High-pressure spark plasma sintering of silicon nitride with LiF additive. Issue 4 (April 2018)

• Record Type: Journal Article
• Authors: Ratzker, Barak; Sokol, Maxim; Kalabukhov, Sergey; Frage, Nachum
• Is Part Of: Journal of the European Ceramic Society. Volume 38:Issue 4(2018)
• Page Start: 1271
• Page End: 1277
• Publication Date: 2018-04
• Subjects: Silicon nitride -- Spark plasma sintering -- High pressure -- LiF; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2017.10.034
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: High-pressure spark plasma sintering of Si3 N4 with Y2 O3, Al2 O3 and LiF additives was employed to fabricate high quality dense ceramics comprising approximately 92% α-Si3 N4 phase and 8% β-Si3 N4 phase. The relatively high pressure applied (up to 650 MPa) had a substantial effect on densification by enhancing particle rearrangement, making it possible to obtain dense Si3 N4 at a significantly lower sintering temperature (1350 °C). Consequently, virtually no α to β phase transformation transpired during the liquid phase sintering process. The LiF additive had an indispensable influence on the densification process by lowering the viscous glass formation temperature, which also contributed to enhanced particle rearrangement. The nearly fully dense samples (theoretical density ≥99%) obtained displayed a good combination of mechanical properties, namely elastic modulus (304–316 GPa), hardness (1720–1780 HV2) and fracture toughness (6.0 MPa m 1/2 ).