Optimization of the composition and properties of a ceramic composite based on barite and bentonite

Introduction. Currently, barium sulfate is actively used in various industries, including paper manufacturing, construction, paints and coatings, rubber, chemical, metallurgical, and electrical engineering industries, as well as in agriculture and medicine. Literature analysis has shown that the composition and properties of barium sulfate depend on its deposit. Different processing technologies have been developed for barium sulfate, including methods for producing materials for a wide range of applications. Particular attention is given to creating radiation-resistant and radiation-shielding materials, including radiation-resistant concretes and ceramics. Methods and materials. In Kyrgyz Republic, there are more than 40 barium sulfate deposits. Among them, the "Arsy" deposit stands out particularly, with sufficient reserves. The chemical composition of barium sulfate from the "Arsy" deposit was analyzed using atomic emission spectrometry, X-ray fluorescence method, and silicate chemical analysis. The analysis results showed that the chemical composition of barium sulfate includes barium sulfate (BaSO₄) at about 89–91%. The remaining components are impurities: calcium (Ca) – 8–8.4%, silicon dioxide (SiO₂) – 1.6–1.8%, aluminum oxide (Al₂O₃) – 0.1–0.13%, and iron oxide (Fe₂O₃) – 0.15–0.25%. Micro-silica is a fine-dispersed powder consisting of silicon dioxide (SiO₂) particles ranging from 0.1 to 0.3 micrometers in size. Its SiO₂ content is approximately 85–98%. It also contains impurities: aluminum oxide (Al₂O₃) – 0.2–0.8%, iron oxide (Fe₂O₃) – 0.1–0.5%, and calcium oxide (CaO) – about 0.5%. The chemical composition of bentonite from the Abshir deposit is characterized by the following component contents: silicon dioxide (SiO₂) – 65.84%, aluminum oxide (Al₂O₃) – 14.8%, iron oxide (Fe₂O₃) – 4.35%, calcium oxide (CaO) – 2.85%, magnesium oxide (MgO) – 1.76%, loss on ignition (LOI) – 2.72%, and other impurities – 7.68%. For processing barium sulfate powder, a hydrocavitator was used, which ensures effective treatment of liquid media through a combination of cavitational and mechanical effects. Results. To develop the technology and optimize the composition and properties of the ceramic composite, bentonite clay, finely ground barium sulfate, and micro-silica were used as raw materials. The experiment was conducted based on a four-factor plan B4. Regression equations describing the dependence of the material’s density, water absorption, strength, and shrinkage on the varying levels of the factors were constructed from the levels of factor variation and the experimental data obtained. Corresponding nomograms reflecting the influence of the studied factors within the experimental plan were developed based on these equations. Optimal parameters ensuring high strength of the ceramic composite were identified: barium sulfate content of about 20–25%, micro-silica content of approximately 5%, firing temperature around 850 °C, and heat treatment duration of 30–45 minutes. Subsequently, the barium sulfate powder was processed using a hydrocavitator, after which the technological modes and physical-technical characteristics of the powder after cavitation treatment were determined. The composition and properties of the barium sulfate powder were analyzed using X-ray diffractometry, performed on an AL-27MINI diffractometer within the 2θ range of 10° to 70°. Fourier-IR spectra were recorded on an IRSpirit-T spectrometer equipped with a QATR-S accessory, within the range of 400–4000 cm–1. Conclusion. Optimization of the composition and properties of the ceramic composite based on the analysis of mathematical models indicates that it is advisable to use barium sulfate powder in an amount of about 20–30% and micro-silica up to 10%, at a firing temperature of 850–900 °C and a heat treatment duration of 30–45 minutes. Such a composition allows achieving high strength and water resistance of the material. After cavitation treatment, barium sulfate powder changes its chemical activity and can be used in the composite in an amount up to 20% by mass relative to the bentonite. Adding more than 20% of barium sulfate powder causes intense chemical reactions due to the presence of sulfur, leading to the destruction of the material’s structure. Therefore, it is recommended to limit the barium sulfate content to a maximum of 20% to avoid undesirable effects, including explosive or destructive processes within the ceramic composite structure.