Effect of addition contents of CaO–Al₂O₃–SiO₂ composite sintering aids on the properties of ZrO2/Al2O3 composite ceramics

The CaO–Al₂O₃–SiO₂ composite sintering aids were prepared by polymer network method using Al(NO₃)₃·9H₂O, Ca (NO) 2·4 H₂O, and C₈H₂₀O₄Si as the raw materials, showing the uniform constituent and high activity in the particle sizes of 3~7 μm.The Al₂O₃ and ZrO₂ raw powders were mixed and dry pressed with the CaO–Al₂O₃–SiO₂ composite sintering aids in the mass fraction of 3%, 5%, 7%, and 9%, and then the ZrO₂/Al₂O₃ composite ceramics samples were pressureless sintered at 1450 ℃ for 4 h.The effect of addition contents of CaO–Al₂O₃–SiO₂ composite sintering aids on the mechanical properties and microstructures of ZrO₂/Al₂O₃ composite ceramics were studied.The results show that, the comprehensive properties of ZrO₂/Al₂O₃ composite ceramics added with the CaO–Al₂O₃–SiO₂ composite sintering aids in the mass fraction of 5% are the optimal as the relative density of 94%, the micro-Vickers hardness of 1204 MPa, the flexural strength of 321 MPa, and the fracture toughness of 4.52 MPa·m^1/2.