Alumina–zirconia–yttria nanocomposites prepared by solution combustion synthesis

Nanostructured zirconia toughened alumina composite has been prepared by solution combustion synthesis. Urea has been used as sacrificial fuel and metal nitrates as precursor reagents. A traditional composition for the final ceramic–ceramic composite has been chosen: 20 vol.% of t-zirconia partially stabilized with 3 mol% of yttria dispersed in alumina matrix. TEM characterization on composite powders as obtained by the combustion synthesis process revealed that nanosized particles of both alumina and zirconia can be obtained with a homogeneous dispersion of zirconia nanoparticles in the alumina matrix. Successively, the behaviour of composite powders during pressureless sintering was evaluated. SEM characterization on sintered body was done thus showing that the nanostructured character and the homogeneous dispersion of zirconia particles obtained by solution combustion synthesis were retained also after the thermal treatments necessary for sintering.