Mechanical properties of Y2O3/Al2O3-coated Y-TZP ceramics

Y2O3/Al2O3-coated monoclinic ZrO2 nanopowder was prepared from a suspension of aluminiumnitrate, yttriumnitrate and ZrO2 powder in an alcohol/water mixture. The influence of the Y2O3 and Al2O3 content as well as the sintering temperature on the mechanical properties of the densified yttria-stabilised tetragonal zirconia polycrystal (Y-TZP) materials was investigated. Fully dense Y-TZP materials could be obtained from the Y2O3/Al2O3-coated starting powders by means of hot pressing in vacuum at 1450 °C. Typical HV10 hardness values of 1130 kg/mm2 were obtained and the fracture toughness could be tailored up to 9 MPa m1/2 by doping the 1.75–2.0 mol% Y2O3-coated ZrO2 starting powders with 2.0 wt.% of Al2O3. The properties and microstructures of the Y2O3/Al2O3-coated powder based ceramics are compared with those of conventional co-precipitated 2Y and 3Y-TZP ceramics, and the differences in fracture toughness are explained in terms of the differences in the grain size and Y2O3 distribution.