On the ability of nanoindentation to measure anisotropic elastic constants of pyrolytic carbon
On the ability of nanoindentation to measure anisotropic elastic constants of pyrolytic carbon
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DOI：
10.1002/zamm.201100128
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
T. Gross;N. Timoshchuk;I. Tsukrov;R. Piat;B. Reznik
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文献类型：
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作者：
T. Gross;N. Timoshchuk;I. Tsukrov;R. Piat;B. Reznik
我们使用立方体角、Berkovich、圆锥球和Vickers压痕器测量了高取向体热解碳的压痕模量，分别垂直于和平行于弹性各向同性平面。我们将测量结果与以前使用应变计方法和超声相谱法获得的弹性常数进行了比较。目前还没有从压痕模量中提取各向异性弹性常数的方法，采用Delafargue和Ulm (DU)[17]方法从已知弹性常数中预测压痕模量。垂直于各向同性平面的压痕模量为%sim；比DU预测高20%，与压头类型无关。平行于各向同性平面的压痕模量比DU预测值低2-3倍，与深度有关，立方体角压痕模量最低。我们将低压痕模量归因于类石墨平面的纳米屈曲，而压痕类型依赖于不同程度的横向应力对纳米屈曲倾向的影响。
We used cube corner, Berkovich, cono‐spherical, and Vickers indenters to measure the indentation modulus of highly oriented bulk pyrolytic carbon both normal to and parallel to the plane of elastic isotropy. We compared the measurements with elastic constants previously obtained using strain gage methods and ultrasound phase spectroscopy. While no method currently exists to extract the anisotropic elastic constants from the indentation modulus, the method of Delafargue and Ulm (DU) [17] was used to predict the indentation modulus from the known elastic constants. The indentation modulus normal to the plane of isotropy was %sim; 20% higher than the DU predictions and was independent of indenter type. The indentation modulus parallel to the plane of isotropy was 2–3 times lower than DU predictions, was depth dependent, and was lowest for the cube corner indenter. We attribute the low indentation modulus to nanobuckling of the graphite‐like planes and the indenter type dependence to the impact of differing degree of transverse stress on the tendency toward nanobuckling.