| 摘要 |
1. An unshaped refractory composition useful for making refractors articles or parts to be used for casting or treating metals, characterized in that it comprises, by weight : a) 49 to 99% of particles having a size from 0.2 mu m to 20 mm of a fused cast refractory material having the following chemical composition by weight : 45-78% MgO, 0-30% Cr2 O3 , 0-35% Al2 O3 , 0-17% FeO and/or Fe2 O3 , with at least 82% of MgO+Cr2 O3 +Al2 O3 +FeO+Fe2 O3 , 1-8% SiO2 , 0-2% CaO+BaO+SrO, 0-10% TiO2 , 0-3% fluorine, with the condition that the quantity of particles of a size below 45 mu m does not exceed 30% by weight, b) 0.5 to 5% of a hydraulic binder, c) 0.5 to 15% of substantially spherical particles chosen from the group consisting of (i) up to 5% of vitreous silica, in which at least 80% of the particles have a size greater than 0.2 mu m and at least 95% of the particles have a size below 10 mu m, (ii) up to 15% of chromium oxide Cr2 O3 in which at least 80% of the particles have a size above 0.2 mu m and at least 95% of the particles have a size below 10 mu m, and (iii) mixtures of these, d) 0 to 50% of particles chosen from chromite, magnesia and their mixtures, the size of these particles being between 10 mu m and 2 mm, e) 0.01 to 1% of a surface-active agent relative to the total weight of the components (a) to (d), and f) 0 to 4% of metal fasteners relative to the total weight of the components (a) to (d). |
