Effects of mechanochemical processing and doping of functional oxides on phase development in synthesis of cordierite

Mechanochemical activation of cordierite precursors (using laboratory planetary milling equipment) was applied as an intentional way of creating defects in the structure in order to affect the sinterability of the material. Effects of doping certain functional oxides on the sinterability and structural development of the resultant composites were also investigated. The microstructure of the sintered samples was considerably modified by intensive milling (even when applied at short times); at the same time, phase transformation of the mechanically milled material resulted in an almost single-phase cordierite ceramic when sintered at 1300 °C/2 h. In cases where the ratio of oxide dopants, ceria/yttria-stabilised zirconia was either 4 or 1/4, the influence of longer activation on the XRD peak intensities of the sintered samples was considerable. Destabilisation of zirconia and formation of zircon were observed in the activated material. Intensive milling also resulted in increased bulk density and shrinkage, and decreased pore content in the sintered composite samples.