Steklo i Keramika (Glass and Ceramics). Monthly scientific, technical and industrial journal

 

ISSN 0131-9582 (Online)

Compositions of ceramic masses for obtaining wollastonite-containing ceramics using domestic carbonate and siliceous raw materials were developed. The features of the formation of the structure and phase composition of synthesized ceramic materials in connection with the physicochemical properties and operational characteristics were established. The influence of a mineralizing additive (naturally occurring wollastonite) on the processes of sintering and phase formation was determined, the relationship between the physical-technical and thermophysical properties, the firing temperature and the amount of additive introduced was revealed. The results of the research are of theoretical and practical interest in organizing the production of refractory products based on wollastonite.
The influence of the mineralogical composition of clays on the microstructure and frost resistance of ceramic bricks has been studied. The pore radii were calculated by the method of capillary water saturation of the samples, their classification into hazardous and reserve ones was made, and the structural characteristics of the material were determined. It was revealed that a frost-resistant structure, with a predominance of reserve pores of more than 10 microns, is formed in the compositions of brick masses with a montmorillonite content of more than 12% and at a ratio of kaolinite and illite to montmorillonite 3:1, 2:1.
The results of the study of the structure and adsorption properties of the Mo/zeolite composite obtained by enriching the zeolite of the Chuguevsky deposit of Primorsky Krai with Mo nanoparticles followed by sintering are presented.
Its phase and elemental compositions are determined. The adsorption-structural characteristics of the composite are investigated using the BET method. In the work, the specific surface area, total pore volume and mesopore size distribution are determined. The results obtained are of interest for the production of catalytically-active materials based on zeolitic raw materials.
The results of theoretical and experimental studies of the influence of scale deposits on heat exchange processes in vitrified pipes washed by seawater are presented. Experimental studies have shown that during long-term operation of heat exchangers, minor scale deposits with a layer thickness of up to 0.4 mm are observed on the surface of glass coatings of pipes, while a strong scale layer up to 2 mm thick is formed on the inner surfaces of metal pipes. The practical absence of deposits in vitrified pipes is explained by the increased cleanliness of the glass surface and its resistance to aggressiveness of substances dissolved in sea water. This eliminates the formation of large foci of scale on the glass surface and washing off the formed scale with a stream of seawater.
Glass-enamel coatings have been modified with nanosized particles, which expands the scope of their application and is a promising direction. It has been established that the introduction of nanosized zinc oxide in the amount of 0.5 wt. % into the composition of the enamel of the Na2O–B2O3–TiO2–SiO2 system imparts antibacterial properties to the coating against gram-positive and gram-negative bacteria. The meaning of the index of antibacterial activity of the surface of the enamel increases on average five times more in relation to Escherichia coli (E. coli) and six times more in relation to Staphylococcus aureus (St. aureus) compared with a control sample that does not contain zinc oxide.
The main directions of application of flexible heat insulating materials and traditional technologies for producing non-woven materials are considered. Various ways of fastening fibers are analyzed, such as: chemical; thermal; mechanical, which in turn includes the following options: needle-punched, knitting-stitching, hydro-jet method used in the production of flexible fibrous thermal insulation. A number of patents are presented that develop methods for obtaining nonwoven materials.
We have obtained the X-ray total scattering patterns at wavelength 0.20735 ? and corresponding to them radial distribution functions (RDF) of electron density for glasses in the La2O3–Nb2O5–B2O3 and BaO–Nb2O5–P2O5 systems. The RDF demonstrate separate peaks at distances below ~1 nm which points on the middle range ordering in the considered glasses. The consideration of RDF for BaO–Nb2O5–P2O5 glasses system with high concentration of BaO show that the middle range order is caused by the polyhedra chains of ideal BaO crystal, and these chains does not belong to any low-index crystal plane. For La2O3–Nb2O5–B2O3 glasses system the polyhedra chains are observed which resemble those in the LaB3O6 crystal, with polyhedra bound through borate groups. For all considered glasses the niobium polyhedra does not form extended chains.
A statistical analysis of the relationship of the redox ratio of the produced float glass with the technological mode of cooking, the charge content and the chemical composition of the glass was carried out. The influence of the redox ratio on the technical and economic performance of the bath furnace and the quality of the glass produced is shown.
Transparent glass-ceramics are attracting more and more attention as a material for protecting the screens of electronic devices. The paper considers the possibility of carrying out ion-exchange of transparent gahnite glass-ceramics containing a small Na2O content. The structure and properties of glass-ceramics before and after ion-exchange were studied by x-ray diffraction analysis, transmission electron microscopy, Raman spectroscopy, laser-induced breakdown spectroscopy, and Vickers hardness determination. It is shown that, under certain conditions, ion-strengthening of glass ceramics with a low content of alkali ions can lead to an increase in microhardness values.
Ceramics Ce0.9Bi0.1O2 – ? was obtained by solid-phase synthesis. It is shown that the obtained samples have a cubic fluorite structure with the space symmetry group Fm3m. The electrical properties of the Ce0.9Bi0.1O2 – ? solid solution were studied by ac impedance spectrometry. It has been established that the activation energy of electrical conductivity has two sections 0.51 eV (400 – 680 ?С) and 1.6 eV (680 – 800 ?С), the activation energy of the dielectric relaxation process was 0.88 eV.