纳米压痕测试技术在复合材料中的应用研究

纳米压痕技术广泛应用于微纳米尺度材料原位力学性能的测试,介绍了近些年来纳米压痕技术在复合材料各组分、界面性能、残余应力等表征方面的应用,在此基础上提出了纳米压痕技术在复合材料应用中存在的问题,并结合今后研究方向展望了其发展趋势和应用前景。     

纳米压痕技术在材料力学测试中的应用

近年来,材料纳米级力学测试日益引起广大研究者的重视。纳米压痕仪凭借极高的载荷和位移分辨率,广泛应用于材料表面的微纳米级力学性能的测试,包括硬度、弹性模量、塑性应变、薄膜界面结合强度以及材料疲劳特性等。综述了几种纳米压痕和纳米冲击技术测试材料力学性能的方法和原理,介绍了纳米压痕技术在材料力学性能测试方面的若干先进应用实例及其测试机理,以及原子力显微镜和扫描探针显微镜在力学测试方面的原理和应用。最后,提出了纳米压痕仪存在的若干问题,并对纳米压痕技术的发展进行了展望,认为纳米压痕技术结合有限元模拟建立材料疲劳断裂模型,是纳米压痕在力学测试方面发展的必然趋势。     

纳米压痕表征技术的应用与发展

纳米压痕技术作为一种新的无损检测、简单方便的材料微纳米尺度力学性能表征方法,被广泛应用于科学研究与现役构件寿命评估等领域。综述了纳米压痕法在性能表征中的各项应用,介绍了目前研究的重点。对纳米压痕技术的研究方向进行了展望。     

基于分子动力学模拟的纳米压痕技术研究进展

纳米压痕技术是一门在微观尺度上测量材料力学性能的新兴技术,分子动力学模拟则可对抛光、超声振动、激光加工等工艺过程进行仿真,在研究加工过程中材料受微观粒子挤压、划擦及冲击等而变化的力学性能机理方面具有显著优势,故总结了分子动力学模拟和纳米压痕技术的基本原理,对采用分子动力学模拟研究纳米压痕技术的现状进行了综述。两种先进技术的有机结合,将极大地促进材料在微观尺度下的研究进程。     

基于纳米压痕测试的超细晶Si_2N_2O-Si_3N_4陶瓷常温弹塑性仿真

对分别在1 600℃、1 650℃、1 700℃条件下热压烧结制备的Si2N2O-Si3N4超细晶陶瓷进行纳米压痕试验测试,获得了材料的硬度值、弹性模量值和载荷-深度曲线。考虑试验中波士压针的磨损缺陷,通过理论和数值模拟相结合的方法,确定压针的尖端球面半径RBerk=500nm。以纳米压痕试验数据为依据,利用MSC.Marc有限元仿真软件模拟纳米压痕试验压针压入材料表面的过程,反推出所测试材料的应力应变关系曲线,其屈服应力随弹性模量的减小而降低,分别为47GPa、43GPa、35GPa。通过比较分析压痕区域的应变场和应力场,分析纳米压痕试验中材料的变形特征。     

微纳米覆盖层材料的力学性能表征探讨

使用Agilent公司G200微/纳米压痕仪对多种微纳米覆盖层材料的力学性能进行了测量。结果表明,通过连续刚度法测量微纳米涂层材料,可以获得涂层硬度和弹性模量,并能得到涂层硬度或弹性模量随厚度的变化规律;通过试验也可以看到,纳米压痕法测量膜材的力学性能存在明显的表面效应;基材对膜材的力学性能没有影响;膜材厚度越大,同一深度测得的膜材的弹性模量越高。     

Cu-30Ni合金机械冲击表面纳米化组织和性能(英文)

