Glass development and production at CSIR-CGCRI for optical applications: some success stories

CSIR-Central Glass and Ceramic Research Institute (CSIR-CGCRI) is the premier glass research institute in the country. From its inception, it is developing and producing various types of glasses for use in different types of optical applications particularly by the strategic sectors and industry. Among these developments and production, the most important glasses and glass-ceramics are classical and new generation optical glasses, radiation shielding glasses, lead-free glasses for use in plasma display devices, chalcogenide glasses and near zero expansion transparent glass-ceramics. In this article, a brief overview of these glasses and glass-ceramics with some events of set up of CSIR-CGCRI is presented

Effect of gamma ray irradiation on optical and luminescence properties of CeO2 doped bismuth glass

High lead oxide based Radiation Shielding Window (RSW) glass is highly toxic in nature and thus health haz-ardous. Therefore, a new way to design environmental friendly non-toxic lead-free RSW glass for nuclear application is very much required. In this work, a lead-free non-toxic glass based on multi-component Bi2O3--BaO-B2O3-ZnO-As2O3-MgO-Na2O system has been studied with different concentrations of cerium oxide (CeO2) as doping agent for enhancing radiation shielding effect. The optical properties of cerium doped bismuth based lead-free radiation shielding glass after exposure to gamma radiation up to 105 rad have been studied. The densities of glass varied from 4.59 to 5.05 g/cc on varying concentrations of bismuth oxide and boron trioxide in glass system. The transmission properties in visible regions from 400 to 1000 nm are investigated through UV-visible spectrometer after exposure to gamma radiation on developed glass using 60Co Gamma Chamber GC5000. The structure of glass as characterized by Raman spectroscopy, XRD, Photoluminescence (PL), FESEM with EDAX, refractive index measurement and dilatometry test has been correlated with its properties. The developed bismuth glass could find its application as lead-free RSW glass in nuclear reactors as an alternative to high lead containing glass

Low Expansion Glass-Ceramics Using Industrial Waste and Low-cost Aluminosilicate Minerals: Fabrication and Characterizations

The recycling of the wastes towards value added product development has become a prime challenge. In this work, a low thermal expansion glass-ceramic material based on ternary LAS (Li2O-Al2O3-SiO2) system has been prepared by adopting meltquenching route using industrial waste (blast furnace slag) and low-cost aluminosilicate minerals (China clay and pyrophyllite) at relatively low melting temperature (similar to 1450 degrees C). A part of the precursor powder for pristine glass has also been prepared by sol-gel processing utilizing Li2CO3 and Al(NO3)(3).9H(2)O to obtain better homogeneity in the glass composition vis-a-vis glass-ceramics at lower melting temperature. Thermal properties of the material have been characterized to optimize the nucleation and crystallization temperatures for converting glass to glass-ceramics. Phase structure and surface morphology of the glass-ceramics have been analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy. XRD study reveals the presence of lithium aluminosilicate as a major phase at the crystallization temperature of 730 degrees C. The developed glass-ceramics show a low thermal expansion coefficient (CTE) value of (19 +/- 0.5)x10(-7)/degrees C in the temperature range of 30 degrees-500 degrees C. The present work can unfold an avenue towards conversion of waste into wealth in the form of low CTE glass-ceramics for possible application as cook-top plate of LPG gas oven

Development of Mullite Based Refractory Pot for High Lead Containing Glass Melting

Radiation shielding window (RSW) glass for nuclear reactor is primarily required for protecting the operating personnel from harmful radioactive rays produced during nuclear energy generation in nuclear hot cells. In this respect, the production of high lead (>70% PbO) containing RSW glass is generally made using platinum pot through bottom pouring flow casting technique. However, owing to low capacity (40 L max.) of high cost platinum pot, the production of glass slab is limited to a maximum dimension of 400x400x100 mm(3). Therefore, an alternate cost effective technology is highly required for making higher dimension glass slabs. To fulfill the requirement, low cost and higher volume refractory pot based tilt casting technology can be adopted. In this regard, the refractory pot is to be developed with adequate thermal, chemical and mechanical stabilities towards sustaining high corrosive lead oxide containing molten glass at 1100 degrees-1200 degrees C. For this purpose, a clay based alumino-silicate pot material enriched with mullite has been developed and characterized systematically. The rectangular bars have been fabricated by slip casting technique and the fabricated bars have been fired between 1450 degrees and 1550 degrees C. The fired materials have been characterized in terms of bulk density, apparent porosity, cold and hot modulus of rupture, etc. The RSW glass with more than 70% lead oxide content has successfully been melted in the pot. The quality of RSW glass produced using the pot has also been studied. In an optimized composition of the pot, the formation of higher content of mullite phase having high thermal shock and corrosion resistance with the desired mechanical stability is the key factor behind the stability of the refractory pot for making defect free RSW glass slabs. This cost effective refractory pot technology can substitute the platinum pot technology for producing larger dimension RSW glass slabs