New route to improve the fracture toughness and flexural strength of Si₃N₄ ceramics by adding FeSi₂

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• 作者：Lujie Wang^a ; ^b ; ^{osatnbaup@shu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Qian Qi^a ; Ping Cai^a ; Hui Zhang^a ; Xiao Yang^a ; ^{yangxiao@mail.sic.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Xuejian Liu^a ; ^{xjliu@mail.sic.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Zheng Jiao^b ; Zhengren Huang^a
• 关键词：Silicon nitride ; Iron silicide ; Reinforcing particles ; β-Si3N4 seeds
• 刊名：Scripta Materialia
• 出版年：2017
• 出版时间：1 January 2017
• 年：2017
• 卷：126
• 期：Complete
• 页码：11-14
• 全文大小：686 K

文摘

Silicon nitride (Si₃N₄) ceramics were pressureless sintered with 0.2 wt% FeSi₂ at 1780 °C for 2 h in nitrogen with Al₂O₃ and Y₂O₃ as sintering aids and found to have high toughness and strength. During the sintering process, β-Si₃N₄ crystal seeds and Fe₅Si₃ reinforcing particles were in situ generated by FeSi₂. Abnormal growth of Si₃N₄ grains was promoted by β-Si₃N₄ crystal seeds. High thermal expansion coefficient of Fe₅Si₃ particles induced residual stresses in the ceramics matrix, which deflected the crack. Ultimately, the fracture toughness and flexural strength of Si₃N₄ ceramics reached 9.8 ± 0.5 MPa·m^1/2 and 1086 ± 48 MPa respectively.