Hafnium dioxide for porous and dense high-temperature refractories (2600 °C)

The dense pieces are made of hafnium dioxide doped with yttrium oxide in order to avoid cracking due to a phase transition which generates an important volumetric expansion. The ceramics obtained after sintering are dense (90%) and present mainly closed porosity. The porous pieces are prepared from a mixture of hafnium dioxide and a porous agent. After sintering, these pieces keep a satisfactory porosity (30-50 vol%) and do not crack during the phase transition.