Refractories and Industrial Ceramics最新文献

The main aspects of obtaining an artificial ceramic binder (ACB) based on the original (quarry) and heat-treated diatomite are considered. The process of obtaining ACB is studied, and the main rheological properties and physicomechanical characteristics of specimens are analyzed. It is established that ACB based upon quarry diatomite exhibits thixotropic rheological behavior, and ACB based upon preheat-treated diatomite pertains to a thixotropic-dilatant type. Use of this technology for preparing a binder makes it possible to reduce molding moisture content in manufacture of various diatomite products and to improve their quality while reducing production costs compared with similar objects prepared by traditional technology.

The effects of TiB₂ and BN coatings on the thermal and stress–strain state of two systems of Si₃N₄–TiC ceramic surface layers under the action of heat flow are investigated. An analysis of results from numerical experiments showed that the TiB₂ coating has a more favorable effect on the stress state of ceramic surface layer; the BN coating, on the stress state of the boundary with the ceramic.

Results of experimental measurements of mechanical and physical characteristics of refractory materials are presented: LTEC, thermal conductivity, heat capacity, dynamic and static elasticity moduli. The study is conducted to select material for the manufacture of a glass furnace arch for solidifying radioactive waste. It is shown that materials of the MKRV-53 and AZS-60SB grades are superior with respect to properties compared with material of the BMKrF grade. The results obtained are used for mathematical modeling of electric furnace arch operating regimes.

A method for assessing technical risks arising during the operation of heat engineering units is presented. Risk assessment is based on the data on the residual life of the unit’s lining and an evaluation of the severity of the consequences of an accident. To obtain primary data when assessing the residual life, an instrument method is used that allows continuous monitoring of the thermal state of the lining. Thermomechanical stresses exceeding the ultimate strength of the material are shown to be the determining destruction factor. These stresses are calculated according to the developed scheme based on numerical methods.

Indicators of strength, density and change in volume of magnesium phosphate materials based upon Kovdor Mining and Enrichment Combine waste after drying in a mold at 90 and 180°C are determined. Graphical dependences of properties on fractional composition of a briquette from forsterite concentrate and heat treatment regime are constructed.

An earthquake-resistant M125-M150 brick based on substandard interlayer clay was obtained using ferrous metallurgy waste, i.e., aspiration dust, as a repellant that was involved in the formation of the framework structure due to the content in it of phases (chromite, forsterite, anorthite, and diopside) bound by a glassy phase. The seismic brick was based on industrial waste without the use of traditional natural materials.

The results of a comprehensive assessment of the quality of coatings obtained by electrospark deposition technique are presented. The assessment was performed using modern measurement instruments and dedicated software packages to determine the parameters of micro- and macro-geometry of the coated surfaces. It has been established that the main criteria for assessing the thickness of electrospark coatings, used to restore and harden parts, are the minimum depth, as well as the maximum height and peak-to-valley distance of the profile. It has been proven that the optimal ratio between the length of the bearing friction surface that receives an external load and the length of the surface covered by lubricant is at least 80 % for tribotechnical friction couples, and at least 60 % for parts with hardened surface.

Compositions prepared on the basis of fine corundum and aluminophosphate binders modified with B³⁺, Cr³⁺, Mo⁶⁺, and Zr⁴⁺ ions are considered. The influence of the ions listed on thermophysical properties of aluminophosphate compositions is studied. Results of comparative tests for the composites obtained in an arc plasmatron flow with estimation of surface melting temperature of the specimens are presented. Results of moisture adsorption studies of the composites with various relative humidity are shown.

The technological process of natural water treatment before being supplied to the water supply network is accompanied by the formation of water treatment sludge. The chemical composition of water treatment precipitation is characterized by the presence of aluminum and iron hydroxides, manganese oxide, and an undissolved residue of chemical reagents used in water treatment. The strategy of sustainable development presupposes proper management of man-made waste, capable of ensuring their reuse and reducing the associated environmental burden on the environment. There are known options for using water treatment sludge in the production of bricks, expanded clay, and cement. The use of water treatment sediments in the production of burnt ceramic materials is effective. A promising direction for the utilization of water treatment sludge is the possibility of its use in a mixture 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, and subsequent drying of the resultant mixture.