Journal of Inorganic Materials ›› 2018, Vol. 33 ›› Issue (11): 1167-1172.doi: 10.15541/jim20180072

• Orginal Article • Previous Articles     Next Articles

Grain Composition on Solid-state-sintered SiC Ceramics

Yuan-Yuan XING1,2(), Hai-Bo WU2(), Xue-Jian LIU2(), Zheng-Ren HUANG2   

  1. 1. University of Chinese Academy of Sciences, Beijing 100049, China
    2. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
  • Received:2018-02-08 Revised:2018-06-12 Online:2018-11-16 Published:2018-10-20
  • About author:XING Yuan-Yuan. E-mail: xingyuanyuan@student.sic.ac.cn

Abstract:

Strengthening and toughening of dense solid-state-sintered SiC (S-SiC) ceramics was achieved by grain composition of coarse and fine SiC powder, whose median particle sizes were ~4.6 μm and ~0.5 μm, respectively. The fraction effects of coarse SiC powder on densification, microstructures, and mechanical properties of S-SiC ceramics were systematically investigated. High relative densities (higher than 98.3%) were successfully acquired for the S-SiC samples with the fraction of coarse powder less than 75wt%. The linear sintering shrinkage of SiC samples sharply decreased with increasing fraction of coarse powder, with the minimum fraction as low as 14.5%. Moreover, the coarse SiC powder significantly suppressed abnormal grain growth in S-SiC ceramics by Zener pining of grain boundaries. As a result, SiC grains became smaller and equiaxial, which was beneficial for obtaining high flexural strength for S-SiC ceramic. Meanwhile, the introduction of coarse SiC powder induced fracture mode transfer S-SiC ceramic from transgranular type to transgranular-intergranular mixture type, resulting in improved fracture toughness. The S-SiC ceramic added with 65wt% coarse powder achieved an increase of 14.0% in flexural strength ((440±35) MPa) and 17.1% in fracture toughness ((4.92±0.24) MPa·m1/2).

Key words: S-SiC, grain composition, microstructure, flexural strength, fracture toughness

CLC Number: 

  • TQ174