日時：2007年10月9日（金）15:00～17:00
場所：南7号館1階101学科会議室
講師：Dr. Qing Huang (Nanoscale Materials Center,National Institute for Materials Science)
講演題目：「Synthesis of Boron Nitride Nanotubes and their Application in Engineering ceramics」
講演内容：
Introducing carbon nanotubes (CNTs) into polymer or ceramic matrices has been a promising approach to obtain ultra-strong, extra-toughened materials as well as multifunctional composites. Most of the previous work on CNT composites has focused on strengthening and toughening of matrix materials at ambient conditions. However, there is hitherto a lack of information on mechanical behavior of these composites at elevated temperature. Recently, single-walled CNTs were found to undergo a superplastic deformation with an appealing 280% elongation at a high temperature (Huang J. Y.; Chen S.; Wang Z. Q.; Kempa K.; Wang Y. M.; Jo S. H.; Chen G.; Dresselhaus M. S.; Ren Z. F. Nature, 2006, 439, 281.). This discovery implies the high probability for the potential usage of CNTs as reinforcing agents in engineering high-temperature ceramics with an improved ductility. Here, we will introduce the counterpart of carbon nanotubes: Boron nitride nanotubes. The synthesis methods developed in our group are summarized. Also, we will discuss the recent result that a small addition of boron nitride nanotubes (BNNTs) can dramatically enhance a high-temperature superplastic deformation (SPD) of engineering ceramics. More specifically, 0.5 wt% addition of BNNTs leads to an inspiring brittle-to-ductile transition in Al2O3 ceramics even at a moderate temperature (1300 oC). The underlying SPD-enhancement mechanism is proposed in terms of inhibition of static and dynamic grain growth of matrix and energy-absorption mechanism of BNNTs. The unraveled capability of BNNTs to enhance the SPD behavior will make BNNTs promising components in cost-effective complex ceramics with good comprehensive mechanical properties.
問合せ先：安田公一 内線2526,kyasuda＠ceram.titech.ac.jp