采用大应力塑性变形(机械冲击)技术对Cu-30Ni合金表面进行纳米化处理。利用原子力显微镜技术、纳米压痕试样、显微硬度测量、电化学分析和电子功函数等手段分别测试原始样品、大应力塑性变形纳米化处理样品的晶粒尺寸、力学性能、腐蚀性能。结果表明,与原始样品相比,大应力塑性变形纳米化处理样品的表面晶粒尺寸达到40nm;力学性能显著改善。电化学测试表明,表面纳米化提高了合金的耐腐蚀性能,耐腐蚀性能变化与电子功函数变化一致。机械冲击工艺技术能够使Cu-30Ni合金表面纳米化,从而提高了表面力学性能和耐腐蚀性能。     

PECVD制备六方金刚石结构碳氢薄膜

利用等离子体增强化学气相沉积技术(PECVD)在单晶硅(100)表面上制备了一层含有六方金刚石结构的碳氢薄膜。采用透射电子显微镜和拉曼光谱仪对薄膜结构进行表征;并用Nano-indenterⅡ型纳米压痕仪和CSM—摩擦磨损试验机对薄膜的力学性能和摩擦学性能进行了测试。结果表明:该碳氢薄膜含有六方金刚石结构,另外还含有少量的纳米弯曲石墨片段;与制备的类金刚石碳氢薄膜相比,该薄膜具有较好的力学性能,同时该薄膜在空气环境下表现出了较好的摩擦学性能。     

碳化钨模仁表面沉积Re-Ir抗高温黏连涂层研究

采用射频磁控溅射技术,在WC模仁基材表面分别生长Re、Ir单层膜及Re/Ir复合多层膜3种膜系。通过扫描电子显微镜、表面轮廓仪、X射线衍射仪以及纳米压痕仪等对所制备涂层的表面形貌、结构以及涂层力学性能进行表征,同时采用高温润湿角测量仪结合常用的镜头玻璃硝材D-ZK3与模仁进行高温浸润测试。结果表明,涂覆3种膜系后模仁力学性能及抗玻璃高温黏连性能都得到了明显改善,且Re/Ir多层膜系综合性能优于Re和Ir单层膜系,在延续基材表面精度的同时,较大幅度地提高了模仁表面硬度及弹性模量,高温状态下与玻璃硝材浸润性明显减弱,接触界面未观察到元素互扩散现象,显示良好的应用前景。     

碳化钨模仁表面沉积Re-Ir抗高温黏连性涂层研究

超精密（纳米精度）模仁是模造技术制备玻璃镜片的核心部件,而模仁表面的保护涂层则决定着模仁的使用寿命及玻璃制件的成型质量与成本。本研究采用射频磁控溅射技术,在WC模仁基材表面分别镀制Re、Ir单层膜及Re/Ir复合多层膜三种膜系。通过扫描电子显微镜、表面轮廓仪、X射线衍射仪以及纳米压痕仪等对所制备涂层的表面形貌、结构以及涂层力学性能进行表征,同时采用高温润湿角测量仪结合常用的镜头玻璃硝材D-ZK3与模仁进行高温浸润测试。结果表明,涂覆三种膜系后模仁力学性能及抗玻璃高温黏连性能都得到了明显改善,且Re/Ir多层膜系综合性能优于Re和Ir单层膜系,在延续基材表面精度的同时,较大幅度地提高了模仁表面硬度及弹性模量,高温状态下与玻璃硝材浸润性明显减弱,接触界面未观察到元素互扩散现象,显示良好的应用前景。     

Cutting performance of coated tools with various adhesion strength quantified by inclined impact tests

Coated tools with PVD-films of almost the same mechanical properties may perform differently. This effect can be attributed to the film adhesion. For highlighting this phenomenon, the adhesion of coatings with practically identical mechanical properties deposited on cemented carbide and powder metallurgical high speed steel inserts was quantified by FEM-based evaluations of inclined impact test and nano-indentation results. Moreover, the films’ mechanical properties were assessed by repetitive nano-impacts. Based on these data and on FEM calculations of the cutting process, the coated tools cutting performance was explained in all investigated material and interrupted cutting process cases.     

