Selection of technological additives to the composition of the moulding mixtures based on water glass

Abstract

ABSTRACT In the foundry for the production of moulds and cores, mixtures based on water glass are widely used. During their hardening, the coagulation of liquid glass occurs, as a result of which the mixture obtains high strength characteristic. A significant drawback of moulding mixtures based on water glass is low knockout due to increased sintering ability of water glass with moulding sand. To improve knockout, weak additives are introduced into the composition of moulding mixtures. This paper analyses the characteristics of organic weak additives for the composition of moulding mixtures based on water glass. It is shown that the main indicators which affecting to the knockout of mixtures are the amount of evolved gases and the forming carbon formation. With an increase in coefficient of thermal destruction, the knockout of the mixtures based on water glass mixture is reduced by increasing the amount of formed carbon.