The thermal behavior of potassium polytitanate modified in an aqueous solution of CrCl 3 for 4 and 18 h and characterized by varying degrees of uniformity of the distribution of chromium in the particles has been investigated. It was shown that, despite the similarity of the chemical composition of the obtained precursor powders, their heat treatment (at 850 C for 2 h) leads to the formation of ceramic nanopowders of various phase compositions. It was shown by impedance spectroscopy that the product obtained on the basis of a powder-precursor with a lower degree of homogeneity of chromium distribution has a significantly higher dielectric constant.
The data obtained in the study of stress relaxation during high-temperature bending of ceramic specimens based on mullite modified with zirconium oxide are presented.
By the example of the study of foundry ceramics, the possibility of calculating the values ??of some characteristics of ceramic materials based on the values ??of the main characteristics of the feedstock: dispersed composition, specific surface area, type of binder and chemical composition of ceramics is shown. Adequate regression equations have been derived, which make it possible to calculate the characteristics for obtaining cast ceramics with specified properties.
The conditions for the synthesis of zircon crystals from a solution in a melt have been studied. The use of CaCl 2 as a flux is proposed. Samples of luminescent zircon were obtained upon activation with Dy 3+ and Eu 3+ ions. The luminescence properties of the obtained materials are investigated, a comparison is made of the luminescence spectra of pure zircon (synthesized using Li 2 MoO 4 and CaCl 2 as fluxes), activated zircons and a reference YAG phosphor. The resulting activated zircon can be used as radiation converters, for example, as a red phosphor in lighting devices.
Phase transformations of model compositions of cordierite ceramics based on silicon dioxide synthesized by micellar technology have been studied by thermogravimetry, differential scanning analysis, and diffractometry. The temperature boundaries of the formation of the cordierite phase in the samples were revealed.
The process of phase formation in the BaCO 3 + TiO 2 system has been studied using solid-phase reactions and synthesis from a melt obtained by exposure to concentrated solar radiation of various power. It is shown that in the power range up to 100 W / cm2, barium metatitanate BaTiO 3 of the cubic system is formed; with an increase in the radiation power, a tetragonal phase of barium titanate is formed. The obtained barium titanates have high values ??of dielectric constant (3000? 3200) and low dielectric losses.
The technology of structural ceramics, based on the use of cold isostatic pressing, provides products with high values ??of the required properties. However, the application of the isostatic pressing method is often limited by the difficulties associated with obtaining shaped articles with thin shape elements and large length-to-cross-sectional ratios. The proposed method for isostatic pressing of powders in molds made of thermoplastic materials helps to solve this problem. The features, advantages and disadvantages of using such molds are considered.
Porous metal-ceramic membranes with improved operational properties have been synthesized by the SHS method with a reduction stage in the thermal explosion mode in vacuum from a mixture of PTYu alloy powders (95% Ni ? 5% Al) + Co3O4. As a result, porous cermet membranes were obtained containing 10 ? Ni and Co nanoparticles in the surface pore layers. 20 nm. A prototype prototype of a power plant with high mass and size characteristics of a battery of cells has been developed: specific volume 3.3 l / kW and 1.6 kg / kW
The structure and thermophysical properties of materials formed in the Dy 2 O 3 -HfO 2 system (molar ratio from 1: 3 to 3: 1 ) as a result of isothermal roasting of X-ray amorphous mixed hydroxides at temperatures up to 1600 C. It has been shown that, at a ratio of 1: 3 to 1: 1, the crystallization process leads to the formation of single-phase solid solutions having the structure of defective fluorite with a pronounced nonequivalence of the parameters of the local environment of Dy and Hf. It was found that ceramics based on dysprosium hafnate (Dy 2 O 3 : HfO 2 = 1: 1) has a low thermal conductivity ~ 1.4 W / (m • K), practically independent of temperature (up to 800 С)
The effect of culture liquids with bacteria Acinetobacter johnsonii str. J221 and Pseudomonas aeruginosa str. Gd on the rheological properties of a porcelain slip. The surface activity of the culture liquid provides a decrease in the fluidity and thixotropic hardening of the porcelain slip. The increase in the mass of the casting during casting is due to the hydrophobization of the surface of the slip particles. The thickening of the porcelain slip is interconnected with the change in the redox state of the medium from weak to strongly reduced, favorable for the development of the aboriginal community of anaerobic microorganisms
