Abstract
Five different 3 mol.% yttria-tetragonal zirconia polycrystals/alumina (3Y-TZP/Al2O3) -glass specimens have been fabricated by the glass infiltration method. graphite additives were added to the (3Y-TZP/20Wt.%Al2O3) to obtain porous structure. The ATZ (Alumina Toughened Zirconia) skeleton have prepared by the normal compaction method. The specimen had been infiltrated by the glass (18Wt.% lithium hydroxide, 72 wt. % feldspar, and 10Wt.% nano Titanium oxide) at 1185ᵒC. Results showed that the porosity of (3Y-TZP/Al2O3) composite was increased while bulk density decreased with increasing graphite additives. The elastic modulus of (3Y-TZP/Al2O3)-glass was decreased (159-109GPa) with increasing the amount of glass infiltrated. Hardness was constant for all the specimens in value of (5.66 GPa), while increment of materials fracture toughening was due to the increasing the glass weight fraction, the kIc was lied between (0.53-1. 54MPa.m1/2). The glass infiltrated (3Y-TZP/Al2O3) process was successfully increased the fracture toughness by penetrated different amounts of glass into the (3Y-TZP/Al2O3) structure.
Highlights
The construction of all-ceramic restorations was demonstrated by several all-ceramic systems
It‟s showed that as the amount of graphite increased, the apparent porosity increases while bulk density decreased
No correlation was observed between Vickers hardness and Young‟s modulus indicating that the decrease in elastic modulus with porosity which leads to increasing glass Wt.% did not cause an increase in the hardness value
Summary
The construction of all-ceramic restorations was demonstrated by several all-ceramic systems. The suggestion of Irwin was that the equation of Griffith must be written again and add the energy of elastic deformation accompanied the process of fracture For that reason, he chose the G parameter, considering the rate of releasing strain energy. Eq (1) can be considered a failure criterion since the brittle fracture of the material will occur when the product of the stress applied by the square root of a crack size is equal to or greater than the material‟s fracture toughness value. The ability of the material to absorb energy from the elastic deformation, accompanied to the tensile stress level which can be achieved before catastrophic fracture initiation near the crack tip was defined as fracture toughness. The main object of this study was to determine the effect of the glass amount infiltrated into the ceramic structure on the fracture toughness of 3Y-TZP/Al2O3
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