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应用纳米压痕技术测试沥青炭的力学性能 总被引:2,自引:0,他引:2
以高温煤沥青为前驱体,采用液相浸渍技术制备了4D炭/炭复合材料。利用纳米压痕技术研究了后处理温度和炭基体位置对沥青炭力学性能的影响。研究结果表明,在同一工艺状态下,束内沥青炭的硬度和模量要远低于束间沥青炭的硬度和模量。经过900℃后处理的沥青炭的模量出现小幅降低,而硬度则出现一定的增加。 相似文献
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基于纳米压痕技术对碳纤维/环氧树脂复合材料各组分的原位硬度、 弹性模量和蠕变性能进行了测试, 实验得到了基体、 纤维和微小厚度界面层的力学性能。结果表明, 从环氧树脂基体到碳纤维过渡过程中, 硬度和弹性模量有明显的梯度变化, 并且纤维和树脂基体的原位弹性模量平均值与其非原位性能有一定的变化, 实验得到纤维的原位弹性模量有所下降, 环氧树脂的弹性模量有所增加。试件制备过程中的机械研磨对其表面产生的残余应力和复合后两种材料的相互影响是组分材料原位性能变化的主要原因。各组分的蠕变性能呈现出明显的差异。 相似文献
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为了探究ECC裂缝自愈合体系中不同物相的微观力学性能,应用纳米压痕技术对经历10个干湿循环环境后裂缝自愈合ECC体系中不同物相的荷载-位移、接触刚度-位移、弹性模量及硬度进行了研究。结果表明:当荷载相同时,压入深度大小顺序为:纤维ITZSHP基体粉煤灰砂子;接触刚度与压入深度近似呈线性关系;粉煤灰和砂子的弹性模量及硬度是体系中最高的,远远高于其他相,其次是基体,接下来是SHP、ITZ,最差的是纤维。 相似文献
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为了研究氧化石墨烯(GO)对聚合物基复合材料力学性能的影响,通过溶液混合法制备了GO/聚乙烯醇(PVA)复合材料。然后,采用XRD、TEM、FTIR、DSC和纳米压痕实验等研究了GO/PVA复合材料的结构、界面结合性能、力学性能、蠕变行为和吸水膨胀率。结果表明:GO可以均匀分散在PVA基体中,二者之间主要通过氢键作用结合,具有较高的界面结合力;与纯PVA相比,1wt% GO/PVA复合材料的硬度和有效弹性模量分别提高了28.9%和23.3%,压入蠕变深度下降了19.8%;GO/PVA复合材料具有较低的无限剪切模量与瞬时剪切模量比,表明GO提高了PVA的蠕变抗力;GO的添加同时增加了GO/PVA复合材料的阻水性并降低了膨胀系数。吸湿纳米压痕实验结果表明:纯PVA的力学性能会随吸湿时间延长而下降,而GO/PVA复合材料吸湿72h后的力学性能基本保持不变。所得结论为石墨烯增强聚合物基复合材料的研究提供了理论指导。 相似文献
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采用准静态和动态纳米压痕技术研究了羟基磷灰石/聚乳酸(HA/PLA)复合材料在微纳尺度的表面力学性能。在静态模式下研究了保载和卸载时间对模量和硬度测试结果的影响。结果发现,当保载时间小于45 s时,由于蠕变使保载和卸载时间对测试结果产生显著影响;保载时间短且卸载时间长时,在卸载段会形成"鼻子",为了避免"鼻子"选择保载时间为45 s。在动态模式下研究了材料的动态力学性能,结果表明,存储模量和硬度均随着压入深度的增加而减小。压痕和划痕实验结果均表明:HA显著提高了PLA的力学性能,与纯PLA相比,9wt% HA/PLA复合材料的模量增加了35.5%,硬度增加了44.7%,蠕变深度下降了9.5%,相同载荷下的最大划痕深度和残余深度均小于纯PLA,表现出良好的弹性恢复能力和抗变形能力。 相似文献
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纳米压痕法在确定纳米结构材料,特别是具有较大高宽比的一维纳米结构/对象的力学特性时,若纳米结构沿压入方向的等效刚度远小于针尖-样品的接触刚度,应用常规数据分析(Oliver-Pharr)模型会导致较大的测量偏差.对常规Oliver-Pharr解析模型进行了推广,以补偿一维纳米材料等效刚度对测量结果的影响,进而提出了适用于此类测量对象的通用纳米压痕分析模型,并应用于分析柱状微纳米结构的准静态压痕测量数据.实验中应用原子力显微镜(AFM)定量测量了湿法刻蚀获得的一维单晶硅柱状结构的几何参数(包括硅纳米柱的直径和长度).实验结果表明,应用常规模型分析对较大高宽比的硅纳米柱(直径386 nm,长500 nm)的压痕数据会导致大于50%的偏差.应用修正模型分析实验数据时,测量结果不受被测对象几何参数的影响,因而可以有效提高应用纳米压痕法对微纳米结构材料,特别是一维材料的测量精度. 相似文献
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一种钠钙硅酸盐玻璃的纳米压痕测试分析 总被引:1,自引:0,他引:1
采用纳米压痕测试技术对一种钠钙硅酸盐玻璃进行微观力学性能的测试分析.测得加载-卸载过程载荷与压入深度曲线,发现被测玻璃的最大压深、残余深度和弹性回复量随最大加载力的增加而增大,但其相对弹性回复率系数基本稳定,平均值为58.2%.通过电子显微镜观察了不同最大载荷下的压痕形貌,发现压痕区域出现了边界沉陷现象.当最大加载力为1 000 mN左右时,三棱锥工具头测试的压痕区域出现了较明显的微裂纹;采用四棱锥工具头时出现微裂纹的最大加载力要小于该值,且裂纹取向均与金刚石工具头的棱角取向一致.利用非线性有限元软件MSC.Marc对纳米压痕过程进行了仿真分析,得到载荷与压入深度的仿真曲线,该曲线与试验结果基本相符;分析了载荷作用下材料内部的应力分布.利用Oliver-Pharr模型得到不同压入深度下被测玻璃的接触刚度值,该值随压入深度的增加而增大. 相似文献
