It is shown that when a reduced pressure is created in the firing zone due to the released gases (Н 2 and CO), the nature of the gaseous medium becomes reductive, which contributes to an earlier reduction of active forms of iron oxides and the formation of a glass phase, intensifying the sintering of clay rocks. ... Tab. 3, ill. 2, bibliography: 2 titles.
Ceramics based on silicon nitride powder obtained by self-propagating high-temperature synthesis have been investigated. Yttrium aluminum garnet and mullite were used as sintering additives. The resulting material has a strength of up to 540 MPa. Il. 3, bibliography: 12 titles.
The SHS method was used to synthesize pink corundums, as well as spinels with chromium-containing additives. The synthesized pigments can be used to decorate porcelain and other ceramic products. Il. 3, bibliography: 4 titles.
The results of a study of the possibility of volumetric coloring of slab masses by the method of clay impregnation with solutions of salts of 3d elements (Ni, Co, Cr, Fe), which makes it possible to obtain pigments of a mullite-like structure with high chromophore indicators using energy-saving technology, are presented. The use of natural raw materials and soluble salts of 3d elements will make it possible to significantly expand the raw material base, reduce the cost of manufactured products by replacing expensive materials and combining the process of synthesizing pigments and firing products. Tab. 1, ill. 2, bibliography: 3 titles.
The article considers a technique for studying the crack resistance of a clay semi-finished product during the drying process. It is proposed to establish the safe drying time for products of complex shapes by plotting a diagram of the maximum possible moisture removal depending on the shape factors (reduced thicknesses) of simple parts of the product. The technique was tested on samples from the studied clay and industrial brick mass. Tab. 2, ill. 7, bibliography: 6 titles.
The results of a study of the phase formation of silicon nitride during the combustion of ferrosilicon in gaseous nitrogen are presented. It is shown that the formation of a- or b-modifications of silicon nitride is mainly determined by the composition of the charge for self-propagating high-temperature synthesis. When ammonium chloride is introduced into the initial ferrosilicon, a combustion product is formed with an increased (up to 80%) content of a-Si 3 N 4 , while dilution with the final product and magnesium fluoride results in to the formation of predominantly (more than 95%) b-Si 3 N 4 . The size and shape of the particles depend on the synthesis conditions and are primarily determined by its temperature and the additives introduced into the initial alloy. Il. 3, bibliography: 8 titles.
A method is proposed for designing a charge composition of a two-component clay mass for the production of rough wall ceramics based on acid loams and the addition of unconventional semi-acid clay with an increased content of iron oxides. Bibliography: 3 titles.
From the standpoint of the chemistry of crystals with defects and synergetics, an explanation is given for the rapid growth of crystals after the beginning of the formation of closed pores in the sintered workpiece. A change in the structure of an infinite cluster from open pores during their transition to closed pores decreases the concentration barrier from vacancies, which prevents diffusion transfer across the crystal boundaries and their growth. Abnormal growth is facilitated by the non-dimensional shape of the crystals and the high rate of diffusion mass transfer. The easy deformability of the crystal boundaries can lead to the adjustment of their crystallographic orientations and the integration of crystals, which ensures their anomalously fast growth. Bibliography: 15 titles.
The technology of ceramics based on hydroxyapatite is considered. Dispersed systems and their evolution at each technological stage are determined. The data of gravimetric and dilatometric analysis, scanning scanning microscopy are presented. The aggregate size distribution in the initial powder and the grain size distribution in sintered ceramics are compared. The structural inheritance of the properties of the initial powders, which is characteristic of ceramic materials, is shown. Il. 7, bibliography: 23 titles.
A porous heat-resistant composite material has been developed from natural powders, which form a cordierite matrix during sintering, and a filler - a fibrous nanostructured aluminum oxide powder with high porosity and reactivity. It was found that the introduction of a nanocrystalline filler of aluminum oxide into a composite with a cordierite matrix causes the formation of a polyporous structure that increases porosity and heat resistance, as well as improves the thermal insulation properties of the material. Il. 5, bibliography: 8 titles.
