添加稀土氧化物对氧化铝复相陶瓷性能的影响

EFFECTS OF ADDING RARE EARTH OXIDES ON PROPERTIES OF ZIRCONIA-TOUGHENED ALUMINA CERAMICS

采用复合烧结助剂降低氧化铝复相陶瓷 (zirconia_toughenedaluminum ,ZTA)烧结温度并保持优良力学性能 ,着重就不同稀土氧化物对材料烧结性、力学性能和显微结构的影响进行了研究 .复合添加剂促进了ZTA陶瓷的烧结 ,但不同添加剂对材料力学性能产生了不同影响 :含Y2 O3 添加剂因生成富钇晶界相而使材料的强度受到损害 ;而含La2 O3 和 /或CeO2 添加剂使材料力学性能获得提高 ,在 14 0 0～ 14 5 0℃烧结强度超过 5 0 0MPa,断裂韧性达 6 .5MPa·m1 /2 以上 .该ZTA陶瓷断裂路径曲折 ,裂纹出现架桥、分叉等现象 。

A small amount of complex sintering aids containing MgO, silicate and rare earth oxide were used to lower the sintering temperature of zirconia_toughened alumina (ZTA) ceramics by taking advantage of coordination effects and to investigate their effects on mechanical properties of ZTA ceramics. It is found that ZTA ceramics can be sintered to high density at temperatures as low as 1 400 to 1 450 ℃ and the optimum mechanical properties are also obtained at such temperatures. Y 2O 3 addition degrades the mechanical properties compared with CeO 2 or La 2O 3 additions due to the formation of yttrium_containing liquid phase. The bending strength and fracture toughness of ZTA with the CeO 2_or La 2O 3_containing complex sintering aids reached over 500 MPa and 6.5 MPa·m 1/2 respectively. Mechanical properties can also be increased by using the strategy of the combination of CeO 2 with La 2O 3. Microstructure observations by SEM and TEM reveal that the intergranular fracture is predominant, while the transgranular fracture is occasionally observed. The fracture surface is much rougher and the crack deflection and bridging occurred for the materials with La 2O 3 and/or CeO 2 inclusions.