GB1437062A - Shaped heat insulating articles - Google Patents

Abstract

1437062 Heat-insulating article G NORTON 14 April 1975 [18 April 1974] 16945/74 Heading C3N [Also in Divisions C5 and D2] A shaped heat-insulating article for forming a molten metal-contacting lining for metallurgical moulds comprises a granular and/or fibrous refractory material which has a high infra-red and ultra-violet radiation opacity, an exothermic mixture of a fuel and an oxidizing agent, and a binder, and having a density below 0À7 g./cc. The granular refractory material may be alumina, magnesia, chromite, titania, or zirconia, or a mixture thereof. The fibrous refractory material may be an aluminosilicate, zircon, calcium silicate or alumina fibre, or a mixture thereof. The fuel may be aluminium powder, or ferro-silicon, silicon, magnesium, or zirconium, or a mixture thereof. The oxidizing agent may be barium sulphate, barium nitrate, iron oxide, manganese dioxide, or a mixture thereof. The binder may be a phenolic resin, urea-resin, furan resin, or starch together with an inorganic binder e.g. colloidal silica sol, colloidal aluminia, or mono aluminium orthophosphate. The composition of which the article is formed may also comprise a fluoride (e.g. cryolite, fluorospar, and/or sodium-silocofluoride) as a catalyst for the exothermic reaction. The lining may be formed by dewatering an aqueous slurry of the appropriate composition on a porous former of the required shape and drying the shape so formed. A dispersing agent, e.g. aluminium sulphate or ferric chloride may be used in the preparation of the slurry. The article may be in the form of a board, slab, or sleeve for use in lining hot tops and risers in foundry moulds.