纳米压痕仪校准模型的研究及在蓝宝石标物定值中的应用

发布时间：2018-06-29 18:28

本文选题：载荷因子 + 面积函数　；参考：《安徽工业大学》2017年硕士论文

【摘要】：纳米压痕仪由于其较高的力和位移分辨率,较高的定位精度等优点,在薄膜新材料和MEMS微器件等领域得到了越来越广泛的应用,由于在使用过程中,压痕仪的针尖会发生磨损,没有经过校准的纳米压痕仪会对于测试的结果产生显著的影响,在较小的压入深度下这种影响更加明。本文对于纳米压痕仪的校准模型进行研究,建立新的校准模型应用到纳米压痕仪的校准中对仪器的载荷因子、机架柔度以及针尖面积函数进行校准,在校准完成的基础上对于蓝宝石标样进行定值。定值完成后的蓝宝石标样块可作为纳米压痕仪的标准样品,实现不纳米压痕仪测量结果的准确可靠和等效可比。首先对于纳米压痕仪的载荷因子建立了校准模型,通过在0.5 mN-10 m N之间等比率选取20个力值进行纳米压痕测试,利用电磁力天平的称重模块与纳米压痕仪针尖实现加载卸载过程,在天平上测出实际的加载力值。每一次的加载过程纳米压痕仪都会给出一个加载的力值,对于两个力值进行线性拟合,拟合出来的直线的斜率即为校准完成的载荷因子。通过载荷因子校准模型校准完成后进行压痕测试发现,载荷因子校准后的纳米压痕仪测量得到的标准熔融石英样的硬度与弹性模量值比校准前更加的准确。在载荷因子校准完成的基础上,使用AFM直接法与迭代法两种不同的校准模型共四种校准方法对于纳米压痕仪机架柔度与针尖面积函数进行校准。校准完成后对于四种校准方法得到的机架柔度与面积函数结果应用到压痕仪器中进行压痕实验可以得到:在纳米压痕仪针尖浅压入深度下单晶钨与熔融石英迭代法校准获得的机架柔度与面积函数较其他三种准校准方法准确;当压入深度逐渐变大,四种校准方法所得到的面积函数与机架柔度都趋近于准确值。在横向的比较中单晶钨对于机架柔度的校准比熔融石英要好;对于面积函数的校准中AFM直接法在浅压入深度下对于仪器的校准要比间接法校准准确的多;当压入深度在60 nm以下时,针尖曲率半径对于测试结果的准确性影响较大,在极浅的压入深度下,采用针尖曲率半径小的针尖会得到比较准确的测试数据。最后将校准得到的载荷因子以及择优选择最佳校准模型校准后得到机架柔度与面积函数应用到纳米压痕仪器中,利用TriboIndenter-900型纳米压痕仪对于定值实验过程中的均匀性带来的不确定度、稳定性带来的不确定度、压痕实验重复性带来的不确定度以及仪器自身带来的不确定度进行分析评定,算出定值实验带来的总的合成不确定度;确定扩展因子,计算定值需要的扩展不确定度;然后对于蓝宝石标样候选物的折合模量与硬度值进行定值。
[Abstract]:Because of its advantages of high force and displacement resolution, high positioning accuracy and so on, nano-indentation instrument has been more and more widely used in the field of new thin film materials and MEMS microdevices, because the tip of indentation instrument will wear out in the process of application. The uncalibrated nanoindentation will have a significant effect on the results of the test, especially at a lower depth of indentation. In this paper, the calibration model of nano indentation instrument is studied, and the new calibration model is established to calibrate the load factor, frame flexibility and tip area function in the calibration of nano indentation instrument. On the basis of calibration completion, the sapphire standard sample is determined. The standard sapphire sample can be used as the standard sample of nano indentation instrument, which can realize the accuracy, reliability and equivalent comparison of the measurement results of non nano indentation instrument. First of all, the calibration model of the load factor of the nano-indentation instrument is established, and the nano-indentation is tested by selecting 20 force values in the range of 0.5 mN-10 mn. The loading and unloading process is realized by using the weighing module of the electromagnetic force balance and the tip of the nano-indentation instrument, and the actual loading force is measured on the balance. For each loading process, a loading force is given by the nano-indentation instrument, and the two force values are fitted linearly. The slope of the fitted line is the load factor completed by calibration. After the calibration of the load factor calibration model, the indentation test shows that the hardness and elastic modulus of the standard fused quartz samples measured by the nano-indentation instrument after the load factor calibration are more accurate than those before calibration. On the basis of the load factor calibration, four calibration methods, AFM direct method and iterative method, are used to calibrate the flexibility and tip area function of nano-indentation machine frame. After calibration, the results of flexibility and area function of four calibration methods are applied to indentation test. The results are as follows: single crystal tungsten and fused quartz are iterated at shallow indentation depth of nano-indentation instrument. Compared with the other three quasi-calibration methods, the frame flexibility and area function obtained by the method are more accurate. When the indentation depth increases gradually, the area function and the frame flexibility obtained by the four calibration methods are close to the exact values. In transverse comparison, the calibration of frame flexibility by single crystal tungsten is better than that by fused quartz, and the calibration of the instrument by AFM direct method is much more accurate than that by indirect method at shallow indentation depth in the area function calibration. When the depth of penetration is below 60 nm, the accuracy of the test results is greatly affected by the radius of curvature of the tip. At the very shallow depth of penetration, more accurate test data can be obtained by using the tip with small radius of curvature of the needle. Finally, after calibrating the load factor and the optimal calibration model, the frame flexibility and area function are applied to the nano-indentation instrument. Using TriboIndenter-900 nano-indentation instrument, the uncertainty caused by uniformity, stability, repeatability of indentation experiment and the uncertainty brought by the instrument itself are analyzed and evaluated. The total synthetic uncertainty caused by the fixed value experiment is calculated; the expansion factor is determined and the extended uncertainty required for the fixed value is calculated; then the equivalent modulus and hardness of the sapphire standard sample candidate are determined.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH87;TQ164

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