Wetting ofAl2O3by Molten Aluminum: The Influence ofBaSO4Additions

Abstract

The effects ofBaSO4additions on the wetting of alumina by molten aluminum were studied by the sessile drop technique. To study the effect ofBaSO4decomposition(1100–1150∘C), the additions were treated at two temperatures700∘C(973 K) and1450∘C(1723 K), respectively.BaSO4additions at low and high temperatures did not improve the nonwetting character of these compositions. However, at higher firing temperature, the formation ofBA6 (BaO•6Al2O3)has a nonwetting trend with increasing its content. To address theBA6specifically a pureBaO•6Al2O3was produced and tested. It was more nonwetting than the pure alumina. After the analysis of the contact angles for theBaSO4and theBA6 (BaO•6Al2O3), it was concluded that these additions to alumina do not inhibit wetting by molten aluminum. In fact, at the addition levels common for refractories, the wetting tendency of molten aluminum is enhanced. Alternative explanations for the effectiveness ofBaSO4additions to alumina refractories are discussed.