纳米压痕技术及其在薄膜/涂层体系中的应用

Nanoindentation Technique and Its Application in Film/Coating System

综述了纳米压痕技术的发展历程及其在薄膜领域的应用。介绍了当前实验室条件下主要采用的电磁驱动式纳米压痕仪的构造和工作过程。为了保证测试结果的准确性,要在合适的温度、湿度下进行压入实验,借助保载来消除一些可以避免的误差。阐述了压头的分类和选择原则,玻氏压头相比于维氏压头具有更小的中心线与棱面夹角,避免了尖端横刃对于压入结果准确性的影响,因此最常用的压头为玻氏压头;表征断裂韧性最合适的压头为立方角压头;表征微机电系统的弯曲采用楔形压头。总结了通过最大载荷和压入面积得到涂层力学参量的分析流程。归纳了将纳米压痕法应用于表征薄膜涂层的硬度和弹性模量、室温下蠕变性能、断裂韧性、残余应力、塑性性能等力学量的研究,如表征硬度和弹性模量的Oliver-Pharr法的应用,识别蠕变柔量的Lee-Radok模型的应用,分析断裂韧性的Lawn-Evans-Marshall模型的应用。在涂层制备过程中,制备参数的改变可以使得涂层具有不同的力学性能,涂层厚度远小于表面尺寸,硬度和弹性模量仍然存在各向异性,非晶态结构涂层具有更高的硬度和弹性模量。采用碳纳米管强化可以提高涂层的断裂韧性,涂层内存在适量的残余应力数值和合适的残余应力类型,可以改善涂层的力学性能。具有多层结构、梯度结构等新型结构的涂层相比于传统涂层具有更优良的力学性能。纳米压痕法结合AFM原子力显微镜可以实现原位测量,结合有限元法可以对于理论模型进行完善,并拓宽模型的适用范围。最后,对于纳米压痕技术在薄膜涂层中的应用前景进行了展望。

In this paper,the development of nanoindentation and its application in coating were reviewed.The construction and working process of the electro-magnetic driven nanoindentation instrument mainly used under current laboratory conditions were introduced.In order to ensure the accuracy of the test results,indentation experiments were carried out at the appropriate temperature and humidity to eliminate some avoidable errors with the help of holding.The classification and selection principles of the indenter were described:the Berkovich indenter has a smaller angle between the centerline and the prism than the Vickers indenter,which avoids the influence of the cross-edge of the tip on the accuracy of the indentation results,so the most commonly used indenter is the Berkovich indenter;the most suitable indenter to characterize the fracture toughness is the cubic angle indenter;the wedge indenter is used to characterize the bending of the MEMS.The analytical procedure for obtaining the mechanical parameters of the coating by maximum load and indentation area was summarized.The application of nanoindentation to characterize mechanical quantities such as hardness and elastic modulus,creep properties at room temperature,fracture toughness,residual stress,and plastic properties of coating were summarized.Such as:the application of Oliver-Pharr method for determining hardness and elastic modulus,the application of Lee-Radok model for identifying creep flexibility,and the application of Lawn-Evans-Marshall model for analyzing fracture toughness.During the preparation of coating,the preparation parameters can be changed to make the coating have different mechanical properties;the thickness of coating was far less than surface dimension,hardness and elastic modulus show anisotropic.Amorphous structured coating has higher hardness and elastic modulus;Carbon nanotube can improve the fracture toughness of coating Some residual stress and the proper type within the coating can improve the mechanical properties of coating.Coatings with multilayer structure and gradient structure,et al.have better mechanical properties.Nanoindentation technology combined with AFM can realize in-situ measurement;combined with the finite element model(FEM)can improve the theoretical model and broaden application of the model.Finally,the prospect of nanoindentation technology in coatings was prospected.