Experimental and finite element analysis for fracture of coating layer of galvannealed steel sheet

Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed to understand better the fracture of coating layer of GA steel sheet during plastic deformation. Yield strength of the coating layer was calculated by using a relative difference between hardness of coating layer measured from the nano-indentation test and that of substrate. To measure shearing strength at the interface between substrate and coating layer, shearing test with two specimens attached by an adhesive was carried out. Using the mechanical properties measured, a series of finite element analyses coupled with a failure model was performed. Results reveal that the fracture of coating layer occurs in an irregular manner at the region where compressive deformation is dominant. Meanwhile, a series of vertical cracks perpendicular to material surface are observed at the tensile stressed-region. It is found that 0.26-0.28 of local equivalent plastic strain exists at the coating and substrate at the beginning of failure. The fracture of coating layer depends on ductility of the coating layer considerably as well.     

Effect of microstructure inhomogeneity on mechanical properties of different zones in TA15 electron beam welded joints

The effects of microstructure inhomogeneity on the mechanical properties of different zones in TA15 electron beam welded joints were investigated using a micromechanics-based finite element method. Considering the indentation size effect, the mechanical properties for constituent phases of the base metal (BM) and heat affected zone (HAZ) were determined by the instrumented nano-indentation test. The macroscopic mechanical properties of BM and HAZ obtained from the tensile test agree well with the numerical results. The incompatible deformation between the constituent phases tends to localize along the softer primary phase α where failure usually initiates in form of localized plastic strain. Compared with the BM, the mechanical properties of constituent phases in the HAZ differ substantially, leading to more serious strain localization behavior.     

单晶金刚石微观性能的纳米压入测量研究

研究单晶金刚石的微观机械性能,可为金刚石工具的研磨和使用性能评价提供技术依据。提出以纳米压入技术研究单晶金刚石微观尺度机械性能,分析了纳米压入技术的主要原理及其技术特点,进行了纳米压入测量实验并分析了各种因素的影响。研究表明:采用10mN的ADO载荷和小于10mN的最大压入载荷对单晶金刚石{100}晶面进行纳米压入测量,可显著减小甚至避免金刚石压头的变形和损伤,获得有效的压入曲线及数据;但在多次测量后会出现金刚石压头的累积钝化。基于测量过程和结果的分析,提出了提高测量有效性的方法。     

钽掺杂对多层Ta-DLC薄膜摩擦及腐蚀行为的影响

目的 解决316L不锈钢在苛刻海洋环境中易磨损、易腐蚀的问题。方法 采用中频磁控溅射技术在316L不锈钢上沉积了Ta/TaN/TaCN/Ta-DLC薄膜。通过扫描电子显微镜、拉曼光谱、X射线光电子能谱、X射线衍射、纳米压痕、往复摩擦磨损试验和电化学测试等手段,重点研究了DLC膜层中Ta元素掺杂含量对薄膜结构、组成成分、力学性能、摩擦学性能和耐腐蚀性能的影响规律。结果 随着Ta元素含量(原子数分数)从2.04%增到4.16%,薄膜中的sp³键含量呈现先升高后降低的趋势,当Ta原子数分数为3.60%时,薄膜中sp³键含量最高,且薄膜的硬度及弹性模量达到最大,分别为7.01 GPa和157.87 GPa。随着Ta元素含量的增加,薄膜的平均摩擦因数逐渐减小,在4.16%(原子数分数)时达到最小0.21。Ta元素含量对薄膜的结合力影响较小,且所有薄膜结合力总体在10 N左右。当Ta原子数分数为3.60%时,薄膜的腐蚀电流密度及钝化电流密度最小,分别为0.006 μA/cm²和0.63 μA/cm²,比其他薄膜的低1~2个数量级,并且薄膜电阻及电荷转移电阻最大,展现出最为优异的耐腐蚀性能。结论 Ta元素的掺杂提高了薄膜的耐摩擦性能,且适当的Ta元素掺杂能够提高Ta/TaN/TaCN/Ta-DLC薄膜的耐磨耐蚀性能。     

Mechanical properties of CO2 corrosion product scales and their relationship to corrosion rates

In order to evaluate the protective ability of CO₂ corrosion scale to steel under flow conditions at various CO₂ partial pressures, the mechanical properties of the scale, i.e., Young′s modulus, fracture toughness, interfacial fracture toughness and adhesion strength between the scale and steel were determined by nano-indentation, Vickers’ indentation and tensile test. The influences of flow rate and CO₂ partial pressure on these mechanical properties as well as the correlations between the properties and corrosion rates were investigated. The interfacial fracture toughness between the scale and steel can evaluate the protective ability of the scale to steel effectively.     

