IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Facile fabrication of fluorine free zirconium zinc stearate based superhydrophobic and superoleophilic coating on cotton fabric with superior antibacterial property
No full textA simple solution technique has been adopted to fabricate in situ generated zirconium zinc stearate based superhydrophobic and superoleophilic fluorine-free coating on cotton fabric with superior antibacterial and excellent photocatalytic properties. The materials properties of the specimen such as crystallinity/crystal phase, chemical bonding, surface morphology, and surface roughness have been characterized systematically. The coated cotton derived from an optimized precursor composition shows the retention of superhydrophobicity with static water contact angle \~163 degrees after several cycles of machine laundering and mechanical abrasion. It is seen that zirconium species may have caused an enhancement in laundering durability and mechanical robustness while hierarchical morphology of zinc stearate is responsible for acquiring superior antibacterial property along with self cleaning ability of the coating to make the coated fabric promising for real life application such as military uniform, biomedical clothing/devices. In addition, the coated cotton is found to be suitable for separation of oil from oil-water mixtures with high efficiency (\~99%) even after 10 cycles of repeated use. Thus, the material can be used for separation of oil from oil-contaminated industrial wastewater/marine water. Moreover, AgBr modified superhydrophobic cotton fabric shows excellent photocatalytic activity towards degradation of organic dye. This facile process can be up-scaled for commercial u
Recycling of coal fly ash for fabrication of elongated mullite rod bonded porous SiC ceramic membrane and its application in filtration
No full textMullite bonded SiC ceramic membranes were synthesized by a facile solid-state reaction process, using SiC, solid waste fly ash as raw materials and MoO3 as catalyst for growth of mullite at 1000 degrees C. The effect of MoO3 catalyst on mullitization reaction and mullite morphology was investigated. Different pore formers were used to enhance the porosity and to observe its effects on the permeability parameters and filtration characteristics. At room temperature Darcian (k(1)) and non-Darcian (k(2)) in both water and air flow were measured and clean water flux was determined. The porous SiC ceramics with addition of 5 wt.% MoO3 exhibited a flexural strength of 38.4 MPa at porosity 36.4 vol% and showed 92% oil removal efficiericy from oily wastewater. This technique, combining low-cost materials and the co-sintering at low temperature, can serve as a cost-effective method for the production of high-performance porous SiC ceramic membrnaes for filtration application
Crystallization and magnetic hardening behaviour of Fe-rich FeSiBNb(Cu) melt-spun alloys
No full textThe sequential, multi-stage crystallization and magnetic hardening behaviour of Fe82B14Si2Nb2, Fe83B13Si2Nb2, Fe83B12Si2Nb2Cu1 and Fe85B13Nb2 melt-spun alloys have been investigated. The microstructure-crystallization-magnetic property relationship was established using X-ray diffractometry (XRD), differential scanning calorimetry (DSC), magnetometry, transmission electron microscopy (TEM) and magneto-optical Kerr effect microscopy (MOKE) techniques. The increase of Fe content (> 82 at%) of as-quenched ribbons imparts microstructural heterogeneity across the ribbon cross-section; i.e., textured alpha-Fe crystals at the free surface to heteroamorphous microstructure in the bulk matrix. The isochronal annealing of hetero-amorphous alloys depicts simultaneous surface and bulk crystallization process occurring before and after the crystallization onset temperature (T-x1) temperature. The annealing temperature range (T-a < T-x1) coinciding with the paramagnetic region of the thermo-magnetic plot, induces irreversible magnetic hardening due to simultaneous coarsening of pre-existing crystal nuclei and exchange de-coupling between nanocrystal and intergranular matrix. The onset of primary crystallization in the pre-crystallized ribbons results in bimodal nanocrystallite distribution having an average crystallite size exceeding the ferromagnetic exchange length of Fe-based alloys. The minor Cu addition alters the growth morphology of pre-existing nuclei from dendrite-like to equiaxed, assisting heterogeneous nucleation and improving intergranular amorphous stability by delaying boride precipitation. The soft-magnetic property deterioration of partially crystallized ribbons is discussed within the framework of Extended-Random Anisotropy models
Q-switched Zirconia-Yttria-Aluminium-Erbium-doped pulsed fiber laser with a pencil-core of graphene as saturable absorber
No full textA flexible and controllable Q-switched using Zirconia-Yttria-Aluminium-Erbium-doped silica fibre as an active gain medium with pencil-core of graphene as saturable absorber (SA) was demonstrated. The zirconia fibre was fabricated using the modified chemical vapour deposition (MCVD) method, whereas the SA was fabricated using a simple and fast preparation of mechanical exfoliation technique from a pencil core of graphene material. At a maximum pump power of 121.5 mW, the repetition rate, pulse duration, signal-to-noise ratio and pulsed energy were 20 kHz, 0.011 mu s, 56 dB and 78.1 nJ, respectively
Project MoC project titled “Development of indigenous process technology for the production of chalocogenide based infrared glasses for thermal imagers”
No full textSpark plasma-sintered MoSi2-reinforced Y-alpha-SiAlON ceramics: mechanical and high temperature tribological properties
