TiO_2/O-′Sialon界面反应过程

Reactive process in interface between TiO_2 and O′-Sialon

以反应烧结的O-′Sialon和金红石型TiO2为研究对象,设计制备了TiO2/O-′Sialon扩散偶,采用X射线衍射(XRD)、扫描电镜(SEM)及电子探针微区分析(EPMA)等方法,对扩散偶的扩散界面及垂直于界面的断面进行了物相分析、形貌观察及元素面分布分析,并在此基础上探讨了TiO2/O-′Sialon界面反应过程。XRD结果表明:TiO2与O-′Sialon在界面处发生反应生成TiN和SiO2,但在1200℃时扩散反应程度微弱,界面处存在Sm2O3偏析,并且与SiO2生成Sm2Si2O7;SEM照片显示TiO2/O-′Sialon界面处存在不规则硅酸盐熔融层;EP-MA元素面分布分析表明Ti、Si等元素富集于硅酸盐熔融层内,只有微量元素扩散至基体内。综合分析结果得出,TiO2/O-′Sialon界面反应过程可分为三个阶段:物理接触阶段、熔融层形成及元素富集阶段、熔融层增长阶段。

TiO2/O′-Sialon diffusion couple was designed and prepared with reactive sintered O′-Sialon and rutile TiO2 as raw materials. The phases of interface and cross-section phases were determined by XRD and morphology and element section distribution were analyzed by SEM and EPMA. On the base of information obtained above, the reactive process in the interface of TiO2/O′-Sialon diffusion couple was discussed. The results of XRD show that TiO2 reacts with O′-Sialon in the interface, which produces TiN and SiO2, but the degree of the reaction is weak at 1200℃, gravity segregation of Sm2O3 is found and Sm2Si2O7 is generated by Sm2O3 and SiO2 in the interface; and irregular fusion zone is observed in the interface through SEM; the analysis of element distribution by EPMA states that element Si and Ti enrich in the zone but there is only micro-element diffusion to the base. The conclusion is obtained by analysis mentioned that the reactive process can be divided into three stages： physical contact, formation of fusion zone and element-enrichment, growth of fusion zone.