Papers by Keyword: Glass

Abstract: The current paper deals with an overview on façade industry with the purpose to be useful for the engineers involved in the structural and architectural design of curtain walls.The research activity has been based on both the structural calculation and the experimental test on the Le Boulevard skylight in Doha (Qatar), measuring 36m by 18m in plan, located at a height of about 42 m and subjected to a wind load of 1.7 KPa. The skylight, composed of steel rectangular curved tubes, glass and aluminium sandwich panels, is designed for a basic wind speed of 25 m/s as per Qatar Construction Standards. Two types of steel frames have been designed, one to support both the glazing and aluminium sandwich panel, and another to transfer all the loads to the main structure. Subsequently, a performance testing on a specimen extracted from the skylight has been performed. The test was carried out by Aluminium Technology Auxilliary Ind. (ALUTEC) on a specimen having length and width of 6.625 m and 3.315 m, respectively. The assessment procedures have been carried out following the “ASTM E283”, “ASTM E331” and “ASTM E330” standards. The results of the test have been found within the acceptable limits for the skylight components specified by the standards and required by the project specification.

Abstract: Pr³⁺-doped Li₂O – Gd₂O₃ – B₂O₃ glasses (LGBO glass) with the formula 60Li₂O:10Gd₂O₃:(30-x)B₂O₃:xPrO₃ were fabricated using melt quenching technique. The five glass samples with different concentrations of Pr₂O₃ were prepared under atmospheric pressure. The samples were investigated on their properties: absorption and photoluminescence. All absorption bands are increase with increasing of Pr³⁺ content. The emission spectra were measured with 446 nm light pumped by xenon lamp. The maximum luminescence intensity was observed at x = 0.50 mol% andthe CIE color coordinates showed the bluish purple emission light for this concentration.

Abstract: The corrosion on glass surfaces causing contamination in the aqueous solutions depend on pH and temperature. This research aims to study the elements leached from the inner glass surfaces that were treated and untreated to aqueous solution. The clear and amber bottles used as the samples were determined the chemical composition by XRF. The samples were treated with 2%, 3% and 5% alum solutions and the hydrolytic resistance test was performed according to ISO 4802-1. The results showed that bottles treated with 3% alum solution gave the most suitable condition to improve the hydrolytic resistance. The treated and untreated bottles were filled with 2% citric acid solution, RO water, and 0.9% sodium chloride solution and kept at 20 and 40°C for 0.125, 1, 2, 4, 10, 20, 40, 60 and 120 days. The pH values of all solutions after ageing were measured and the leached elements – Na, Ca, Al, Cr, Mn, and Pb – in RO water and citric solution were analyzed by AAS. There was significant increase of pH with time at 40°C within 10 days before it had slightly rose to nearly 9.7 of both treated and untreated bottles. However, samples filled with citric solution shows no change in pH value. Na leached from the untreated samples which showed the highest concentration at 2.3 ppm from clear glass and 4 ppm from amber glass respectively. Other elements were not found.

Abstract: The project aims to produce quality enamel colors from locally available materials in order to reduce costs. In the course of the research, information is collected on imported enamel colors and a study is carried out on chemical compositions and quality of the colors. At the same time, there is a study on local materials which can potentially be used to produce enamel colors, starting from basic colors such as red, blue and green. The study has found that the imported enamel colors qualify as lead glass because it contains 23-28% of lead. The study has also found that red enamel (transparent) blue enamel (transparent), blue enamel (opaque), green enamel (transparent), and green enamel (opaque) have similar level of density and hardness. Red enamel (opaque) has lower level of density and hardness due to its porosity which can be observed with naked eyes. The COE level is similar for all of the tested colors because their chemical compositions are similar. The study produces quality blue and green enamel at much lower cost. Colors of the enamel are achieved by adding different metal oxide. The color blue (translucent and opaque) is from adding cobalt (Co). Chromium (Cr), manganese (Mn), iron (Fe), cobalt and copper (Cu) together produces translucent dark green, while chromium and copper (without cobalt) produces opaque as lighter green. However, it has not been able to produce red enamel yet but has requested for samples from another research project “Developing New Technology to Produce Jewelry from Synthesized Red Crystal” for further study.Keywords: Enamel; Jewelry; Glass; Local Raw Materials

Abstract: We report on the mechanical properties of xCuO-(50-x)PbO-50B₂O₃ (x from 0 to 30 mol%) copper-lead-borate glasses. Their mechanical properties were investigated by the mechanical resonance technique and by the indentation measurement. The replacement of lead by copper improves the packing efficiency, and enhances the elastic moduli, hardness and the fracture toughness of glasses.