No full textSilicon aluminum oxy-nitride commonly abbreviated as SiAlON is indeed one of the most promising non-oxide engineering ceramics due to its ease of formation compared to extremely covalent silicon nitride ceramic and scope of tailoring the material properties as per application demand. To make it more suitable for high-performance applications, composites containing various secondary phases have been attempted so far to improve the mechanical performance over its monolithic counterpart. In the present work, reinforcement of particulate molybdenum disilicide (MoSi2) in Y-alpha-SiAlON matrix has been undertaken under spark plasma sintering (1750 degrees C, 10 min, 50 MPa die pressure) followed by Vickers hardness (HV), fracture toughness (K-IC), and high-temperature tribological properties under different conditions of the formed composites containing 10 and 20 wt.% secondary phase were investigated. Sintered specimens were >= 97.5% dense with negligible porosity. Addition of MoSi2 in Y-alpha-SiAlON resulted in reduced HV. The 20 wt.% MoSi2/Y-alpha-SiAlON composite showed similar to 11% lower HV1 compared to the monolith. On the contrary, K-IC of the 20 wt.% MoSi2/Y-alpha-SiAlON composite was found to be around 24% higher compared to pure Y-alpha-SiAlON (K-IC approximate to 3.9 MPa-m(0.5)). Additional fracture energy dissipation through crack deflection and bridging by the dispersed MoSi2 particulates was the primary reason behind obtaining higher fracture toughness for the composites. Unlubricated reciprocating ball-on-disc experiments against dense silicon nitride ball revealed a significant effect of MoSi2 oxidation in achieving improved wear resistance of the composites over the monolith, especially, beyond 300 degrees C in ambient air under applied normal loads up to 90 N and sliding distance up to 70 m
Estimating Powder-Polymer Material Properties Used in Design for Metal Fused Filament Fabrication (DfMF(3))
No full textMetal fused filament fabrication (MF3) combines fused filament fabrication and sintering processes to fabricate complex metal components. In MF3, powder-polymer mixtures are printed to produce green parts that are subsequently debound and sintered. In the design for MF3 (DfMF(3)), it is important to understand how material properties of the filament affect processability, part quality, and ensuing properties. However, the materials property database of powder-polymer materials to perform DfMF(3) simulations is very limited, and experimental measurements can be expensive and time-consuming. This work investigates models that can predict the powder-polymer material properties that are required as input parameters for simulating the MF3 using the Digimat-AM process design platform for fused filament fabrication. Ti-6Al-4V alloy (56-60 vol.%) and a multicomponent polymer binder were used to predict properties such as density, specific heat, thermal conductivity, Young's modulus, and viscosity. The estimated material properties were used to conduct DfMF(3) simulations to understand material-processing-geometry interactions
Impact of raw material surface oxide removal on dual band infrared optical properties of As2Se3 chalcogenide glass
Get PDFThe manufacturing of low loss chalcogenide glasses (ChGs) for optoelectronic applications is ultimately defined by the concentration of impurities present in starting materials or imparted via processing. We describe a rapid method for purifying metallic starting materials in As2Se3 glass where oxide reduction is correlated to optical and physical properties. Specifically, As-O reduction enhances the glass' dual-band optical transparency proportional to the extent (13-fold reduction) of oxide reduction, and is accompanied by a change in density and hardness associated with changes in matrix bonding. A significant modification of the glass' index and LWIR Abbe number is reported highlighting the significant impact purification has on material dispersion control required in optical designs. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Broadband (Ultraviolet to Near-Infrared) Photodetector Fabricated in n-ZnO/p-Si Nanowires Core-Shell Arrays with Ligand-Free Plasmonic Au Nanoparticles
No full textWe report a high-response optical detector based on n-ZnO/p-Si nanowires (NWs) core-shell arrays decorated with plasmonic Au nanoparticles (NPs) that works in the broad frequency range from UV (300 nm) to NIR (1100 nm) and consumes low power (few mu W). The optical detector combines the visible and NIR detectability of Si NWs with the UV detectivity of ZnO through the core-shell structure and broadband detectivity in the visible range has been achieved by decorating core-shell arrays with ligand-free Au NPs synthesized by using pulsed laser ablation in liquid. The photodetector uses n-ZnO as the active photoconductive channel that is sensitive in the UV region. However, using photogating as well as favorable band alignments, the carriers generated at longer wavelengths in visible and NIR in Au NPs and Si NWs arrays were introduced into the conduction band of ZnO, leading to its broadband performance. We observed significant enhancement of responsivity R not only in the visible range but also in the UV and NIR region with a high detectivity of 10(11) cm Hz(1/2) W-1. The responsivity of the detector is similar to 1 A/W from 700 nm to a longer wavelength (at a bias of 1 V) and, in the visible region, the responsivity of the photodetector with Au NPs is >0.5 A/W and increases to >1 A/W in the UV region
Enhancement of photoluminescence in white light emitting glasses by localized surface plasmons of Ag and Au nanoparticles
No full textHere we report a white light emitting glass system, photoluminescence (PL) intensity of which, can be enhanced and tuned by thermal treatment. Ag and Au metal nanoparticles (NPs) are generated into a Dy3+ doped glass by in situ thermochemical reduction. Ag and Au NPs start to grow with heat treatment. Absorption spectra show the characteristic surface plasmon resonance bands for respective nanometals. When excited at 447 nm, the glasses exhibit visible white emission. 4 to 6 times enhancement in PL intensity has been achieved as the combined effect of the metal NPs and matrix crystallization