Abstract:
Recently, ceramic materials have been given a lot of attention as candidates for
implanting materials as they posses certain highly desirable characteristics for
thesis applications. Ceramics used for the repair and reconstruction of debased
or damaged part of the body, are known as bioceramics. Ceramics have been
used for some time in dentistry owing to their inertness to the body fluids, high
compressive strength and good esthetic appearance. One problematic aspect of
ceramic materials and of dental ceramics in particular is their low mechanical
resistance and fracture toughness. Generally, in dental application, ceramics
should have greater stiffness, higher elastic limits, better fracture resistance, and
improved wear characteristics. The last point deserves special attention. The
alumina-zirconia (Al2O3-ZrO2) composites are one of the relatively good and
promising candidates for biomaterials application, due to biocompatibility and
their mechanical properties that combines high flexural strength with a high
toughness.
In the present work ZrO2 toughened Al2O3 (ZTA) composites with 10-40 wt % of
ZrO2 were prepared by conventional pressureless sintering technique at 1550,
1600 and 1650 °C for 2 hours. The density, porosity, structural properties and
mechanical properties of Al2O3-ZrO2 composites with respect to ZrO2 content as well as
sintering temperature have been explored here. Microstructure was observed using
scanning electron microscope (SEM) and phase content was detected by mean of X- ray
diffraction (XRD). Microhardness was measured using the Vickers indentation technique.
The introduction of ZrO2 in Al2O3 as an additive causes the formation of solid solution
which may promote the densification process by the introduction of defects. About 22% higher density of ZTA composite has been achieved in the present
work and lower modulus of elasticity has been observed for ZTA composite of
higher ZrO2 content. The microstructures are highly homogeneous and finer with
less porosity when compared to pure Al2O3. From XRD analysis it has been shown
that three phases i.e., corundum Al2O3, tetragonal and monoclinic ZrO2 are present and
no reaction has been occurred between Al2O3 and ZrO2. For pure Al2O3 the
microhardness number is in the range 17-20 GPa while the decreasing of
hardness value has been observed with the addition of ZrO2 content as well as
sintering temperature. The approach adopted in the present study may provide an
alternative to design Al2O3-ZrO2 composites with improved mechanical properties.
