コンプライアンスによるナノ結晶電着ニッケル薄膜の疲労き裂長さの自動計測とΔ<i>K</i>漸減試験

Abstract

In fatigue crack propagation tests of thin films, crack length has been measured by an optical microscope. In the present study, a fatigue crack propagation testing system was developed for thin film by the automatic measurement for crack length with compliance. Nickel thin film used for this test was prepared by electrodeposition method. Two types of electrodeposited nickel thin films with different grain sizes were prepared by changing the concentration of brightener (0.0 g/L and 0.8 g/L). As results of EBSD analysis, the grain size of nickel thin film tended to decrease with increasing the additive amount of brightener. ΔK-decreasing tests were conducted on nickel thin films under stress the ratio R of 0.3 in a laboratory atmosphere. The automatic measurement of crack length with compliance was effective in fatigue crack propagation tests for nickel thin film, and the threshold stress intensity range, ΔKth, which obtained in our developed tensing system, showed a tendency to decrease with decreasing grain size.