Non-contact Laser Ultrasonic Characterization of Thin Films and Coatings

薄膜和硬涂层的厚度和机械性能的表征在诸如微电子器件、机床和发动机部件等广泛的领域中是至关重要的。 虽然传统的接触方法，如机械压痕目前流行，激光超声（LU）方法提供了几个好处，包括非接触式快速操作，耦合剂的独立性，高保真度，并在恶劣的环境中执行的能力。该项目旨在：1。开发多层结构中激光产生超声的理论模型，允许计算时域表面位移; 2.设计有效产生超声波的实验程序，并实施能够在粗糙和光滑涂层上以良好灵敏度工作的自适应光学检测系统;以及3.用LU实验对一系列技术相关的多层结构进行理论模型的验证，重点是过渡金属氮化物和碳化物（即，TiN、TiC、ZrN、CrN）;该项目的目标是开发下一代激光超声表征薄膜和涂层厚度和弹性模量所需的方法。

Characterization of the thickness and mechanical properties of thin films and hard coatings is of vital importance in a wide range of areas such as microelectronic devices, machine tools, and engine components. While conventional contact methods such as mechanical indentation are currently in vogue, laser ultrasonic (LU) methods offer several benefits including non-contact rapid operation, couplant independence, high fidelity, and the ability to perform in hostile environments. This project aims to: 1. Develop theoretical models for laser generated ultrasound in multi-layered structures allowing for the calculation of time domain surface displacements; 2. Devise experimental procedures for efficient generation of ultrasound and implement an adaptive optical detection system capable of working with good sensitivity on rough and smooth coatings; and 3. Validate the theoretical models with LU experiments on a range of technologically relevant multi-layered structures with a focus on transition metal nitrides and carbides (ie. TiN, TiC, ZrN, CrN); The goal of the project is to develop the next generation methodologies necessary for laser ultrasonic characterization of thickness and elastic moduli of thin films and coatings.