| 摘要 |
A refractory shaped structure is produced by a process comprising forming a shaped article of a fugitive material and a composition consisting of (a) aluminium or aluminium alloy particles of - 45 mesh (U.S.S.), (b) refractory particles of - 20 mesh, there being 15-95% by weight aluminium and 85-5% refractory correspondingly, (c) at least 0.5% by weight, based on the Al weight, of a catalyst for the oxidation of Al, and (d) a binder to bond the fugitive material to the composition, then firing the shaped article in an oxygen-containing atmosphere at a temperature from 600 DEG C. to the melting-point of the refractory material until at least 60% of the Al has been oxidized. The shaped article may be a self-supporting film or sheet of fugitive material not more than 2 mm. thick in the form of paper, cardboard, woven or non-woven fabrics of cellulose, polyethylene, polypropylene, polyethylene terephthalate, nylon, or glass or ceramic fibres coated on each side with a layer not more than 0.19 inch thick of the said composition, the latter being applied as an aqueous dispersion and dried before firing. The binding agent for the fugitive material and composition may be sodium silicate, clay, sodium alginate, or sodium carboxymethyl cellulose. The catalyst may be an alkali metal oxide or hydroxide, an oxide of Ba or V, or an equivalent amount of a substance yielding the aforesaid on firing. Suitable refractory materials are alumina, corundum, magnesia, magnesite, dolomite, clay, burnt clay grog, asbestos, silicon carbide or forsterite. Two or more shaped articles may be formed separately and then joined together before being fired. The products are characterized by a structure of thin-walled sections of thickness not more than 0.38 inch of a crystalline refractory material containing at least 25% alumina, having a uniform porosity of 20-70% and a flexural strength at 1550 DEG C. of at least 130 p.s.i. |
