Influence of Sintering on the Development of Alumina-Toughened …
177
was measured using a hot disk thermal constants analyzer on both the conventional sintered (CS) and microwave (MW) sintered ATZ nanocomposite samples
and is shown in Fig. 7a. The microwave (MW) sintered sample was subjected to
rapid heating, which led to a suppression of grain growth when compared to the
sample obtained by conventional sintering (CS) resulting in higher densification and
a smaller grain size, which contributed to improving the thermal conductivity of the
developed composites. In microwave (MW) sintering, the rapid heating is favorable
for retaining the overall stability of the tetragonal zirconia phase, which results in
improved thermal conductivity of the developed composite. The thermal conductivity of the conventional sintered (CS) sample was 2.3 ± 0.15 W/mK while thermal
conductivity of the microwave (MW) sintered sample was 2.6 ± 0.1 W/mk. This is
shown in Fig. 7b.
Conclusions
The below conclusions can be drawn from the present work:
1. From the X-ray diffraction patterns, the stability of the t-ZrO 2 phase in the
microwave (MW) sintered sample was considerably higher than that of the
conventional sintered (CS) sample. However, it shows the highest peak intensity for the t-ZrO 2 phase and a few minor peaks corresponding to the alumina
(Al 2 O 3 ) and m-ZrO 2 phases.
2. The relative density of the microwave (MW) sintered sample was higher than the
conventional sintered (CS) sample due to rapid heating and suppression of grain
growth.
3. Porosity of the microwave (MW) sintered ATZ sample was lower than the conventional sintered (CS) sample due to essentially to the occurrence of more or
increased level of densification during microwave (MW) sintering.
4. The microhardness of the microwave (MW) sintered sample was considerably
higher than the conventional sintered (CS) sample due to rapid heating that
suppresses grain growth resulting in a much smaller grain size in the microwave
(MW) sintered samples.
5. The surface roughness of the microwave (MW) sintered ATZ sample was considerably lower than the conventional sintered (CS) sample due to suppression of
grain growth leading to a reduction in both the peaks and valleys on the surface
of the microwave (MW) sintered sample.
6. The 3 mol% Yttria-doped zirconia revealed reduced monoclinic phase in the
matrix. The increase in the tetragonal phase led to a dense microstructure that
resulted in an overall improvement in fracture toughness of the sintered samples.
7. The fracture toughness of the microwave (MW) sintered sample was considerably
higher than the conventional sintered (CS) counterpart due to the stability of the
tetragonal zirconia phase that favors crack deflection, which contributes to an
increase in fracture toughness.
177
was measured using a hot disk thermal constants analyzer on both the conventional sintered (CS) and microwave (MW) sintered ATZ nanocomposite samples
and is shown in Fig. 7a. The microwave (MW) sintered sample was subjected to
rapid heating, which led to a suppression of grain growth when compared to the
sample obtained by conventional sintering (CS) resulting in higher densification and
a smaller grain size, which contributed to improving the thermal conductivity of the
developed composites. In microwave (MW) sintering, the rapid heating is favorable
for retaining the overall stability of the tetragonal zirconia phase, which results in
improved thermal conductivity of the developed composite. The thermal conductivity of the conventional sintered (CS) sample was 2.3 ± 0.15 W/mK while thermal
conductivity of the microwave (MW) sintered sample was 2.6 ± 0.1 W/mk. This is
shown in Fig. 7b.
Conclusions
The below conclusions can be drawn from the present work:
1. From the X-ray diffraction patterns, the stability of the t-ZrO 2 phase in the
microwave (MW) sintered sample was considerably higher than that of the
conventional sintered (CS) sample. However, it shows the highest peak intensity for the t-ZrO 2 phase and a few minor peaks corresponding to the alumina
(Al 2 O 3 ) and m-ZrO 2 phases.
2. The relative density of the microwave (MW) sintered sample was higher than the
conventional sintered (CS) sample due to rapid heating and suppression of grain
growth.
3. Porosity of the microwave (MW) sintered ATZ sample was lower than the conventional sintered (CS) sample due to essentially to the occurrence of more or
increased level of densification during microwave (MW) sintering.
4. The microhardness of the microwave (MW) sintered sample was considerably
higher than the conventional sintered (CS) sample due to rapid heating that
suppresses grain growth resulting in a much smaller grain size in the microwave
(MW) sintered samples.
5. The surface roughness of the microwave (MW) sintered ATZ sample was considerably lower than the conventional sintered (CS) sample due to suppression of
grain growth leading to a reduction in both the peaks and valleys on the surface
of the microwave (MW) sintered sample.
6. The 3 mol% Yttria-doped zirconia revealed reduced monoclinic phase in the
matrix. The increase in the tetragonal phase led to a dense microstructure that
resulted in an overall improvement in fracture toughness of the sintered samples.
7. The fracture toughness of the microwave (MW) sintered sample was considerably
higher than the conventional sintered (CS) counterpart due to the stability of the
tetragonal zirconia phase that favors crack deflection, which contributes to an
increase in fracture toughness.