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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 influence of hydrothermal action on the physical and mechanical properties of ZrO2–Y2O3(3 mol%) ceramics was investigated. The properties of specimens sintered at 1350°C in air and at 1850°C in vacuum followed by oxidative annealing at 1200°C in air were compared. The characteristics of specimens sintered at 1850°C were shown to be practically unchanged after hydrothermal treatment while specimens sintered at 1350°C showed a significant drop in strength and hardness of about 40 – 50%.

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 paper discusses the multipurpose use of technogenic and natural raw aluminous materials for extracting valuable components, while solving environmental issues. The authors analyzed the process of granulating kaolin, obtained from the Ural region, which involves the addition of aqueous sulfuric acid solution and subsequent firing of the granules. Sulfuric-acid leaching of kaolin-containing raw materials at various acid concentrations and precipitate production times was considered. A certification of the obtained aluminum hydroxide powders was performed.

We present the results of investigation of the regularities of sintering and properties of corundum ceramics based on alumina with admixtures of ultradispersed powder of Al2O3(Al2O3 UDP) synthesized by the electrochemical method. It is shown that, as the firting temperature and the concentration of Al2O3 UDP increases, we observe a regular elevation of the linear shrinkage, microhardness, and ultimate strength in bending of the ceramics (the maximum values attained at 1550°C are as follows: 27.8%, 17 GPa, and 340 MPa, respectively). The introduction of Al2O3 UDP makes it possible to get an apparent density of the ceramics equal to 3.87 g/cm3 even at 1550°C.

Requirements for special-purpose alumina for the ceramic, electronic and refractory industries are considered. Analysis and comparison of acidic methods for preparing alumina from the point of view of efficiency, adaptability and production safety are provided. The risks of alumina acidic production methods are estimated. The advantage of the sulfuric acid method versions is substantiated.

The results of studies of the structure, phase composition and specific surface area 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 were studied, as well as some properties of the ceramics. It has been shown that fine-grained 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.

Results are provided for thermal cycling tests of a number of highly refractory products. It is shown that periclase products from fuzed powders coated with ZrO2 are the most resistant to cyclic variable thermal loads. The structure of corundum products in the process of thermal cycling tests deteriorates significantly due to recrystallization and the formation of new phases. In order to organize the lining and test unit heat exchange fittings operating under conditions of variable loads in pulsed piston units objects made from fuzed periclase powders modified with ZrO2 are recommended.

The effect of natural additives on aluminosilicate sintering capacity is studied. It is demonstrated that addition of natural alkaline aluminosilicates with predicted viscosity and amount of melt makes it possible to prepare stronger ceramic materials.

The effect of aluminum silicate material composition on its sintering capacity is investigated. It is shown that a reduction in average particle size with the same chemical and substance compositions makes it possible to prepare strong ceramic materials.

Results are reported on the sintering ability of pure synthetic magnesium oxide (MgO) using variously pretreated eutectic sintering additives. It was established that the sintering ability of synthetic MgO was affected by the type of precursors used to prepare both the MgO and eutectic sintering additives. The best sintering ability was observed for MgO prepared from magnesium bicarbonate. The sintering additive made of natural quartzite and technical aluminum and magnesium hydroxides was most effective.

Results are provided for a study of diatomite of the Il’insk field (Sverdlovsk region) for preparation of unmolded insulation materials and their use as heat insulating materials in crucibles with molten aluminum. Use of diatomite as a heat insulating material makes it possible to reduce power consumption during holding molten aluminum in the resistance furnace crucible, prevents development of hydrogen porosity, and does not lead to melt saturation with silicon.

We present the results of investigations of the process of sintering and the changes in the properties of corundum ceramics depending on the content and type of introduced highly dispersed Al2O3. The specimens are produced by the slip casting and sintered at various temperatures. It is shown that, for the other identical conditions, it is reasonable to use highly dispersed powders with spherical particles with an aim to improve the physicomechanical properties of corundum ceramics. In the production of dense ceramics, the shape of particles of highly dispersed powders does not have any significant influence on the decrease in the temperature of sintering.

Substance, chemical, grain size compositions, and properties are determined for Poletaev deposit kaolin. Results are provided for a study of the possibility of preparing a dense aluminosilicate filler for refractory and ceramic material objects. Addition of aluminosilicate material makes it possible to prepare filler with an increased Al2O3 content.

Methods are described for producing aluminium-magnesium spinel by solid phase synthesis using commercial alumina and caustic magnesite. It is proposed to replace commercial alumina by dust deposited in the aspiration system for an aluminum hydroxide calcination rotary furnace that makes it possible to exclude the stage of milling alumina. Methods are provided for spinel synthesis in electric arc furnaces with block melting and pouring of a charge. The effect of the MgO/Al2O3 ratio in electrically melted material on its properties, method for adding a charge to an electric furnace during melting for pouring, features and properties of spinel materials with subsequent molded object sintering, are studied.

