Sintering highly dense ultra-high temperature ceramics with suppressed grain growth
Sintering highly dense ultra-high temperature ceramics with suppressed grain growth
复制标题
烧结具有抑制的晶粒生长的高致密超高温陶瓷
DOI：
10.1016/j.jeurceramsoc.2019.11.056
复制
发表时间：
2020-04-01
影响因子：
5.7
通讯作者：
Fu, Zhengyi
中科院分区：
文献类型：
--
作者：
Gu, Junfeng;Zou, Ji;Fu, Zhengyi
晶粒粗化通常发生在烧结的最后阶段，导致晶粒内出现截留孔隙，从而降低陶瓷的密度和性能，尤其是超高温陶瓷（UHTC）。在这里，我们建议在特定的温度范围和相对较高的压力下烧结此类陶瓷。延迟的晶界迁移和压力增强的扩散确保了致密化的进行，即使在最后阶段也是如此。使用 C-f/C 模具在 1850 ℃ 下通过高压放电等离子烧结，在 250 MPa 下制备出平均晶粒尺寸为 1.48 μm 的高致密化 TaC 陶瓷（98.6%）。表明最终阶段致密化主要归因于晶界塑性变形机制。与使用高温（> 2000摄氏度）和常压（< 100 MPa）的通常烧结路线相比，这项工作为获得高致密和细晶粒的UHTC提供了一种有用的策略。
Grain coarsening normally occurs at the final stage of sintering, resulting in trapped pores within grains, which deteriorates the density and the performance of ceramics, especially for ultra-high temperature ceramics (UHTCs). Here, we propose to sinter this class of ceramics in a specific temperature range and coupled with a relatively high pressure. The retarded grain boundary migration and pressure-enhanced diffusion ensure the proceeding of densification even at final stage. A highly dense TaC ceramic (98.6 %) with the average grain size of 1.48 mu m was prepared under 250 MPa via high pressure spark plasma sintering using a C-f/C die at 1850 degrees C. It was suggested that the final-stage densification is mainly attributed to grain boundary plastic deformation involved mechanisms. Compared to the usual sintering route using a high temperature (> 2000 degrees C) and normal pressure (< 100 MPa), this work provides a useful strategy to acquire highly dense and fine-grained UHTCs.