The steel industry is one the biggest consumers of refractories. In this industry, refractories are commonly used as linings for steel production equipment, because they can sustain high temperature and corrosive attack in their working environment. However due to the harsh conditions, their life span is limited. Corrosion mainly by slag and molten steel is the principal phenomenon responsible for degradation and wear of the refractory bricks. It is a complex phenomenon that is due to infiltration (penetration) into and subsequent dissolution of the refractories by slags and molten steel. A thorough understanding of these mechanisms is necessary in order to improve the refractories behavior for steel making applications. However, even nowadays, no laboratory test can reproduce the real working conditions in the steel industry. According to the parameter of interest several testing methods have been developed. They can be static like the sessile drop test or crucible test or dynamic like the rotary slag test. This paper describes the principal corrosion tests used in the steel industry in order to give an overview of the way to determine and finally alleviate the impact of corrosion on refractories. Corrosion tests for refractory materials intended for the steel industry -A reviewCeramics - Silikáty 64 (3) 278-288 (2020)

In this paper, the corrosion mechanism of commercial alumina-spinel refractory was investigated at 1350 and 1450 °C. Disc samples were coated with shells of two different slags containing 4 and 10 wt.% SiO2. The after-corrosion refractory was investigated in view of changes in its microstructure and phase composition by SEM/EDS and XRD techniques, respectively. At 1350 °C slags slightly infiltrated the microstructure, whereas at 1450 °C slags infiltrated the alumina-spinel refractory causing its significant corrosion. As a result of corrosion, new phases were formed, including calcium dialuminate (Ca2Al4O7), calcium hexaluminate (CaAl12O19), and gehlenite (Ca2AlSi2O7). Formation of calcium aluminate layers in the microstructure of the refractory inhibited further dissolution of alumina aggregates; however, expansive behavior of CaAl12O19 raised the microstructure porosity. The additional SiO2 in the slag doubled the amount of low melting gehlenite in the matrix, accelerating the corrosion process of alumina-spinel brick at high temperatures.