Synthesis of (h-BN)/SiO₂ core-shell powder for improved self-lubricating ceramic composites

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• 作者：Hui Chen^a ; ^b ; ^c ; Chonghai Xu^a ; ^b ; ^c ; ^{xch@qlu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Guangchun Xiao^a ; ^b ; Zhaoqiang Chen^a ; ^b ; ^c ; Jun Ma^a ; ^b ; Guangyong Wu^c
• 关键词：D. SiO2 ; Core-shell structure ; Hexagonal boron nitride ; Self-lubricating ceramic composites
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：42
• 期：4
• 页码：5504-5511
• 全文大小：3274 K

文摘

An easy and effective preparation method has been achieved for the fabrication of core-shell-structure (h-BN)/SiO₂ composite powders. Ammonium hydroxide (NH₄OH) was used as a catalyst. Silica (SiO₂, ~50–100 nm) was coated on the surface of lamellar hexagonal boron nitride (h-BN, ~5–10 μm) particles via hydrolysis and condensation reaction of tetraethylorthosilicate (TEOS). The resulting composite powders were characterized using XRD (X-ray diffraction), SEM (Scanning electron microscopy), EDS (Energy-dispersive X-ray spectroscopy) and TEM (Transmission electron microscopy). A completely compact and uniform SiO₂ coating binds tightly to h-BN particles. In addition, the effects of the reaction temperature and molar ratio of H₂O and NH₄OH between TEOS on the coating results are studied. The coating processes of the composite powders reveal that SiO₂ nucleates and grows first on the surface of h-BN particles. By adding (h-BN)/SiO₂ instead of h-BN as a solid-lubricant to Al₂O₃/TiC, the resulting microstructure, fracture-toughness and flexural strength of the composite are noticeably improved.