Vol 76, No 7-8 (2019)

The structural parameters of glass membranes are studied as a function of their porosity in the model of non-intersecting tortuous capillaries, which specialists generally use, and it is shown that the expression for the average radius of the pores is not accurate. A more accurate procedure is proposed for calculating the structural parameters of glass membranes using a model of randomly arranged spheres for a cavernous medium and a model for powder materials. This made it possible to obtain additionally the average coordination number and the radius of spherical pores as well as the average radius of the necks of the spherical pores of membranes.

The results of investigations of the porosity of heat-efficient ceramic materials based on clays with different mineralogical composition with a porous glass component (PGC) and their impact on the frost resistance and thermal conductivity are reported. It was found that the content of the illite and montmorillonite subgroup of clay minerals in compositions with PGC determines the optimal quantitative ratio of meso-, macro-, and also ‘dangerous’, reserve, and ‘safe’ pores, which promotes high frost resistance and reduction of the thermal conductivity of the materials.

The possibility of using plasma technologies in glass production is examined. The specifics of the glassmaking process are presented for the synthesis of silicate lumps in a plasma glassmaking furnace. It is shown that the plasma-forming waste gases can be used for heat-treatment of granulated batch.

The possibility of obtaining artificial porous aggregates based on cullet and ash-slag wastes from thermal power plants is examined. Experimental studies are performed to optimize the aggregate production technology. The method of experimental planning was used to minimize the number of experiments and maintain statistical reliability of the results. The Multiple Regression module of the STATISTICA system was used to construct multi-factor regression models.

An investigation of the properties of multifunctional coatings based on silicon dioxide and titanium dioxide with inclusion of silver nanoparticles in their structure is presented. Methods for obtaining coatings based on Ag + SiO₂ and Ag + TiO₂ particles are now known, but complex expensive laboratory equipment is required to implement most of these methods. The aim of the present work is to determine the optimal conditions of synthesis for obtaining stable sols of silicon and titanium dioxide and to study their properties by physicochemical methods of analysis.

The results of research on the possibility of using igneous rock from Belarus for synthesizing glasses, petrositalls, and cast stone are presented. Acomponent of hierarchical modeling—the construction of cluster structures (dendrograms) — was used to optimize the technological processes. The properties, structure, and form of the formed crystalline phases are revealed to be dependent on the chemical-mineral composition of the rock and the temperature-time parameters of heat-treatment as the main criteriological factors in the directed structure- and phase-formation in obtaining glass-ceramic materials.

One of the reasons for the comparatively low quality of dense ceramic materials (porcelain tiles, facade tiles, and floor tiles) resulting from the appearance of a black core is the presence in them of unburned carbonaceous particles remaining in the articles after firing because of poorly selected compositions and heat-treatment regime. Studies have shown that the highest weight content of C (carbon) with respect to other layers of porcelain stoneware is found in the black porous core (9.68%). The appearance of a black core is explained by the fact that in the heating process organic impurities are charred primarily in the inner layers of the porcelain tile which are isolated from the air oxygen. Moreover, the formation of the black core will also be promoted by sintering with the participation of a liquid phase, which will isolate from the air the not yet fully oxidized carbonaceous material.

The grain size of ground glass as the main component has a decisive influence on the quality of construction products made from foam-glass concrete. This means that the grain size must be regulated for definite types of products and it must be possible to make in-line adjustments in the comminution of technogenic cullet. To this end an adaptive vibratory mill equipped with an electronic-hydraulic control system for making in-line adjustments in the technological regime of comminution as a function of the initial material and the required grain size of the comminuted glass was developed.

Relations obtained from an analysis of published data and as a result of mathematical modeling of a glass furnace are presented for calculating the heat flux density into the environment from the outer surfaces of the enclosure of an industrial furnace — sidewalls, roof, and hearth. On the basis of a comparative analysis of these relations for a glass furnace recommendations are formulated for selecting and using relations for calculating the coefficients of heat emission from the outer walls of the enclosure for the purpose of making a better determination of the heat balance of a furnace.

The results of an investigation of glasses and glass ceramic materials synthesized in the system R₂O(Na₂O, K₂O)–MgO–CaO–Al₂O₃–SiO₂ using granitoid screenings from the Mikashevichskoe deposit are reported. Glass ceramic materials which in terms of the performance characteristics can be used as proppants in the oil and gas industry were obtained.

Single- and multi-component sintering additives for aluminum oxide ceramics are presented. It was determined from the published data that because of their higher melting temperatures and the impossibility of simultaneously influencing a number of properties of the desired material single-component additives are less effective than multi-component additives. Because of synergy multi-component additives makes it possible to simultaneously improve the properties of sintered samples based on aluminum oxide, specifically, greater compaction (porosity about 0.1%) of the samples, sintering temperature reduction to 1400°C, preservation of a fine-crystalline structure (average grain size about 3 μm), higher crack resistance about 5.86 MPa · m^1/2, and higher ultimate strength in bending about 600 MPa.

Studies of the effect of fly ash from the incineration of municipal solid wastes on the properties, durability, and environmental toxicity of fired aluminosilicates are presented. In the fabrication of aluminosilicates, fly ash was introduced into the batch in the amounts 2.5 – 7.5%, the firing temperature of the articles was 1000°C, and the isothermal soaking time was 1 h. The investigations showed that the introduction of 2.5% fly ash into aluminosilicates promotes leaching of heavy metals, sulfates, and chlorides according to the current regulation 200333EC. The density of such fired aluminosilicate is equal to 1.8 g/cm³, the strength in compression 24 MPa, water absorption 15.3%, total open porosity 31%, and frost resistance at least 25 freezing-thawing cycles.

The physicochemical properties of the carboxylic cationite Tokem-200 and the sulfo-cationite Tokem-140 as well as their Ca²⁺-ion selectivity under equilibrium conditions were investigated and Tokem-200 based biomaterials of spherical form were synthesized from solutions by the sol-gel method. The material frame is represented by TiO₂–SiO₂; the inner part is filled with the oxide Ca²⁺ (sample TiO₂–SiO₂ /CaO). Unlike Tokem-140, the carboxylic cationite Tokem-200 possesses the highest Ca²⁺-ion selectivity, which makes it promising for the development of biomaterials. The solutions were found to remain suitable for up to 5 days for obtaining materials. To obtain a homogeneous material stepped heat-treatment is required (after drying at 60°C) at 150, 250, and 350°C (30 min at each step) and at 600°C for 6 h. Additional post-drying immersion of the samples into phosphoric acid does not favorably affect the properties of the material.