種結晶添加と押出し成形を組み合わせた手法による一軸配向窒化ケイ素セラミックスの作製と機械特性

概要

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Silicon nitride with unidirectionally oriented elongated grains was fabricated by the combination of seeding and extrusion process. Development of such highly anisotropic microstructure is due to the high shear stress exerted during the extrusion process, which allowed the unidirectional alignment of rod-like seed particles. Small matrix grains were almost consumed by selective grain growth into larger grains grown from seed particles, consequently, large elongated grains with high aspect ratio were dominant in the microstructure of this material. Such microstructure development is related to the fact that the unidirectional alignment of seeds along a precise direction inhibits mutual impingement of elongated grains during growth along their length direction. Both high strength of about 1.4 GPa and high fracture toughness of about 14 MPa・m^<1/2> could be achieved by testing in the direction parallel to grain alignment.
社団法人日本セラミックス協会の論文
1999-12-01