In-situ production of Alumina-Titania-Graphite composite by mechanical milling and sintering

Al2O3-TiO2 composite is an excellent thermal shock resistance which can up to 1000°C and also has higher thermal insulation but because of the presence of Al2O5Ti which are unstable could influence the performance of thermal shock of Al2O3-TiO2 composite. In order to prevent it, another phase which is graphite need to be added because graphite will retard Al2O5Ti formation in the Al2O3-TiO2 composite phase. In this study, the effect of different milling time and compaction pressure on microstructural and structural of Al2O3-TiO2-Graphite composite was prepared by mechanical milling and sintering. Elemental powders of alumina (Al2O3), titania (TiO2) and graphite were milled using low energy ball mill with 10 mm alumina ball at 30, 60, 90 and 120 h and were compacted using cold compaction at 200, 400, 600 and 800 MPa. Then, the compacted composites were sintered at 600°C. The composites were characterized for its structural properties, morphology and compressibility. Milling up to 120 h results in reduction of crystallite size and increment of internal strain. Increasing milling time the morphology of composite only had a slight change. The densification of Al2O3-TiO2Graphite composite depends on compressibility of the powder particles. It is also enhanced with increasing compaction pressure.