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

Yongning Han; Wenying Zhou; Jian Li; Zhuoqun Han; Lunan Bi; Zheng Zhang; Yang Wang; Ling Li; Degang Zhao

doi:10.1016/j.jmbbm.2025.106901

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

J Mech Behav Biomed Mater. 2025 Jan 20:164:106901. doi: 10.1016/j.jmbbm.2025.106901. Online ahead of print.

Authors

Yongning Han¹, Wenying Zhou¹, Jian Li¹, Zhuoqun Han², Lunan Bi², Zheng Zhang³, Yang Wang⁴, Ling Li⁵, Degang Zhao⁶

Affiliations

¹ School of Materials Science and Engineering, University of Jinan, Jinan, 250022, China.
² Shandong Industrial Ceramics Research & Design Institute Co., Ltd., Zibo, 255000, China.
³ CNRS, CEMHTI UPR3079, Univ. Orl'eans, Orl'eans, France.
⁴ School of Materials Science and Engineering, University of Jinan, Jinan, 250022, China. Electronic address: mse_wangy2023@ujn.edu.cn.
⁵ Shandong Industrial Ceramics Research & Design Institute Co., Ltd., Zibo, 255000, China. Electronic address: kaiye_1980@126.com.
⁶ School of Materials Science and Engineering, University of Jinan, Jinan, 250022, China. Electronic address: mse_zhaodg@ujn.edu.cn.

PMID: 39862545
DOI: 10.1016/j.jmbbm.2025.106901

Abstract

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 m^1/2. 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.

Keywords: Mechanical properties; Microstructure; SBF immersion; Silicon nitride; Sintering aid.

Publication types

Review