5. 結言 Fig.7 繰返し照射回数と密着強度 本研究では，レーザー衝撃試験（Laser Shock Adhesion Test : LaSAT）を援用して硬質コーティング膜の密着強度および密着耐久性を非接触で定量的に評価した．はじめに，LaSATを改良することで繰返し引張応力を付与できる試験環境を構築した．また，剥離の判定及び剥離タイミングの同定には膜表面の面外変位波形の相関係数を用いる手法を採用し，有限差分時間法（FDTD法）による波動伝播シミュレーションから界面に付与される引張応力を算出した．最後に，密着耐久性評価を行うために繰返しレーザー照射試験を実施し，レーザーエネルギーを変化させながら各点で繰返し照射回数と密着強度の関係を調べた．以上の試験結果より，鉄鋼基材上に製膜された無電解Ni-Pめっき膜の密着強度の定量評価を実現し，さらにはその疲労強度特性を評価できた．このような界面材料に繰返し負荷を加えると，均質なバルク材料の疲労強度特性と同様の傾向を示すことが分かった． 本研究は，平成29年度公益財団法人天田財団（AF-2017023）の支援によって行われました．記して謝意を表します．また，協力いただいた中央大学大学院生の金森公平君に感謝いたします． 謝 辞 参考文献 (1) J. Liu, X. Wang, H. Li, and W. Yang, “Delamination mechanism maps for coatings/substrates system subjected to adhesive contact loads,” Thin Solid Films, vol. 626, pp. 159–167, Mar. 2017. (2) B. D. Beake, T. W. Liskiewicz, A. Bird, and X. Shi, “Micro-scale impact testing - A new approach to studying fatigue resistance in hard carbon coatings,” Tribology International, Apr. 2019. (3) G. Skordaris, O. Lemmer, K.-D. Bouzakis, S. Kombogiannis, P. Charalampous, and E. Bouzakis, “Fatigue strength of diamond coating-substrate interface assessed by inclined impact temperatures,” Diamond Related Materials, vol. 50, pp. 77–85, 2014. (4) J. L. Mead, M. Lu, and H. Huang, “Inducing stable interfacial delamination in a multilayer system by four-point bending of microbridges,” Surface Coatings Technology, vol. 320, pp. 478–482, Jun. 2017. (5) H. Ito, S. Kiminami, H. Cho, "Evaluation of adhesion quality of oxide scale on low carbon steel at high temperature using a laser spallation technique," Transactions of the JSME (in Japanese) 81 (2015) 1-12. (6) G. Bégué et al., “Laser Shock Adhesion Test (LASAT) of EB-PVD TBCs: Towards an industrial application,” Surface Coatings Technology, vol. 237, pp. 305–312, Dec. 2013. (7) A. Lelevic and F. C. Walsh, “Electrodeposition of Ni P alloy coatings: A review,” Surf. Coatings Technol., vol. 369, pp. 198–220, Jul. 2019. (8) J. Naderi and A. A. D. Sarhan, “Measure and evaluate the hardness of the electrodeposited Nickel-Phosphorous (Ni-P) thin film coating on carbon steel alloy for automotive applications,” Measurement, vol. 139, pp. 490–497, Jun. 2019. (9) Y. Watanabe, S. Fujisawa, A. Yonezu, and X. Chen, “Quantitative evaluation of adhesion quality of surface coating by using pulse laser-induced ultrasonic waves,” Surface Coatings Technology, vol. 286, no. 286, pp. 231–238, Jan. 2016. (10) Y. Watanabe, A. Yonezu, and X. Chen, “Measurement of Interfacial Fracture Toughness of Surface Coatings Using Pulsed-Laser-Induced Ultrasonic Waves,” Journal of Nondestructive Evaluation, vol. 37, no. 1, p. 2, Mar. 2018. tests at ambient and elevated − 186 −
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