Исследовано влияние маршаллита при полной замене им кварца и добавок волластонита (2,0 мас.%) на процессы спекания, фазообразования, структуру и свойства электротехнического фарфора. Объектом исследования является электротехнический фарфор традиционного компонентного состава (каолин, пластичная глина, полевой шпат, кварцевый песок). Установлено, что процессы плавления и спекания при обжиге фарфора исследованных составов не соответствуют равновесным. Образования расплавов тройных эвтектик систем R₂O-Al₂O₃-SiO₂ при температурах 985 и 1050 °С в количествах 45–60% не происходит. Образование расплава при обжиге керамики происходит за счет частных бинарных эвтектик «альбит –кремнезем» и «ортоклаз-кремнезем» при взаимодействии полевого шпата с кремнеземсодержащими компонентами (990 – 1060 °С). Связано это с тем, что первичный муллит образуется при температурах его стабильного состояния выше 1200 °С. Фактические процессы образования расплава при обжиге фарфора не являются равновесными. Перекристаллизация муллита происходит за счет растворения первичного муллита в расплаве с последующей кристаллизацией игольчатого муллита. Замена кварцевого песка на маршаллит приводит к снижению температур взаимодействия кремнезема с полевым шпатом и образованию первичного расплава, что отражается на снижении температуры обжига керамики на 70° с 1340 до 1270 °С. Добавка волластонита – CaSiO₃ (2 %мас.) интенсифицирует процесс растворения первичного муллита и кристаллизацию игольчатого муллита. Длина игл муллита увеличивается от 2–3 мкм до 7–10 мкм, иглы муллита образуют агрегаты, что обеспечивает увеличение прочности фарфора при изгибе на 36% до 80 МПа. Для цитирования: Верещагин В.И., Курбанбаев М.Е., Есимов Б.О., Роот Л.О., Могилевская Н.В. Процессы спекания, фазообразования, формирование структуры и свойства электротехнического фарфора с использованием маршаллита и добавок волластонита. Изв. вузов. Химия и хим. технология. 2024. Т. 67. Вып. 5. С. 87-98. DOI: 10.6060/ivkkt.20246705.6960.

Original compositions of electrical ceramics have been developed and tested using marshalite and wollastonite as raw materials. An analysis of the equilibrium states of the created porcelain masses at different temperatures in Na₂O-Al₂O₃-SiO₂ and K₂O-Al₂O₃-SiO₂ systems was carried out. The amount of melt in these systems was calculated based on equilibrium flux curves. The characteristics of the sintering process of the masses were identified. A scheme for the formation of key secondary needle-like mullite during the thermal treatment of the masses was outlined and the temperature intervals for the formation of intermediate compounds were found. X-ray diffraction patterns and micrographs of the synthesized samples were decoded, and the phase composition and microstructure of the samples were analyzed. The effective influence of silica component dispersion on the mineral formation processes during the sintering of the porcelain masses in model samples of feldspar compositions with quartz sand and marshalite was noted. The optimal firing temperatures for full mineral formation and structure formation have been determined, as well as the physical–mechanical and dielectric properties of the obtained ceramic samples.

Original compositions of electrical ceramics have been developed and tested using marshallite and wollastonite as raw materials. An analysis of the equilibrium states of the created porcelain masses at different temperatures in the Na2O-Al2O3-SiO2 and K2O-Al2O3-SiO2 systems has been carried out. The amount of melt in these systems has been calculated based on the equilibrium flux curves. The characteristics of the sintering process of the masses have been identified. A scheme for the formation of the very important secondary needle-like mullite during thermal treatment of the mass has been outlined, and the temperature intervals for the formation of intermediate compounds have been found. X-ray diffraction patterns and micrographs of the synthesized samples have been decoded, and the phase composition and microstructure of the samples have been analyzed. The effective influence of the dispersion of the silica component on the mineral formation processes during the sintering of porcelain masses on model samples of compositions of feldspar with quartz sand and marshallite has been noted. The optimal firing temperatures for full mineral formation and structure formation have been determined, as well as the physical-mechanical and dielectric properties of the obtained ceramic samples.

The development of the ceramic industry requires the creation of new innovative products with improved properties. Given the growing demand for high-quality finishing materials and the limited availability of traditional raw materials, the search for more efficient technologies for porcelain stoneware production is a relevant challenge. The aim of this study was to develop porcelain stoneware with enhanced performance characteristics. The research presents the results of a study aimed at improving the production technology of porcelain stoneware in Kazakhstan using local raw materials and microsilica. The raw materials from the Turkestan region were examined for their suitability for porcelain stoneware production. The influence of technological parameters (firing temperature, particle size) on the properties of porcelain stoneware was studied. New ceramic compositions with various microsilica contents, a byproduct of silicon production, were investigated. Different compositions with varying raw material mixtures and microsilica content were prepared and fired at temperatures of 1100, 1150, and 1200°C. The optimization of process parameters for producing porcelain stoneware in different compositions showed the degree of yield dependence on firing temperature and time, as well as the effect of microsilica content. The temperature, time, and visually determined parameters at which different yield values were achieved were highlighted in different colors. The results showed that changes in the mixture composition and sintering temperature affect the quality of ceramic tiles. The final experimental conclusions demonstrated that the production of ceramic tiles containing up to 3% microsilica at a firing temperature of 1200°C, with improved engineering characteristics that meet the minimum ISO-13006 standards, is quite feasible. The addition of microsilica increases the flexural strength of porcelain stoneware to 41 MPa (exceeding the standard), reduces water absorption to 0.023%, increases frost resistance to 107 cycles, and also enhances shrinkage. These findings open new prospects for the development of the domestic ceramic industry, the expansion of the product range, and the resolution of environmental issues.