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


ISSN 0131-9582 (Online)

The article briefly provides basic information about the 24th International Exhibition “World of Glass” held in Moscow, which was directly attended by about 100 companies from 12 countries. New technologies of production and quality control of glass products, the main structural elements of glass furnaces, methods of their high-quality production were demonstrated. Examples of the most successful enterprises of the glass industry are given.
Porcelains were prepared by using kaolin clay, potassium feldspar, and quartz as the raw materials, and ZrO2 as a reinforcing material. This study investigated the effects of the amount of ZrO2, the firing temperature, and the holding time on the porcelain bending strengths and fracture toughness values, and compared the reinforcing effects of two types of ZrO2. The results show that the effect of the two types of ZrO2 (pure ZrO2 and Y2O3-stabilized ZrO2) on porcelain reinforcement were similar and that the optimal porcelain reinforcement was obtained with a ZrO2 content of 6 wt.%, firing temperature of 1300 ?, and holding time of 30 min. The bending strength increased from (58 ± 6) MPa to (89 ± 8) MPa (pure ZrO2) and (87 ± 8) MPa (Y2O3- stabilized ZrO2), with the respective growth rates reaching 62 and 58 %. Radial stress was generated in the matrix during the cooling process because of the difference between the thermal expansion coefficients of ZrO2 particles and the matrix.
This increased the porcelain strength. The phase transformation of ZrO2 improved the fracture toughness of the porcelain, but had little effect on reinforcement of the porcelain.
Hollow glass microspheres from sodium borosilicate glass were obtained by high-temperature method, the composition of mass%: 10 Na2O; 8 CaO; 0,3 MgO; 0,2 Al2O3; 9 B2O3; 0,5 SO3; 72 SiO2. It is established that the maximum yield of microspheres up to 87% is observed when using a propane-air torch with the characteristics: the air/propane ratio is 1,3; the maximum temperature on the torch axis is 1900 °C; the opening angle is ~15°; the flow rate of the transporting gas is 0,2 g/s. The hollow glass microspheres obtained in this mode are characterized by a median diameter of 60 microns, an average wall thickness of 1,3 microns, a bulk density of 260 kg/m3 and a calculated strength of 50 MPa.
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.