纳米压痕技术理论基础

针对纳米压痕技术的应用现状和存在的问题,分析了现有理论研究方法以及它们的不足之处。在纳米压痕试验的基础上,提出了微硬度的新定义并根据量纲分析方法给出了微硬度的表达式。结果表明纳米尺度上的微硬度可以表达为一个与压入深度无关的常量和一个随压入深度减小而增大的分量,这为深入研究纳米压痕技术及纳米硬度的尺寸效应提供了简单易行的新方法。     

纳米压痕技术及其应用

介绍纳米压痕的一般要领及纳米压痕系统的组成，阐述纳米压痕技术在几个方面的具体应用。     

纳米压痕技术及其试验研究

介绍纳米压痕技术的基本原理和计算方法 ,从定义、适用范围和压痕面积的获得方法等三个方面指出纳米硬度与常规硬度之间的重要区别 ,对硬度的概念做了进一步讨论。通过试验得出了单晶铝材料的纳米硬度值 ,并与传统计算方法获得的硬度值进行了比较。     

纳米压痕测量精度的影响因素

通过比较45钢拉伸试验与纳米压痕试验得到的弹性模量,分析了影响纳米压痕测试精度的因素及其对测试结果的影响.结果表明:纳米压痕法得到的弹性模量大于拉伸试验法得到的弹性模量;压头形状与尺寸、试样表面粗糙度、定位零点等是影响测量精度的主要因素,尤其是压头尖端的不规则形状使得压头在压入材料的初始阶段与材料之间的相互作用变得复杂.     

纳米压痕法测试电刷镀镍镀层的硬度和弹性模量

介绍一种新型的多功能纳米材料性能测试仪,阐述仪器工作原理和压痕数据分析法。应用该仪器对钢基体上的电刷镀镍镀层的硬度、弹性模量以及抗压痕形变能力等微观力学性能进行测试,并研究镀层力学性能随镀层厚度的分布规律。结果显示,镀层表层和亚表层存在硬度和弹性模量较高的区域,镀层内部存在缺陷区域的硬度和弹性模量降低,在镀层与基体的界面处存在过渡区。除此以外,整个镀层的力学性能较为一致,没有明显的梯度分布,其平均硬度和弹性模量分别为7.02GPa和183GPa,其中硬度为钢基体的2.9倍。在试验载荷下镍镀层具有比钢更好的抗压痕形变能力。为改进镀层工艺、开发新型体系材料以及扩大镀层应用领域提供了有效数据。     

纳米硬度技术在表面工程力学性能检测中的应用

结合纳米硬度技术测量各类薄膜和块体材料表层的纳米压痕硬度、弹性模量、断裂韧性、膜厚、微结构的弯曲变形，采用纳米划痕硬度技术测量各类薄膜和块体材料的粗糙度、临界附着力、磨擦系数、划痕横剖面。纳米硬度计是检测材料表层微米乃至几十纳米力学性能的先进仪器，可广泛应用于表面工程中的质量检测。     

磷酸二氢钾单晶体纳米压痕的力学行为

磷酸二氢钾(KH2PO4, KDP)单晶体的纳米力学特性是研究其超精密加工重要依据之一.试验针对(001)晶面和三倍频晶面采用带有针尖半径为50 nm的Berkovich压头的纳米压痕仪对KDP晶体进行力学特性分析,结果表明,两个晶面的纳米硬度H和弹性模量E都表现出强烈的载荷依赖效应.应用Meyer定律和修正比例样件阻尼(Modified proportional specimen resistance, MPSR)模型揭示和说明KDP晶体纳米压痕尺寸效应现象是一种载荷和压痕深度非线性比例阻尼的结果;对加工样件的Raman光谱分析结果表明,加工表面残余应力是影响压痕尺寸效应的非线性程度的重要因素.对材料加载位移曲线的进一步观测发现存在加载突进现象,该现象和材料的弹塑性转变密切相关.     

Nano Indenter Ⅱ纳米显微力学探针

Nano Indenter Ⅱ纳米显微力学探针是我室1994年从美国 Nano Instru-ments公司引起的,目前是国内唯一一台。它是一种新型的材料微区力学性能检测系统,它使我们能够得到距材料表面几纳米至几十微米厚或亚微米范围的力学性能。从而使我们对材料微区力学性能的研究成为可能。     

分子沉积膜的纳米压痕试验

制备了金衬底表面上的分子沉积膜，用原子力显微镜观测了其表面形貌；用纳米压痕仪研究其纳米力学特性。结果表明，沉积一层膜后衬底表面的弹性模量、硬度都减小，而且弹性变形增加，塑性变形减小，从而证明膜改善了金衬底的力学特性。     

TiCx/NiAl复合材料界面纳米硬度与弹性模量分布

对C、Ti比x分别为0.6，0.75，0.8和0.9的四种不同TICx/NiAl复合材料进行扫描电镜研究，发现陶瓷颗粒随着C、Ti比的增加而变小，并且Ti元素向金属相存在较强的扩散，而Ni和Al元素几乎没有向陶瓷相中扩散，扩散形成了两相界面处直接的原子结合，提高了复合材料相界面结合的强度和韧性。利用纳米压痕技术得出材料相界面附近的纳米硬度H和弹性模量E呈连续梯度分布，C、Ti比为0.75的复合材料相界面处的纳米硬度和弹性模量值较大。     

Nanoindentation of silica nanoparticles attached to a silicon substrate

The nanomechanical properties of individual silica nanoparticles attached to a single crystal silicon (100) substrate were investigated using nanoindentation technique. The sample used in this study was fabricated by spin coating colloidal silica nanoparticle solution on the silicon substrate and then annealing the sample in a nitrogen environment. Environmental scanning electron microscopy (ESEM), scanning probe microscopy (SPM), and nanoindentation techniques were used to characterize the morphology and mechanical properties of the silica nanoparticles. The elastic modulus and hardness of the silica nanoparticles were found to be 68.9 ± 9.6 GPa and 2.8 ± 0.4 GPa, respectively. Several interesting phenomena were observed at the nanometer scale, including strain hardening, reverse plastic deformation, both ductile and brittle behaviors of the silica nanoparticles, and the increasing deformation resistance of the silica nanoparticles when subjected to repeated indentations.     

