IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Room temperature curable inorganic-organic hybrid nanocomposite hydrophobic coating: mechanistic understanding of the role of Ti(iv) and the diamine based curing agent
No full textRoom temperature (RT; 30 & PLUSMN; 5 & DEG;C) curable inorganic-organic hybrid nanocomposite single layered transparent hard hydrophobic coatings have been developed on ceramic tile and glass substrates by sol-gel spray coating using (3-glycidyloxypropyl) trimethoxysilane (GLYMO), tetraethylorthosilicate (TEOS), polydimethyl siloxane (PDMS) trimethylsiloxy terminated, and poly (propylene glycol) bis (2-aminopropyl ether) as a curing agent in the presence of titanium(iv) isopropoxide (TTIP). The role of Ti(iv) and the diamine based curing agent in epoxy ring breakage toward enhancement of polymerization reaction and facilitating hard hydrophobic coatings has been investigated through a proposed mechanism. The bonding characteristics of the polymeric network were confirmed by ATR-FTIR. The coated substrates showed good pencil hardness (5H) with hydrophobic (water contact angle, WCA, 104 & PLUSMN; 2 & DEG;) property. They exhibited good abrasion resistance, chemical durability, UV resistance and thermal shock resistance properties as evidenced from their WCA measurements. Nanoindentation measurements indicated an optimized effective hardness of 0.5162 & PLUSMN; 0.01 GPa and an elastic modulus of 6.73 & PLUSMN; 0.2 GPa at the load of 2 mN. The developed RT curable hard hydrophobic coating could find application in the fabrication of ceramic tiles for house-hold purposes as well as window glass for domestic uses and solar cover glass for efficient photovoltaic application
Biosensing by Polymer-Coated Etched Long-Period Fiber Gratings Working near Mode Transition and Turn-around Point
No full textA methodology to enhance the sensitivity of long-period fiber gratings (LPFGs) based on the combination of three different enhancement approaches is presented; the methods here adopted are the working near mode transition (MT) of a cladding mode (CM), working near the turn-around point of a CM and the enhancement of the evanescent field of CMs by reducing the cladding diameter or by increasing the order number of CMs. In order to combine these enhancement methodologies, an electrostatic self-assembly (ESA) process was used to deposit a polymeric overlay, with a chosen thickness, onto the etched fiber. The add-layer sensitivity of the sensor was theoretically calculated, and the demonstration of the real applicability of the developed LPFG as a biosensor was performed by means of an IgG/anti-IgG immunoassay in human serum in a thermostated microfluidic system. The limits of detection (LODs) calculated by following different procedures (three times the standard deviation of the blank and the mean value of the residuals) were 6.9 x 10(-8) & mu;g/mL and 4.5 x 10(-6) & mu;g/mL, respectively. The calculated LODs demonstrate the effectiveness of the applied methodology for sensitivity enhancement
Low Temperature Processing of Iron Oxide Nanoflakes from Red Mud Extract toward Favorable De-arsenification of Water
No full textIron oxide (Fe2O3) wassynthesizedfrom red mud extract followed by hydrothermal reaction at 150 & DEG;C/6-24h in the presence of NH4OH. The crystallinity of Fe2O3 increased with reaction time as confirmed byX-ray Diffraction, while Fourier transform infrared spectroscopy andRaman illustrate the symmetric stretching vibration of the Fe-Obond in Fe2O3. The X-ray photoelectronspectroscopic analysis shows O 1s spectra at 530.6, 531.2, and 532eV, signifying the lattice oxygen in Fe-O, surface oxygen defects,and oxygen in adsorbed hydroxyl groups, respectively. The morphologyof Fe2O3 nanoflakes was noticed fromfield emission scanning electron microscopy and transmission electronmicroscopy. The developed particles reveal the BET surface area inthe range of 136-347 m(2)/g. The maximum As(V) adsorptioncapacity of 32-41 mg/g was obtained for adsorbent dose of 0.25g/L. The arsenic level could be lowered down to 2-3 g/L(<10 g/L as per WHO's limit) with contaminated realwater (64 g/L) using 0.25 g/L of sample dose within 5 min of adsorption
Enhanced piezoelectric response in BTO NWs-PVDF composite through tuning of polar phase content
