铝素坯烧结过程微结构演化的实时观测  

Microstructure Evolution Real-Time Observation of Compacted Aluminum Bulk Ceramics during Sintering Process

作　　者：牛玉[1] 许峰[1] 胡小方[1] 李永存[1] 缪泓[1] 赵建华[1] 

机构地区：[1]中国科学技术大学中国科学院材料力学行为和设计重点实验室,合肥230026

出　　处：《实验力学》2012年第2期140-147,共8页Journal of Experimental Mechanics

基　　金：国家自然科学基金重点项目(10902108、10732080、10872190);中央高校基本科研业务费专项资金;北京同步辐射实验室(BSRF)基金共同资助

摘　　要：为实现对金属粉末压坯烧结过程的实时观测,从而验证现有的相关理论,本文利用同步辐射CT(SR-CT)技术,对铝压制陶瓷坯体的固相烧结过程进行实时投影成像;应用滤波反投影算法和数字图像处理技术,得到了陶瓷坯体在整个固相烧结过程中内部微结构演化的三维重建图像,实现了对铝压制陶瓷坯体整个固相烧结过程的无损原位观测,得到了样品由烧结中期进入烧结后期的完整的演化过程图像。通过重建图像,清晰观测了样品的固相烧结过程:在烧结前、中期(烧结时间t<180min、温度T<600℃),烧结颈形成并随烧结时间生长;由烧结中期开始进入后期时(烧结时间t≥180min、温度T≥600℃),样品内部结构演化加剧,气孔由相互连通演化为相互孤立并球化。进一步在实验图像的基础上分析了二面角等烧结特征的变化情况,得到烧结颈尺寸与时间对数有较好的线性关系,并可根据曲线分辨中期、后期。统计了样品在不同烧结时间的孔隙率,得到了孔隙率随烧结时间和烧结时间对数的变化曲线;分析了样品在不同烧结阶段的致密化特点,得到了烧结中期孔隙率和时间对数的线性关系。实验结果验证了现有的烧结理论,并为进一步完善烧结理论以及建立扩散和本构模型提供了高质量的实验数据。In order to realize real-time observation of the sintering process for compacted metal powder bulk and accordingly verify existing theories, real-time and non-destructive observation of compacted aluminum bulk ceramics in sintering process was realized by synchrotron radiation x-ray computerized tomography （SR-CT） technique. 3-D reconstructed images describing ceramic body interior microstructure evolution during the whole sintering process were obtained based on filtered back projection algorithm and digital image processing technology. Microstructure evolution of the specimen during solid-state sintering process is as follows： in the early and middle stages （Sintering time t〈180 min, Temperature T〈600℃） the sintering neck is formed and growing with sintering time; when from middle stage into later stage （Sintering time t≥180min, Temperature T≥600℃）, the sample＇s internal structure evolution increased, the former interconnected pores become isolated. There is a linear relationship between sintering neck size and time logarithm. Middle stage and later stage can be recognized based on the curve characteristics. Densification characteristics of the sample in different sintering stages were analyzed, and linear relationship between porosity and time logarithm in the middle stage of sintering was obtained. Results verify the existing sintering theory, and provide high quality experimental data for further improving the sintering theory and establishing diffusion and constitution model.

关 键 词：陶瓷 固相烧结 同步辐射CT 微结构演化 

分 类 号：O432[机械工程—光学工程]