2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 6: Yagi Intl. Symp. / Metals & Alloys Processing
| Editors: | Kongoli F, Akiyama T, Nogami H, Saito K, Fujibayashi A |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 480 pages |
| ISBN: | 978-1-987820-46-1 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Combustion Synthesis of alpha-Si3N4 Assisted by Salt Additives
Xuemei Yi1; Shota Suzuki2; Jing Niu3; Tomohiro Akiyama3;1, Yangling, China; 2HOKKAIDO UNIVERSITY, sapporo, Japan; 3HOKKAIDO UNIVERSITY, Sapporo, Japan;
Type of Paper: Regular
Id Paper: 168
Topic: 3
Abstract:
1. Introduction: Power device technology is advancing toward higher voltage, larger current, greater power density. However, the high power will induce large thermal stresses in the devices, which poses great challenges for the assembly of the devices and the packaging materials, especially the brittle ceramic substrates that provide functions of electrical insulation and heat dissipation [1,2]. Si3N4 ceramics have excellent mechanical and thermal properties, which are deemed as an attractive substrate material for high-power electronic device applications. Sintered silicon nitride has excellent toughness and thermal conductivity, which is mainly attributed to the alpha to beta phase transformation accelerating grain growth and densification during high temperature, Therefore, 再alpha-Si3N4 powder is necessary for obtaining dense bulk silicon nitride. Then the purpose of this research is to synthesize high ratio alpha-Si3N4 powder using combustion synthesis method assisted by salt additives. 2. Experimental: The mixture of the starting materials (Si, Si3N4, and salts) was first subjected to dry planetary milling and then was combustion synthesized at a nitrogen pressure of 1 MPa. The alpha/beta ratio was estimated by the intensity ratio of the X-ray Diffraction (XRD). 3. Results: NaCl, MgCl2, and MgCl2∙6H2O were added in the raw mixtures for assisting synthesis of high ratio alpha-Si3N4. Among these three kinds of salts, NaCl showed the best appropriate additive in which 57.8 % alpha-Si3N4 was obtained when 30 mass% NaCl was added. Ball milling of the raw mixtures could increase the contact area of Si and NaCl by the dispersion of NaCl particles, 84 % alpha-Si3N4 was obtained after 120 min milling. References: [1] H. Okumura, Jpn. J. Appl. Phys. 2006, 45, 7565.[2] C. R. Eddy Jr., D. K. Gaskill, Science 2009, 324, 1398.