Role of SiO2 on Mold Making Process in Foundry Metallurgy

Abstract

Natural sands are varied, both chemically and physically. SiO2 is the largest content besides of Na2O, K2O and Fe2O3 with variety of grain size distribution. For molding purposes, sands should have a minimum of 95% SiO2, a maximum of 1.50% Na2O + K2 O and maximum 1.0% Fe2O3 with wide distribution of grain sizes. Chemical composition, grain-size distribution, grain fineness number, shape, and clay content are the common test for basic characteristics. Another additional characteristic such as permeability, compressive strength, shearing strength have also being carried out on the natural sands used in mold making process in foundry such as CO2 mold and green sand mold. CO2 mold consist of SiO2 with Na2SiO3 (Sodium Silicate) and for green sand mold consist of SiO2 with bentonite.