Computer Aided Design of Microstructure for Highly Functional Ceramics Coating Films

陶瓷涂层是制备高性能涂层的最有前途的途径之一。例如，陶瓷超晶格在一定的叠层周期下，其压痕硬度和热稳定性显著提高，有望用作刀具、滑道等重摩擦表面的耐磨涂层。然而，由于难以高可靠性地测量陶瓷涂层的力学性能和观察涂层的微观结构，因此对陶瓷涂层的硬度增强机理还没有很好的理解，本研究旨在阐明陶瓷涂层的微观结构与力学性能之间的相关性，并建立高功能陶瓷涂层设计的指导原则，提出了适用于纳微尺度的扩展分子动力学（MD）计算机模拟的分析方法，包括MD/FEM混合模型和重整化群MD 关于我们 模拟结果表明，至少在TiN/ZrN超晶格膜的情况下，没有出现迄今为止报道的用于硬度增强的最佳层压周期。另一方面，在电弧离子镀TiN/ZrN超晶格薄膜的实验结果表明，与2.5 nm的周期为12 nm的硬度提高更大。由于这些薄膜具有多晶结构，在薄膜中不可避免地包括原子错配和晶界。周期较小的薄膜中含有较多的缺陷，会使薄膜的力学性能下降。目前正在继续对包括缺陷在内的模型进行进一步模拟。为了阐明硬度增强的机理，需要在微观尺度的MD模拟和宏观尺度的实际测试之间进行更多的对比研究。然而，分子动力学模拟可以是一个有用的工具，以帮助清楚地了解在原则上的陶瓷超晶格的微观结构和力学性能之间的关系。少

Ceramics coating film is one of the most promising approaches for highly functional coating films. For example, the ceramics superlattice shows remarkable enhancement in indentation hardness and thermal stability with a specified laminating period, it is expected to be used as a wear-resistant corting films on the surfaces subjected to heavy duty friction such as cutting tools and slide ways. However, the mechanism of hardness enhancement has not been understood well due to the difficulties in highly reliable measurement of mechanical properties and observation of microstructure of the film.In this research, to clarify the correlation between the microstructure and mechanical properties of ceramics coating films and to establish the guidelines for design of highly functional ceramics coating films, the useful analytical methods of extended molecular dynamics (MD) computer simulations, which include MD/FEM hybrid model and renormalization groupe MD, are proposed for nano to micro scale … More analysis of material behavior.The results of simulations suggest that optimum laminating period, which was reported so far, for hardness enhancement does not appears at least in case of TiN/ZrN superlattice film. On the other hand, experimental results of microindentation on arc ion-plated TiN/ZrN superlattice films with the period of 12 nm shows larger hardness enhancement than that with 2.5 nm. As these films have polycrystalline structure, atomic misfits and grain boundaries are inevitably included in the film. A larger number of defects included in the film with smaller period may deteriorate its mecanical properties. Further simulations on the model including defects are now being continued. To clarify the mechanism of hardness enhancement, more efforts for comparative studies are required between MD simulation in micro scale and practical testing in macro scale. However, MD simulation can be an useful tool to help clear understanding in principle the correlation between microstructure and mechanical properties of ceramics superlattice. Less