The investigation of high-temperature strength of SiC based refractories

The Brew-Instron apparatus was used in order to investigate the temperature dependence of bend strength of SiC based refractories in the range from room temperature up to 1400°C. The results obtained show that the strength of the samples strongly depends on the type and amount of bonding phase used (silicate, nitride) as well as on the grain size and the grain size distribution of the SiC phase. Nitride bonded materials are superior to silicate bonded and by decreasing the SiC grain size the high-temperature strength can be markedly increased. The extend of deformation is governed mainly by the SiC grain size, whereas the amount of binder phase does not influence it significantly. The results are discussed with reference to other methods which are used to characterize the performance of the refractories.