No full textWe have fabricated a flexible, environment friendly piezoelectric nanogenerator (PENG) based on the ferroelectric Polyvinylidene fluoride (PVDF) composite incorporated with Barium titanate (BaTiO3) nanowires (NWs) of piezoelectric coefficient d (33) = 308 pm V-1. The single-layered PENG can deliver output power density of 10 mu W cm(-2) and an output voltage of 2 V with a nominal mechanical load of 1 kPa. BaTiO3 (BTO) NWs of different concentrations were incorporated into PVDF to tune the polar phase content, internal resistance, and optimize the output power. We show that there exists a critical value of BTO NWs loading of 15 wt%, beyond which the piezoelectric energy harvesting characteristics of the PVDF nanocomposites decrease. The oxygen vacancies present in the BTO NWs surface attract the fluorine ions of PVDF chain and favour the formation of beta phase. The enhanced value of dielectric constant and dielectric loss of BTO-PVDF samples in the low frequency region suggest strong interfacial polarization in the composite system. The fabricated PENG can charge a super-capacitor up to 4 V within 35 s. The origin of the high power output from the BTO (15 wt%)-PVDF composite is attributed to the combined effect of enhanced polar phase content, strong interfacial polarization, and reduced internal resistance. This study provides an effective pathway in enhancing the performance of BTO-PVDF based piezoelectric energy harvesters
Influence of friction stir processing on microstructure, mechanical properties and corrosion behaviour of Mg-Zn-Dy alloy
No full textIn the present study, friction stir processing (FSP) was carried out on as-cast Mg-Zn-Dy alloy to tailor grain size and texture which alter the mechanical properties and corrosion behaviour. The grain size of the as-cast alloy was reduced from 60 +/- 2 mu m to 3 +/- 0.1 mu m after FSP due to dynamic recrystallization. The effect of grain size, crystallographic orientation and fine precipitates on mechanical properties were investigated using field emission scanning electron microscope (FESEM) and electron back scattered diffraction (EBSD). The ultimate tensile strength, yield strength, % elongation and hardness of FSPed alloy improved by 55%, 60%, 53% and 46% when compared to as-cast alloy. The FSPed Mg-Zn-Dy alloy exhibited a 79% decrease in corrosion rate when compared to as-cast alloy which can be attributed to grain refinement, uniform distribution of secondary precipitates and strong basal texture. The surface of FSPed sample after immersion corrosion exhibited calcium phosphate rich minerals which help in apatite formation on the sample surface. Cytotoxicity studies using MTT assay revealed more than 80% cell viability for both as-cast and FSPed alloy illustrating non-toxic nature of both the samples. The results of this study indicate that FSPed Mg-Zn-Dy alloy is a potential material for biodegradable implants due to its high strength, corrosion resistance and biocompatibility
Patient-specific femoral implant design using metamaterials for improving load transfer at proximal-lateral region of the femur
No full textLoading configuration of hip joint creates resultant bending effect on femoral implants. So, the lateral side of femoral implant which is under tension retracts from peri-implant bone due to positive Poisson's ratio. This retraction of implant leads to load shielding and gap opening in proximal-lateral region, thereby allowing entry of wear particle to implant-bone interface. Retraction of femoral implant can be avoided by introducing auxetic metamaterial to the retracting side. This allows the implant to push peri-implant bone under tensile condition by virtue of their auxetic (negative Poisson's ratio) nature. To develop such implants, a patient-specific conventional solid implant was first designed based on computed-tomography scan of a patient's femur. Two types of met-amaterials (2D: type-1) and (3D: type-2) were employed to design femoral meta-implants. Type-1 and type-2 meta-implants were fabricated using metallic 3D printing method and mechanical compression testing was conducted. Three finite element (FE) models of the femur implanted with solid implant, type-1 meta-implant and type-2 meta-implant were developed and analysed under compression loading. Significant correlation (R2 = 0.9821 and R2 = 0.9977) was found between the experimental and FE predicted strains of the two meta-implants. In proximal-lateral region of the femur, an increase of 7.1% and 44.1% von-Mises strain was observed when implanted with type-1 and type-2 meta-implant over the solid implant. In this region, bone remodelling analysis revealed 2.5% bone resorption in case of solid implant. While bone apposition of 0.5% and 7.7% was observed in case of type-1 and type-2 meta-implants, respectively. The results of this study indicates that concept of intro-duction of metamaterial to the lateral side of femoral implant can prove to provide higher osseointegration-friendly environment in the proximal-lateral region of femur
