PHYSICOCHEMICAL STUDIES OF ZIRCONIA AND MAGNESIA DOPED ZIRCONIA CERAMIC POWDER

Spherical fine zirconia (ZrO2) and 9 mol % magnesia doped zirconia (Mg O-ZrO2) ceramic powders (diameter of similar to 0.2 mm) have been synt hesized from a hydrothermally treated sol of zirconium and magnesium s alts by spray pyrolysis. The results revealed that synthesized powders can be sintered into uniformly sized fine grained ceramic of > 97% th eoretical density at temperature as low as 1100 degrees C. The phases, purity, crystallite size, agglomeration structure, particle size, spe cific surface area, pore size distribution and porosity of ZrO2 and Mg O-ZrO2 ceramics were measured by XRD, SEM, N-2-gas adsorption and Hg-d iffusion techniques. The results of X-ray diffraction and scanning ele ctron microscopy showed that the ZrO2 and MgO-ZrO2 remained amorphous up to 700 degrees C, but on increasing the heat treatment temperature to around 1200 degrees C for 8 hrs. monoclinic crystals were obtained. Thermogravimetric (TG) and differential scanning calorimetric (DSC) t echniques were used to measure the burnout temperatures and enthalpy ( Delta H) of polyvinyl alcohol (PVA) and methylcellulose (MC) polymers used as binders. Burnout of these polymers is 100% in an oxidizing atm osphere; 90% burnout was achieved in an inert atmosphere.