Effect of Cr₂O₃ on Microstructure and Mechanical Properties of SrO-ZTA Composite Ceramics

With 3Y-TZP, α-Al₂O₃ and Sr(NO₃)₂ as raw materials, ZTA composite ceramics doped with SrO and Cr₂O₃ were prepared by using the combination of pressureless pre-sintering and hot isostatic pressing sintering. Cr₂O₃ was derived from Cr(NO₃)₃·9H₂O. The effect of Cr₂O₃ on microstructure and mechanical properties of the SrO-ZTA composite ceramics was studied. With increasing content of Cr₂O₃, the XRD diffraction peaks of α-Al₂O₃ and SrAl₁₂O₁₉ shifted to the low angles, suggesting that the lattice parameters gradually increased. Combined with EDS analysis, it is speculated that Cr₂O₃ entered the lattice of SrAl₁₂O₁₉, positively affecting mechanical properties of the final composite ceramics. The doping of Cr₂O₃ promoted grain growth of the composite ceramics. As the content of Cr₂O₃ was increased, fracture toughness and flexural strength first increased and then decreased. When the Cr₂O₃ content was 0.50 wt.%, microhardness, fracture toughness and flexural strength reached 18.45 GPa, 6.9 MPa·m^1/2 and 910 MPa, respectively.