Uso do óxido de cobalto (II) como aditivo em refratários aluminosos densos conformados

Abstract

The refractories are technical ceramics which main feature is to keep its shape and do not melt when subject to high temperatures and/or harsh environments. For these reasons, the refractories have been used as industrial equipments lining as in iron and steel, glass, cement and polymers processing. Due to the rising demand for increased production and waste reduction, the refractory industry has the interest to develop more resistant products with lower consumption rate. Based on magnesium aluminate spinel action, the cobaltic oxide II has shown a promising use as additive for alumina reaction producing cobaltic aluminate spinel and solid solution formed with magnesium oxide. The addition of CoO as additive has indicated some properties improvement at lowest temperatures (up to 1000 ºC), including higher cold crushing strength at cured sample for hydrated phase formation, however, at highest temperatures (1400 – 1600 ºC), the over spinel formation has damaged the microstructure of the additived sample. Due the intense blue color of CoAl2O4, it has aroused interest as location indicator and, indirectly, as temperature indicator during service.