Precision casting mould binder - based on silica organosol diluted with aq. phosphate soln. for increased stability

摘要

A precision casting mould based on refractory aggregates is made using a binder which is prepd. by mixing a silica hydrosol, contg. 3-6% SiO2, with an organic liq., and, after separating, recovering an organosol contg. 16-30% SiO2. The organosol is diluted up to approx. 20 vol.% with water contg. is approx. 4% phosphates. The refractory aggregates are bonded by colloidal silicic acid as well as by a phosphate bond during melting of the metal to be cast. A low cost mould with a strong SiO2 organosol bond is mfrd. The mechanical properties and stability are improved. Conventional appts. is used in the prepdn. of the organosol and the mould. It is not necessary to supply any energy nor is there any evolution of pollutants. The sols. are compatible with all the usual refractory materials used in precision casting moulds. Heavier parts can also be cast.