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Hits: 7114
For the synthesis of mullite 3Al
2 O
3 & middot; 2SiO
2 , hydrated aluminum oxide (GOA) and silicon dioxide SiO
2 obtained by sulfuric acid treatment of nepheline, as well as commercial finely dispersed aluminum hydroxide (MDHA) were used. The difference in the mechanism of synthesis has been established. When using GOA, mullite is formed directly by the interaction between aluminum and silicon oxides. When sintering with MDHA, the synthesis of mullite passes through the stage of formation of an intermediate aluminosilicate phase of sillimanite Al
2 O
3 & middot; SiO
2
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Hits: 7071
The influence of wollastonites and marshallites on phase transformations, processes of formation of the mineral composition and structure of electrical porcelain is determined. The positive dynamics of changes in the amount and ratio of crystalline and glassy phases, as well as mullitization in the masses, has been established. Samples corresponding to the standards were obtained in experimental laboratory conditions. The results will serve as a criterion for implementation in production
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Hits: 7113
It is shown for the first time that filamentary & # 171; whiskers & # 187; aluminum oxide with a porous structure. The morphology of the grown & # 171; whiskers & # 187; was studied. It is shown that & # 171; mustache & # 187; has the shape of a cone with a drop of metal at its top. X-ray phase and electron microscopic studies with mapping of whiskers have been carried out. There is a complex composition of a drop of metal at the top of the & # 171; whisker & # 187;. A possible mechanism of their formation is discussed.
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Hits: 7385
The structure and phase composition of lanthanum hexaboride ceramic material samples prepared by sintering are investigated. It was found that the formation of a high-quality consolidated structure with closed pores is observed at a sintering temperature of 1850 ° C. It is shown that the addition of nickel intensifies the sintering process and neutralizes the effect of the sintering temperature on the grain size and pore volume fraction. Nickel was found both in the main material of LaB
6 grains and in the form of fine intermetallic compounds at grain boundaries
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Hits: 7335
The results of the possibility of using dolerite fine-grained waste of crushed stone production in ceramic charges for the manufacture of low-shrinkage products are presented. It was found that solid-phase sintering wastes reduce fire shrinkage in all types of raw materials use. When sintering in the presence of a liquid phase, they perform a reinforcing role in the formation of the structure of a ceramic material and provide products with high physical and mechanical properties.
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Hits: 7302
The composition of the charge based on low-plasticity clay has been developed, which additionally contains (by weight) 6 & # 37; boric acid and up to 10 & # 37; molybdenum trioxide as fluids, facilitating liquid-phase sintering. It was found that the use of molybdenum trioxide also makes it possible to lower the surface tension of the melt and increase the bond strength between the crystalline and glassy phases in the bulk of the ceramic. The combined effect of the applied additives on the formation of the structure, composition, and main operational properties of the resulting ceramics has been investigated. Molybdenum-containing ceramics was obtained that meets the regulatory requirements for products for external cladding of walls and plinths of buildings and structures.
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Hits: 7837
An experience of manufacturing a complex ceramic part using the additive technology LCM (Lithography-based Ceramic Manufacturing) and an analysis of the economic feasibility of its use in serial and pilot production of ceramic parts in comparison with slip casting technology are presented.
The results obtained are of interest in the development and manufacture of new complex experimental ceramic parts and the choice of technology, batch production equipment
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Hits: 7831
A porous cordierite glass-ceramic was obtained. The processes of crystallization and sintering are considered, some properties of cordierite glass-ceramics made of magnesium-aluminosilicate glass are determined. The best properties are possessed by glass-ceramic material obtained under heat treatment conditions at a temperature of the first stage T
1 = 850 & # 176; C with an exposure & # 964;
1 = 3 hours and a temperature the second stage in the interval T
2 = 1315 - 1350 & # 176; C with exposure for & # 964;
2 = 1 - 5 hours
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Hits: 7778
The results of the synthesis of erbium-doped yttrium-aluminum garnet nanopowders by the glycine-nitrate method to obtain optically transparent ceramics are discussed. The effect of synthesis conditions on the characteristics of powders (Y
0.5 Er
0.5 )
3 Al
5 O < sub> 12 and their subsequent machining for the properties of the resulting ceramics
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Hits: 7753
The possibility of obtaining samples of lead-free piezoelectric ceramics using vibration molding at a pressing pressure of less than 0.3 MPa is being considered. The experiments were carried out on the material K
0.49 Na
0.49 Sr
0.02 NbO
3 , synthesized according to the standard ceramic technology of solid-phase synthesis. Piezoceramic samples made using vibration molding are similar in their characteristics to ceramic samples obtained by static pressing at a pressure of 100 - 150 MPa. The advantages of the vibration compaction process are indicated: a decrease in the cost of tools and equipment, a decrease in elastic deformation, an increase in the density of products