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A Study on Absolute Evaluation of Fracture Strength of Thin Films by Indentation

压痕法绝对评价薄膜断裂强度的研究

基本信息

批准号：
02452098
负责人：
ICHIKAWA Masahiro
金额：
$ 4.42万
依托单位：
The University of Electro-Communications
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

项目摘要

In this research, a method was proposed to evaluate absolutely fracture strength of a thin film coated on a substrate by indenting a spherical indenter, and feasibility and usefulness of the method were studied. The term "absolutely" was used to intend that the proposed method was not for mere relative evaluation of different films. When a spherical indenter is indented to a brittle film coated on a substrate and the indentation load is increased, a ring crack is formed in the film. By measuring the ring crack initiation load and analying the stress field in the film, it is expected that fracture strength of the film can be obtained. The results of the present research are summarized as follows.1. In this research, a SiO_2 film of 2mum thickness coated on a SUS440C substrate by ion beam spattering was indented using s SIC spherical indenter of 750mum radius. Evaluation of its fracture strength required stress anlysis as well as indentation experiments. An elastic finite element stress … More analysis was first carried out. An approximate expression was derived for the stress field of the film when the film thickness was much smaller than the radius of the contact circle.2. For taking into account plastic deformation of the SUS440C substrate under indentation, an elasto-plastic finite element stress analysis was then carried out. It was found that the radial tensile stress appears in the film outside the contact circle in this case too.3. Before evaluation of fracture strength of the film, the proposed method was applied to evaluation of fracture strength of a bulk material. An indentation experiment was carried out on a sodalime glass plate. It was confirmed that fracture strength could be evaluated properly using the proposed method.4. The fracture strength of a SiO_2 film coated on a SUS440C substrate was evaluated by indenting a SiC spherical indenter. In order to take into account the size effect, a probabilistic treatment using a Weibull distribution was employed. The residual compressive stress in the film was also taken into account. A reasonable value was obtained for the fracture strength of the film. Less

本研究提出了一种用球形压头压痕法评估基底上涂层薄膜绝对断裂强度的方法，并对该方法的可行性和实用性进行了研究。使用“绝对”一词是为了表明所建议的方法不仅仅是对不同电影的相对评价。当球形压头压入涂覆在基材上的脆性薄膜时，压痕载荷增加，在薄膜中形成环形裂纹。通过测量环裂纹起裂载荷和分析膜内应力场，可以得到膜的断裂强度。本文对本文的研究成果进行了总结。本研究采用离子束溅射法在SUS440C衬底上涂覆了厚度为2mum的SiO_2薄膜，并用半径为750mum的SIC球形压头压痕。其断裂强度的评估需要应力分析和压痕实验。首先进行了更多的分析。推导出了当膜厚远小于接触圆半径时，膜应力场的近似表达式。考虑压痕作用下SUS440C基板的塑性变形，进行了弹塑性有限元应力分析。在这种情况下，接触圈外的膜也出现径向拉应力。在评价薄膜断裂强度之前，将该方法应用于块状材料断裂强度的评价。在钠盐玻璃板上进行了压痕实验。结果表明，采用该方法可以较好地评价材料的断裂强度。用SiC球形压头对SUS440C衬底上SiO_2涂层的断裂强度进行了评价。为了考虑大小效应，采用了威布尔分布的概率处理。同时考虑了薄膜中的残余压应力。得到了薄膜断裂强度的合理值。少