3517 水素ガス流量計用圧電素子PZTの破壊靱性評価(S20-4 水素環境での静的強度と破壊じん性,S20 材料強度特性に及ぼす水素の影響)

概要

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The effect of hydrogen on fracture toughness of PZT for the ultrasonic hydrogen flow sensor was investigated by micro-indentation method. PZT specimens were charged with hydrogen gas at 1.0MPa and 303K for 70 hours. No hydrogen was detected in both hydrogen-charged specimens and uncharged specimens. In consequence, there were no definite differences in indentation crack lengths and fracture toughness Kic even after hydrogen-charge. During the loading process, indentation cracks were initiated and propagated only in a plane perpendicular to sensor's vibration axe. These cracks increased in length during the unloading process as well. The residual tensile stress, which probably affected the indentation crack formation, was generated during the unloading process. K_<IC> of PZT in the maximum tensile stress direction was evaluated as 0.55MPa・m^<1/2> by using Niihara's evaluation formula. Three-dimensional shape of cracks and plastic zone beneath the indentation were observed by serial sectioning method.
社団法人日本機械学会の論文
2006-09-15