Fabrication of mullite-zirconia composites by reaction sintering of zircon, alumina and zirconia dopant mixtures

摘要

Different mixtures of Al_2O_3 + ZrSiO_4 were planetary milled, pressed and pressureless sintered with the purpose to obtain mullite-ZrO_2 composites in accord to the reaction in air: 3Al_2O_3 + 2ZrSiO_4 → (3Al_2O_3·2SiO_2) + 2ZrO_2 (1) In the original mixture, small quantities of CaO, Ce_2O_3, MgO or Y_2O_3 were aggregated. These are dopant materials that serve as retainers of the tetragonal ZrO_2 phase that emerge from ZrSiO_4 decomposition. Results show that with the use of Ce_2O_3, CaO or MgO reaction progress is good. However, denser composites are produced when Y_2O_3 is used. On the other hand, with the use of MgO or Y_2O_3 more tetragonal ZrO_2 phase is present in the composite, consequently toughness in these composites is higher than toughness in composites with CaO or Ce_2O_3.