Mechanical and Chemical Properties of Zr and P-Doped Lithium Disilicate Glass Ceramics in Dental Restorations

摘要

The Weibull modulus, flexural strength, fracture toughness, Vickers microhardness, and chemical durability of sintered Li_2O-SiO_2 glass ceramic specimens doped with P_2O_5 or ZrO_2 were evaluated in accordance with the norm of EN ISO 6872. Peak crystallization temperatures, crystalline phases, and microstructure were characterized by means of differential thermal analysis, X-ray diffraction, and scanning electron microscopy methods, respectively. Phase formation induced by the addition of P_2O_5 led to precipitation of Li_3PO_4, which in turn caused more intensive crystallization of Li_2SiO_3. The high-temperature crystalline phase Li_2Si_2O_5 was precipitated more intensively in P_2O_5 containing specimens resulting in an interlocked microstructure of needle like disilicate crystals. Therefore, the P-doped glass ceramic exhibited the optimum mechanical and chemical properties (i.e., m= 15,σf = 181±15MPa, KIC= 1.94±0.19MPam~1/2, HV = 3.7 ± 1.1 GPa, chemical solubility =53 + 9 μg/cm2 )