研削された部分安定化ジルコニア(Y-TZP)の曲げ強度

概要

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Specimens of tetragonal zirconia containing 3 mol % Y_2O_3 (Y-TZP) were ground with a diamond wheel of grain number 200/230. The residual stress and the monoclinic content were measured by the X-ray diffraction method. The bending stress was applied in the directions parallel and perpendicular to the grinding direction of the specimen. The residual stress on the ground surface was compressive, and the compression zone extended to about 30 μm in depth. The monoclinic content on the ground surface was raised to 7 to 8 percent. The bending strength increased in both directions because of the residual compressive stress near the surface introduced by grinding. For ground specimens, defects at the nucleation site of bending fracture were pores or coarse grains, but not grinding defects. Since the lower content of Y_2O_3 near the nucleation site raised the toughness of the material, the fracture toughness for fracture from small defects was larger than that of the single edge precracked specimen. The increase in the Weibull modulus due to grinding was discussed on the basis of fracture mechanics.
1993-05-25