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学术报告:Development of multifunctional Si3N4 ceramics by advanced powder processing

 

 

主讲人:Prof. Junichi Tatami                                                           

时间:2019年4月30日(星期二)上午10:00-12:00

地点:大学城校区实验三号楼201会议室

摘要:

Although Si3N4 ceramics have been developed for engineering applications, such as bearings, Si3N4 itself has also many kinds of functions including high thermal conductivity, high electrical insulation, high transparency in visible and infrared light and so on. In this talk, recent development of multifunctional Si3N4 ceramics developed by advanced powder processing will be introduced. Si3N4 ceramics are expected to be used as a substrate for SiC power modules because of good mechanical properties. Alignment of c-axis of Si3N4 is effective in higher thermal conductivity of the Si3N4 ceramics because thermal conductivity of c-axis of ?-Si3N4 has much higher than that of a-axis. We have fabricated the c-axis oriented Si3N4 ceramics using graphene / Si3N4 nanocomposite particles by molding in low and static magnetic field. The graphene / Si3N4 nanocomposite particles were prepared by mechanical treatment. A slurry composed of the seed particles, α-Si3N4 and sintering aid powders was prepared, and then it was molded in the low and static magnetic field. As a result, c-axis of the graphene-coated ?-Si3N4 seeds were successfully oriented under the magnetic field of 0.4 T. After firing at high temperature, dense Si3N4 ceramics in which c-axis of elongated β-Si3N4 grains were well oriented were obtained. We also prepared the transparent and luminescent α-SiAlON ceramics by cyclic CIP and HIP process for high power white LED application alternative to phosphor / resin composites. The developed Ce doped Y-α SiAlON ceramics showed over 60% transparency at 600 nm in wavelength and blue or blue-green emission excited by UV light. The maximum excitation and emission were obtained at 370 and 480 nm, respectively. Transparent Eu doped Ca-α SiAlON ceramics was also developed, of which emission was yellow color by blue light excitation.  It was confirmed that advanced powder processing is very important to develop such multifunctional Si3N4 ceramics.

主讲人简介:

Professor Junichi Tatami is Professor of Graduate School of Environment and Information Sciences at Yokohama National University since 2012. He received Doctor of Engineering from Department of Inorganic Materials, Graduate School of Engineering, Tokyo Institute of Technology in 1997. After his graduation, he was a JSPS postdoctoral fellow in Tokyo Institute of Technology. He joined Yokohama National University as a research associate of Faculty of Engineering. His current research interests are high performance nitride ceramics, such as Si3N4, SiAlON and AlN ceramics, mechanical properties of ceramics, and powder processing for better ceramics. Prof. Tatami has given many invited talks in the international conference on advanced ceramics. He also wrote over 100 peer reviewed papers in the journals. He is the Fellow, The Ceramic Society of Japan (2019), a recipient of the CerSJ Award for Academic Achievement in Ceramic Science and Technology (2016), Late Shri Jaswant Singh Minhas Memorial Award-2016, Indian Ceramic Society (2016), the JSPS Prize (2014), the Rechard M. Fulrath Award from the American Ceramic Society (2011), the Young Scientists’ Prize: The commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology, Japan (2009).

 

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