| 摘要 |
PURPOSE:To enhance the lifetime of the vessel in the high-temp. oxidative atmosphere by incorporating the specified amount of alumina, carbon and Al. CONSTITUTION:This refractory for molten metal consists of by weight 70 to 94% Al2O3, 3 to 20% C and 3 to 10% Al. At least 10 to 30% of Al2O3 particle is constituted of particles having <=44mum and Al powder is constituted of particles having <=44mum. When this refractory is utilized in the high-temp. oxidative atmosphere, the partial pressure of O2 is lowered and the partial pressure of CO is raised in a matrix constituted of graphite, fine Al2O3 particles and metallic aluminum powder. Therefore, Al and Al2O3 are allowed to react with C, respectively and Al4C3, Al4C3 +CO2 and carbide are deposited and the matrix is made dense. In the operating surface, Al4C3 is allowed to react with O2 and fine Al2O3 particles are deposited and sintered together with Al2O3 in the matrix and a dense layer is formed. The abovementioned refractory is made inferior in heat resistance, thermal shock resistance and resistance to slag penetrability in C<3%. Resistance to oxidation is remarkably lowered in C>20%. Further a difficult point is caused in resistance to oxidation in Al<3%. Generation of a crack is accompanied in Al>10%. |
