Shylovych Y. Process of nanomodifying of ceramics and prognosis of physical and mechanical properties of nanoceramic materials

The dissertation concerns mainly the research of the process of nanomodification of ceramic materials during their manufacturing, in particular insertion of nanoparticles contained in a water-based suspension into the ceramic slip in process of its manufacture into ceramic mass. However, it also explores the process of nanomodified suspension as the nanoparticle agglomerates are dispersed with ultrasonic dispersion technology. Cavitation pressure adequate for dispersion of said nanoaglomerates is defined, which is crucial for further calibrating of dispersion equipment designed for nanoceramic material production. Pre-process of nanomodification in carbon nanomaterials ceramics, prepared with for ceramic slip and ceramic glaze. For the introduction into the slip, a water suspension was prepared with addition of mass of nanoparticles from 0.5 to 9 wt. %. To be added to the glaze, it was prepared with water a suspension with a mass of nanoparticles 5; 7; 9 wt %. Directly before introduction into the mass, the aqueous suspension was subjected to ultrasound dispersions for breaking up agglomerates of nanoparticles and their uniform distribution in the volume of liquid. The aqueous suspension was introduced into the liquid mass (slip and glaze) by mixing with a mechanical stirrer. From the received samples of ceramics were made for the study of their physical mechanical properties and samples of glazed coatings for research their hydrophobic properties. Nanomodified ceramics were studied by indicators: moisture content, linear shrinkage, porosity, mechanical flexural strength. The obtained results were compared with the values for the reference samples. The results showed that nanomodification affects the following properties: moisture content decreased by 1 – 4 %, linear shrinkage decreased by 0.6 – 4 %, porosity decreased by 1.5 times. Mechanical strength in bending increased by 25 – 36 %. Nanomodified glaze was applied to ceramic tiles and studied for its hydrophobic properties, namely the angle of wetting the surface of the glaze with water was experimentally investigated by static and dynamic drop method. It is determined that nanomodified on the glaze has better hydrophobic properties compared to the reference glaze: an increase in the contact angle between the water droplet and nanoglazed surface by 71.1 % and reducing the rolling angle of the drop at 68.5 %. According to the calculations and based on known data it was substantiated that ultrasonic effect during dispersion of nanoparticles in aqueous suspension is attributed to cavitation effects that occur when microbubbles collapse in the aqueous solution. The calculation of cavitation pulse and mechanical stress that occur when bubbles collapse in the range of changes in their radius (Rmax – R0 ) is proposed. As a result, a recommendation for the selection or practical application of dispersant of a certain power in the manufacture of a nano-containing suspension is developed. To model the processes of linear and nonlinear deformation nanotubes of different types using methods of molecular mechanics and molecular dynamics developed a special finite element (FE) on based on the moment scheme of finite elements. Covalent bonding forces between carbon atoms in a finite element are described on the basis of Morse potential. The first scheme of the type "overlap" establishes docking by providing stitching of knots of two finite elements, joined by displacements. Another scheme carried out by transferring forces through a special hexagon FE - "atom". Approbation of the developed finite element is performed by comparing the results of numerical experiments with known ones numerical solutions, namely the study to determine reduced modulus of elasticity of nanotubes such as "armchair" and "zigzag". A multi-scale strength criterion is proposed for nanomodified brittle materials, which binds the processes of occurrence damage on a macro-, micro- and nanoscale.