Microstructure development in hot-pressed silicon carbide: Effects of aluminum, boron, and carbon additives
Microstructure development in hot-pressed silicon carbide: Effects of aluminum, boron, and carbon additives
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DOI：
10.1016/s1359-6454(03)00209-x
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发表时间：
2003-08
期刊：
影响因子：
9.4
通讯作者：
X. Zhang;Qing Yang;L. Jonghe
中科院分区：
文献类型：
--
作者：
X. Zhang;Qing Yang;L. Jonghe
用铝、硼和碳添加剂对碳化硅进行热压。对Al含量进行修改，以获得含有连续Al梯度的SiC样品，或改变平均Al含量。在这两种情况下，Al含量的增加导致SiC晶粒数密度的降低，但却显著提高了伸长晶粒的展弦比。当Al含量超过4 wt%时，晶界膜也发生了非晶向结晶的转变。此外，Al的增加降低了SiC的立方到六方相变程度。对硼和碳的平均含量进行了类似的处理和表征。系统实验表明，热压过程中硼和碳通过促进碳化硅从3c到4h的相变，促进了拉长晶粒的形成。实验还阐明了微观组织改性对材料力学性能的影响。定制SiC微观结构以适应不同的应用是可能的。
SiC was hot-pressed with aluminum, boron, and carbon additives. The Al content was modified either to obtain SiC samples containing a continuous Al gradient, or to vary the average Al content. In both cases, it was found that increasing Al content resulted in decreased number density but dramatically enhanced aspect ratio of the elongated SiC grains. Amorphous-to-crystalline transformation was also confirmed in grain boundary films when Al content exceeded 4 wt%. In addition, increasing Al decreased the degree of cubic-to-hexagonal SiC phase transformation. Similar processing and characterization were done with modified boron and carbon average contents. The systematic experiments demonstrated that boron and carbon promoted formation of elongated grains through promoting 3C-to-4H SiC phase transformation during hot pressing. The experiments also clarified the mechanical property responses to microstructural modification. Tailoring of the SiC microstructure to suit different applications would be possible.