Effect of Mechanical Activation on Alumina-Zircon Mixture for Producing Mullite-Zirconia

Zircon and alumina were mixed in accordance with the atoichiometry ratio and activated in a planetary ball mill from 1 to 10 hours. After finishing mechanical activation processes and removal the iron impurities, each mixture was isothermally heated for one hour in a tube furnace at different temperatures. XRD results showed the decomposition of zircon reduced to about 13000C in a one-hour-milled sample. The amount of retained tetragonal zirconia in the one-hour-milled sample was higher than the un-milled samples after isothermal heat treatment. With increasing temperature up to 14500C, the amount of tetragonal zirconia some how decreased in the activated samples, whilst the increasing in amount of tetragonal phase was observed in the un-milled samples.