Investigation of the Topside Ionosphere over Cyprus and Russia Using Swarm Data
Get PDFUsing the topside electron density (Ne) measurements recorded over Cyprus and Russia, we investigate the latitudinal variation in the topside electron density during the interval 2014-2020, encompassing a period of high-to-low solar activity. The selected topside electron density dataset employed in this study is based on the in situ Langmuir probe data on board the European Space Agency (ESA) Swarm satellites, in the vicinity of the three Digisonde stations in Nicosia (35.14 degrees N, 33.2 degrees E), Moscow (55.5 degrees N, 37.3 degrees E) and Saint Petersburg (60.0 degrees N, 30.7 degrees E). Our investigation demonstrates that the ratio Ne_(Swarm)/NmF2 between the coincident Ne_(Swarm) and the Digisonde NmF2 observations is higher than one on various occasions over Nicosia during the nighttime, which is not the case over Moscow and Saint Petersburg, signifying a discrepancy feature of the electron density at Swarm altitudes which depends not only on the solar activity and time of day but also on the latitude
La-doped LiMnPO4/C cathode material for Lithium-ion battery
No full textLiMnPO4 and LiMn1-xLaxPO4 (0.01 <= x <= 0.1) nanostructures with in-situ carbon coating are synthesized by low temperature solvothermal method using Glycerol: Water (2:1) ratio as solvent. Powder X-ray diffraction (XRD) studies confirmed the orthorhombic crystal structure of LiMnPO4 and LiMn0.99La0.01PO4. X-ray diffraction shows that up to 1% La3+ ion doping into manganese sites does not affect the crystal structure of LiMnPO4. Field emission scanning electron microscopy (FESEM) of LiMnPO4 and LiMn0.99La0.01PO4 depicts the formation of nanosized particles with spherical morphology. Electrochemical properties of LiMnPO4 and LiMn0.99La0.01PO4 are investigated by galvanostatic charge discharge tests. The present studies show that 1% La3+ ion doped LiMnPO4 could be a promising cathode material that can improve the performance of Lithium-ion cell by increasing the electrochemical stability at higher C-rate.(c) 2023 Elsevier Ltd. All rights reserved
Oxidation and Hot Corrosion Behavior of Thermal Barrier Coatings-A Brief Review
No full textOxidation and hot corrosion occur on metallic parts of gas turbines on account of exposure to high temperature. Thermal barrier coatings (TBCs) are used to protect gas turbine components made of Ni-based superalloys from high temperature oxidation as well as hot corrosion. The stability of coated metallic gas turbine components is higher than that of non-coated ones. Suitable coating is crucial for obtaining higher turbine inlet temperature. However, the problem of conventional TBC system is the failure of yittria-stabilized zirconia (YSZ) top coat due to formation of thermally grown oxide (TGO) layer between the bond coat and YSZ top coat. The TGO formation should be properly controlled in order to prevent the spallation of the top coat. In the current review paper, an attempt has been made to focus oxidation and hot corrosion behavior of conventional thermal barrier coatings applied on gas turbine components for increasing the efficiency of gas turbines
Thermally stable bioactive borosilicate glasses: Composition-structure-property correlations
No full textProcessing of commercial bioactive glasses in the form of scaffolds, fibers and coatings on metal implants is a major challenge due to their high crystallization tendency leading to loss of many desirable functionalities relevant to bone tissue engineering applications. In this context, this work focuses on developing borosilicate bioactive glasses with improved thermal stability from the detailed understanding of composition-structure-property correlations. Structural studies through Raman and magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy revealed the formation of a highly crosslinked network rich in B-O-Si bonds facilitating enhanced thermal stability (> 150 ?) for 17.96-35.92 mol% B2O3 containing glasses. These glasses also exhibit substantially improved in vitro biological properties such as biomineralization, cell proliferation, alkaline phosphatase (ALP) expression and antibacterial efficacy owing to predominance of B-O-Si and B-O-B bonds. However, more detailed data with pre-clinical studies are needed to confirm these observations, and for using them for specific applications