纳米ZrO_2-微米Al_2O_3复合陶瓷中“内晶型”结构的形成与机理

FORMATION AND MECHANISM OF INTRAGRANULAR STRUCTURE IN ZIRCONIA - TOUGHENED ALUMINA CERAMICS WITH NANO-ZrO_2 AND MICRO-Al_2O_3

考察了不同烧结状态的氧化错增韧氧化铝陶瓷(zirconia—toughened alumina,ZTA)的晶粒长大与“内晶型”形成的关系。烧结过程中,ZTA陶瓷中晶粒生长与温度、保温时间、第二相ZrO2含量有关,其中温度的影响最为显著。第二相粒子有沿主晶相晶界移动聚集的趋向。内晶结构的形成机理可概括为第二相粒子被夹在主相两晶粒之间不能移动,在随后的主晶相长大过程中,两晶粒共同晶界发生迁移或晶粒“合并”,将第二相粒子纳入晶粒内部。而没有被主相颗粒挤住的可移动的第二相粒子则聚集成较大的晶问第二相颗粒。

The relationship between the grain growth and the formation of intragranular structure in zirconia-toughened alumina (ZTA) ceramics with nano-ZrO2 and micro-Al2O3 was studied in different sintering conditions. The grain growth in ZTA during the sintering process is related to the sintering temperature, soaking time and ZrO2 volume fraction, among those the effect of temperature is the most obvious. The ZrO2 particles as the second phase tend to move and gather along the Al2O3 boundary. The mechanism of formation for the intragranular ZrO2 could be viewed that the second phase grains are clamped by the two neighboring major phase grains and can not move, and then in the following major phase grain growth process the grain boundary migration of major phase or the combination of two grains enwraps the second phase grains. Those second phase grains, which are not clamped and can move, would conglomerate to form bigger intergranular grains.