Fabrication of Nanostructured Monoclinic Zirconia Ceramics by Colloidal Processing

Abstract

ABSTRACTFabrication of fine-grained monoclinic zirconia ceramics has been attempted from acid and neutral zirconia sols, which have been prepared by different methods. Complete re-dispersion of flocculated particles for the neutral sol is impossible even by changing its pH, while no flocculation is observed for the acid sol. Chloride ions, which are inevitably present in the acid sol, are removed effectively by using anion exchange resin. Consolidation of the sols is performed by the pressure filtration method at 10 MPa, followed by CIP treatment at 400 MPa. It is possible to densify the compacts from both sols to >98% of theoretical density by pressureless sintering in air at 1100 °C. This temperature is lower than that for the monoclinic to tetragonal transformation of pure zirconia. Fine and homogenous-grained microstructures, which have an average grain size of 92 nm, are observed for monoclinic zirconia fabricated from the acid sol. However, more coarse and heterogeneous microstructures are observed for the compact fabricated from the neutral sol.