Preparation, aging behavior and interface bonding of cordierite glass-ceramics as veneer porcelain for Si₃N₄ ceramics

In this work, aiming at developing veneer porcelain for Si₃N₄ dental ceramics, the cordierite glass-ceramics were prepared via the sintering method and the effects of glass powder particle size and accelerated aging time on the structure and properties of cordierite glass-ceramics were investigated. With the milling time extension, the glass powder particle size decreases and becomes more uniform, the sintering property, bending strength and fracture toughness increase and then decrease. The cordierite glass-ceramics prepared from glass powder with ball milling time of 10 h exhibit the optimum performance which meets the standard requirements for dental ceramics. Accelerated aging test was conducted in distilled water at 134 °C and 2 atm. After accelerated aging for 10 h, the performance of the samples still can meet the standard requirements, suggesting good stability and anti-aging properties. Effects of HF acid etching and oxidation treatment of Si₃N₄ ceramics on the microstructure, bonding strength and failure mechanism of the cordierite glass-ceramics/Si₃N₄ ceramics interface were assessed. HF acid etching can effectively improve the surface roughness of Si₃N₄ ceramics, and the interface exhibits a mixed failure mode with a bonding strength of 8.49 MPa.