Si_3N_4セラミックスの2次元及び3次元粒子形態と破壊靱性の相関性

概要

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Silicon nitride ceramics with different grain morphology and fracture toughness were prepared by sintering at 1900℃ for 2 to 24h in a N_2 atmosphere of 0.9 MPa. Two- and three-dimensional (2-D and 3-D) distributions of grain size and aspect ratio were analyzed to clarify the relationship between microstructure and fracture toughness. The 2-D and 3-D grain size distributions were in good agreement. However, the 3-D aspect ratio distribution curve shifted toward the higher value with a broader distribution as compared with that of 2-D. The improvement in fracture toughness was attributable to the increase in the volume and number fractions of grains in a particular elongated grain group (grain size: 1 to 1.5 μm, aspect ratio: 4 to 8) in the 3-D distribution. The increase in fracture toughness was also explained by the increase in the area and number fractions of grains in a particular grain group modified in the 2-D distribution.
1992-10-01