A new material — Quartz light-diffusing glass

Translated from Steklo i Keramika, No. 7, pp. 9–10, July, 1991.     

Quartz crystal resonator study of glass transitions in polyvinylbutyral (PVB) films

Glass transitions in polyvinylbutyral (PVB) films deposited on a gold substrate have been studied using a quartz crystal resonator technique by measuring the resonant frequency shift and resonant peak broadening of the quartz crystal coated with a PVB film. Using the measured frequency shift and peak broadening of the resonance of the quartz crystal due to changes in the coated PVB film, the storage moduli of the film were derived. The results show rapid drops in the storage moduli of the PVB films at temperature closer to that of glass transition of bulk PVB. The transitions at different frequencies were assessed by simultaneously measuring the resonance of the quartz crystal at multiple harmonics. No significant change in the glass transition temperature at multiple harmonics was observed. The results of the storage moduli for PVB films of different thickness show that glass transition temperatures in the films decrease with the film thickness; the decrease become more noticeable as the film thickness is less than 500 nm where the characteristic of changing of storage moduli become distinctly different from that in thicker film and in bulk materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45433.     

Quartz sands from cheremshansk deposits as prospective raw material for the glass industry

Glass and Ceramics -     

Quartz glass-base unfired Refractories

Conclusions Quartz-glass-base increased heat-resistance unfired quartz refractories were produced having after hardening a compressive strength of 24–26 MPa and an open porosity of 14.3–14.5%. Their strength may be increased by heat and moisture treatment. Such refractories do not lose strength in the whole range from 110 to 1300°C and are promising for the steel and construction material industries.Translated from Ogneupory, No. 8, pp. 34–37, August, 1985.     

Conversion of Quartz to Tridymite

The conditions under which tridymite becomes a stable phase have been reinvestigated. When quartz was heated with 2% alkali oxide, tridymite formed directly at 872° to 898°C. with Na₂O, at 883° to 902°C. with K₂O, and above 1005°C. with Li₂O. Cristobalite occurred as an intermediate phase above 893°C. with Li₂O, above 898°C. with Na₂O, and above 902°C. with K₂O. When quartz plus sodium chloride was heated in vacuum, tridymite did not form but cristobalite started to appear at 1050°C. The results showed that the formation of tridymite can be strictly a solid-state process. New schematic tentative diagrams for the high-silica region of binary systems are suggested. Quartz and cristobalite are regarded as the only stable crystalline phases of pure silica. Tridymite is pictured as a binary incongruently melting phase.     

Fusion of Quartz and Cristobalite

The melting point of quartz is established to be below 1450°C. and possibly above 1400°C. The product of fusion is a liquid of high viscosity which undergoes slow transformation to give the commonly encountered vitreous silica. At temperatures between 1450deg; and 1700°C., both cristobalite and glass are formed when quartz is heated in air for periods in excess of 15 minutes. The quartz-cristobalite transformation is sensitive to the ambient atmosphere. After heating to temperatures above 1730°C., inhomogeneities are still present in both fused quartz and fused cristobalite in the form of unmelted microcrystals. Their presence is indicated by X-ray diffraction, metallographic, infrared, and hardness measurements.     

Transformation of Quartz to Cristobalite

The transformation of quartz to cristobalite was studied in the temperature range 1400° to 1650° C. The process which was believed to be a direct one was found to be a consecutive reaction involving an intermediate transition phase. Both Madagascar and Brazilian quartz were used to study the transformation reaction. The reaction rate was found to be much faster for the Madagascar quartz than for the Brazilian quartz, although no difference in their impurity content was found in the spectrographic analysis. An approximate consecutive reaction kinetics was applied and the deviation of the experimentally observed values of the transition phase at a particular temperature from that of the mathematical prediction was noted and is discussed.     

石英陶瓷材料的增强方法

综述了石英陶瓷材料增强的主要方法，内容涉及表面涂层增强、短纤维增强、三维石英纤维编织体增强、单向排列碳纤维增强、石墨颗粒弥散增韧及有机硅树脂增强，并且介绍了这些材料的主要力学性能及用途。     

对石英陶瓷烧结过程的研究

根据文献资料的分析和专题研究的结果表明，在对石英陶瓷制品进行热处理的过程中，加热与冷却速度对材料性能不会产生重大影响，只是可能对工艺设备的操作条件作出某种限定。在生产石英陶瓷制品时，提高加热与冷却速度可产生重大的经济效益。     

Polymer-Surfactant Interactions in Flotation of Quartz

Abstract

Separation of minerals currently often involves the use of polymers along with surfactants. Polymer-surfactant interactions in flotation are studied here for quartz, which along with clay is present in coal, oil shale etc., using nonionic, anionic, and cationic surfactants. Polymers are found under most conditions to affect flotation. It can activate or depress flotation markedly depending on the nature of the charge of the reagents. Possible mechanisms by which flotation is affected by the polymers are discussed. Reasons for the observed maximum in flotation vs. amine concentration are also considered here briefly.