China's Refractories

Abstract: The oxidation tests of different SiC refractories including Si₃N₄-SiC bricks, Si₃N₄-Si₂N₂O-SiC bricks from China (SNO-1), Si₃N₄-Si₂N₂O-SiC bricks from overseas (SNO-2), SiAlON-SiC bricks, oxides bonded SiC bricks, self-bonded SiC bricks as well as SiC castables were carried out in the steam atmosphere (1 000 ℃, 32 kg · m^-3 · h^-1) for different durations (100, 200, 300, 400 and 500 h). The mass, the volume, the bulk density and the apparent porosity before and after the oxidation were tested. The XRD and SEM analyses were conducted. The results indicate that: (1) under the steam atmosphere condition (1 000 ℃, 32 kg · m^-3 · h^-1), as the oxidation time increases from 0 to 500 h, the volume and the mass of the silicon carbide refractories increase, while the bulk density decreases; in terms of the apparent porosity, oxides bonded SiC bricks and SiC castables present an increasing trend, Si₃N₄-SiC bricks, SiAlON-SiC bricks and self-bonded SiC bricks present an increasing trend first and then a decreasing trend, and Si₃N₄-Si₂N₂O-SiC bricks present a decreasing trend or a trend of decreasing first and then increasing; (2) as for Si₃N₄-Si₂N₂O-SiC bricks, SNO-1 and SNO-2 have basically the same chemical and phase composition, SNO-2 has the lower mass change rate than SNO-1 during oxidation from 200-500 h, which indicates that SNO-2 has the better steam oxidation resistance than SNO-1.

Key words: silicon carbide, refractories, steam, oxidation resistance