Strengthening of alumina by cerium-zirconate (Ce_(2)Zr_(2)O_(7))

摘要

Composite powders of Al_(2)O_(3) and 0 to 30 vol% Ce_(2)Zr_(2)O_(7) are prepared by a hybrid sol-gel method using Al_(2)O_(3) powders and a sol formed from Zr-alkoxide and cerium nitrate. All the Zr from the sol goes to form the cerium zirconate phase when the powders are calcined in N_(2). Pressureless sintering in air at 1500℃ yields composites with high density (～98%). Maximum values of fracture toughness and strength, 6.5 MPa m~(1/2) and 620 MPa respectively, (e.g. 3.5 MPa m~(1/2) and 350 MPa for pure Al_(2)O_(3)) are obtained in 10 vol% Ce_(2)Zr_(2)O_(7) composite sintered in air. The dominant mechanism for enhancement in K_(IC) is believed to be crack bridging. Crack bridging activity in the 10 vol% composite is found to be maximum and extends upto ～190 μm from the crack tip.