| 摘要 |
<p>Refractory materials containing alumina, for bricks, mortar, crucibles, or the like, are formed from the ordinary raw materials relatively free from iron by causing aluminium or aluminium alloys and aluminium nitride in the form of foundry skimmings to be oxidized in situ during mixing, shaping, or baking, the oxygen being obtained from the air during baking, from the water during mixing and shaping, or, partly, from zinc oxide which may be included in the mix, the zinc being volatilized during subsequent treatment. During the reaction, aluminium hydroxide may be produced first, and acts as a bonding agent for the other ingredients, which include kaolin and other clay of low iron content, together with crushed firebrick, magnesite, chromite, zirconium silicate, graphite, or other refractory material. According to examples, foundry skimmings from the refining of aluminium alloys, containing the alloys with magnesium, manganese, zinc, and cadmium, and aluminium nitride, are ground and mixed with plastic white clay and crushed firebrick, zircon, chromite, or magnesite, and zinc oxide may be included. The Specification as open to inspection under Sect. 91 refers also to the use of materials for acid-resisting sheets and containers, abrasive stones, or the like, and describes the use in the reaction of basic, acidic, or neutral catalytic agents such as sodium hydroxide, the oxides of calcium, magnesium, and zinc, sulphuric acid, aluminium or copper sulphate, and the chlorides of calcium, magnesium, and zinc, sodium silicate and sodium aluminate; mercuric oxide and cadmium oxide are referred to as alternatives to zinc oxide for the supply of oxygen. This subject-matter does not appear in the Specification as accepted.</p> |
