Abstract:
Microcrystalline γ-Al
2O
3is used as raw material to prepare α-Al
2O
3from γ-Al
2O
3using the hinge-type cubic press under the pressure of 5 GPa with different temperatures. The results of X-ray diffraction analysis show that the obtained powders and bulk materials are pure α-Al
2O
3phase. The scanning electron microscope analysis shows that the minimum grain size of the α-Al
2O
3is about 80 nm and the average grain size of the α-Al
2O
3synthesized under the pressure of 5 GPa and the temperature of 800 ℃ is 340 nm. Experimental results show that the submicron α-Al
2O
3is fabricated by high pressure phase transformation of microncrystalline γ-Al
2O
3. Compared with the normal pressure sintering method, the complete phase transformation from γ-Al
2O
3to α-Al
2O
3can be achieved at 600 ℃ by high pressure sintering, which obviously reduces the synthesis temperature of α-Al
2O
3materials.