Densification of Reaction Bonded Silicon Nitride with the Addition of Fine Si Powder - Effects on the Sinterability and Mechanical Properties

Abstract

The densification behavior and strength of sintered reaction bonded silicon nitrides (SRBSN) that contain Lu 2 O 3-SiO 2 additives were improved by the addition of fine Si powder. Dense specimens (relative density: 99.5%) were obtained by gas-pressure sintering (GPS) at 1850 o C through the addition of fine Si. In contrast, the densification of conventional specimens did not complete at 1950 o C. The fine Si decreased the onset temperature of shrinkage and increased the shrinkage rate because the additive helped the compaction of green bodies and induced the formation of fine Si 3 N 4 particles after nitridation and sintering at and above 1600 o C. The amount of residual SiO 2 within the specimens was not strongly affected by adding fine Si powder because most of the SiO 2 layer that had formed on the fine Si particles decomposed during nitridation. The maximum strength and fracture toughness of the specimens were 991 MPa and 8.0 MPa•m 1/2 , respectively.

Rheology and Curability Characterization of Photosensitive Slurries for 3D Printing of Si3N4 Ceramics

“…Due to the grain growth during the densification process, researchers tend to use the as-received powder with a size of nano-to submicronmeter to produce high-performance ceramic materials. As for the fabrication of Si 3 N 4 ceramics, a forming method named sintered reaction-bonded silicon nitride (SRBSN) is well-known, which uses the relative cheaper Si raw powders instead of Si 3 N 4 powder [48]. Herein, we replaced a portion of Si 3 N 4 powder with the coarse 5 µm Si powder to see whether it can help to improve the curing ability of slurries.…”

“…This result, appearing as the probable cause of the higher molecular weight which NPG2PODA possesses, deserves further investigation and will be discussed in our future work. ceramics, a forming method named sintered reaction-bonded silicon nitride (SRBSN) is well-known, which uses the relative cheaper Si raw powders instead of Si3N4 powder [48]. Herein, we replaced a portion of Si3N4 powder with the coarse 5 μm Si powder to see whether it can help to improve the curing ability of slurries.…”

Enhanced thermal conductivity and flexural strength of sintered reaction‐bonded silicon nitride with addition of (Y0.96Eu0.04)2O3

“…However, the high cost of high-purity Si 3 N 4 powder is the main barrier to the application of sintered Si 3 N 4 ceramics (SSN). Compared with the conventional SSN, sintered reaction-bonded silicon nitride (SRBSN) has many advantages, such as lower total oxygen content and lattice oxygen, 31,32 lower sintering shrinkage, lower cost of Si powders, [33][34][35][36][37] higher mechanical properties, and higher thermal conductivity. [38][39][40] For example, the SRBSN sample with high thermal conductivity (105 W/(m.K)) and high flexural strength (736 MPa) was fabricated by Zhou et al 38 But the development and application of SRBSN ceramics were limited by the long nitridation time.…”

Microstructure and Thermal Conductivity of Sintered Reaction‐Bonded Silicon Nitride: The Particle Size Effects of MgO Additive

“…It is known that the particle size of silicon powder is one of the most critical factors affecting the mechanical properties of the resulting SRBSN [11][12][13]. Specifically, the pore size of reaction-bonded silicon nitride (RBSN) is generally dependent on the particle size of the starting silicon powder.…”