Refractories and Industrial Ceramics最新文献

This article presents the results of the experimental studies of basalt rocks from the Berkurtau and Ushtau deposits of Karakalpakstan. Samples of basalt rocks from the investigated deposits can be used as the main raw material component for the production of ceramic materials, which helps expand the raw material base for the production of ceramic materials for construction purposes.

Removal of adhered and adfrozen clay material from dumpcar bodies is a labor- and time-consuming process. In this work, we develop a method for electromagnetic shedding of clay material from container walls. Additionally, a classification of soils by stickiness is presented. Complete discharge of the dumpcar body from adhered and adfrozen rock mass under a slight tilt or in the absence of a tilt reduces the duration of the process, allowing the number of trips to be increased.

The main purpose of a liquid binder in the composition of mineral wool products is to bond individual fibers to each other to create a strong and elastic structure. The combined use of an organic (phenol-formaldehyde resin) and an inorganic binder based on cold dissolution liquid glass is accompanied during their mechanical mixing by the formation of complex carbon-silicon compounds, which stabilize the formation of chelate compounds with an orienting effect of silicon ion during heat treatment, converting the polymer structure to a more ordered and dense structure with additional bridging hydrogen bonds. This process is accompanied by the parallel development of a polycondensation reaction of the organic binder and methylol groups and curing of the liquid glass. The presence of intramolecular bonds between the organic and inorganic parts of the binder increases the bond strength of the mineral fibers when forming the structure of fibrous thermal insulation materials by 20 – 30% with a slight increase in their water absorption. Limited use of cold dissolution liquid glass additives (not more than 0.4%) allows a reduction in the total consumption of organic binder by 20 – 25% with the possibility of reducing the required amount of mineral part by up to 10 – 15% while maintaining the required strength and operational properties of finished heat-insulating products.

A structural model of two-fraction ceramic dispersions in the form of two single fraction subsystems is proposed. The first contains a given volume fraction of spherical large particles interconnected mainly through a matrix phase consisting of small particles, aerosil and SAS (surface active substances). The second subsystem includes just small particles of quartz and aerosil with an average particle diameter of less than one micron, and the second matrix phase is formed by water and surfactants. The second subsystem forms an endless network between large quartz particles, maintaining these particles in suspension. The model permits calculation of the average coordination numbers and distances between particles in both systems.

Calculations of the residual silicon content in the structure of reaction-sintered silicon carbide are presented. The dependence of the ultimate bending strength on the initial carbon content was experimentally established. An optimal composition of powder mixtures, which allows materials with maximal strength characteristics to be obtained, was determined.

Results of studying the process of producing reactive alumina in the presence of a complex additive, including polycarboxylate ester (PCE) and polyethylene glycol (PEG), are presented. The effect of such reactive alumina on rheotechnological properties of matrix systems and low-cement refractory castables is evaluated. The synergetic effect of combined introduction of PEG and PCE during fine milling of raw alumina is established. It is shown that the deflocculating effect of polycarboxylate ester and the intensity of the milling process are strengthened.

The present study investigates the impact of quartz, mullite, spinel, and corundum fillers on the rheological properties and extrudability of silica glass suspension-based compositions. The results indicate that materials containing mullite, spinel, and corundum exhibit dilatant flow behavior, which impedes their use as inks in 3D printing. Conversely, suspensions containing quartz filler display a nonlinear viscoplastic flow. The addition of polyvinyl alcohol to compositions with quartz filler enhances their shape retention factor during extrusion by increasing their yield stress and viscosity.

The paper is dedicated to studying the structural and mechanical properties of ceramic coatings obtained by micro-arc oxidation (MAO) using a cathodic-anodic mode in alkali-silicate, borate, and alkali-silicate-phosphate electrolytes from an experimental sample of compositions. Coatings formed using borate electrolyte have the best mechanical properties, resulting in the improvement of wear resistance of an unprotected aluminum surface by 2.1 to 3.1 times, depending on the content of borate ions in the utilized electrolyte. Ceramic MAO coatings offer a potential for use at the Russian repair and maintenance enterprises, which are engaged in the repair and restoration of worn aluminum and steel materials used in critical components of agricultural machinery.

The functional characteristics of materials based on bismuth titanate Bi₂Ti₄O₁₁ largely depend on the synthesis conditions. The preparation of nanocrystals of this compound is timely because of the problem with miniaturization of electronic components. The features of phase formation and the optimal conditions for the formation of a nanoceramic material based on Bi₂Ti₄O₁₁ via coprecipitation from salt solutions are studied in the present work. The morphological features, formation temperature, and activation of sintering of the material were established.

The influence of additives of different nature on grinding, compressibility, and sintering of calcined magnesite was investigated. It was found that the investigated recycled additives, when introduced in the amount of up to 0.5 wt.%, have no significant effect on the grain composition of calcined periclase after grinding, the compressibility of powders, and their chemical and phase composition after firing at a temperature of up to 1870°C. An additive based on dust wastes of titanium production enables increasing the density of the obtained briquette by 1.0 – 3.5 % or reducing the briquette firing temperature by 50 – 100°C.