Improved toughness of spark-plasma-sintered Si3N4 ceramics by adding HfB2. Issue 6 (15th March 2021)

• Record Type: Journal Article
• Authors: Luo, Si-Chun; Guo, Wei-Ming; Plucknett, Kevin; Lin, Hua-Tay
• Is Part Of: Ceramics international. Volume 47:Issue 6(2021)
• Page Start: 8717
• Page End: 8721
• Publication Date: 2021-03-15
• Subjects: Si3N4 ceramics -- HfB2 additive -- Phase transformation -- Microstructure -- Mechanical properties; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.11.201
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: High toughness and high hardness Si3 N4 ceramics with fine and bimodal microstructure was prepared by combination of HfB2 additive and spark plasma sintering (SPS). HfB2 -free SPSed Si3 N4 ceramics at 1600 °C exhibited major α-Si3 N4 phase, a fine and equiaxed grain microstructure, high Vickers hardness (21.3 ± 0.2 GPa), and low fracture toughness (3.7 ± 0.3 MPa m 1/2 ). The introduction of 2.5 vol% HfB2 into Si3 N4 ceramics at 1600 °C promoted α-to β-Si3 N4 phase transformation, produced a fine and bimodal microstructure, significantly improved the toughness (7.7 ± 0.6 MPa m 1/2 ) but slightly decreased the hardness (20.4 ± 0.6 GPa) which was higher than that of traditionally hot-pressed or pressurless sintered Si3 N4 ceramics (~14–18 GPa).