Preparation and properties of cordierite glass-ceramic as veneer porcelain for silicon nitride dental ceramics

To develop thermally matched veneer porcelain for silicon nitride as potential dental ceramics, cordierite glassceramics with TiO2 and ZrO2 as nucleating agents and CaCO3 as sintering aids were prepared by sintering method. The cordierite glass-ceramics prepared by sintering and crystallization at 1100 degrees C for 1 h show the best comprehensive properties and meet the ISO 6872:2015 with flexural strength of 95 MPa, fracture toughness of 1.56 MPa.m(1/2), Vickers hardness of 5.06 GPa, coefficient of thermal expansion of 2.99 x 10(-6)/degrees C and chemical solubility of 60 mu g/cm(2), respectively, and no cytotoxicity. The chromaticity values L*, a*, b* were 93.84, 0.18 and 7.10 respectively, which still needs to be slightly adjusted to fall into the range of natural tooth. Interface bonding of cordierite glass-ceramics/Si3N4 ceramics was preliminarily explored by powder coating, sintering and shear strength tests, which exhibits a bonding strength up to 7.75 MPa and a hybrid mode of cohesive and adhesive failure.