Effects of the variations in milling time and sintering temperature on the production of mullite-ZrO₂ composites

Based on reactive sintering technology, imillite-ZrO₂ composites were fabricated. A powder mixture of 64% wt ZrSiO₄, 18.5% wt AI and 17.5% wt Al₂O₃ was attrition milled for different times (0.5, 3, 6, 12 and 24 h). Precursor powder was cold isostatic pressed at 400 MPa and heat-treated in air at 1450, 1500, 1550 and 1580°C for 2 h. During firing Al oxidizes to Al₂O₃ completely, and ZrSiO ₄ dissociation allows the production of mullite with finly dispersed ZrO₂. XRD analysis shows that increases in the milling time and sintering temperature favors densification and mullitization. The influence of both milling time and sintering temperature upon the phases evolution, microstructural development and final mechanical properties, as well as the processing details are discussed in this study.