Carbothermal synthesis of silicon nitride (Si3N4): Kinetics and diffusion mechanism

✍ Scribed by A. Ortega; M.D. Alcalá; C. Real

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 501 KB
• Volume: 195
• Category: Article
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2007.05.004

✦ Synopsis

Sample controlled reaction temperature (SCRT) has been used for the first time to study the kinetics of the carbothermal reduction of silica in nitrogen to obtain silicon nitride (Si 3 N 4 ).

It is noteworthy to point out that SCRT method allows both a good control of pressure in the sample surroundings and the use of reaction rates low enough to keep temperature gradients at a negligible level to avoid any heat or mass transfer phenomena. It has been shown that the carbothermal synthesis of silicon nitride is best described by a two-dimensional diffusion kinetic model with an activation energy of about 306 kJ/mol. Effects of experimental parameters on the activation energy has been investigated. By using SCRT it has been possible to obtain ceramic powder with a determined phase composition and a controlled microstructure.