仿生织构图案的设计、加工及应用的研究进展

表面织构在提升零件的耐磨性、界面接触的减摩性、材料表面的减阻性以及增强或降低材料的吸附性等方面展现出良好的效果.根据表面功能的不同,分别从耐磨表面、减阻表面、疏水表面、粘(脱)附性表面进行研究,综述了各种仿生织构的设计、加工及应用现状.研究发现,耐磨仿生织构图案尺寸相对较大,多在20μm以上,稳定的结构可以承受较大的外力;减阻疏水表面具有细微的突起状结构,能有效地通过微结构改变表面力学性能;粘附性表面得益于生物体微结构的形状尺寸,毛状微结构拥有良好的吸附性.加工方式上,激光刻蚀能精确控制加工尺寸和几何形状,化学刻蚀能得到更细微的表面形貌.仿生织构在机械密封、活塞环、刀具、滑动轴承及齿轮等应用上起到了良好的效果,但是截至目前,表面仿生织构研究较杂,并且未形成体系,相关设计和作用机理并不完善.通过分析仿生织构图案的功能性设计、多尺度复合加工和对零件服役性能的影响,为仿生织构图案的设计提供思路和更加科学的设计方法,并找到适合每种功能表面的加工技术.将仿生学应用于织构技术上,从生物体借鉴优良的功能特性,以期在工程上得到更广泛的应用.     

Tribological properties and lubricating mechanisms of Cu nanoparticles in lubricant

Wear and friction properties of surface modified Cu nanoparticles as 50CC oil additive were studied. The effect of temperature on tribological properties of Cu nanoparticles was investigated on a four-ball tester. The morphologies, typical element distribution and chemical states of the worn surfaces were characterized by SEM, EDS and XPS, respectively. In order to further investigate the tribological mechanism of Cu nanoparticles, a nano-indentation tester was utilized to measure the micro mechanical properties of the worn surface. The results indicate that the higher the oil temperature applied, the better the tribological properties of Cu nanoparticles are. It can be inferred that a thin copper protective film with lower elastic modulus and hardness is formed on the worn surface, which results in the good tribological performances ofCu nanoparticles, especially when the oil temperature is higher.     

聚醚醚酮骨植入体生物改性研究进展

聚醚醚酮是一种热塑性材料,凭其良好的生物相容性和X射线可透射性,被广泛用于生物医学领域。而PEEK骨植入体与人体骨骼强度存在一定差距,与人体骨组织结合能力较差和抗菌性能等不足,使其在生物领域的应用受到了限制。为了使PEEK更好地应用于人体骨植入领域,获得优异生物性能的PEEK骨植入体已成为研究的重点。概述了PEEK的加工技术、力学性能、骨整合性能和抗菌性能的研究。在此基础上,重点综述了近年来提高PEEK骨植入体力学性能与生物性能的各种改性方法的研究进展。在力学性能方面,对PEEK常用的填充材料碳纤维进行了概述,由于PEEK与碳纤维界面结合强度影响其整体力学性能,重点介绍了提高其结合强度的改性方法。在骨整合性能方面,对钛、二氧化钛和羟基磷灰石涂层材料及喷涂方法进行了概述,以及对等离子喷涂、喷砂、激光蚀刻和浓硫酸刻蚀表面处理方法的优缺点进行了分析。在抗菌性能方面,银离子释放浓度过高时会导致细胞毒性,重点阐述了如何控制银离子释放速度的研究。最后展望了PEEK骨植入体加工和改性的未来发展方向。