Refractories and Industrial Ceramics最新文献

Ceramic composite materials based on stabilized zirconium oxide with up to 9 mol.% of the stabilizing additive Y₂O₃ were obtained in this work by self-propagating high-temperature synthesis. The effect of the stabilizing additive content on the combustion characteristics of the obtained materials and their phase composition was studied. Introduction of Y₂O₃ into the studied materials was shown to lead to the formation of the cubic modification of ZrO₂ in the synthesis products, while three ZrO₂ modifications were observed without introduction of Y₂O₃ into the synthesis products.

Ceramic materials based on cordierite Mg₂Al₄Si₅O₁₈ and their various compositions and methods of preparation are considered. Results of thermal shock resistance tests of ceramic samples of different compositions are presented. The thermal shock resistance of the obtained samples is >15 heat changes (1000°C – 15°C tap water). Cordierite material, which is proposed to be produced using only domestic raw materials, has good potential when used as a thermally stable catalyst support for controlling industrial emissions and automobile exhaust gases.

High-magnesium waste, which is a promising secondary mineral raw material for the production of refractory building materials, ceramics, and several other types of products, is of particular interest among various types of technogenic raw materials. This group of waste includes caustic magnesite dust from the Magnezit Plant, which is subjected to intense hydration in the dump. Technogenic raw materials are predominantly weakly cemented fine-grained sandstones and fine-grained aggregates. The mineral base of the material is magnesite, brucite, and dolomite. The force required to destroy technogenic magnesium material was determined as 0.5 – 3.9 kN.

The effect of technological parameters on the characteristics of filtering acid-resistant ceramics is investigated. A technology has been developed for producing large-sized products from ceramic electric-grade material of subgroup 110 by aqueous casting into gypsum molds. The water filtration rate was 0.02 – 0.03 ml/(cm²·h), the percentage of pores greater than 1 µm was 8 – 10%, and the average pore size was 0.04 – 0.06 µm. The variation in the pore structure of ceramic samples made of nanostructured aluminum hydroxide has been studied. The potential for their use to create ultraporous coatings is shown.

This paper presents information about the use of electric glass-melting furnaces in the production of various glasses. Notably, only fused-cast refractories are used to line the most vulnerable parts of furnaces. Previous studies showed that the developed high-chromium refractory HPL-85 can be recommended for melting borosilicate glass E, while the chromium spinelide refractory HAC-26M can be recommended for melting borosilicate glass BS1 for the vitrification of radioactive wastes. Therefore, the necessity of the industrial production of chromium-containing fused-cast refractories based on Russian practice considering the best international achievements and developments has been reported.

This article considers the issues of resource conservation and integrated development of deposits, as well as their involvement in the processing of ore rocks, such as gabbro-diabase of the Bazhenov deposit, which has reduced the environmental burden and the costs of dumping and reclamation. Melting of gabbro-diabase of the Bazhenov deposit makes it possible to obtain a new product, i.e., basalt (rock) wool, which is a good heatproof, soundproof, and fireproof material for the construction industry. Based on this material, a unique hydroponic substrate is produced, which is widely used in agriculture. Increasing the complexity of processing mineral resources is an opportunity to obtain additional profit for the enterprise from new types of products.

Under conditions of increasing loads and temperatures on engineering products the problem of selecting efficient materials is relevant, especially in relation to import substitution. One task for modern materials science is production of high-temperature special engineering components, including complex shapes. Metal and ceramic materials have a number of unique properties, which on the one hand determine prospects for their use in construction of special engineering products, and on the other hand cause a number of production problems, without whose solution exploitation of such products is extremely difficult. Analysis of advanced materials used for products of special high-temperature engineering, including production of various gas turbine engine components, is presented, as well as research results for development of materials with improved properties.

This study discusses the aspects of constructing a computational algorithm for calculating circular suction sockets under oncoming flow conditions using the discrete vortex ring method. Flow patterns are presented for different ratios of oncoming and suction airflow velocities. The dependencies of the characteristic dimensions of the vortex zones arising at the inlet of the suction sockets on the velocity of the oncoming flow and the length and angle of inclination of the socket have been determined. Furthermore, equations are derived for the critical velocity of the oncoming flow, at which the flow separation mode for vortex zone 1 changes from separation inside the socket to outside it. The results obtained can be used to design local suction systems profiled according to the revealed outlines of the vortex zones.

Results of research into formation of ultrapure silicon carbide by self propagating synthesis are described. This synthesis provides a reduction in process time and energy costs. It is established that the main structural transition is caused by phase transformations and polymorphism phenomenon within silica (α-SiO₂ to β-SiO₂ transition) which is necessary to produce pure silicon carbide. It is determined that in a given time interval under the influence of imposed conditions and subsequent interaction with silicic acid and active carbon spontaneous transition begins with formation of ultrapure silicon carbide. Implementation of the proposed technology increases silicon carbide yield to 95 – 99% with a nanoscale product (40 – 60 nm) of 99.99% purity.

Results of studying features of spinel structure formation in the CoO–Fe₂O₃ system obtained using various production techniques are presented. The possibility of forming cobalt (II) ferrite at the surface of a number of carriers is considered. It is shown that depending upon structural characteristics of the substrate, the cobalt (II) ferrite formed has different dispersion and degree of reversibility. It is established that increased catalytic activity in the process of purification of an aqueous solution from an organic dye during hydrogen peroxide breakdown of synthesized materials with an organic carrier has been established.