Effects of nucleation agent particle size on properties, crystallisation and microstructure of glass-ceramics in TiO₂-ZrO₂-Li₂O-CaO- Al₂O₃-SiO₂ system

Abstract

Abstract

The objective of this study was to evaluate the effects of P₂O₅ particle size distribution on the crystalline phases and microstructure of lithium disilicate glass-ceramics derived from the TiO₂-ZrO₂-Li₂O-CaO-Al₂O₃-SiO₂ system for dentistry applications. The samples were made via fusion and casting procedure. Crystallisation as well as the morphology and microstructure of the samples were investigated using X-ray diffraction, differential scanning calorimetric and scanning electron microscopy. The results showed that the crystallisation of the samples occurred in the range of 500-650°C. The main crystalline phase was lithium disilicate (Li₂Si₂O₅) along with Lithium metasilicate (Li₂SiO₃), spodumene [LiAl(SiO₃)₂], lithium orthophosphate (Li₃PO₄) and cristobalite as secondary phases. With decreasing size of P₂O₅ particles, the morphology of Li₂Si₂O₅ crystals was transformed from needle shaped to spherical-like and the mechanical property was improved. The optimal flexural strength of 280 MPa and microhardness of 620 HV were obtained at the lithium disilicate glass-ceramics with P₂O₅ nanoparticles.

Keywords:

• Dental ceramics
• Lithium disilicate
• Glass-ceramic
• Microstructure
• Crystallisation
• Mechanical properties