Researches on development of alumina-chromia-zirconium silicate refractories containing 60 % Cr2O3

Abstract

Researches of a branch composition and firing atmosphere influence on structure and properties of pressed alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content were carried out. The optimal branch composition which after firing in oxidizing atmosphere provides obtaining of samples with open porosity 24.8 %, apparent density 3.46 g/cm3, cold crushing strength 78 N/mm2 and thermal shock resistance by 950 ºС — water — 7 thermal cycles was established. The phase composition of samples was determined. It has been shown that, firing in a reducing atmosphere, as well as titanium oxide addition, have no significant effect on samples properties.
 Corrosion resistance comparative researches of alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content and refractory brand KHTSS-30 with 30 % Cr2O3 content to glass «E» and basalt melts by crucible method at a temperature of 1580 °C with an exposure time of 8 hours were carried out. It has been established that, glass «E» and basalt impregnate refractories, moreover for samples with the developed optimal composition the impregnation depth was the smallest in comparison with samples of other compositions. The corrosion mechanism has been established, which consists in the penetration of glass «E» and basalt melts into refractory with further dissolution of corundum grains in them. Sintered Cr2O3 and solid solutions based on it in the composition of samples prevent corrosion, reducing the interaction area of melts with corundum grains, and when exposed to basalt melt, also forming spinelid with its components, which slows down further penetration of melt into refractory structure, thereby reducing its corrosive effect on the refractory.
 Based on the obtained results, a technology of a new domestic type of product (alumina-chromia-zirconium silicate refractories with 60 % Cr2O3 content manufactured by semi-dry pressing method) was developed.