Possibilities are considered for using discrete carbon fibers as a reinforcing element within the structure of carbon-containing refractories. Results of laboratory and pilot plant tests are provided.

The change in LTEC is analyzed on heating and cooling ceramic materials of the Al2O3–ZrO2 system in the range 200 – 1500°C. The effect of structural and phase components and measurement regime (heating/cooling) on form of the relationship Δl/l 0 = f(t), and also the dependence of LTEC on composite chemical composition are established. Results obtained are discussed from the point of view of material phase composition and published data are analyzed. Data are provided for average and true LTEC values.

Results are provided for study of a series of high refractoriness objects for thermal shock resistance and determination of their actual heat capacity. It is shown that under high temperature conditions and sharply varying thermal loads good resistance develops for objects with the highest ratio of heated surface area to volume. Two-phase materials demonstrate the best thermal shock resistance. Periclase objects with a protective coating based on ZrO2 have thermal shock resistance comparable with that of zirconia objects.

Microstructure, phase composition, and physicochemical properties of domestic and imported carbon materials used in refractory concretes are studied. It is established that graphites of different origin have different surface morphology, crystal lattice structure, and wetting capacity.

The possibility is considered of using carbon fibers as a reinforcing element within the structure of periclase-carbon refractories. Laboratory and industrial test results are provided.

A simplex-lattice method is used for planning an experiment for sorting the grain size composition of high-alumina chamotte grade RASC in order to prepare mullite material. Optimum chamotte grain size composition is established proving an improvement in operating properties.

The working layer of a ladle furnace unit (LFU) lining made from periclase-graphite refractory is most strongly subjected to the effect of corrosion factors that concern thermal, mechanical, and chemical action. The strongest destructive effect on a lining is the chemical factor. This article provides results of studying the effect slag phase composition on chemical breakdown of a LFU periclase-graphite lining.

are provided for a study of the effect of different graphites GE-1 and GCh (Russian Federation), Falke 94100 and Falke 9280 (Brazil), +592 (PRC), +595 (Madagascar), and FLS 897 (Norway) on physicochemical properties of periclase- and corundum-graphite refractories. It is shown that the type of graphite affects charge properties even in the preparation stage, and object physicochemical properties.

Methods are considered for preparing periclase-carbon refractories of “mini-key” (MK) format by compaction sideways and edgeways. Under OOO Ogneupor conditions objects are prepared with dimensions 102/113/160/200 mm that are installed edgeways in the lining of OAO MMK steel-pouring ladles. Objects demonstrate good life, there are no typical vertical cracks, and there is no erosion of horizontal joints.

Results are provided for a study of the microstructure, phase composition, and physicochemical properties of domestic and imported graphites for the refractory industry. It is established that graphites of different origin have a different morphological surface, crystal lattice structure, and oxidation resistance.

The properties of three samples of low-melting clays (Tyumen Oblast) were investigated for the purpose of application in the production of ceramic building brick. It was determined that the clays of the samples Nos. 1 and 3 can be used to produce No. 150 clayey, frost-resistant, face brick by the plastic molding method. Clay from sample No. 2 can be used to produce clayey, frost-resistant, face brick with the introduction of additives that improve the drying properties.

The composition of the ladle slag in units designed for the secondary treatment of steel needs to be optimized in order to increase the service life of the units’ linings. On the one hand, the slag subjects the refractories to chemical wear. On the other hand, under certain conditions the slag is capable of forming a protective crust inside the units. The Nizhniy Tagil Metallurgical Combine has chosen certain refractories for the most heavily worn part of the lining of its vacuum chambers, since only the installation of a lining of a differentiated design that equalizes the rate of wear around the lining’s perimeter will allow the desired effect to be obtained from optimizing the composition of the slag. An efficient composition for the slag was also chosen, the slag having high contents of MgO and Al2O3. The use of such a slag helps form a protective slag crust of the composition MgO·Al2O3 on spinel refractories having the compositions MgO·Cr2O3 and MgO·Al2O3.

Results are reported from studies of the rate of oxidation of different carbon-bearing materials. It is shown that the quality of these materials can be evaluated with the use of modern instruments and methods of investigation.

Results are provided for a study of the effect of carbon component on physicochemical and production properties of corundum-silicon carbide-carbon concrete. It is shown that carbon with a more perfect structure provides better concrete mix rheological properties, greater object density and strength, and also better oxidation resistance.

The composition and products of reclamation of spent molding sand made of quartz sand and a pulverized fraction and the potential for its use as a component of a raw mixture of silica brick articles are considered. Results of laboratory and commercial tests employing the technology used in the production of silica brick for coke ovens and the determination of the properties of articles produced from the addition of products from the reclamation of “burnt Earth” are presented.

