Features of high-density industrial ceramics technology. Selection of modifying additives

The effect of modifying additives on sintering, microstructure control, and the properties of ceramics was demonstrated. The types of additives with a different type of reaction with the crystal lattice of the basic oxide in sintering were examined. Oxides that form solid solutions are the most effective additives that significantly affect sintering and microstructure formation processes.     

High density technical ceramics: Technology and preparation of green articles for sintering

It is shown that the degree of aggregation of powders and the properties of aggregates (size, strength, porosity) affect the degree of sintering and the microstructure characteristics of the ceramic fabricated. The conditions for obtaining low-aggregation powder and methods for de-aggregating powder are examined. The requirements which powders must satisfy in order to obtain compacts with a uniform pore size and uniform sintering over the volume of the articles are formulated.     

High-temperature creep of refractory ceramics. Kinetics and the effect of experimental conditions

High-temperature creep curves of samples of refractory ceramics are considered. It is shown that in the vast majority of cases strain in samples accumulates linearly. Regularities of creep flow rate change under the effect of temperature and loads are established. The sample structure is shown to affect the creep kinetics.Translated from Ogneupory, No. 6, pp. 2–8, June, 1994.     

Cesium-137 of Chernobyl origin in lake–river systems of Eastern Fennoscandia: 30 years after the accident

Contamination of waters of lake–river systems after many-year migration of ¹³⁷Cs in water bodies was studied. In lakes with the ¹³⁷Cs fallout density lower than 8 kBq m^–2, the radionuclide concentrations in water after 24–29 years did not exceed 2–3 Bq m^–3, and at a fallout level of 37 kBq m^–2 it was in the range 11–34 Bq m^–3. The natural half-clearance time Т of lake waters from ¹³⁷Cs was 6–7 years at the exposure of up to 20 years. The ¹³⁷Cs migration in the lake–river systems that occurred during ~30 years did not lead to structural changes in the water contamination: The initially low ¹³⁷Cs level in lake waters did not become high, and vice versa. Among rivers feeding Lake Ladoga, the ¹³⁷Cs level in the Vuoksa River is ~3 times higher than in waters of the Volkhov and Svir rivers. During the period 1988–2015, 21.3 TBq of ¹³⁷Cs was supplied to Lake Ladoga with Vuoksa waters. The Vuoksa source from the Saima lake system with increased contamination with ¹³⁷Cs of Chernobyl origin leads to long-term supply of this radionuclide to Lake Ladoga.     

Deformation of unfired phosphate-bound refractories. Part 3. Deformation of hardened cements on heating and cooling

Deformation tests have been made on hardened cements. A difference from unhardened ones, which show considerable plastic (viscous) deformation, is that the hardened ones show mainly elastic strain with a small inelastic component at a temperature exceeding the preliminary heat treatment value. __________ Translated from Novye Ogneupory, No. 3, pp. 139–143, March, 2007. Continuation: start in Nos. 1 and 2 for 2007.     

Deformation of nonfired refractories on phosphate binders. 4. Deformation due to heating and creep of cement composition

Results of a study of deformation due to heating and of creep of phosphate materials are presented. The range of necessary loads and the rate of temperature growth under nonisothermal conditions are determined. The role of the grain composition of the filler (α-Al₂O₃) of the model alumophosphate cement composition is shown. __________ Translated from Novye Ogneupory, No. 4, pp. 30–35, April, 2007.     

High-temperature creep in refractory ceramics. Porous materials

Results on high-temperature creep in porous ceramics and refractories obtained for model specimens are presented. The role of the shape, size, and number of pores and the effect of some manufacturing parameters (grain composition of the charge and compaction pressure) are discussed. It is established that the deformation rate is independent of the shape and size of the pores and is determined by the porosity and the degree of development of interparticle contacts.Translated from Ogneupory, No. 10, pp. 2–6, October, 1994.     

High-temperature creep in refractory ceramics. Densely sintered multiphase materials

High-temperature creep in densely sintered multiphase ceramics is considered. The presence of other phases, namely, crystalline and glassy, is shown to affect the behavior of specimens. Data on creep during phase transitions in the materials are presented.Translated from Ogneupory, No. 9, pp. 2–8, September, 1994.