PREPARATION OF ZIRCONIA-TOUGHENED BIOACTIVE GLASS-CERAMICS

Bioactive glass-ceramics toughened by tetragonal zirconia polycrystal (TZP) were prepared by hot-pressing mixed powders of the MgO-CaO-P//2O//5-SiO//2 glass and TZP containing 20 to 80 percent alumina. The bending strength and the fracture toughness of the composite materials were improved compared with those of the material without TZP. These composites showed high bending strengths (400 to 500 MPa) and high fracture toughness (approximately 2. 8 MPa m**H**L**F). The existence of a crack deflection mechanism was observed by scanning electron microscopy. After soaking in simulated physiological solution at 100 degree C, no phase transformation from tetragonal to monoclinic of TZP in the composites and no degradation in bending strength occurred.