Milling of chromite concentrate is studied in equipment with different milling methods and energy intensity. It is established that milling gives rise to a different chromite fine particle surface structure, different nature and amount of microdeformation within particles, and different chemical activity. Milling has almost no effect on material phase composition. Within a layer more than 50 A there is magnesium silicate entirely screening chromium spinelid at a chromite particle surface subjected to fine milling.

Physicochemical possibilities are considered for entry of carbon into the structure of fuzed MgO during crystallization from a melt. It is established that fuzed periclase contains carbon, which during periclase grinding is concentrated at the surface of MgO crystals. With fine milling in a vibration mill carbon concentration is higher at the surface of MgO than with milling in a jet mill, and comprises 41.40 and 35.42 wt.% respectively. Melting MgO in an experimental electric arc furnace confirms the possibility of preparing periclase saturated with carbon.

Compositions and manufacturing technology are developed for manufacturing a crucible lining for master alloy preparation by an aluminothermic method. Slag is the main material used for lining manufacture, formed during reduction of aluminum metal oxides containing 80 – 84% α-Al2O3. Charge compositions are developed within which soda and high-alumina cement are tested as binder. The technology is introduced into OAO Uralredmet.

Results are presented from the development of a new series of low-cement concretes for use under different conditions in high-temperature equipment employed in ferrous metallurgy. The concrete mixtures are made with the use of a wide range of fillers—from fused corundum to fireclay. The service temperature of the concretes is within the range from 1450 to 1750°C, the specific temperature depending on the composition of the filler. The concretes do not soften during heating and have excellent quality characteristics. Their practical application in high-temperature equipment and ladles used to transport molten metal at the Magnitogorsk Metallurgical Combine has demonstrated their durability in service.

Possibilities are considered for using carbon fibers as a reinforcing elements within the structure of periclasecarbon refractories. Laboratory research results are provided.

The requirements and service conditions of the refractories used to line rotary kilns in the cement industry are examined and possible ways of using them more efficiently are discussed. Results obtained from an analysis of the durability of the linings and the properties of the refractories are used to propose a new classification for the factors that affect the service life of rotary kilns in the cement industry.

Results are given for a study of sintering and its effect on corundum ceramic pore structure with addition of zirconium dioxide. Powder composites of Al2O3 and ZrO2 (stabilized with 5 wt.% Y2O3) are prepared by slip casting and different temperature sintering regimes. It is established that under stable uniform conditions the original pore surface, sintering temperature, and isothermal soaking duration affect the change in pore surface during sintering.

Dilatometry is used to study kinetic features of sintering composite ceramic of the ZrO2 (Y)–Al2O3 system in the zirconium dioxide concentration range, stabilized with Y2O3, from 0 to 100 wt.%. Composites are prepared by mixing aqueous dispersions of the corresponding oxides. It is shown that within the heating regime with a constant shrinkage rate for composite ceramic xZrO2(Y) – (100 – x)Al2O3, within which x has a value from 0 to 100, does not proceed linearly. The maximum shrinkage rate and minimum temperature for the start of compaction applies to compositions containing 25 – 35 wt.% ZrO2(Y).

The composition and content of exchange cations on the surface and in the interior volume of different clays are studied. It is found that the atomic (ionic) composition of the surface of clay particles influences the adsorption and rheological properties of a suspension upon introduction of electrolytes. The possible exchange reactions between the molecules of the electrolyte and the ions of a clay particle are determined.

Production of refractory cements by sintering is difficult as a result of the narrow temperature range for sintering and high synthesis temperature. In order to expand the temperature range for sintering and reducing firing temperature it is proposed to form an intermediate metastable phase in of high-alumina cement sinters. Results are presented for synthesis of high-alumina cement sinters with formation within them of intermediate metastable sulfatized phases.

Contemporary oxide-graphite materials are analyzed. Density, ultimate strength in bending, and porosity of zirconia-graphite materials are studied using experimental planning. The effect of various components on properties of the materials obtained is evaluated.

Basic requirements are formulated for starting materials for manufacturing porous ceramic diaphragms, and alumina-containing raw materials of domestic and overseas production are studied. Porous ceramic is manufactured with 35% open porosity and ultimate strength in compression of 72 MPa. © 2013 Springer Science+Business Media New York.

The effect of fraction composition of aluminum-magnesium antioxidant with a Al:Mg ratio of 1:1 on some periclase-carbon object properties and their relationship towards highly basic slag are studied. It is established that introduction into the composition of periclase-carbon charges of aluminum-magnesium alloy in an amount of 5% most effectively protects carbon in the refractory, reducing the amount of the decarburized area, and increasing ultimate strength in compression for objects to 36.7 MPa after coking firing. © 2012 Springer Science+Business Media New York.