Efficient Excitation of Hybrid Modes in a THz Clinotron

Journal of Infrared, Millimeter, and Terahertz Waves - Various regimes of hybrid, bulk-surface, modes being excited in the clinotron oscillator with a sheet electron beam and nonuniform grating...     

Modern high-density oxide ceramics with a controlled microstructure. Part V. Dense chemically stable ceramics based on yttrium,scandium, and aluminum oxides

Data on the technology of dense Y₂O₃ ceramics are presented. Special features of the structure of powders and their effect on shaping of specimens and their sintering are described. Methods for leveling the characteristics of Y₂O₃ powders with different properties and decreasing the sintering temperature are developed.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 12, pp. 2–6, December, 1996.For the beginning of the article see No. 1 of 1996, for the continuation see Nos. 2, 4–7, and 9.     

Sialons — Promising Refractory and Ceramic Materials

Available data on the chemical composition and structure of sialon phases are reviewed. Properties of the phases and their potential applications are discussed.     

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.     

Modern high-density oxide ceramics with controlled microstructure. Part II. Substantiation of the choice of modifying additives that affect the degree of sintering of oxide ceramics

It is established that additives that form solid solutions provide substantial densification of oxide ceramics due to defects of the crystal lattice. The use of combined additives that form solid solutions of isovalent and nonisovalent substitution makes it possible to create oxide ceramics with an exceptionally high density, which may result in the formation of optical transparency.Translated from Ogneupory, No. 4, pp. 2 – 13, April, 1996.The first two articles of the series have been published in Nos. 1 and 2, 1996.     

Modern high-density oxide ceramics with a controlled microstructure. Part II. Substantiation of the principles for choosing modifying additives that affect the degree of sintering of oxide ceramics

The types of solid solutions that additives form with monoxides and oxide compounds are determined. Formulas are suggested for the solid solutions. It is shown that for any type of solid solution formed the materials can be sintered to a very high density up to a transparent state. The main role here belongs to the gaseous medium for firing. Some principles for introducing the additives are formulated and the sinterability of the powders is considered. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 2–9, May, 1996. For the beginning of the article see No. 1, 1996, and for the continuation see Nos. 2 and 4, 1996.     

Modern high-density oxide ceramics. Part III. Microstructure and recrystallization processes in ceramic oxide materials

Recrystallization processes in oxide ceramics at high temperatures are considered. It is established that the microstructure of the ceramics remains equal-size-grained at all heating temperatures. The proportion of crystals with minimum and maximum sizes is controlled by the initial grain composition. The growth of crystals in coarse-crystal structures occurs by the joining of crystals in their rotation due to the stresses that develop. It is established that the degree of crystal growth in solid solutions depends on the sign of the change in the lattice parameter; as the parameter decreases, the structure always becomes fine-crystalline, and vice versa.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 6, pp. 2 – 9, June, 1996.For the beginning of the article see No. 1 of 1996, and the continuation is in Nos. 2, 4, 5 of 1996.