On the fabrication and mechanical properties of Si₃N₄ ceramics with low content sintering additives

Abstract

Si 3 N 4 ceramics were prepared by hot pressing (HP) and spark plasma sintering (SPS) methods using low content (5 mol%) Al 2 O 3 -RE 2 O 3 (RE = Y, Yb, and La)-SiO 2 /TiN as sintering additives/secondary additives. The effects of sintering additives and sintering methods on the composition, microstructures, and mechanical properties (hardness and fracture toughness) were investigated. The results show that fully density Si 3 N 4 ceramics could be fabricated by rational tailoring of sintering additives and sintering method, and TiN secondary additive could promote the density during HP and SPS. Besides, SN-AYS-SPS possesses the most competitive mechanical properties among all the as-prepared ceramics with the Vickers hardness as 17.31 ± .43 GPa and fracture toughness as 11.07 ± .48 MPa m 1/2 .

Advanced Fabrication Method and Mechanical Properties of Silicon Nitride/Boron Nitride Fibrous Monolithic Ceramics

“…The deterioration of the service environment necessitates more stringent requirements for radomes on high Mach number aircraft, which are essential for maintaining structural integrity and enabling precise communication guidance. Silicon nitride (Si 3 N 4 ) demonstrates excellent transparency to electromagnetic waves, along with notable properties such as high strength, high temperature stability, and exceptional resistance to oxidation [ 1 , 2 , 3 , 4 ]. Wave transparency primarily relies on the inherent composition and structure of the material system [ 5 , 6 , 7 , 8 ], which can be achieved through meticulous material preparation processes.…”