GB1283301A - Improvements in or relating to the manufacture of foundry cores and moulds - Google Patents

Abstract

1283301 Foundry moulds A M LIASS and PABORSOOK 3 July 1970 32360/70 Addition to 1085651 Heading C3N Foundry moulds and cores are produced from a mixture of granular refractory material and a self-hardening binder comprising sodium silicate with a proportion of SiO 2 to Na 2 O ranging from 1À5 up to, but not including 2À5 and as a hardening material cement, said mixture further incorporating water and a foaming agent, the amount of water being such that foaming of the aqueous phase converts the mixture to a fluid condition, the mixture being poured to form the core or mould whilst in the fluid condition. The foaming agent may be used in an amount 0À05- 0À3% by weight of dry ingredients and is preferably an anionic surfactant such as an alkylaryl sulphonate, alkyl sulphonate or a primary or secondary alkyl sulphate but cationic and non-ionic surfactants may be used. The filler may be quartz sand, whilst the amount of cement added is preferably 2-5% by weight, and the content of an aqueous solution of sodium silicate preferably varies from 5-7% by weight of the dry ingredients. An alkali metal phosphate, such as a mono-substituted, di-substituted or tri-substituted phosphate of potassium or sodium, preferably in an amount 0À05-0À35% by weight of dry ingredients. The invention also provides, as a modification of parent Specification, the addition of such an alkali metal phosphate to foundry mould compositions containing sodium silicate with a higher molar ratio of SiO 2 to Na 2 O, say up to 3À0 to 1.