8月9日下午3点湍流重点实验室报告－东京工业大学Kishimoto教授
发布时间: 2010-08-08 06:40:00
SEMINAR SERIES
北京大学工学院 ![]()
力学与空天技术系
湍流与复杂系统国家重点实验室
题目：Evaluation of the Interfacial Strength of Layered Structures by Nano-Indentation Method
报告人：Professor Kikuo Kishimoto
Mechanical Science & Engineering, Tokyo Institute of Technology, Japan
Abstract: The delamination of thin coating films from substrates is a critical issue for the reliability of micro- and nanoelectronic devices. Scratch test and peel test are widely employed to measure the interface strength of thin coating. However, results of scratch test usually depend on the thickness and hardness of coating. In peeling test, there is a problem in cramping of weak or brittle film specimens. On the other hand, nano-indentation techniques are widely applied to evaluate the mechanical properties of thin films such as hardness, elastic modulus and viscoelasticity. Application of nano-indentation method to measure the interface strength between films and their substrates is receiving increasing attention. During indentation tests, the information obtained is the indentation load (P) and indentation depth (h) relations (i.e. P-h curve) along with the indentation impression. Therefore, it is necessary to develop a suitable method for evaluating the interfacial strength from those limited information. The energy dissipation during indentation tests for a coating layer on an elastic substrate is analyzed by the finite element method with the damage-based cohesive zone model. Focusing on the discontinuous point during the indentation tests and introducing the balance of energy before and after the onset of delamination, the evaluation method of the interfacial strength from P-h curve is introduced. The applicability of the method is examined by the experiment on PI coating / Si substrate specimen with deferent coating thickness. It is shown that small scale yielding condition does not hold for thinner coating thickness specimen and the interfacial strength is underestimated by the method. Rate dependency of indentation load and influence of plastic deformation is discussed and a revision of method is introduced.
主持人：方岱宁 教授
时 间：8月9日（周一）下午3:00
地 点：力学楼434会议室
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