Porous glass ceramic materials with decorative-protective coating

This study was aimed at producing a porous layered glass ceramic material with a decorative-protective coating via one-stage firing. Waste products were used as gas-forming agents to fabricate a glass ceramic material, which partially solves a problem of their utilization; available natural raw materials were also used as gas-forming agents. A decorative-protective coating was applied simultaneously with the formation of the main layers of the material. It consisted of glass cullet and various amounts of coloring oxide. Firing of the samples was carried out at the temperature of 7500С. The coating containing 99.9 wt.% of glass cullet and 0.1 wt.% of Cr2O3 with the thickness of 425 m and having a greenish color was stated to be the coating of the highest quality. As a result of the research, a three-layer porous glass ceramic material was obtained with a low coefficient of thermal conductivity (0.056 W m–1 K–1). The presence of a fourth front decorative-protective layer will allow using this material in construction as a heat-insulating and structural material without additional cladding.

Thermophysical properties of glass-ceramic material during thermal insulation of pipelines of heating mains and utilities

It is proposed to use porous heat-insulating glass-ceramic material (SCM) in the form of segments based on glass, plasticizer, organic additives and a gas generator for thermal insulation of pipelines of heating mains and utilities. Research on the use of SCM in pipelines was carried out according to the key methodology for studying new materials: composition, structure, properties, their changes under the influence of external factors, application. The basis for determining the effectiveness of thermal insulation materials for thermal insulation of pipes was on the physical and technical characteristics of the coolant, pipes and thermal insulation materials. During the study, heat losses and thermal resistances through the insulated surface of the supply and return pipelines of heat networks were determined when installed on the surface. When calculating the heat loss through the pipe using various heat insulators, the layer thickness was assumed to be the same value. Studies have shown that when using a shell made of granular SCM, the heat loss transmitted by thermal conductivity is 1.36 times less than that of a vermiculite shell, 2.45 times than that of mineral wool segments and 2.11 times than that of brand 500 sovelite shells. The use of products made of granular glass-ceramic material (SCM) significantly reduces heat loss and the thickness of the heat-insulating layer of pipelines, and saves fuel and energy resources.

Использование щелочной активации для получения пористого стеклокерамического материала из глинистого сырья

Целью исследования являлось определение возможности использования местной легкоплавкой глины месторождения Кустиха и техногенного отхода производства гранитного щебня для получения экологически безопасного пористого теплоизоляционного материала с использованием метода щелочной активации. Изучено влияние щелочной активации на формирование пористого стеклокерамического материала из смеси легкоплавкой глины и отходов гранитного производства. Показано, что смесь глины месторождения Кустиха с гранитоидным отсевом, содержащая свободный диоксид кремния, способна вспучиваться под действием щелочи при температурах обжига до 950 градусов Цельсия. Методами термогравиметрии и ИК-анализа установлено, что под действием щелочной активации вода удерживается в исходной смеси за счет образования дополнительных гидроксильных связей вплоть до 500 градусов Цельсия. При дальнейшем обжиге наличие таких гидроксильных связей способствует переходу материала в пиропластическое состояние и его вспучиванию. Установлено, что полученный гранулированный стеклокерамический материал обладает высокой пористостью (коэффициент вспучивания 4,2), при этом его плотность в 5,4 раза меньше, чем у материала, полученного из неактивированной смеси глины с гранитоидным отсевом. По данным элементного и фазового анализа полученная стеклокерамика не содержит органических и других токсичных примесей, что позволяет отнести ее к экологически безопасным теплоизоляционным материалам. The objective of this study was to determine the possibility of using local low-melting clay from the Kustiha deposit and technogenic waste from the production of crushed granite to obtain an environmentally friendly porous heat-insulating material using the alkaline activation method. The alkaline activation's effect on the formation of a porous glass-ceramic material from a mixture of low-melting clay and granite waste was studied. It was shown that the clay mixture from the Kustiha deposit with granitoid’s screenings containing free silicon dioxide is able to swell under the action of alkali at calcination temperature up to 950 degrees Celcius. Using methods of thermogravimetry and IR analysis, it was found that under the action of alkaline activation water is retained in the initial mixture due to the formation of additional hydroxyl bonds up to 500 degrees Celcius. With further firing, such hydroxyl bonds contribute to the transition of the material into the pyroplastic state and its expansion. It was found that the obtained granular glass-ceramic material has high porosity (expansion coefficient is 4.2 plus/minus 0.2), while its density (0.26 plus/minus 0.03 gram/cubic centimeter) is 5.4 times lower than that of the material obtained from an inactive mixture clay with granitoid's screening. According to elemental and phase analysis, the glass ceramic obtained does not contain organic and other toxic impurities, which allows it to be attributed as an environmental friendly heat-insulating material.

Use of Bypass Cement Dust from Al-Kufa Cement Factory for Production of Glass Ceramic Material

Bypass cement dust was supplied from Alkufa cement factory, which has been used in preparing glass ceramic material. The percentage of bypass cement dust which is included in the overall batch is about 30 wt%. The bypass cement dust composition has been modified by adding other materials like marble, granite, and silica, to prepare glass ceramic material by powder technology. The prepared samples with different ratios ingredients were pressed under a load of 15 tons/cm2 for 90 sec, in a steel mold of 30 mm in diameter, liquid phase sintering is carried out by using High-Temperature Furnace at 100 – 1250 º C and 208/ 240 VAC. Techniques including SEM (Scanning electron microscopy) and XRD (X-ray diffraction) tests were then used to evaluate the produced material. The obtained glass ceramic material have high bulk and apparent density, low apparent porosity , high compression strength and hardness , low electrical and thermal conductivity. The XRD and SEM results showed that glass ceramic materials are formed. The phase transformation has happened and the titanite, wollastonite, diopside, periclase, and silica condense clusters phase are formed, which are the important phases of glass ceramic. Tests show that the sample A5 contains 38% bypass cement dust, 30%granite, and 32% silica , the sample C5 contains 28% bypass, granite 30%, marble 10%, and silica 32% and the sample B4 contains 59% bypass , 25% marble, and 16% silica . Showing properties A5 and C5 which conform to that of glass ceramic properties better than B4. The research is considered a pioneer work in the field of investment of dust of bypass cement for producing glass ceramic materials. It represents an important step and could be the basis for future researches leading to the achievement of glass ceramic production in Iraq.