Evaluation of Local Mechanical Properties in Depth in MoDTC/ZDDP and ZDDP Tribochemical Reacted Films Using Nanoindentation

Local mechanical properties in depth and near the surface of MoDTC/ZDDP and ZDDP tribofilms, which exhibited obviously different friction coefficients in a pin-on-disc test, were determined by using a nanoindentation technique combined with in-situ atomic force microscopy (AFM) observation. Tapping-mode AFM observation revealed that the MoDTC/ZDDP film was much rougher than the ZDDP film. Nanoindentation measurement revealed that the MoDTC/ZDDP and ZDDP tribofilms possessed different elasto-plasticities around a depth of several nanometers from the surface, although both films showed the same hardness and modulus depth distributions except in the surface area. The same mechanical depth distributions indicated that both kinds of tribofilm were functionally graded materials; that is, they consisted of a layer near the surface with lower hardness and modulus and providing lubrication and a base layer with higher hardness and modulus and serving to modify property differences at the interface. Most importantly, the different elasto-plasticities near the tribofilm surfaces revealed that the MoDTC/ZDDP tribofilm possessed lower shearing yield stress than the ZDDP tribofilm. The results of this study suggest that the presence of some solid lubricants such as MoS₂ just below the MoDTC/ZDDP film surface reduced the boundary friction coefficient.     

Chemomechanical Properties of Antiwear Films Using X-ray Absorption Microscopy and Nanoindentation Techniques

The first chemomechanical comparison between an antiwear film formed from a solution containing zinc dialkyl-dithiophophates (ZDDPs) to a solution containing ZDDP plus a detergent (ZDDPdet) has been performed. X-ray absorption near-edge structure (XANES) analysis has shown a difference in the type of polyphosphate between each film. The ZDDPdet film has been found to contain short-chain polyphosphates throughout. X-ray photoelectron emission microscopy (X-PEEM) has provided detailed spatially resolved microchemistry of the films. The large pads in the ZDDP antiwear film have long-chain polyphosphates at the surface and shorter-chain polyphosphates are found in the lower lying regions. The spatially resolved chemistry of the ZDDPdet film was found to be short-chain calcium phosphate throughout. Fiducial marks allowed for the re-location of the same areas with an imaging nanoindenter. This allowed the nanoscale mechanical properties, of selected antiwear pads, to be measured on the same length scale. The indentation modulus of the ZDDP antiwear pads were found to be heterogeneous, ~120 GPa at the center and ~90 GPa at the edges. The ZDDPdet antiwear pads were found to be more uniform and have a similar indentation modulus of ~90 GPa. A theory explaining this measured difference, which is based on the probing depths of all techniques used, sheds new insight into the structure and mechanical response of ZDDP antiwear films.     

有机相对人牙釉质力学性能影响的有限元分析

人牙釉质是最硬的人体组织,对咀嚼磨耗有较大的抵抗力,其由羟基磷灰石晶体和有机物相间排列而成,显微组织结构与纤维增强材料类似。采用有限元方法分别建立原始牙釉质和去除有机相牙釉质2种模型,研究牙釉质中的有机相对其力学性能的影响。研究结果表明,牙釉质具有各向异性的力学性能,随着偏离羟基磷灰石晶体C轴方向的角度增加,釉质的压缩弹性模量和压缩屈服应力降低,在45°方向达到最小值;牙釉质中的有机相会显著影响其力学性能,当有机相被去除后,牙釉质的压缩弹性模量、剪切弹性模量和剪切屈服应力均降低,压缩屈服应力无显著变化。研究结果有助于揭示牙釉质化学组成和微观结构对其力学性能的影响,为牙科修复材料的仿生设计提供理论依据。     

纳米硬度计及其在微机电系统中的应用

微机电系统（MEMS）技术的迅速崛起，推动了对其所用材料和结构的力学性能研究。本文简要介绍纳米硬度技术的发展、理论模型和MTS公司的NanoInkdenterXP系统的配置、测量原理及功能。并根据我们的一些研究结果，说明它在微机电系统中的应用。     

多晶硅微悬臂梁断裂失效强度的尺寸效应

为了了解构件尺寸的微型化给材料的强度和弹性模量带来的影响,利用纳米硬度计通过微悬臂梁的弯曲实验来测量其力学特性.该方法可精确测量微悬臂梁纳米级弯曲形变,但必须考虑压头在微悬臂梁上的压入及微悬臂沿宽度方向的挠曲.试验研究表明,多晶硅微悬臂梁的平均弹性模量为156GPa±(4.52～9.83)GPa,其失效断裂强度表现出对构件有效体积和表面积的尺寸效应.由实验测得的失效强度得到KC=1.62MPa*m1/2,计算出的缺陷尺寸a为58～117nm.     

洁净度和显微组织对管线钢性能的影响

研究了洁净度和组织均匀性对四种管线钢板坯性能的影响。发现洁净度对钢材冲击韧度的影响要高于对强度的影响，提高洁净度可以大幅度提高钢材的冲击韧度。通过测量四种材料晶粒内部和晶界附近的纳米显微硬度，总体来看，晶界附近的硬度通常比晶粒内部高；而这种差别越小，所对应材料的冲击性能越好。