Abstract: Composites of a long-lasting phosphor, SrAl₂O₄:Eu,Dy, and glass were prepared by sintering the phosphor and glass powder. To enhance the afterglow luminescence, a borosilicate glass composition was chosen so that the refractive index of the glass matched that of the phosphor. Additional components with a high refractive index, such as La₂O₃ and Nb₂O₅, were added to the glass to increase the overall refractive index. As they tend to induce crystallization during sintering, small amounts of at least three types of such components were added to the glass to prevent crystallization. The surface of the composite was observed by a digital microscope with dark-field lighting. The phosphor particles became almost transparent because of the refractive-index matching, although bubbles were observed inside the phosphor particles. The afterglow luminance was, however, almost the same and the transmittance of the composite was not high because of many voids when compared to as that of the sample using the glass with a lower refractive index. The sample prepared under vacuum showed coloration and similar afterglow luminance even though the number of voids inside the composite decreased. To suppress the coloration, the amount of tin in the glass was increased, after which higher transparency and afterglow luminance were obtained. A 4-mm-thick sample showed a luminance of 118 mcd∙m^-2 60 min after irradiation by a D65 lamp with 200 lx for 20 min.

Abstract: Europium doped lithium barium borate glasses were fabricated by conventional melt-quench method and were analyzed their physical, optical and luminescence properties through absorption, excitation, emission and decay analysis at room temperature. The experimental data revealed that the five discrete absorption bands peaking at 393, 464, 532, 2032 and 2212 nm due to the transitions from ⁷F₀ ground state level to various excited states of Eu³⁺ ions. The luminescence of Eu³⁺ in visible bands were observed under 394 nm pumping.

Abstract: The Dy³⁺ doped Y₂O₃-CaO-SiO₂-B₂O₃ glasses with molar composition 25Y₂O₃ : 10CaO : 10SiO₂ : (55-x)B₂O₃, where x is 0.0 to 0.5 mol%, have been prepared by melt quenching method and are characterized through absorption, photoluminescence and decay analysis. From the luminescent spectra, observed a strong yellow and blue emission from ⁴F_9/2→ ⁶H_13/2 (575 nm) and ⁴F_9/2 → ⁶H_15/2 (482 nm) transition of Dy³⁺ ions respectively. The tunable white light emission at different excitation wavelengths are investigated through CIE 1931 diagram. The decay curves show the decreasing of lifetimes when addition of Dy₂O₃ concentration.

Abstract: The influence of process parameters on amorphous reactively sputtered silicon nitride thin films is reported in this study. The films were prepared with various argon and nitrogen flows, and sputter power in in-line horizontal coater by DC magnetron reactive sputtering from Si (10% Al) target. Refractive index and mechanical properties like residual stress, hardness and elastic modulus were studied. We show that process pressure has an important influence on mechanical properties of the sputtered film. On the other hand, the nitrogen content is the key factor for the optical properties of the films.

Abstract: This research studied the effect of composition of a glass-based high temperature adhesive on the bond strength of 96% alumina bars. The adhesives studied were composed of 40-70% glass powder, 5-30% polyvinyl alcohol (PVA), and 15-55% water. Half-lengths of green alumina bend bars were bonded together with the adhesive to form a full length bar and then sintered. The flexural strengths of the sintered bars were measured and the resultant fracture surfaces were examined by SEM. The results showed that an initial increase in the PVA and glass content increased the flexural strength to the highest value of 120 MPa, but that further increases resulted in decreased strength. The strength values fluctuated when the PVA content was above 20% and the glass content was 40% or 60%, which indicated poor adhesive homogeneity. SEM analysis of the fracture surfaces showed a separation layer between the alumina and glass adhesive when the glass or PVA content were either too high or too low, which again indicated poor adhesive homogeneity. It was concluded that the optimal composition of the adhesive was 45-55% glass and 7-15% PVA, which gave a minimum flexural strength of 80 MPa.