L.) were studied. Fish were treated with varying concentrations of Cd+2 (0.22, 1.1 and 2.2 mg l−1) daily for 14 days. The results obtained show that serum Pi and ALP concentrations were elevated by increasing Cd+2 concentration in water containing fish whereas serum Ca level was decreased. At the same time, the protective role of waterborne zinc (Zn+2, 1 mg l−1) on the same parameters was also investigated. Results showing that daily treatment of fish with Zn+2, increased the concentrations of Ca and ALP in serum by 2.07 and 1.86 fold and decreased serum Pi level by 57.7% in comparison with Cd+2 treatment. The combination of Cd+2 and Zn+2 on the same parameters was studied next. There was a significant (P < 0.05) elevation in serum Ca and ALP levels in comparison with Cd+2 treatment. Decreasing in serum Pi level was not significant in comparison with Cd+2 treatments. The protective effect of Zn+2 on Cd+2 disturbances in serum parameters related to bone metabolism in this manuscript has been also discussed
Dry Sliding Wear Behaviour of an Aluminium Alloy-Granite Particle Composite
No full textIn the present study, the effect of granite reinforcement on the dry sliding wear behaviour of an aluminium–silicon alloy (BS:LM6) was investigated using a pin-on-disc machine. The composite was prepared using liquid metallurgy technique wherein 10 wt.% granite particles were incorporated in the matrix alloy. Sliding wear tests were conducted at applied loads in the range 0.2–1.6 MPa and speeds of 1.89, 3.96 and 5.55 m/s. The matrix alloy was also prepared and tested under identical conditions in order to see the influence of the dispersoid phase on wear behaviour. It was observed that the composite exhibited lower wear rate than that of the matrix alloy. Increasing applied load increased the wear rate. In the case of the composite, the wear rate decreased with speed except at higher pressures at the maximum speed; the trend reversed in the latter case. On the contrary, the matrix alloy exhibited minimum wear rate at the intermediate test speed. Seizure pressure of the composite was significantly higher than that of the matrix alloy, while temperature rise near the contacting surfaces and the coefficient of friction followed an opposite trend.\ud
SEM examination of the worn surfaces, subsurface regions and debris enabled to understand the operating wear mechanisms
Development of pyrophyllite based machinable ceramics.
No full textThe results of the studies on the effect of sintering temperature on machinability (cutting time and material weight loss) of pyrophyllite - sodium hexa metaphosphate system (90:10% w/w) are presented in the paper. The thermal behaviour of the composition was investigated using TGA. The % water absorption (w/w) and impact strength of the ceramic bodies sintered at different temperatures have also been evaluated. The phases formed at different temperatures of sintering were identified by X-ray diffraction method and have been correlated with the mechanical strength and machinability of the ceramic body. The SEM micrograph of the fractured surface shows the surface morphology indicating presence of micaceous phase in the ceramic body
evaluation of aqueous copper removal by adsorption on low grade phosphate mineral surface.
No full textDetoxification of Aqueous Zinc Using\ud Fluorapatite - Bearing Lean Grade Rock\ud Phosphate
No full textDetoxification of aqueous zinc was studied using the adsorption technique by application of fluorapatite bearing low grade phosphate as a sorbent. The effects of particle size of adsorbent, contact time, initial concentration of zinc and temperature on the adsorption process were studied. Initial rate of adsorption of zinc increases with time up to 30 min and thereafter it reaches equilibrium. Percent adsorption is adversely affected by increase in initial concentration of zinc and increase in particle size of sorbent. Adsorption processes follow first order kinetics and are found to be exothermi
Air gap thermally stimulated discharge current on unstretched and stretched polypropylene film thermoelectret
No full textEffect of Microstructure on the Sliding Wear Performance of a Zn-Al-Ni Alloy.
No full textSome observations pertaining to the sliding wear characteristics of a zinc–aluminium alloy containing nickel under varying material and test conditions have been reported in this investigation. Dry sliding wear tests were conducted on as-cast and heat-treated zinc-based alloy pins using a pin-on-disc machine. A steel disc was employed as the counterface. Sliding speeds adopted were 0.42, 2.68 and 4.60 mrs while the traversal distance was fixed at 500 m. Wear tests were conducted at different pressures using separate pins in each case. Seizure pressure of the pins �prior to traversing the sliding distance of 500 m. was determined at each speed. Wear rate and the extent of frictional heating increased with pressure and speed whereas seizure pressure practically followed a reverse trend. The wear rate versus pressure plot of the as-cast alloy pins assumed two slopes at the lowest speed wherein low slope\ud
�indicating the occurrence of mild wear situation. was noticed initially. This was followed by the attainment of a higher slope suggesting severe wear condition at increased pressures. At higher speeds, one slope only �identical to the higher slope at the minimum speed. was noted. Wear rate versus pressure plots of the heat-treated alloy pins followed a trend similar to the as-cast ones except that two slopes were noted up to the intermediate speed in the former case. Heat treatment changed the as-cast dendritic structure of the zinc-based alloy into the one with an improved uniformity of the distribution of various microconstituents, the nickel containing phase remaining practically unaffected. Softening of the �as-cast. alloy was also observed as a result of the heat treatment. However, in spite of reduced hardness, the heat-treated alloy pins attained improved wear behaviour �i.e. reduced frictional heating and low wear rate. over the as-cast ones irrespective of the test conditions. This was attributed to a more uniform distribution of microconstituents and reduced cracking tendency of the alloy as a result of the heat treatment. The alloy pins also attained better seizure pressure in heat-treated condition comparing with the as-cast ones at all the speeds except the maximum for the same reasons. A reversal in the trend at the maximum speed was thought to be due to the over-softening of the already\ud
softened �heat-treated. alloy pins under the influence of large frictional heat generated at the �maximum. speed. Under the circumstances, the heat-treated alloy pins tended to adhererfuse with the disc extensively while this tendency was relatively less for the as-cast ones in view of their higher hardness. Further, the extent of the negative influence of cracking tendency reduced allowing thermal stability to predominate the wear behaviour of the as-cast alloy pins in this case. The factor led to somewhat higher seizure pressure of the �as-cast. alloy pins at the maximum speed comparing with the heat-treated ones. Low wear rates correlated with less damage to the worn surfaces and to the regions below the worn surfaces and finer debris formation. Seizure led to severe damage to the worn surfaces and to the regions below the worn surfaces while the debris formed was quite bulky and coarser