深圳大学学报理工版

纳米压痕是一种常用的薄膜硬度评价方法.然而,当薄膜厚度< 10 nm时,该方法难以去除基体对薄膜硬度的影响,因而无法获得薄膜自身的硬度,限制了纳米结构与硬度之间关系的认知,阻碍了超薄纳米结构薄膜的应用.本研究提出一种基于纳米压痕硬度标定下的纳米划痕硬度评价方法,并将其应用于纳米结构碳膜的硬度研究.首先,利用自行设计搭建的纳米刻划装置,通过对比碳膜在纳米划痕和纳米压痕方法下的残余变形深度,分析不受基体影响的临界薄膜厚度,得到纳米划痕深度不受基体影响的临界薄膜厚度.其次,采用压头形状等效接触模型,利用划痕的残余顶角、宽度和深度,通过计算压头前端的接触压力分布得到硅基体的纳米划痕硬度,与纳米压痕硬度标定结果一致.最后,将纳米划痕硬度方法应用在电子回旋共振等离子体溅射方法制备的3种不同纳米结构碳膜上,得到交联结构碳膜和非晶碳膜的硬度分别约为19.1 GPa和14.6 GPa,高于硅基体11.2 GPa的硬度,而石墨烯嵌入式碳膜的硬度约为2.7 GPa.分析不同纳米结构碳膜的刻划机理表明,在sp2含量较高的纳米结构碳膜中,sp3含量并不是决定碳膜力学特性的唯一因素,小尺度、多石墨烯层间交联结构能够有效增加层间的剪切强度,薄膜展现出较好的耐刻划特性.研究结果有助于进一步拓展纳米划痕方法的应用,也为不同纳米结构碳膜的应用提供了理论基础.

Nanoindentation is a well-known method to evaluate the hardness of nano-film. However, when the film is thinner than 10 nm, it is very hard to eliminate the substrate effect on the hardness measurement of ultrathin nano-films. As a result, the relationship between nanostructure and hardness is hard to be understood, and the applications of ultrathin nanostructured films are impeded. Therefore, in this study, the nanoscratch hardness evaluation method is proposed. The method is calibrated with the nanoindentation method, and its application on the hardness of carbon based nanostructured films is investigated. Firstly, a self-designed nanoscratch apparatus is used to perform the nanoscratch tests on carbon films with different thicknesses, the residual deformation depths caused by nanoscratch and nanoindentation are compared, and the critical film thickness without substrate effect during nanoscratch tests is obtained. Secondly, an equivalent contact model is established with the measured apex angle, scratch depth and scratch width, and then the nanoscratch hardness of silicon substrate is calculated with the contact pressure of the tip ahead the sliding direction. The result is nearly consistent with the calibrated nanoindentation hardness. Finally, the nanoscratch method is applied on the hardness evaluation of three different kinds of nanostructured carbon films prepared by electron cyclotron resonance plasma sputtering. The scratch hardness of graphene layer cross-linking and amorphous carbon films are 19.1 GPa and 14.6 GPa, respectively, which are larger than that of the silicon substrate with 11.2 GPa. While the graphene sheets embedded, carbon films have much smaller nanoscratch hardness of 2.7 GPa. The characterization mechanism of carbon films with different nanostructures shows that the content of sp3 is not the only factor determining the mechanical properties of carbon films with high sp2 content. The small-scale multi-graphene cross-linking structure can increase the interlayer shear strength, and the film exhibits better nanoscratch resistant performance. The results can further expand the application of the nanoscratch hardness evaluation method and provide research foundation for the application of carbon films with different nanostructures.

引言
1 实验
2 实验结果及分析
3 结论

图1 纳米刻划装置示意图及其测试方法<br/>Fig.1 Schematic of the nanoscratch test apparatus and the test method

图1 纳米刻划装置示意图及其测试方法
Fig.1 Schematic of the nanoscratch test apparatus and the test method

图2 非晶碳膜纳米压痕及划痕测试结果<br/>Fig.2 The nanoindentation and nanoscratch test results of amorphous carbon films

图2 非晶碳膜纳米压痕及划痕测试结果
Fig.2 The nanoindentation and nanoscratch test results of amorphous carbon films

图3 不同薄膜厚度非晶碳膜的残余划痕深度和残余压痕深度,以获得不受基体影响的临界薄膜厚度<br/>Fig.3 The residual depth of nanoindentation tests and nanoscratch tests to reflect the critical test thickness without substrate effect

图3 不同薄膜厚度非晶碳膜的残余划痕深度和残余压痕深度,以获得不受基体影响的临界薄膜厚度
Fig.3 The residual depth of nanoindentation tests and nanoscratch tests to reflect the critical test thickness without substrate effect

图4 划痕硬度分析计算模型<br/>Fig.4 Analysis model for nanoscratch hardness calculation

图4 划痕硬度分析计算模型
Fig.4 Analysis model for nanoscratch hardness calculation

图5 不同刻划载荷时4种样品的刻划深度汇总<br/>Fig.5 Scratch depths of four kinds of samples under different scratch loads

图5 不同刻划载荷时4种样品的刻划深度汇总
Fig.5 Scratch depths of four kinds of samples under different scratch loads

表1 不同纳米结构碳膜的刻划硬度计算参数<br/>Table 1 Parameters of nanoscratch hardness calculation for carbon films with different nanostructures

表1 不同纳米结构碳膜的刻划硬度计算参数
Table 1 Parameters of nanoscratch hardness calculation for carbon films with different nanostructures

表2 拟合得到的a和b值,以及当h/t=0.1时计算得到的刻划硬度H0.1<br/>Table 2 The fitted constant values of a, b, and the calculated scratch hardness H0.1 with h/t=0.1

表2 拟合得到的a和b值,以及当h/t=0.1时计算得到的刻划硬度H0.1
Table 2 The fitted constant values of a, b, and the calculated scratch hardness H0.1 with h/t=0.1

图6 不同刻划深度下不同纳米结构碳膜的划痕硬度<br/>Fig.6 The nanoscratch hardness of different nanostructured carbon films with different scratch depths

图6 不同刻划深度下不同纳米结构碳膜的划痕硬度
Fig.6 The nanoscratch hardness of different nanostructured carbon films with different scratch depths

图7 GLCL-C中纳晶结构的高分辨TEM照片<br/>Fig.7 High resolution TEM picture of nanocrystal structure

图7 GLCL-C中纳晶结构的高分辨TEM照片
Fig.7 High resolution TEM picture of nanocrystal structure

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备注

引言

1 实验

2 实验结果及分析

3 结论

附加材料_增强文件请点击下载

期刊信息

备注

引言

1 实 验

2 实验结果及分析

3 结 论

附加材料_增强文件请点击下载

期刊信息

1 实验

3 结论