GB661607A - Insulating fire brick and process of manufacture - Google Patents

Abstract

661,607. Refractories. MORGAN CRUCIBLE CO., Ltd. (Babcock & Wilcox Co. of America). May 6, 1949, No. 12197/49. Classes 22 and 70 A high temperature insulating fire brick is obtained by forming a thixotropic slip containing a calcined refractory material and a small amount of particles of a metal which reacts with an acid to form hydrogen dispersed therein, chemically bloating the slip by reacting the metal particles with acid to evolve hydrogen in the slip, slop casting the slip in a mould while absorbing water from the slip to effect a thixotropic set. and drying and firing the moulded shape. Specified refractory materials are the oxides of aluminium, magnesum, beryllium and zirconium. The metal particles which may be iron are preferably obtained by grinding the alumina till it all passes a 200 mesh sieve by means of steel balls thus giving an iron content of about 0.1 per cent. The mould may be made of plaster of paris or iron. Porosity may be increased by additon of a small quantity of sawdust. In an example, alumina ground as above, was wet mixed with sawdust, ammonium dihydrogen phosphate and hydrochloric acid added. After moulding the mixture was fired at 3200‹F. In another example the phosphate is omitted and plaster of paris added, also the hydrochloric acid was replaced by sulphuric acid. In a further example, additional iron is included in the mix. The iron content is either removed by volatilization or is left as an iron salt on the outside of the fired material and may then easily be removed by trimming.