Modified hydrated sodium silicate as a modern binder for ecological moulding sands

Abstract

This article is devoted to ecological moulding sands with hydrated sodium silicate as binder. The inorganic nature of the binder results in poor knock-out properties and low ability to mechanical reclamation of tested moulding sands. In the present study authors focused on developing a new addition to the composition of these environmental friendly foundry moulding sands, providing them better knock-out properties. The analysis of the literature data let authors focus on the use of additives containing Al2O3 as components of moulding sands with hydrated sodium silicate. These additives provide better knock-out properties of moulding sands measured according to retained strength Rctk and also lead to lower thermal expansion of moulding sands. The authors have developed a new supplement containing Al2O3 and demonstrated its positive impact on moulding sand with hydrated sodium silicate knock-out properties.