【作者】 刘琦；

【导师】 姚英学；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 随着微小零部件与薄膜材料的广泛应用,对于材料微纳米表层力学性能的检测必须给予重视。在材料力学性能的检测中,硬度是评价材料力学性能的一种简单、高效的手段。然而材料微纳米表层硬度的测量结果出现了硬度值随着压痕深度或载荷减小而增大的压痕尺寸效应,并且不同的硬度评价方法计算得到的硬度值差别较大,导致无法得到材料微纳米表层的真实硬度值。因此对于微纳米表层硬度检测技术及其理论方法的研究具有重要的现实意义和使用价值。本文提出一种基于压痕功的微纳米表层硬度检测方法,并开发了样机。基于压痕功的材料微纳米表层硬度检测系统可以得到材料的载荷-压深曲线和压痕三维形貌,为获得材料微纳米尺度下的真实硬度和理解压痕尺寸效应的产生根源提供理论基础和实验手段。运用有限元分析软件对纯铝试样进行了微纳米硬度的有限元仿真研究,建立了有限元仿真模型,通过仿真结果得到材料的载荷-压深曲线和压痕三维形貌,采用多种硬度计算方法评价和分析试样硬度,提出了基于压痕功的硬度检测方法,认为采用通过分段拟合并积分载荷-压深曲线得到的塑性功除以压痕塑性变形总体积得到的材料硬度值更能反映材料的真实硬度,更有利于建立起微纳米尺度下硬度与宏观硬度之间联系。针对基于压痕功的微纳米表层硬度检测方法的要求,设计了集载荷力加载与压头位移测量功能于一体的测头,采用电磁力方式进行载荷驱动,通过优化驱动器结构,满足了无摩擦、小尺寸、高分辨率和大载荷的设计要求。位移测量采用电容式位移传感器,适用于小量程高分辨率的测量要求。载荷力驱动及位移测量控制器的研制过程中采用合理的设计方案并充分考虑外界干扰的影响,取得了令人满意的实验效果。设计了一种将压痕制备和形貌扫描功能相结合的微纳米表层硬度检测系统,并进行了样机的研制。此检测系统能同时获得材料的载荷-压深曲线和压痕三维形貌,可灵活应用多种硬度计算方法获得材料微观硬度值。在基于压痕功的硬度检测系统基础上,通过实验得到单晶铝和单晶硅在不同压痕深度下的载荷-压深曲线和压痕三维形貌,结合数学计算软件对数据进行处理,应用多种硬度计算方法进行硬度值的计算和分析,验证了基于压痕功的硬度计算方法相对于其他方法具有随压痕深度的减小变化平缓,更能反映材料真实硬度的优点。基于压痕功的微纳米表层硬度检测系统的研制为分析和研究压痕尺寸效应的成因奠定了基础,根据单晶铝和单晶硅实验数据,通过分析多种理论模型,提出了一种基于能量平衡方法的理论模型——HAV模型,用来解释压痕尺寸效应的成因。基于压痕功的硬度检测方法,减小了压痕尺寸效应的影响,可以得到材料微纳米尺度下的真实硬度值,为检测材料微观力学性能提供技术支持,为微小构件的可靠使用提供了保障。更多还原

【Abstract】 Along with the widespread availability of micro-components and thin-film material, the measurement and evaluation of micro-components’surfacial mechanical property must be paid attention to. Hardness is a simple and efficient means in material’s mechanical property measurement. However, hardness measuring results of material’s micro-nano surface shows indentation size effect, what means hardness value gets larger as the indentation depth or load gets smaller. And different hardness evaluating methods get discrete calculating results with each other, so the real hardness value of material’s micro-nano suface is impossible to be got. Then, research on micro-nano hardness measurement technique and theory makes sense and has use value.In this paper, a kind of micro-nano hardness measuring approach based on indentation work is proposed, and the prototype instrument is developed. Material micro-nano hardness measurement system based on indentation work can gain the load-depth curve and indentation 3D image, which can provide theoretic foundation and experimental means for getting material’s micro-nano real hardness and understanding the sources of indentation size effect.The finite element simulation of aluminum sample is carried on by using finite simulation software, and the finite element simulation model is established. By using the simulation results of load-depth curve and indentation 3D image, different evaluating methods are used to obtain and analyze the sample’s hardness value. A kind of hardness measuring approach based on indentation work is brought forward, and it is considered that the hardness value which is equal to the whole volume of plastic deformation divided by the plastic work gained from stepped fit and integration of load-depth curve, can reflect the real hardness of material and help to establish the relationship between microcosmic hardness and macroscopical hardness.In response to the demands of micro-nano hardness measuring approach based on indentation work, the probe device which has load drive and displacement measurement functions is designed. This device has an electro-magnetic force drive, which can meet the no mechanical friction, small size, high resolution and large force demands by optimizing the structure parameters. Capacitance sensor, which can meet the demands of small range and high resolution, is chosen to measure the displacement of the indenter. The force drive and displacement measurement controller is designed technically, and the environment disturbs are considered adequately, so that satisfactory experimental results are obtained. Then a kind of micro-nano superficial hardness measurement system composed of indentation preparation and image scan functions is proposed, and the prototype instrument is developed. This measurement system can obtain load-depth curve and indentation 3D image, which provide more information for getting material’s micro-hardness value by using some different hardness calculating methods flexibly.On the basis of this micro-nano hardness measurement system, the load-depth curves and indentation 3D image with different depth of single crystal aluminum and single crystal silicon are obtained, then after processing these data by math operation software, some different hardness evaluating methods are used to obtain and analyze the hardness value. It is validated that the hardness value got from the calculating method on the basis of indentation work changes evenly with the minishing of indentation size, and can reflect the real hardness of material better than other measuring methods. The development of micro-nano hardness measurement system based on indentation work provides foundation for analyzing and studying the sources of indentation size effect. According to the experimental results, some theoretic models are analyzed, and a new HAV model is proposed based on energy balance approach, which can explain the indentation size effect well.Hardness measurement based on indentation work minishes influence of indentation size effect and can achieve the real hardness value of material in micro-nano size, which provides technical support for measuring material’s micro-mechanical property and assurance for reliably using of micro-components.更多还原