Sintering of High-Strength Dense Al₂O₃ Using Rod-Like Submicron Al₂O₃ as Sintering Aid

Rod-like submicron Al2O3 powder was prepared by the controllable hydrolyzation of aluminium isopropoxide in streams atmosphere. XRD data show the rod-like Al2O3 has a γ- Al2O3 structure. TEM images display the length of the submicron Al2O3 is in the range of 100-300 nm and the slenderness ratio is above 10. The rod-like Al2O3 powder was added into the submicron Al2O3 (D50 = 0.5 μm, purity > 99.99%) to increase the bending strength of the sintered body and to decrease the sintering temperature. SEM images display that the Al2O3 sintered at 1450 °C with rod-like Al2O3 added has a higher density than the virgin Al2O3 and the Al2O3 grains have the trans-crystalline fracture. The bending strength of the sintered Al2O3 with 5 wt% rod-like Al2O3 added is 205 MPa, which increases 241%. A sharp shrinkage in 1300-1400 °C appeared in the sintering shrinkage curves characterized by DIL show the rod-like Al2O3 also acts as the sintering aid.