Investigation on the Effect of Alumina Nanopowder on Thermal Shock Resistant of Alumina-Mullite Nanocomposite

In the recent years, application of alumina-mullite composites in refractory industry has gained remarkable attention due to their high strength and life duration. In the present work, preparation of alumina-mullite composite was studied in optimal temperature and time condition using alumina nanopowder. Addition of alumina nanopowder in comparison with its micrometer sized powder in alumina-mullite composites increased mechanical strength and thermal shock resistant. Also, addition of micrometer and nanometer-sized alumina powder to alumina-mullite composites increased and decreased the thermal expansion coefficient, respectively. SEM and EDS analyses showed that the addition of alumina nanopowder increased the amount of mullite phase which improved the strength and thermal shock resistant. Also, addition of micrometer-sized alumina in alumina-mullite composite increased porosity and water absorption and decreased the density. The addition of alumina nanopowder decreased the porosity while water absorption increased the density.