Search

The possibility of using diatomite from the Ilyinsky deposit as an unshaped thermal insulation for open risers of castings from aluminum alloys of different alloying systems: technical aluminum A5, AK7, AMg10, VAL10 has been studied. It was found that when the continuity of the oxide film on the surface of a diatomite particle is broken, an exchange reaction occurs with the formation of a silicon transition layer. Since silicon is wetted by aluminum, the diatomite particle sinks in the melt, forming a blockage. As a criterion for the continuity of the oxide film, it is proposed to use the Pilling‒Badworth factor of the alloy components. It has been shown that a high level of the Pilling‒Badworth factor, even at a low content of the component (~ 1 %), leads to the formation of blockages. Ill. 6. Ref. 12. Tab. 1.

Исследовано влияние скорости обжига обогащенного каолина Кыштымского месторождения на свойства шамота. Спецификой каолина Кыштымского месторождения является петрографическое разнообразие исходных пород, что отрицательно сказывается на его качестве как огнеупорного сырья. Изучены пластические свойства каолина, позволяющие формовать брикет без дополнительного использования связующих, включая воду. Исследования скорости, конечной температуры обжига и длительности выдержки при конечной температуре показали, что скорость подъема температуры в процессе обжига шамота несущественно влияют на качество получаемого шамота. В то же время повышение конечной температуры обжига и выдержки существенно влияет на качество и фазовый состав шамота, закономерно снижая его водопоглощение, увеличивая выход муллита и уменьшая количество непереродившегося свободного SiO2. Установлено, что максимальная температура обжига обогащенного каолина Кыштымского месторождения на шамот составляет 1350‒1400 оС, скорость подъема температуры 35‒45 оС/мин.

На основе алюмосиликатного сырья Республики Казахстан предложена технология получения сверхплотных алюмосиликатных огнеупоров с повышенной шлакоустойчивостью для тепловых процессов утилизации фторсодержащих углеродистых отходов. Использование «керамической» технологии позволяет получать структуру с водопоглощением менее 1 % как у шамота, так и у огнеупорных изделий с разным содержанием Al2O3.

The composition and properties of two types of calcined magnesium oxide powders, differing in chemical composition, are investigated. The difference in chemical and phase composition determines the different behavior of powders during firing, which is smoothed only at a temperature of more than 1850 °C. The microstructure of the obtained briquettes differs in the amount of glass phase, the type and size of pores, as well as the size and quality of the crystals of the periclase. From the studied powders of decarbonized magnesium oxide without sintering additives, a briquette with an apparent density of at least 3,35 g/cm3 required to obtain high-quality products can be obtained only at a firing temperature of at least 1850 °C with an exposure at the final firing temperature of at least 2 hours. Ill. 2. Ref. 14. Tab. 4.

The processes of obtaining ceramic microporous diaphragms based on aluminum and zirconium oxides have been studied. The diaphragm test results for long-term corrosion resistance are presented. It was shown that a ceramic material based on zirconium and aluminum oxides obtained at 1350 °C with linear shrinkage of 7,5 % has an open porosity of 49 % and a flexural strength of 48 MPa. The diaphragms obtained from this material can withstand pressure up to 1.0 MPa and can work under the conditions of electrolysis of aqueous solutions of chlorides for at least 40,000 hours.

The results of studies of the structure, phase composition and specific surface of powders based on zirconium dioxide obtained by the method of thermal decomposition of a mechanical mixture of hydroxide and a stabilizing additive are presented. The forming and sintering of ceramic samples obtained from calcined powders, some properties of ceramics were studied. It has been shown that finegrained dense high-strength ceramics with a flexural strength of 860 MPa and microhardness up to 12‒13 GPa can be obtained from the synthesized powders. Ill. 2. Ref. 12. Tab. 3.

The possibility to produce the vibro- and self-flow lowcement periclase concretes was investigated in the article. It was shown that when the concrete mixture is prepared in conventional conditions the aggregate and the fne ground component based on the fused periclase hydrate very little if any: over three days of the concrete curing the brucite content doesn't exceed 1 %. The data received can be used as the basis for the further development of the magnesia concretes with advanced properties.Ill.1. Ref. 17. Tab. 2.

The effect of natural additives on the sintering ability of an aluminosilicate material has been investigated. It is shown that the introduction of natural alkali aluminosilicates with a predicted viscosity and amount of melt allows to obtain more durable ceramic materials.Ill.6. Ref 4. Tab. 2.

The alumina-silicate material's granular composition effect on its sintering behavior was investigated in the article. It was shown that the average particle size decreasing, the chemical and material compositions being equal, allowed to prepare stronger materials.Ill.2. Ref. 6. Tab. 4.

The investigating results are given in the article for both the sintering and the corundum ceramics' properties change depending on the inserted highdispersed Al2O3's content and kind. The samples were prepared by means of the slurry casting and were sintered at various temperatures. It was established that all else being equal the highly-dispersed sphericalshaped powders are the most advantageous to use for the corundum ceramics' physical and mechanical properties improvement. The shape of the highlydispersed powder doesn't influence significantly on the temperature reducing while preparing of the dense ceramics. Ill. 4. Ref. 12. Tab. 2.

The material, chemical and grain compositions as well as the properties of the Poletaev' deposit's kaolin were studied. The possibility is investigated to prepare on base of this kaolin the dense aggregate for the refractory and ceramic materials production and the investigating results are given in the article. The introduction of the aluminasilicate materials allows the aggregate obtaining with the elevated Al2O3 contents. Ill. 6. Ref. 3. Tab. 6.

The pressing methods «on flat» and «on the edge» for the «mini-key» (MK) periclase-carbonaceous refractories manufacturing are regarded in the article. At the «Ogneupor» Ltd the MK refractory items were produced and then installed edgewise in the JSC MMK steel-teeming ladles' lining. The items showed high strength, the typical vertical cracks and the horizontal joints erosion were absent. Ill. 5. Ref. 15. Tab. 1.