A. E. Zhukovskaya

How corundum refractories are wetted by molten steel

ConclusionsWe studied corundum refractories, modified with additions of Mg, Cr, and Zr oxides and silicon-containing substances designed for making the tiles of gate valves, on the wettability of steel 45 at 1550°C.It was established that within the limits studied the incorporation of oxides of Zr, Cr; mixtures of Cr, Mg and Zr oxides; and also silicon-containing additives, increases the wetting angle of corundum refractories.The low wettability of these refractories by steel to a significant degree determines the high metal resistance in service of the gate-valve tiles made on their basis.

A separator for deironing sintered corundum

ConclusionsProcessing of corundum chamotte on a PBSTs-63/100 separator ensures qualitative deironing of the material and permits a decrease in the mass fraction of iron oxides to 0.2%, regardless of their content in the initial chamotte.

Effect of iron oxide on the phase composition of zirconia refractories

ConclusionsIt has been established that in the compositions ZrO2∶Y2O3∶Fe2O3 and ZrO2∶Nd2O3∶Fe2O3 the processes of formation of rare earth ferrites and ZrO2 cubic solid solutions occur simultaneously. At temperatures of up to 1300°C the ferrite-formation process is fastest; with a further increase in the temperature the synthesis of ZrO2 cubic solid solutions is significantly intensified.In the mixture of CaO, ZrO2, and Fe2O3, the calcium oxide reacts only with ZrO2.The greatest stability in relation to the action of Fe2O3 is clearly found in the case of the zirconia-calcium oxide solid solutions.In the mixtures of cubic solid solutions of Nd2Zr2O7-ZrO2 or ZrO2-Y2O3 and Fe2O3, an interaction is only possible in the case where the synthesis of ferrites is not accompanied by the restructuring of the crystal lattice of ZrO2, i. e., by destabilization of the material.The presence of Fe2O3 prevents the decomposition of zirconia-calcium oxide and zirconia-neodymium oxide solid solutions under conditions of prolonged heating in air at 1300°C. The zirconia-yttria cubic solid solution is the most stable and does not decompose, regardless of the concentration of Fe2O3, after a dwell of 250 h at 1300°C.

Influence of oxide additions on the sintering of corundum refractories

Influence des oxydes de Mg, Ti et Cr et de leurs melanges sur la structure du corindon fritte

Silicone polymers in oxide refractories technology

ConclusionsWe developed a method for obtaining silicone bonds for refractory materials based on nonhydrolyzed ethyl silicate, silicone resins, and organic adhesive component.Using corundum and periclase refractories as examples we demonstrated that use of the new bonds contributes to a significant strengthening of the materials in the range 20–900°C, and they are therefore prospective for preparing unfired refractories. The use of bond ensures densification and strengthening of corundum refractories, while simultaneously reducing the shrinkage, and leads to an increase in the stabilization of the high-temperature strength of the articles and a reduction in their wettability by molten steel. It is shown that the new oxide materials may be obtained in the production of tiles for the gate valves of steel-casting ladles.

Thermoplastic properties of corundum refractories

ConclusionsThe authors have measured the creep of certain corundum refractory materials. They have shown that it is determined by the silica content, the annealing temperature of the artifacts, and the microstructure of the latter.

Use of silicoorganic polymers in alumina-refractory technology

ConclusionsUsing alumina refractories as an example, it is shown that the newly developed silicoorganic bonding containing an ethyl silicate base and polymethylphenylsiloxane resin dispersed in it, provides a sufficiently strong crock; a significant increase in the strength of the articles after heat treatment at 350–1000°C; and helps to improve the thermal-block resistance, density and the strength of the refractories and reduces shrinkage on firing.

Service of corundum plates in sliding gates during teeming of steel into ingot molds from 140-ton ladles

ConclusionsSpecial tests have been made on magnesia biceramic and corundum plates in sliding gates of steel teeming ladles. It is found that better teeming of steel from 140-ton ladles into ingot molds is obtained with corundum plates.There is hope of increasing the number of times which the corundum plates can be used.