B. N. Dudkin

Corundum/lanthanum hexaaluminate/alumina nanofiber ceramic composite

We describe a corundum-matrix ceramic composite loaded with layered lanthanum hexaaluminate microparticles and reinforced with alumina nanofibers. The components of the composite are prepared by sol-gel processing. Scanning electron microscopy results indicate that the microparticles and nanofibers are uniformly distributed over the matrix. Surface-modified alumina nanofibers are shown to have the best effect on the strength of the matrix.

Ceric oxide effect on heat-induced transformations of zirconium oxide microfibers prepared by impregnation of cotton fiber

Thermal effects accompanying heat treatment of cotton fibers impregnated with mixed sols of zirconium and ceric oxides have been studied by thermogravimetric analysis and differential scanning calorimetry. Increase of ceric oxide fraction changes the temperature of zirconium oxide transition into the high-temperature tetragonal modification.

The Effect of Yttrium Oxide on the Microstructure and Properties of Ceramics Based on Lanthanum Hexaaluminate Synthesized by the Sol–Gel Method

The effect of a sintering aid, yttrium oxide, on the properties of ceramic materials based on lanthanum hexaaluminate synthesized by a sol–gel method is studied. The synthesis of a sol of ternary oxide composition conducted via hydrolysis of a mixed salt solution leads to the formation of particles with a “nucleus – shell”-type structure. The synthesis of lanthanum hexaaluminate with the participation of these particles proceeds at 1000 – 1100°C, and the sintering of ceramic at 1400 – 1500°C. Ceramic based on yttrium-containing lanthanum hexaaluminate exhibits improved strength properties.

Modification of magnesium silicate with 13(1)- N -methylamide-17-methyl-15-diethylene glycol ester of chlorin е 6

Magnesium silicates modified with 13(1)-N-methylamide-17-methyl-15-diethylene glycol ester of chlorin е6 have been prepared for the first time via heat treatment. The studies by means of X-ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis have revealed that variation of the synthesis conditions affords products differing in the size, particles morphology, and chlorin concentration.

Microstructure of zirconium oxide ceramic fibers obtained by template synthesis

Ceramic fibers of zirconium oxide partially stabilized by ceric oxide were obtained by the template synthesis using sols of initial metals oxides. The formation of the microstructure of ceramic fibers has been studied by the methods of thermal analysis, differential scanning calorimetry, X-ray analysis, scanning electron microscopy, and X-ray spectral analysis. Features of formation of a microstructure of fibers depending on conditions of their preparation were revealed.

Modification of the surface of alumina oxide nanofibers by zirconia nanoparticles

Reinforcement of ceramic alumina oxide-lanthanum hexaaluminate composite by alumina nanofibers, whose surface is modified by nanodispersed zirconia, improves significantly the mechanical properties of the material (bending strength up to 700 MPa and stress intensity factor up to 8 MPa m0.5).

Synthesis of organically modified layered magnesium silicate by the sol-gel method

Organically modified layered magnesium silicate was for the first time synthesized by thermal treatment of a sol of silicon dioxide, magnesium hydroxide, and hexadecyl trimethylammonium bromide, with reflux of the liquid phase. The material obtained can be used as an ultradispersed component in polymer-inorganic composites.

Modification of magnesium silicate with 15(2)-methyl ester of 13(1),17(3)-diamino- N,N ′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e 6

Magnesium silicates modified with 15(2)-methyl ester of 13(1),17(3)-diamino-N,N′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e6 have been synthesized by heat treatment in water containing small fraction of ethanol. X-ray phase analysis, differential scanning calorimetry, thermogravimetry, and UV-Vis spectroscopy studies have shown that the synthesized samples contain individual molecules of 15(2)-methyl ester of 13(1),17(3)-diamino-N,N′-bis(2-hydroxyethyl)-13(1),17(3)-dioxochlorin e6 held on the inorganic substrate surface by electrostatic interaction and hydrogen bonding.

Ceramic composite [78ZrO2–21CeO2–Y2O3]/La0.85Y0.15Al11O18/Al2O3. Microstructure and properties

A ceramic composite [78ZrO2–21CeO2–Y2O3]/La0.85Y0.15Al11O18/Al2O3 (zirconium dioxide submicroparticles stabilized by cerium and yttrium oxides), which consists of a matrix filled with layered submicroparticles of lanthanum hexaaluminate modified by yttrium oxide and reinforced by Al2O3 nanofibers, was obtained. Components of the composite were synthesized by the sol-gel method, except for Al2O3 nanofibers obtained by the electric explosion method. The microstructure and properties of the composite depend on the composition and methods of its formation and sintering. The composite is intended to be used as a construction material.

Mechanochemical synthesis of organically modified magnesium silicate

Magnesium silicate modified with hexadecyltrimethylammonium cations was synthesized by mechanochemical treatment of a mixture of magnesium hydroxide, silica xerogel, lithium fluoride, and hexadecyltrimethylammonium bromide. The X-ray diffraction analysis, scanning electron microscopy, and differential scanning calorimetry examinations and thermogravimetric analysis showed that variation of the synthesis conditions led to the formation of products differing both in the degree of structural order and in the particle size.