Spark plasma sintered Al₂O₃-YSZ-TiO₂ composites: Processing, characterization and in vivo evaluation

Al₂O₃ and Al₂O₃-YSZ composites containing 3 and 5 wt.% TiO₂ were prepared by spark plasma sintering at temperatures of 1350-1400 °C for 300 s under a pressure of 40 MPa. The grain growth of alumina was suppressed by the addition of YSZ. Al ₂O₃-YSZ composites showed higher hardness than monolithic Al₂O₃. There was not a considerable difference in hardness values for Al₂O₃-YSZ composites containing 10 and 20 vol.% YSZ and the addition of TiO₂ decreased the hardness of the composites. The fracture toughness of Al₂O₃ increased from 2.8 MPa·m^1/2 to 4.3 MPa·m^1/2 with the addition of 10 vol.% YSZ, further addition resulted in higher fracture toughness values. The fracture toughness values were increased with TiO₂ addition and the highest value of fracture toughness, 5.3 MPa·m ^1/2, was achieved with the addition of 20 vol.% YSZ and 5 wt.% TiO₂. Preliminary in vivo tests demonstrated the biocompatibility and osseointegration of the composites after 6 week post-implantation in femur of Wistar rats.