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The nanoindentation technique is used to quantify the interfaces between dissimilar materials. The interfaces can be generally referred as to the transition regions in polymers due to environmental aging, or the regions between fibers and polymer matrix in composites, or other similar situations. It is proposed to use a nanoindenter equipped with small spherical tip to cross-indent the interfaces of dissimilar materials. The nanoindentation tests were carried out through 3-dimensional finite element simulations with varying properties of the two dissimilar materials, including various combinations of modulus (E1/E2), yield strength (σy1/σy2), hardening index (n1/n2), and the interface sizes (R/T). The mechanical properties are calculated across the interfaces and a quantitative model for predicting the effective interfacial thickness is established. 相似文献
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This review is focused on an attractive class of polymer-derived high-temperature ceramics, namely, polymer-derived nonoxide materials. With a brief introduction of high-temperature nonoxides, the origin of using polycarbosilane (PCS) polymer melt spinning to synthesize silicon carbide (SiC) fibers is traced back. For SiC formation, the four stages for the conversion from polymer precursors to microcrystalline ceramics are examined first: crosslinking, polymer decomposition, ceramic formation, and crystallization. Also, the important parameters related to PCS pyrolysis are explained, and polymer-derived SiC microstructures and compositions are evaluated. Solid-solution carbides and transition metal carbides are further reviewed. For boride materials, the discussion is focused on transition metal borides and boride composites. Similar to PCS conversion to SiC, nitride materials mostly start with polycarbosilazane (PSZ) precursors and form into the final materials through pyrolysis. With different carbide and nitride precursors mixed and pyrolyzed together, high-temperature nonoxide composites are formed. Such molecular-level intermixing and versatile capability of forming different shapes enable many exciting properties. Among these are mechanical and thermal properties, along with electrical conductivity, electromagnetic shielding, and charge storage capability. An overview of applications of polymer-derived nonoxides is provided, followed by a summary and outlook. 相似文献
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激光技术在材料科学中的应用进展 总被引:1,自引:0,他引:1
对激光技术在材料表面改性中的应用、在纳米材料中的应用以及在材料加工制造中的应用等进行了综述,对激光技术在材料科学中应用的进展有一个较全面的阐述。 相似文献
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With attractive research and development of biomaterials,more and more opportunities have been brought to the treatments of human tissue repairs.The implant is usually no need to exist in the body accompanied with the recovery or regeneration of the tissue lesions,and the long-term effect of exotic substance to human body should be reduced as lower as possible.For this purpose,biodegradable materials,including polymers, magnesium alloys and ceramics,have attracted much attention for medical applications due to their biodegradable characters in body environment.This paper in turn introduces these three different types of widely studied biodegradable materials as well as their advantages as implants in applications for bone repairs.Relevant history and research progresses are summarized. 相似文献