Direct Characterizing of Densification Mechanisms during Spark Plasma Sintering
Direct Characterizing of Densification Mechanisms during Spark Plasma Sintering
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DOI：
10.1111/jace.12796
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发表时间：
2014-03
影响因子：
3.9
通讯作者：
D. Chakravarty;A. Chokshi
中科院分区：
文献类型：
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作者：
D. Chakravarty;A. Chokshi
放电等离子烧结（SPS）是一种方便、快速的生产致密陶瓷坯体的方法。然而，负责快速致密化的机制还没有得到令人满意的确定，不同的研究使用间接的方法产生不同的值的致密化参数。本文研究了在1173 ~ 1423 K温度和25 ~ 100 MPa应力条件下，对高纯纳米氧化铝进行SPS烧结。一个直接的方法，在一个恒定的密度分析，揭示了应力指数类似于1和逆晶粒尺寸的依赖性类似于3，符合Coble蠕变过程。而直接的方法给出了一个应力指数类似于1，间接的方法，以前使用的应力指数范围从2.2到3.5与相同的数据，从而揭示了潜在的虚假值的致密化参数从传统的间接方法来表征致密化。SPS过程中的快速致密化与快速加热速率和增强致密化驱动力的施加应力所保留的更细的晶粒尺寸有关。
Spark plasma sintering (SPS) is a convenient and rapid means of producing dense ceramic compacts. However, the mechanisms responsible for rapid densification have not been identified satisfactorily, with different studies using an indirect approach yielding varied values for the densification parameters. This study involved SPS in high purity nanocrystalline alumina with temperatures ranging from 1173 to 1423K and stresses from 25 to 100MPa. A direct approach, with analyses at a constant density, revealed a stress exponent of similar to 1 and an inverse grain size dependence of similar to 3, consistent with Coble creep process. Whereas the direct approach gives a stress exponent of similar to 1, the indirect approach used previously gives stress exponents ranging from similar to 2.2 to 3.5 with the same data, thereby revealing potentially spurious values of the densification parameters from conventional indirect approaches to characterizing densification. The rapid densification during SPS is related to the finer grain sizes retained with the rapid heating rates and the imposed stress that enhances the driving force for densification.