Enhanced mechanical properties and in vitro bioactivity of silicon nitride ceramics with SiO2, Y2O3, and Al2O3 as sintering aids.

Silicon nitride (Si₃N₄) ceramics exhibit excellent mechanical properties and biocompatibility, making them highly suitable for biomedical applications, particularly in implants. In this study, the mechanical properties and bioactivity of Si₃N₄ ceramics with varying amounts of Y₂O₃-Al₂O₃-SiO₂ sintering aids were investigated. Increasing the sintering additive content from 4 wt% to 8 wt% substantially improved the bulk density of the ceramics, leading to notable enhancements in mechanical properties. These included a Vickers hardness increase to 10.07 GPa, a flexural strength increase to 605 MPa, and a fracture toughness increase to 2.43 MPa m1/2. The optimal combination of mechanical properties was achieved with 8 wt% sintering additives due to the higher aspect ratio and lower porosity. After immersion in simulated body fluid (SBF), the surface of the Si₃N₄ ceramics was coated with a Ca and P-rich layer, morphologically similar to hydroxyapatite. The layer formation was facilitated by the presence of SiO₂, which promoted hydroxyapatite nucleation and growth, as well as the rapid release of Ca2⁺ ions and the sustained stability of the apatite layer. Copyright © 2025 Elsevier Ltd. All rights reserved.

Citation

Yongning Han, Wenying Zhou, Jian Li, Zhuoqun Han, Lunan Bi, Zheng Zhang, Yang Wang, Ling Li, Degang Zhao. Enhanced mechanical properties and in vitro bioactivity of silicon nitride ceramics with SiO2, Y2O3, and Al2O3 as sintering aids. Journal of the mechanical behavior of biomedical materials. 2025 Apr;164:106901

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PMID: 39862545

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