氧化锆增韧陶瓷(ZTC)的晶界结构

Grain Boundary Structure of Zirconia Toughened Ceramics (ZTC)

本文用 JEM200CX 超高分辨型透射电子显微镜对 ZTC 陶瓷的晶界结构进行了研宄。发现 Al_2O_3与ZrO_2之间的晶界存在共格点、共渗和无序结构形式,并发现晶界处常为 ZrO_2相变的成核区。ZrO_2(m)和ZrO_2(t)之间的晶界,既能成为 ZrO_2相变的成核区,也能阻止 ZrO_2相变的延续发展。只有当两个 ZrO_2晶粒的同类型晶面取向相近时,ZrO_2的相变才容易通过晶界而发展。ZrO_2(t)和 ZrO_2(t)之间的晶界具有较好的共格点结构,形成交错的锯齿状,这是 TZP 陶瓷具有高强和高韧的原因之一。

HREM studies on the boundary of zirconia toughened ceramics (ZTC) havebeen made by JEM 200 CX.It is found that there are coherence,mutual penetra-tion and amorphous structures between Al_2O_3 and ZrO_2 grains,and there are alsocrystal transformation region for ZrO_2(t) during nucleating in the boundary.Buton contrary,the boundary can also suppress the extension of the phase transfor-mation,If the orientation of both the ZrO_2(t) and ZrO_2(m) grains alongside theboundary is less misfit,the transformation of ZrO_2(t) can extend and pass throughthe boundary easily.The boundary between ZrO_2(t) and ZrO_2(t) grains has lessdefects in coherence structure.Above all,the boundary can extend crosswise likesawteeth.This is perhaps one of the reasons that TZP ceramics have high strengthand toughness.