Sintering experimental results of alumina ceramics under different sintering pressures
Following the previous experiment, please pay attention to the analysis of the results of this experiment.
Experimental results:
According to the density of alumina ceramics consolidated at different temperatures (as shown in Figure 2), at 900°C (60.3%), 1100°C (81.9%) and 1300°C (97.4%), corresponding to the initial, intermediate and and final stage. That is, whether in the initial, intermediate or final stages of sintering, oscillating pressure is applied, it helps to accelerate densification.
In addition, the higher the temperature at which the oscillating pressure is applied, the more favorable the densification is. The use of oscillating pressure in the middle and final stages of sintering can also promote solidification of the ceramic.
In all three stages, the density of samples exposed to oscillatory pressure was much higher than that of samples sintered by one-step hop or high pressure.
The relationship between hardness and porosity for all samples was satisfactory, indicating that the increase in material hardness was mainly due to the increase in density.
The fracture strength of the material was tested, and the results are shown in Figure 4. The results show that the fracture strength of HOP sintered samples is significantly higher than that of HP sintered samples; in addition, the bending strength error range of HOP ceramics is smaller than that of HP samples.
Applying oscillating pressure during sintering improves the mechanical properties of alumina ceramics. Compared with HP-ALL, the fracture strength of the HOP-ALL group was increased by about 19%, which may be due to the higher density and smaller grain size.
Regardless of the sintering step, the oscillating pressure is beneficial to improve the sintering behavior of alumina ceramics. Furthermore, the higher the temperature at which the oscillating pressure is applied, the better the mechanical properties of the samples, which is especially evident for ceramics subjected to oscillating pressure in all three stages. Therefore, the oscillating pressure produces a coupling effect on the properties of the material, thereby improving the properties of the material.
