CS-SPSed p-SiAlON

The Vickers hardness of polished CS-SPSed P-SiAlON compacts was measured using a Vickers microhardness tester with a diamond indenter of regular pyramid with an opposite angle of 136°. The experiments were performed under the loads between 0.981 N (0.1kg) and 19.614N (2.0kg) at room temperature. The dwell time for each load was 20 s. An average of at least five readings at different locations of the specimen surfaces was taken for each specimen. The Vickers hardness GPa) was calculated according to Equation 4.4... 

Figure 4.8 shows the measured as a function of indentation load for the CS-SPSed P-SiAlON (z= 1-3). The variation ofwith applied indentation test load for all samples shows that decreases with the increase of apphed load at low load region. It reaches a saturation value at higher loads when F > 4.903 N for z = 1 and 2. However, for z = 3, the ISE is more clear than that of z = 1 and 2. Also, as the figure shows, decreases with the increase in z value. At the max applying... 

As the conclusion for CS-SPSed P-SiAlON, the Vickers hardness ranges between 14.7 and 17.6 GPa due to different z values under the indentation load of 19.614 N. 

Figure 4.9 represents the temperature dependence of thermal diffusivity, heat capacity, and thermal conductivity of the fi-SiAlONs from room temperature to 800 C. The thermal diffusivity decreases with increasing temperature for all of the samples. And with increase in z value, the thermal diffusivity decreases. Our data show higher than that of sintered fi-SiAlON. For all of these CS-SPSed P-SiAlONs, Z2 shows the highest heat capacity, and Z3 shows the lowest data. The thermal conductivity of fi-SLAlONs gradually decreases with the increase of... 

The XRD patterns of CSed powder synthesized with the optimum quantity of diluent and of CS-SPSed fractures are shown in Figure 4.5. The CS reaction did not self-sustain when excessive diluent was added due to too low adiabatic temperature (r j) < 1800 K, according to Munir and Holt [8]. Pure P-SiAlON with z value of 4 was not obtained by SPS due to the low purity and short z value of CSed powder. 

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