Methods: Three novel glasses were developed based upon a parent ternary (barium fluormica-cordierite-calcium phosphate) compositions. To this original composition YSZ was added incrementally (5, 10 and 15 % mol ZrO2). Glasses were heat treated to produce glass-ceramics. SEM, TEM and X-ray Diffraction were performed to investigate the microstructure and the nature of crystallisation in the glass-ceramics produced. Edge fracture toughness, biaxial flexural strengths and micro-hardness were determined.
Results: The addition of 5, 10 and 15 % mol YSZ has increased the edge fracture toughness to 266±19.7, 272.1±8.3 and 332±10.2 N/mm respectively in comparison to 171±6 N/mm of the parent glass ceramic. The biaxial flexural strength has increased by more than 35 % to 137±4, 168±11 and 170±22 MPa respectively in comparison to that of the parent glass ceramic (100±15 MPa). Hardness values of the glass ceramics with 5, 10 and 15 % mol zirconia were measured at 156±4.3, 151±3.3 and 170±12.3 kg/m2 HV respectively while it is only 117±6.2 kg/m2 HV for the parent glass ceramic.
Conclusion: Edge fracture toughness, biaxial flexural strength and hardness of the glass ceramics increased with addition of YSZ. Zirconia was separated from yttria and acted as a nucleating agent for the subsequent crystallisation of mica. This work is supported by the Ministry of Health of Saudi Arabia