Effect of alumina on ceramic properties of cordierite glass–ceramic from basalt rock

Cordierite–anorthite–alumina compositions have been obtained by mixing alumina powder with cordierite–anorthite glass powder which were previously prepared from basalt rock. Alumina has been added in progressive proportions ranging from 10 to 30%. The prepared specimens were thermally treated at 1100 °C for 3 h. Addition of alumina did not result in a new phase formation, but inhibits the cordierite grain growth. Adding 10% alumina had increased the porosity and decreased the modulus of rupture (MOR), but higher addition had not revealed an observable effect. Alumina content is observed to help in decreasing the dielectric constant.