IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Correction to: "Illite crystallinity index from the Mesoproterozoic sedimentary cover of the Kaladgi basin, southwestern India: Implications on crustal depths of subsidence and deformation" (vol 128, pg 101, 2019)
Get PDFPerformance investigation of Pb(II) removal by synthesized hydroxyapatite based ceramic ultrafiltration membrane: Bench scale study
No full textIn this study, a low pressure novel ultrafiltration membrane has been developed using synthesized hydroxyapatite nanoparticle over low cost clay-alumina based porous ceramic substrate with multichannel configuration. The nanoparticles and membrane were characterized by FESEM, EDX, XRD, BET, FTIR analyses. The FESEM and EDX images revealed a crack free uniform hydroxyapatite coating layer over porous support with maximum presence of Ca and P at top of the active layer compared to other ceramic elements. The nominal pore size of the membrane was measured as 2.8 nm (BET analysis). Bench scale membrane separation process was performed for the removal of toxic Pb(II) from spiked aqueous solution using 500 mm long synthesized hydroxyapatite ceramic membrane. The clean water permeability and the flux were 79.8 L m(-2)h(-1) bar(-1) and 28.4 L m(-2)h(-1) (at 0.5 bar pressure), respectively. The developed membrane showed 99.6% rejections of Pb(II) from 5 mg L-1 solutions at 1 bar pressure. Furthermore, pH effect on rejection efficiency was also studied and it demonstrated maximum rejections at pH 7.4. The probable mechanism of high rejection was established by XPS analysis as complexation reaction. The membrane was regenerated and subsequently reused. However, this study highlights on designing, fabrication and performance evaluation of novel hydroxyapatite clay-alumina ceramic ultrafiltration membrane in bench scale via simple method that can be potentially applied for industrial purposes
Possible mechanisms for degradation of photo induced micro actuation effect in a ferromagnetic shape memory alloy at high temperatures
No full textFerromagnetic shape memory alloys (FSMAs) have been in active research nowadays for their unique properties of responses to both temperature changes and external magnetic fields. Recently, one such material, a CoNiAl based system, showed a photoinduced microactuation (PIMA) effect in which an incident spot of a tiny laser beam could induce actuation in these systems. This is unparalleled in ordinary materials, and its real cause is yet to be found. However, we tried to still use it in real world engineering applications, and for that, the limitations on its usability should be found. With this idea, we studied here in detail the effect of continuous degradation of the PIMA effect on a ribbon sample through TEM, as it was exposed to higher temperatures from room temperature. While the as-spun alloy had microstructured B2 ordered (Ni, Co)-Al micrometer sized grains embedded in a continuous L1(2) ordered cobalt-rich matrix channel, at 400 degrees C where the PIMA effect was fully destroyed, Co-rich nanosized precipitates were found to have formed inside the B2 grains, the actual FSMA component in the sample, and these are also found to have been oxidized. Concurrent oxidation studies showed the formation of an irregular shaped composite oxide layer with a thickness of about several hundred nanometers at the top surface. These are possibly the reasons behind the hindrance in the actuating motion. This was corroborated by magnetic studies also. Published under license by AIP Publishing
Ultra-thin multilayered erosion resistant Ti/TiN coatings with stress absorbing layers
No full textIn this high speed era, several machine components are operated at high speeds and at high temperatures. Machine components such as gas turbine compressor blades and vanes are exposed to high speed dust particles. Consequently, engine performance deteriorates and in extreme cases catastrophic accidents can happen. In order to protect these engine components, ultra-thin multilayered erosion resistant Ti/TiN coatings (thickness similar to 9-10 mu m) with stress absorbing layers were developed using magnetron sputtering. Stress absorbing metallic layers were introduced to control the internal stress and also to maintain balanced ductile and brittle nature of the coating. Ultra-thin (3-4 nm) metal/ceramic bilayers provided high number of interfaces and ultra-small grain sizes. Erosion resistance performance of the developed coatings and also bare Ti6Al4V substrates was tested according to the ASTM-G76-13 standard at 400 degrees C. Tests were conducted with three different erodent speeds of 30, 60 and 100 m/s at four different impinging angles 90 degrees, 60 degrees, 45 degrees and 30 degrees. The average erosion rate ratios between Ti6Al4V substrate and optimized coating were 74, 13 and 12 for the erodent speeds of 30, 60 and 100 m/s, respectively. Influence of the substrate on the coating performance was also studied. Morphological, elemental and spectral analyses of the erosion scar were also probed. Structural stability, mechanical properties and erosion resistance performance of the optimized film were tested after 100 h annealing in air and vacuum at a temperature of 400 degrees C. Erosion resistant performance of the optimized film was unaffected after 100 h annealing
Investigation on synthesis of cordierite bonded porous SiC ceramics with emphasis on bond phase formation
No full textCordierite-bonded porous SiC ceramics were synthesized from SiC, Al2O3 and MgO powders with varying petroleum coke (PC) as the sacrificial pore former. To trace the path of development of the oxide binder phase and mechanistic steps of oxidation reaction of a PC pore former powder, thermal analysis (up to 1400 degrees C in air) of the precursor powders was studied with non-isothermal method varying different heating rates. The results indicated the transformation of cordierite binder phase and the average activation energy was determined to be 840 +/- 27 kJ mol(-1). The formation of the oxide binder phase (cristobalite (24-31 wt%) and cordierite (21-28 wt%)) and pore phase (porosity of 30-67 vol% and average pore size of 3-36 mu m) were further analysed by conducting X-ray diffraction test, chemical analysis and microstructure examination for better understanding the formation of the pore phase and the binder phases of the ceramics for its applicability in the field of porous media at hostile conditions
