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Effect of ZrB 2 content on phase assemblage and mechanical properties of Si 3 N 4 –ZrB 2 ceramics prepared at low temperature
Author(s) -
Guo WeiMing,
Wu LiXiang,
Yu JunJie,
Zeng LingYong,
Sun ShiKuan,
Li JingXi,
Wu ShangHua,
Lin HuaTay,
Wang ChengYong
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15860
Subject(s) - materials science , fracture toughness , microstructure , ceramic , flexural strength , composite material , vickers hardness test , equiaxed crystals , toughness , phase (matter) , composite number , hot pressing , chemistry , organic chemistry
Abstract Based on the previous work on Si 3 N 4 –ZrB 2 [Wu et al. J Eur Ceram Soc ;2017,37:4217], the influence of ZrB 2 addition on the phase and microstructure evolution of Si 3 N 4 –ZrB 2 composites was emphatically investigated, and the mechanical properties were compared with pure Si 3 N 4 ceramics. It was revealed that the ratio of β‐ to (α+β)‐Si 3 N 4 significantly increased from 14.3% in pure Si 3 N 4 ceramics to 39.8% in Si 3 N 4 with 15 vol% ZrB 2 addition, indicating that the introduction of ZrB 2 promoted α‐ to β‐Si 3 N 4 phase transformation. As a consequence, the microstructure of the composite showed the bimodal distribution, containing both elongated and equiaxed Si 3 N 4 grains. For the pure Si 3 N 4 , Vickers hardness, fracture toughness and flexural strength was 22.8 GP a, 7.6 MP a m 1/2 , and 334.5 MP a, respectively. In contrast, the composite of Si 3 N 4 –30 vol% ZrB 2 simultaneously possessed an excellent combination of mechanical properties: 19.5 GP a in hardness, 9.8 MP a m 1/2 in toughness and 702.0 MP a in strength. Present study suggested that Si 3 N 4 ‐based ceramics with high hardness, high toughness, and high strength could be obtained by the combination of appropriate ZrB 2 content and low hot‐pressing temperature.