The corrosion behaviour of a pitch-bonded magnesia-carbon refractory exposed to a CaO-SiO_2-MgO-Al_2O_3-Cr_2O_3 slag is investigated by rotating finger tests in a vacuum induction furnace at high temperatures and low oxygen partial pressures. The refractory degradation mechanisms are studied through post-mortem microstructural characterisation. The MgO-C reaction is the major decarburisation mechanism, while decarburisation by oxygen from the atmosphere and/or reducible slag components was limited under the present test conditions. Three kinds of metallic particles with different size, shape, location and composition were observed in the refractory specimens. Their distinct formation mechanisms are discussed in detail.
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