VOL 91, No. 4 (2018)

The technological parameters for the synthesis of an optically transparent glass-crystalline material based on lithium silicate glass under the conditions of a two-stage low-temperature short-term heat treatment have been developed. It has been established that such a material, characterized by high mechanical properties, heat resistance and light transmission 72 & # 37;, is promising in the development of transparent sitalls for the protection of optical devices of special equipment.

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.

Elemental analyzes of ceramic samples over 1000 years old showed that the main chemical elements are, & # 37 ;: for samples: the outer part of the bricks: 24.45 Si; 14.31 Ca; 12.68 C; 11.55 Al; 5.60 Fe; 4.29K; the inside of the bricks: 32.23 Si; 17.66 Al; 12.66 Fe; 5.52K; 3.07 C; 1.36 Ti; 1.34 Ca; inclusions in bricks: 53.11 C; 13.40 Ca; 5.46 Si; 3.08 Al; 2.63 K; 1.78 Fe. It was determined by X-ray phase and electron microscopic methods of analysis that the strength properties of ceramic samples are given by mullite, anorthite and wollastonite. In addition, the presence of closed porosity in ceramic specimens with isometric and oval pores contributes to increased durability.

The influence of the introduction of the superplasticizer & # 171; Polyplast SP-3 & # 187; into a concrete mixture, which made it possible to regulate the construction and technical properties of concrete. The acceleration of the setting speed of the composition with the additive due to its peptizing effect has been established. At the same time, an increase in the strength indicators and frost resistance of the modified concrete was found.

The results of X-ray diffraction and infrared analyzes of powders of zinc-substituted hydroxyapatite and tricalcium phosphate are presented, and the technology of plasma spraying of coatings based on them is presented. Structural-morphological and physicochemical characteristics of the obtained coatings were investigated, and their adhesion strength and degree of hydrophilicity were determined.

Profiled leucosapphire, which possesses a set of unique technical characteristics, in some cases is the only material that makes it possible to create new highly efficient devices and devices operating under extreme conditions on its basis.

Samples of electrodes with an active layer based on TiO ₂, RuO ₂, and SnO ₂ oxides have been obtained. The physicochemical characteristics of the electrode surface have been determined. Their electrochemical behavior was studied. The values ??of the current-free potentials are determined. The dependences of the rate of the anodic processes of chlorine and oxygen evolution on the composition of the electrode are presented. SEM images and 3D images of sample surfaces are shown.