Coarsening of boron carbide grains during the infiltration of porous boron carbide preforms by molten silicon. Issue 16 (December 2016)

• Record Type: Journal Article
• Authors: Zhang, Cuiping; Ru, Hongqiang; Zong, Hui; Sun, Weikang; Zhu, Jinghui; Wang, Wei; Yue, Xinyan
• Is Part Of: Ceramics international. Volume 42:Issue 16(2016)
• Page Start: 18681
• Page End: 18691
• Publication Date: 2016-12
• Subjects: Grain coarsening -- Reaction-bonded boron carbide -- Infiltration temperature -- Grain shape; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2016.09.006
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: This work investigates the coarsening of boron carbide grains during the infiltration of porous boron carbide preforms by molten silicon with respect to fabrication of reaction-bonded boron carbide ceramics. Experimental results reveal that the shape of boron carbide grains evolve from the irregular shape to faceted shape due to dissolution-precipitation during infiltration. For infiltration temperatures below 1750 °C, the boron carbide grains are irregular and exhibit an unimodal size distribution, which can be ascribed to the normal grain growth. The growth of the irregular grains follow a cubic law of diffusion control. In contrast, for infiltration temperatures above 1750 °C, the boron carbide grains become faceted and exhibit a bimodal size distribution, indicative of the typical abnormal grain growth. The abnormal growth of faceted grains is proposed to be controlled by coalescence-enhanced two-dimensional nucleation.