On the basis of a comprehensive study of the physicochemical properties and behavior during firing of quartz-pyrophyllite raw materials, the suitability of its use in the composition of porcelain masses as a substitute for quartz and partially for kaolin is shown. The resulting household porcelain has a low firing temperature (1280 - 1300 ° C) and has good physical and mechanical properties. Tab. 1, ill. 2, bibliography: 6 titles.
Zinc oxide ceramics used for the manufacture of varistors are considered. The most probable mechanism of the non-ohmic behavior of a material with various alloying additions under the action of an electric field is discussed. Il. 3, bibliography: 15 titles.
Ceramic pigments with diopside and anorthite structures based on natural wollastonite have been obtained. It has been shown that the reactions of the synthesis of the diopside structure proceed in a multistage manner, with the formation of intermediate products. For a more complete phase formation of the anorthite structure, mineralizer additives are required. The resulting pigments have a bright color and can be used to decorate porcelain-faience and majolica products. Tab. 5, ill. 2, bibliography: 4 titles.
Abstract — Polymorphic transitions in oxides controlled by diffusion proceeding by the vacancy mechanism are considered. To ensure the neutrality of the total electric current arising during the movement of ions, a certain ratio of vacancies in cation and oxygen is required. Since oxides usually have an excess of oxygen vacancies at high temperatures, a further increase in their concentration due to the introduction of appropriate additives slows down diffusion, prevents the polymorphic transition, and stabilizes the phase. The introduction of additives leading to an increase in the concentration of vacancies in the cation, on the contrary, accelerates diffusion and promotes the polymorphic transition. Bibliography: 10 titles.
Discrete thermomagnetic analysis allows one to identify the mineral composition of free iron compounds: goethite and hematite (as a result of heating in a reducing environment), iron carbonate and siderite (as a result of heating in an oxidizing environment). New informative criteria were used - the reducing and oxidizing ability of free iron compounds. A classification of clay-containing materials used in the ceramic industry into three groups in accordance with the gradation of the reducing ability of free iron compounds is proposed. Tab. 1, ill. 4, bibliography: 7 titles.
The physicochemical processes occurring during heat treatment in gel compositions with the addition of Н 3 VO 3 are considered. The phase composition of the heat treatment products is studied. The synthesis of oxygen-free compounds SiC and В 4 С during heat treatment of sol-gel compositions in a reducing environment has been recorded. Tab. 1, ill. 6, bibliography: 6 titles.
The structure of initial glasses with a molar content of 7.5 - 15.0% B 2 O 3 , as well as glaze coatings based on them, has been investigated. The original glasses had a liquation structure. During heat treatment of glaze coatings, it was established that anorthite was precipitated as the primary crystallization phase, and not zirconium-containing, as noted in glazes richer in B 2 O 3 . The formation of crystalline phases is carried out on the basis of liquation drops. Il. 4, bibliography: 9 titles.
The reaction sintering of ceramics based on hexagonal boron nitride is investigated. It was found that the use of pre-sintered and then ground to a particle size of 45 - 125 ?m aluminum nitride is much more effective than the use of fine boron nitride or coarse aluminum nitride as an inert filler. Tab. 2, ill. 1, bibliography: 7 titles.