Effect of ZrO2 on the densification behavior and properties of Indian magnesite
No full textNatural magnesite is the primary source for magnesia-based refractory materials. India has vast deposits of magnesite in Salem and Almora regions. However, due to the presence of large amount of impurities which forms low-melting compounds at elevated temperature, its high-temperature application is restricted. Raw magnesite was evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, and phase assemblage. Zirconia (1-5 wt %) was added to Indian natural magnesite of Salem region to minimize the low-melting phase formation at high temperatures. Samples were sintered in the temperature range of 1550-1700 degrees C. Sintered samples were characterized in terms of densification, mechanical and thermo-mechanical properties, phase assemblage, and microstructure. It was found that the addition of zirconia reduced the formation of detrimental phases like monticellite and thereby improved the high-temperature mechanical properties
Use of high temperature X-ray diffraction and pair distribution function for the study of carbonation characteristics of Barium Titanate at nanoscale
No full textBarium titanate (BT) is extensively used in electronic industries for its high dielectric constant. However, the dielectric properties of BT significantly change due to carbonation at nanoscale. Commercially available tetragonal BT powder was milled to study the local atomic distribution and phase transformation behaviour with temperature. Nano BT powder was prepared by the high energy ball milling (90 h) from its bulk counterpart. It was carbonated when it was exposed to open atmosphere. The milled BT sample was characterised by high temperature X-ray diffraction (HT-XRD), pair distribution function (PDF) and transmission electron microscope (TEM). Local atomic distribution was obtained from PDF analysis. The peak due to C-O and Ba-C pair distance were observed from PDF for 90 h milled carbonated BT. TEM analysis revealed that particle diameter was in the range of 15-50 nm. How the phase of nano BT ceramics transformed with temperature was strudied. It was observed that orthorhombic BT transformed into tetragonal and cubic phase via the monoclinic phase during heating at 900 degrees C. Coexistence of multi phases of BT was also observed from HT-XRD. BaCO3 disappeared at high temperature
Potential of growth factor incorporated mesoporous bioactive glass for in vivo bone regeneration
No full textMesoporous bioactive glass (MBG) has drawn much attention due to its superior surface texture, porosity and bioactive characteristics. Aim of the present study is to synthesize MBG using different surfactants, viz., hexadecyltrimethylamonium(CTAB) (M1), poly-ethylene glycol (PEG) (M2) and pluronic P123 (M3); bioactivity study; and to understand their bone regeneration efficacy in combination with insulin-like growth factors (IGF-1) in animal bone defect model. SBF study revealed the formation of calcium carbonate (CaCO 3 ) and hydroxyapatite (HAp) phase over 14 days. Formation of apatite layer was further confirmed by FTIR, FESEM and EDX analysis. M1 and M2 showed improved crystallinity, while M3 showed slightly decrease in crystalline peak of CaCO3 and enhanced HAp phase. More Ca-P layer formed in M1 and M2 supported the in vivo experiments subsequently. Degree of new bone formation for all MBGs were high, i.e., M1 (80.7 +/- 2.9%), M2 (74.4 +/- 2.4%) and M3 (70.1 +/- 1.9%) compared to BG (66.9 +/- 1.8%). In vivo results indicated that the materials were non-toxic, biodegradable, biocompatible, and is suitable as bone replacement materials. Thus, we concluded that growth factor loaded MBG is a promising candidate for bone tissue engineering application
Micro pop-in issues in nanoindentation behaviour of 10 ZTA ceramics
No full textHere we report for the very first time, the detailed mechanisms of the formation of `micro pop-in' events observed during nanoindentation at 10-1000 mN load in a 10 ZTA (i.e., 10 vol% zirconia toughened alumina) ceramic. Explicit analysis of the experimental results backed up by comprehensive Field Emission Scanning Electron Microscopy (FESEM) based evidences suggests that the maximum shear stress (tau(max)) generated underneath the nanoindenter, the formations of shear bands and localized microcrackings play significant role in the initiation of nanoscale plastic events in the present ZTA ceramic
Immobilization of tannery industrial sludge in ceramic membrane preparation and hydrophobic surface modification for application in atrazine remediation from water
No full textChromium laden waste produced from tannery industry was immobilized in ceramic matrix for fabrication of the tubular single channel microfiltration membranes by extrusion. The presence of chromia resulted in substitutional solid solution formation with alumina and catalyzed mullite phase growth, hence increasing the mechanical and chemical stability of the membranes. The structural, morphological and water permeation characteristics of the membranes were studied to analyze their formation mechanism and effect of different parameters, viz. the sintering temperature, amount of waste added, presence of organics and extent of chromium immobilization. The surface of the macroporous membrane was hydrophobically modified, by polydimethylsiloxane (PDMS), producing contact angle of 141 degrees. The process efficiency of the hydrophobic membrane was assessed in terms of the removal of atrazine, a contaminant of emerging concern, following the principle of hydrophobic interaction. Effect of different operating parameters affecting atrazine removal, viz. transmembrane pressure, cross flow velocity and filtration time was studied in cross flow filtration mode. High atrazine removal of >95% was obtained along with the maintenance of high flux during the filtration operation. The prepared cost-effective microfiltration membranes can thus be further modified for efficient water treatment applications