Refractories and Industrial Ceramics最新文献

Information is provided about thermally expanded graphite (TEG) properties and production by oxidation modification, excluding graphite matrix destruction. The possibility of introducing TEG into the structure of periclase concrete as a carbonaceous component is studied. Physicochemical properties of periclase-carbon concrete are determined using TEG, as well as slag resistance of the samples obtained.

High-temperature annealing of a composite material based on the Ti₃SiC₂ MAX-phase dispersion-strengthened with TiC and TiB₂ particles obtained by free SHS compression was carried out. The annealing was carried out in an oxidizing atmosphere at 900, 1100, and 1300°C for 10 h and at 1400°C for 4 h. Experimental dependences of the specific weight gain of the oxidized samples and the oxidation rate on the temperature and annealing time were plotted. The effect of annealing temperature on the phase composition, structure, and mechanical properties of the materials was established based on x-ray phase analysis, scanning electron microscope images, and energy-dispersive analysis. The proportion of the MAX-phase increased from 26 to 63 wt.% as the annealing temperature of the material increased.

This paper presents the results of the development of low-cement refractory concrete (LCRC) based on an aggregate made of kaolin chamotte with a maximum application temperature of 1500°C. To obtain high rates of workability, narrow fractions of aggregate with reduced water demand should be used. Acomparative analysis of the effectiveness of superplasticizer additives was performed, and their effect on the properties of kaolin chamotte-based LCRC was evaluated. Results establish that the use of kaolin chamotte provides high strength for refractory concrete (>50 MPa after drying and first heating to operating temperatures).

In this article, we review the existing types of binders for thermal and acoustic insulation made of glass and mineral fibers. The current interest in the development and modification of binders for the manufacture of thermal insulation used in the transport, construction, and other industrial sectors is associated with increased requirements for their operational, environmental, and fire-retardant characteristics. Directions in the development of binders for fiber thermal insulation materials that meet modern requirements are indicated. Thus, thermal protection systems should possess sufficient strength and flexibility to maintain their integrity during manufacture, transportation, and installation in target volumes, as well as sufficient elasticity to restore their volume after compression, low specific gravity, low coefficient of thermal conductivity, flame resistance, low smoke emission, and resistance to moisture gain during heating and cooling.

An attempt was made to synthesize for the first time composite electrochemical coatings using bulk-reinforced Al–TiB₂ composite powder. The effect of the current density at the fixation stage of composite particles to the sample surface on their volume fraction in the coating was investigated. Heat treatment of the obtained coatings produced very hard protective layers of the intermetallic(ceramic system with a thickness up to 200 μm and high microhardness.

Sustainable development implies proper management of man-made waste to ensure its reuse, thus mitigating the associated environmental burden. Apromising direction for recycling of water treatment sludge consists in its mixing with peat as a potential raw material for the production of construction and ceramic materials. An installation is developed for the collection of milled peat, its mixing with water treatment sludge, drying of the resultant mixture, and its grinding for use in the production of construction and ceramic materials.

The specifics of a manufacturing technology for products and structures made of heat-resistant concrete are considered. The main disadvantages of the production of ready-made mixtures of heat-resistant concrete directly on the construction site are highlighted. The expediency of using dry mixtures of heat-resistant concrete to ensure the proper quality of products and structures is argued. The technological aspects of manufacturing ready-to-use mixtures based on semi-finished products under the conditions of a construction site are described. Examples of successful application of heat-resistant concrete made from dry mixes at industrial facilities of the Russian Federation and Kazakhstan are given.

The duration of converter campaigns has increased significantly because of improvements in steel smelting technology, the quality of the refractories used, the lining design, and various methods of maintaining the lining in working condition during the campaign (hot repair).

The technology for 3D printing large-format ceramic refractories used in thermal units and refractory equipment has been developed. Because of the capillary effect at the grain boundaries in printed layers, the proposed technology enables achieving very high interlayer cohesion, obtaining ceramic refractory products not limited by geometric dimensions and shape, including the finished lining of any thermal units.

This paper presents the results of the studies of refractory materials produced by the company Keralit, the Borovichi Refractories Plant, and Scientific and Technical Center Bakor (STC Bakor) and intended for the roof of an EP-6 electric furnace for high-level waste vitrification. These studies determined the strength properties and acid resistance of these materials when exposed to nitric-acid in vapor and solution forms. The results of the studies show that the optimum materials for constructing the melter roof are MKRTU-50 and MKV-65 produced by the Borovichi Refractories Plant and STC Bakor, respectively.