Gelcasting of alumina–zirconia–yttria nanocomposites with Na-alginate system

The alumina–zirconia–yttria (AZY) nanopowders ranging from 30–110 nm were synthesized via the sol–gel method. θ-Alumina and t-zirconia phases were identified in the nanopowders calcined at 900 °C for 1 h. Sodium alginate was used for gelcasting process of green bodies. The viscosity of castable slurries with highest nanopowder loading, 15 vol.%, is about 800 mPa.s. The dried gels were pressureless sintered at 1400, 1450 and 1500 °C for 3 h. Grain boundary diffusion seems to be the controlling sintering mechanism with increasing zirconia content from 5 up to 10 wt.%, whereas in the range of 10–15 wt.% zirconia content increase, lattice diffusion is the controlling.