Consolidation of industrial silicon carbide powder was carried out using a spark plasma sintering unit. It has been shown that preliminary mechanical activation is a promising method for introducing a high content of boron additives into silicon carbide. The effect of the amount of boron additive on sintering, microstructure and properties of ceramic material has been studied. The obtained ceramics based on silicon carbide with a mass content of 10 & # 37; boron with a density of 3.12 g / cm 3 , a hardness of 31.9 GPa and a fracture toughness factor of 5.65 MPa • m 1/2 , promising for use as a structural material in nuclear reactors and gas turbine engines
A refined analytical method is proposed for determining the average (hydraulic) radius of a capillary on the basis of a three-dimensional model of the porous structure of materials, taking into account the geometry of the capillaries. The derived calculation formula for the mean radius is much more accurate than the generally accepted Kozeny formula. Good agreement with experimental data was obtained. On the basis of this model and a fundamentally new approach, a technique was developed and a calculated expression for the average radius was obtained from the data of liquid absorption into a porous material, which is several times more accurate than the known methods. The calculation results are given.
A comprehensive assessment of the state of the glazed porcelain surface by mechanical and optical means has been carried out. It is shown that both of these tools can be used to assess the quality of the glazed surface, but in combination they are more informative. It was determined that the brilliance of the surface is more influenced not by the depth of irregularities, but by their width. In terms of the surface quality of the feldspar glaze, the hard porcelain specimens are inferior to the bone porcelain specimen.
The results of studying the properties of heat-efficient ceramic materials from substandard clay raw materials and microgranules of foam glass as a porous, emaciated component are presented. Foam glass micro-granules shorten the drying process and reduce the firing temperature. The structural and textural features of the obtained heat-efficient materials and their influence on the physical and mechanical properties have been investigated.
A method of manufacturing ceramic cores from ytterbium oxide enriched in ytterbium-168 isotope is presented. This method is based on sintering ytterbium oxide powder under a high isostatic pressure of about 8 GPa in order to obtain its B-modification with a monoclinic crystal lattice structure. The equipment used, the sintering modes and the results of the analysis of the obtained samples are described, which, due to their high density (up to 10.2 g / cm 3 ), are promising for use as sources in contact radiation therapy of tumors
The composition of the charge for the production of facing ceramics based on low-plasticity clay has been developed. As additives, the mixture is introduced (mass content, & # 37;) 10 & # 37; titanium dioxide, 5 & # 37; boric acid and up to 5 & # 37; galvanic sludge. The influence of charge components on the composition and structure of the developed material, as well as the main operational properties of products obtained on the basis of the developed composition, has been investigated. The results confirm the possibility of synthesizing environmentally friendly ceramics obtained due to the vitrification (self-glazing) effect on the surface of products and on the surface of ceramic particles throughout its volume.
The rheological properties of highly concentrated suspensions consisting of nanocrystalline zirconium oxide powders of monoclinic, tetragonal and cubic modification (stabilized at a molar content of yttrium oxide 4 and 8 & # 37;) and liquid UV photocurable monomers of various nature have been investigated. Dynamic viscosity of suspensions with the highest filling by volume up to 32 & # 37; was 3 Pa & # 215; s at a shear rate of 10 s -1 and about 1 Pa & # 215; s at 100 s -1 at 20 & # 176; C
It is proposed to control the redox conditions of porcelain firing in sity (& # 171; in place & # 187;) by reflection spectra in the UV-VIS-NIR region. The difference in color characteristics of glazed porcelain has been shown to be correlated with reflection at .lambda; & # 8776; 1100 nm, which depends on the Fe 2+ / Fe 3+ ratio, mainly in the glaze composition. It was found that with an increase in the intensity of the band of the optically active center of Fe 3+ luminescence, the reflection coefficient of glazed porcelain at? & # 8776; 1100 nm
The results of the study of solid-phase synthesis and technological parameters for obtaining weather-resistant ceramic pigments of gray, gray-yellow and gray-brown colors are presented. The physicochemical and technological properties of the synthesized pigments have been investigated.
Samples of supports for membrane catalysts using a boehmite suspension were synthesized on the basis of alumina. The morphology, phase composition and porous structure of the carriers have been investigated.
