Thermal conductivity of refractory glass fibres

In the present study, the current international standards and corresponding apparatus for measuring the thermal conductivity of refractory glass fibre products have been reviewed. Refractory glass fibres are normally produced in the form of low-density needled mats. A major issue with thermal conductivity measurements of these materials is lack of reproducibility in the test results due to transformation of the test material during the test. Also needled mats are inherently inhomogeneous, and this poses additional problems. To be able to compare the various methods of thermal conductivity measurement, a refractory reference material was designed which is capable of withstanding maximum test temperatures (1673 K) with minimum transformation. The thermal conductivity of this reference material was then measured using various methods according to the different standards surveyed. In order to compare different materials, samples have been acquired from major refractory glass fibre manufacturers and the results have been compared against the newly introduced reference material. Materials manufactured by melt spinning, melt blowing and sol–gel have been studied, and results compared with literature values

Exploratory research in alternative raw material sources and reformulation for industrial soda-lime-silica glass batch

For energy saving and CO2 emissions reduction, in addition to extending the range of suitable raw material sources for glass manufacture, compositional reformulation, and alternative raw materials have been studied in the context of industrial container and float‐type soda‐lime‐silica (SLS) glasses. Lithium, potassium, and boron were applied to modify benchmark glass compositions. Reformulation impacts on key glass properties including the viscosity‐temperature relationship, thermal expansion, liquidus temperature, forming behavior and color. Compared to the benchmark glass, representative of commercial SLS glasses, melting temperatures (taken as temperatures corresponding to log (viscosity/dPa·s) = 2) of reformulated glasses are reduced by 11°C‐55°C. Investigation of four industrial by‐products (seashell waste, eggshell waste, biomass ash, and rice husk ash), and their potential suitability as alternative glass batch raw materials, was also conducted. Seashell waste and biomass ash were successfully introduced into representative green glass formulations

Thermal behaviour of yttrium aluminate glasses studied by DSC, high-temperature X-ray diffraction, SEM and SEM–EDS

DSC, SEM-EDS, XRD and high-temperature XRD analysis was used to study thermal and crystallization behaviour of yttrium aluminate glasses prepared in the form of microspheres. The glasses YA-E (eutectic composition from the pseudo-binary system Al2O3-Y3Al5O12) and YA-G (a composition identical to the stoichiometric Y3Al5O12 (YAG) phase) were prepared by combination of the Pechini method with flame synthesis. The resulting microspheres were largely amorphous, but contained traces of yttrium-aluminium garnet as the main crystalline phase embedded in the yttrium aluminate glass matrix. Crystallization of the YAG phase was observed as the dominant exothermic process on DSC curves. From the DSC records, the basic thermal characteristics of the matrix glass, i.e. T (g) (glass transition temperature), T (x) (onset of crystallization peak temperature), T (f) (temperature of the inflection point of the crystallization peak) and T (p) (maximum of crystallization peak temperature), were determined. HT XRD experiments in the temperature interval 750-1200 A degrees C and isothermal HT XRD experiments at 932, 998 and 1200 A degrees C with 6-h holding time were also performed. Crystallization experiments at lower temperatures 932 A degrees C (YA-E) and 915 A degrees C (YA-G) were conducted to study phase development in a low-temperature region. Crystallization experiments at higher temperatures (1000, 1300 and 1500 A degrees C) with maximum holding time of 6 h were performed to study crystallization of alpha-Al2O3 in the eutectic system. The SEM and SEM-EDS examination of polished cross sections of crystallized microspheres revealed slow volume crystallization of the YAG phase in the AY-E glass. Eventually, polycrystalline microspheres with fine-grained microstructure were prepared after 6-h treatment at 1500 A degrees C