Glass formation and properties of glasses in the system SrO–B2O3–SiO2–xAl2O3 (x=0; 10 mol.%)

The paper shows the prospects of the system SrO–Al2O3–B2O3–SiO2 as a basis for the synthesis of new vitreous and glass-ceramic materials, which are widely used as electrical insulated and high-temperature coatings, for sealing of solid oxide fuel cells, and in the production of heat resistant materials. We experimentally established the conditions of glass formation, regions of glass-forming melts and properties of glasses, the chemical composition of which is limited by the following content of components (mol.%): SrO 30–80, B2O3 10–60, SiO2 10–60, and Al2O3 0–10. It is shown that during the synthesis of glasses in the corundum crucible at the temperature of 13500С the region of glass formation in the system SrO–B2O3–SiO2 is limited by the following content of components (mol.%): SrO 30–60, B2O3 10–60, and SiO2 10–50. It is found that the introduction of Al2O3 to the composition of these glasses expands the region of glass formation towards increase of the SiO2 content in the glass up to 60 mol.%. Experimentally determined values of glass properties are within the following limits: coefficient of linear thermal expansion (67–118)10–7 К–1; glass transition temperature 570–6600С; dilatometric softening point 580–7000С; and density 2.62–3.71 g cm–3. The established patterns of influence of the components and conditions of glass formation on the physical and chemical characteristics of glasses may serve as an experimental basis for designing of new materials with a complex of specified properties, which allows solving the problems of their practical use.

Glass-Ceramics: Improving Glass Properties through Crystallization

Controlled crystallization of glasses is a broad research area within glass science in which researchers from academia and industry are both involved [...]

Spraying Cooling System for PV Modules: Experimental Measurements for Temperature Trends Assessment and System Design Feasibility

The hallmark of the PhotoVoltaic (PV) electricity generation is its sustainability, while its main weakness is the low conversion efficiency. A drawback to which is added the PV cell sensitivity to temperature variations: the higher the cell operating temperature, the lower the efficiency. Considering that in-operation modules reach a conversion efficiency in the range of 10 to 15%, there is an urgent need to control their temperature to enhance the electricity generation. To this purpose, the authors developed a PV spraying cooling system able to drastically knockdown modules operating temperature. Using experimental measurements acquired through a dedicated test rig and after an in-depth literature review, the authors analyze the nozzles number, geometry, and position, as well as water and module’s temperature distribution, limestones formation, degradation of front glass properties, water consumption, and module power production with and without the cooling system. The experimental campaign shows that a cooling system equipped with three nozzles with a spraying angle of 90°, powered by water at 1.5 bar and managed in ON/OFF mode (30 s on to 180 s off), can improve the module’s efficiency from 11.18% to 13.27% thanks to a temperature reduction of up to 24 °C. Despite the improvement in electricity production (from 178.88 W to 212.31 W per single module), at the time of writing, the equipment and installation costs as well as the plant arrangement complexity make the investment not eligible for financing also in the case of a 1 MW floating PV facilities.

Atomic-scale homogeneous plastic flow beyond near-theoretical yield stress in a metallic glass

The onset of yielding and the related atomic-scale plastic flow behavior of bulk metallic glasses at room temperature have not been fully understood due to the difficulty in performing the atomic-scale plastic deformation experiments needed to gain direct insight into the underlying fundamental deformation mechanisms. Here we overcome these limitations by combining a unique sample preparation method with atomic force microscopy-based indentation, which allows study of the yield stress, onset of yielding, and atomic-scale plastic flow of a platinum-based bulk metallic glass in volumes containing as little as approximately 1000 atoms. Yield stresses markedly higher than in conventional nanoindentation testing were observed, surpassing predictions from current models that relate yield stress to tested volumes; subsequent flow was then established to be homogeneous without exhibiting collective shear localization or loading rate dependence. Overall, variations in glass properties due to fluctuations of free volume are found to be much smaller than previously suggested.