Fabrication and Microstructure of Silicon Nitride/Boron Nitride Nanocomposites |
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Authors: | Takafumi Kusunose Tohru Sekino Yong Ho Choa Koichi Niihara |
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Affiliation: | Insitute of Scientific and Industrial Research, Osaka Univeristy, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan |
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Abstract: | A chemical process for fabrication of Si3N4/BN nanocomposite was devised to improve the mechanical properties. Si3N4/BN nanocomposites containing 0 to 30 vol% hexagonal BN ( h -BN) were successfully fabricated by hot-pressing α-Si3N4 powders, on which turbostratic BN ( t -BN) with a disordered layer structure was partly coated. The t -BN coating on α-Si3N4 particles was prepared by reducing and heating α-Si3N4 particles covered with a mixture of boric acid and urea. TEM observations of this nanocomposite revealed that the nanosized hexagonal BN ( h -BN) particles were homogeneously dispersed within Si3N4 grains as well as at grain boundaries. As expected from the rules of composites, Young's modulus of both micro- and nanocomposites decreased with an increase in h -BN content, while the fracture strength of the nanocomposites prepared in this work was significantly improved, compared with the conventional microcomposites. |
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Keywords: | nanocomposites silicon nitride boron nitride |
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