高純度cBN多結晶体の微細構造と特性 [in Japanese] Microstructure and Properties of High-purity Polycrystalline cBN [in Japanese]
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Microstructural features and some properties of high-purity polycrystalline cBN synthesized from hBN by the direct conversion method were investigated. A fine-grained (<0.5μm) and homogeneous high-purity polycrystalline cBN was obtained at 7.7GPa and 2200-2400°C. At lower pressure and lower temperature than these conditions, compressed hBN remained in the polycrystalline sintered body. Some cBN grains became larger rapidly at higher temperature above 2400°C, and inhomogeneous microstructure was formed. The fine-grained and homogeneous polycrystalline cBN had higher hardness and TRS, compared with the coarse-grained and inhomogeneous polycrystalline cBN. The thermal conductivity of the polycrystalline cBN increased with increasing grain size or synthesis temperature. The thermal conductivity of the fine-grained polycrystalline cBN, however, was 3 to 4 times higher than conventional cBN compacts containing binder materials. The fine-grained and homogeneous high-purity cBN is expected to have high potential in cutting tool applications because of its excellent mechanical and thermal properties.
- Journal of the Japan Society of Powder and Powder Metallurgy
Journal of the Japan Society of Powder and Powder Metallurgy 49(4), 327-332, 2002-04-15
Japan Society of Powder and Powder Metallurgy