GB609771A - Improvements relating to the manufacture of bladed turbine discs, compressor rotors or the like - Google Patents

Abstract

In a method of casting rotary bladed bodies such as turbine discs, (see Group XXII), a wax model is coated with a suspension of silica or other refractory oxide or silicate in a solution containing sodium silicate or ethyl silicate as a binder. The mould is formed by pouring around the coated wax model, finely ground refractory material in suspension, a preferred composition consisting of 10 lbs. of solid refractory material comprising 60 per cent calcined fireclay "grog" and 40 per cent of silica flour, and 1 litre of a liquid consisting of 25 per cent tetra ethyl silicate, 50 per cent alcohol or methylated spirit, and 25 per cent of a solution of 15 per cent concentrated hydrochloric acid in 80 per cent aqueous alcohol. The refractory material has a grading as follows:- Silica Flour-All through 200 B.S.S. sieve. Grog-2 per cent on 10 B.S.S. sieve. 20 per cent through 10 or 30 B.S.S. sieve. 18 per cent through 30 or 60 B.S.S. sieve. 17 per cent through 60 or 100 B.S.S. sieve. 20 per cent through 100 or 170 B.S.S. sieve. Remainder through 170 B.S.S. sieve. The setting of the mould may be accelerated by the addition to the mould material of a refractory material and alkali such as magnesium oxide or other basic compound.