Influence of water glass modification with nanoparticles of MgO on strength properties of moulding sands

Angelika Kmita, Barbara Hutera, Ewa Olejnik

Quarterly No. 1, 2013 pages 14-18

DOI:

keywords: moulding sands with water glass, MgO nanoparticles, modification

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abstract An attempt was made to modify water glass with a propanol suspension of magnesium nano-oxide obtained by the thermal method. Foundry binders are usually complex synthetic materials of different chemical nature. Due to their specific chemical composition, they often pose a threat to both humans and the environment. Therefore, the constantly tightening rules on environmental protection have compelled the foundry industry to replace hazardous organic binders with less harmful ones, i.e. inorganic. Considering the above requirements, a foundry binder with a promising future seems to be water glass. It is cheap, easily accessible, and non-toxic. At the same time, the potentials of water glass as a binder for moulding and core sands have not been so far fully explored. The effect of the modifier and its content on the R_m^U tensile strength of loose moulding sands was examined. The content of modifier was determined at which the sand reaches the highest and the lowest values of R_m^U. This content amounts to 3 mass% and 5 mass% giving 1.61 MPa and 0.42 MPa, respectively. It was proved that the maximum value of R_m^U was the effect of the chemical reaction of water glass with magnesium nano-oxide, while the minimum value of R_m^U was due to the excessive binder wettability of the sand grains, hindering the formation of strong binding bridges in the sand mixture. FT-IR studies revealed the presence of chemical reactions taking place between the binder and modifier, the result of which was the presence of Mg²⁺ cations in the of water glass structure.