Vol 76, No 3-4 (2019)

The particularities of the impact of the addition of lanthanum cations on the thermochemical behavior of modified zirconium hydroxide were investigated. It is shown that the composition and properties of the obtained materials are determined by the concentration of the modifier and the formation temperature of the oxide phase.

Oxide chemical analysis of White Tower samples showed that the major oxides (content > 5%) are, %: SiO₂–50.07; Al₂O₃– 16.3; Fe₂O₃– 7.04; CaO – 9.08. The loss on ignition is 11.32. In addition, elemental analysis determined a heightened carbon content carbon – 9.59%. The heightened carbon content (9.59%) in the inclusions attests the introduction of fuel into the green body, which increases the porosity of the articles and promotes uniform sintering of the ceramic, and the heightened content of alkali oxides (R₂O > 3 – 4%) promotes the formation of a glass phase up to 1000°C. X-ray phase analysis showed the presence of anorthite, hematite, and wollastonite, which promotes greater strengthening. Moreover, the presence of isometric pores and oval closed porosity in the ceramic samples increases durability.

It is demonstrated that femtosecond laser pulses can be used to form birefringent microregions in sodium borosilicate glass with the composition 68 SiO₂, 27 B₂O₃, 4 Na₂O, and 1 Al₂O₃ (mol.%); the birefringence is associated with the formation of nanogratings and its slow axis is oriented perpendicular to the polarization plane of the writing laser beam. The dependences of the phase shift of the light passing through these microregions on the number and energy of the laser pulses forming them are determined. It is shown by means of confocal RS spectroscopy that the content of sodium cations decreases in the formed microregions.

The special design features of transport-process lines for conditioned quartz sand used in the preparation of glass batch in batch plants are examined. Different variants of the schemes used to unload, store, and class a given raw material are presented. It is noted that additional separation of conditioned quartz sand containing random foreign impurities is necessary.

The results of a comparative study of compacts obtained by spark plasma sintering from nano- and ultradisperse (UD) aluminum oxide powders with spherically shaped particles are reported. It is shown that the compacts obtained from UD-powder have higher density and greater strength, microhardness, and structural uniformity with smaller grains than compacts obtained from nanopowder. Preliminary magnetic-pulse compaction of powders prior to sintering improves the characteristics of both compacts but higher density and strength with smaller grains are achieved in compacts obtained from UD-powder. In both cases of preliminary preparation the UD-powder compacts have advantages over nanopowder compacts.

Pigments and binders for obtaining radiation-resistant thermal-control coatings (TCC) for spacecraft were studied. A radiation-resistant thermal-control coating was obtained on the basis of the chosen components. The 15-year resistance of the coating in a geostationary orbit (GSO) was evaluated on the basis of ground-based tests. The comparative characteristics of white TCC (based on BaSO₄), which are currently the most widely used coatings in Russia, are presented.

Technologies were developed for fabricating tiles and porous aggregate from cellular glass based on ash-slag waste from the Novocherkassk State District Power Plant (SDPP) as well as heat-insulating lightweight construction concrete. Three-ply energy efficient panels for use in frame-panel home construction were obtained on their basis.

The results of an experimental study of the influence of twisting and bending forces on pins resulting in loss-of-tightness in sealed metal-glass articles (MGA) are reported. The critical values of the angles of rotation and bending of the pins at which glass begins to break are indicated. The technological features of MGA fabrication that increase the strength of a metal-ceramic seal are shown. The results are of interest for the manufacture of different hermetic relays and devices and explain the possible causes of the loss-of-tightness in devices.

The introduction of 10 – 50% (by weight) brushite powder, preheated at 50° and then fired at 1200°C, into a permeating suspension based on hydroxyapatite powder heat-treated at 800°C results in partial decomposition of hydroxyapatite to the α- and β-modifications of tricalcium phosphate. The presence of a tricalcium phosphate phase in calcium phosphate foam ceramic promotes an increase of the porosity from 40 to 60% and the resorption with significant static strength reduction from 3 – 7 to 0.3 MPa.

The use of alkali glass in micromechanical sensors, specifically, accelerometers, is shown. Alkali glass is used in the sensitive elements of the indicated devices. The main technological operation in the assembly of such sensitive elements is electrostatic bonding, also known as the anodic bonding. In this process a number of complex physical effects occur in the glass. Reliable functioning of the fabricated devices depends on the quality of the execution of the parts made of alkali glass and silicon.