caa a22 4500 465779735 CHVBK 20180323111952.0 cr unu---uuuuu 170327e19900301xx s 000 0 eng 10.1007/BF01282353 doi (NATIONALLICENCE)springer-10.1007/BF01282353 Specific features of the phase transformations occurring during the sintering process of the beta-alumina based ceramics and their properties [Elektronische Daten] [G. Tel'nova, T. Efimovskaya, L. Fateeva, N. Astakhova, A. Ivanova] Conclusions: During the sintering process of beta-alumina obtained using the method of plasmochemical synthesis, the β″ → β structural transformation occurs and it is accompanied by the separation of the excess Na2O and the formation of an intergranular meltlike phase that is saturated with sodium and is characterized by high dielectric properties. The quantity of the meltlike phase and the magnitude of the β″/(β″ + β) ratio determine the degree of stabilization (stability) and the final resistivity of the material and depend on the initial chemical composition and the heating rate maintained during the sintering process. It was shown that when the duration of residence of the material in the hot zone of the furnace is increased or when the specimens sintered maintaining high heating rates are subjected to additional heat treatment, one observes the occurrance of the β → β″ reverse structural transformation that is characterized by an increase of the phase ratio β″/(β″ + β) → 1, a reduction in the quantity of the meltlike phase right up to its complete disappearance, and a decrease of the electrical resistivity of the material. In the materials having a large excess quantity of sodium oxide, the process of crystallization of the intergranular NaAlO2 phase occurs simultaneously with the second β → β″ phase transformation. The best ceramic and electrophysical parameters were obtained when sintering the material contained 7.9% Na2O. Plenum Publishing Corporation, 1990 Tel'nova G. Scientific-Research and Production Complex ‘Kvant', USSR aut Efimovskaya T. Scientific-Research and Production Complex ‘Kvant', USSR aut Fateeva L. Scientific-Research and Production Complex ‘Kvant', USSR aut Astakhova N. Scientific-Research and Production Complex ‘Kvant', USSR aut Ivanova A. Scientific-Research and Production Complex ‘Kvant', USSR aut Refractories Kluwer Academic Publishers-Plenum Publishers 31/3-4(1990-03-01), 146-152 0034-3102 31:3-4<146 1990 31 11148 https://doi.org/10.1007/BF01282353 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01282353 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tel'nova G. Scientific-Research and Production Complex ‘Kvant', USSR aut NATIONALLICENCE 700 1- Efimovskaya T. Scientific-Research and Production Complex ‘Kvant', USSR aut NATIONALLICENCE 700 1- Fateeva L. Scientific-Research and Production Complex ‘Kvant', USSR aut NATIONALLICENCE 700 1- Astakhova N. Scientific-Research and Production Complex ‘Kvant', USSR aut NATIONALLICENCE 700 1- Ivanova A. Scientific-Research and Production Complex ‘Kvant', USSR aut NATIONALLICENCE 773 0- Refractories Kluwer Academic Publishers-Plenum Publishers 31/3-4(1990-03-01), 146-152 0034-3102 31:3-4<146 1990 31 11148 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer