105 ジルコニア系ファインセラミックス3Y-TZPの高温疲労強度特性と相変態に関する研究(超塑性と材料および造形法)

概要

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Zirconia based fine ceramics have a mechanism to improve the strength and the fracture toughness due to the stress induced phase transformation (the t-m phase transformation). They are expected to be used as a candidate material of the high heat resistant structures with complex shapes such as the core barrel and the upper shield block in high-temperature gas cooled reactors. Detailed data of the fatigue characteristics of zirconia based fine ceramics, however, aren't sufficient at high temperatures yet. In this study, the fatigue strength properties of 3mol% yttrium-stabilized tetragonal zirconia polycrystals (3Y-TZP) are estimated by 4-point bending fatigue test at high temperatures. The changing of the crystal structure of 3Y TZP after the fatigue test is also evaluated by the X-ray diffraction analysis. In the fatigue test, the fatigue limits of the 3Y TZP are 500 [MPa], 300 [MPa] and 250 [MPa] under a condition of a ratio of the minimum and the maximum stresses of 0.1 at 523 [K], 773[K] and 873 [K], respectively. And the most important cause to determine the fatigue strength finds to be the phase transformation due to the cyclic stress and the test temperature.
一般社団法人日本機械学会の論文
2007-09-28