Study of the chromium oxide and zirconium dioxide additives effect on the properties of pressed highalumina refractories

This article presents the results of research aimed at studying the effect of chromium oxide and zirconium dioxide refractory additives, the method of their introduction — with separate introduction of each of them or with their joint introduction, as well as with the joint introduction of these additives and the additional introduction of dispersed active alumina A α­form additive, on the main properties (primarily cold crushing strength and thermal shock resistance) of pressed high­alumina refractories. Comparative studies of the effect of additives of 5 % Cr2O3, 3 % ZrO2, 5 % Cr2O3 and 3 % ZrO2, 10 % Cr2O3 and 3 % ZrO2, 10 % Cr2O3 and 3 % ZrO2, and B % dispersed active alumina A of α­form on the apparent density of unfired samples and their property indicators after firing at a temperature of 1580 ºС were carried out. The optimum composition of the additive (10 % Cr2O3 and 3 % ZrO2 and B % dispersed active alumina A of α­form) was determined, which ensures the production of fired samples with a set of high property indicators: content of Al2O3 86.50—86.70 wt. %, Cr2O3 9.85 wt. %, ZrO2 3.0 wt. %, Fe2O3 0.3 wt. %; apparent density 3.14 g/cm3; open porosity 23 %; cold crushing strength 118 N/mm2; thermal shock resistance (1300 ºС — water) not less than 7 heat changes. The research was the basis for developing the technology of pressed alumina­chromium oxide refractories, for the composition of which an application for the invention was filed and a patent of Ukraine was obtained. The developed technology ensures the production of these products with a cold crushing strength that is ~ 2 times higher and ~ 1.8 times higher thermal shock resistance (in the 1300 ºС water regime) compared to similar characteristics of refractories of the same composition but without the additive. Based on the research results, regulatory documentation was developed, and the range of competitive refractory products manufactured by the Institute was expanded.