The effect of BaO and Al2O3 addition on the crystallization behaviour of cordierite glass ceramics in the presence of V2O5 nucleant

The effect of V2O5 nucleant on crystallization of stoichiometric cordierite glass ceramics in the presence of various amounts of BaO and Al2O3 additives were investigated by DTA, XRD and SEM. It was shown that 3 wt.% V2O5 and 1.5 wt.% BaO were the optimum amounts of the additives effective in inducing both surface and bulk crystallization in the above glass ceramics.This resulted in ∼90 wt.% cordierite after a 3 h heat treatment at 1020 °C. The specimens possessing 4–5 wt.% Al2O3 in excess of the stoichiometric cordierite composition, developed mullite along with cordierite in the temperature range of 1045–1055 °C, whereas in the specimen containing 6 wt.% excess Al2O3, mullite was detected as the sole crystallization product.