Effect of Aluminum Content on Mechanical Properties and Thermal Conductivities of Sintered ReactionBonded Silicon Nitride

被引:31
作者
Kusano, Dai [1 ,2 ,3 ]
Hyuga, Hideki [2 ]
Zhou, You [2 ]
Hirao, Kiyoshi [1 ,2 ]
机构
[1] Nagoya Inst Technol, Dept Frontier Mat, Showa Ku, Nagoya, Aichi 4668555, Japan
[2] Natl Inst Adv Ind Sci & Technol, Nagoya, Aichi 4638560, Japan
[3] Japan Fine Ceram Co Ltd, Sendai, Miyagi 9813203, Japan
关键词
ADDITIVE COMPOSITION; OXYGEN-CONTENT; SI POWDER; BETA-SI3N4; LATTICE; IMPURITIES; CERAMICS; CRYSTAL; YTTRIA;
D O I
10.1111/ijac.12035
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
A systematic study was conducted of the effect of Al impurities on the mechanical and thermal properties of sintered reaction-bonded silicon nitrides (SRBSNs). 2mol.% Y2O3 and 5mol.% MgSiN2 were added as sintering aids to high-purity raw Si powder, followed by respective additions of 0, 0.01, 0.1, 0.2, and 0.4 mass% of Al relative to Si. The prepared powder mixes were press formed and nitrided in a 0.1MPa nitrogen atmosphere at 1400 degrees C for 8h. Postsintering of the nitrides was conducted under a pressurized nitrogen atmosphere of 0.9MPa at 1900 degrees C for 6h. The SRBSN specimens exhibited hardly any difference in their four-point bending strength, which ranged from 800 to 850MPa. However, their fracture toughness clearly decreased with increasing additive Al content. This is thought to be due to a reduction in the proportion of coarse prismatic grains improving the toughness with increasing additive Al content. A significant reduction in the thermal conductivity was also observed with increasing additive Al content. This is conjectured to be due to the formation of SiAlON through a substituted solid solution of aluminum (Al) and oxygen (O) in -Si3N4 crystals. An inductively coupled plasma and hot gas extraction method were employed to directly analyze Al and O in -Si3N4 particles. Approximately half of the additive Al was confirmed to be in solid solution in -Si3N4 particles along with the solid solution of O in a chemical formula that nearly corresponds to -Si6-zAlzOzN8-z. The chemical analysis results give a Z value range of 0.0006-0.024.
引用
收藏
页码:534 / 542
页数:9
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