It is very important to measure local deformations for an in-depth understanding of mechanical properties and fracture mechanism of structural and functional materials. In this paper, different types of model grid fab...It is very important to measure local deformations for an in-depth understanding of mechanical properties and fracture mechanism of structural and functional materials. In this paper, different types of model grid fabrication methods and many types of electron Moire methods using an electron beam drawing system, a scanning electron microscope or a focus ion beam are reported, together with their applications in the measurement of deformations occurring in various engineerings and materials science research.展开更多
膨润土作为缓冲或回填材料,具有吸水性极强、膨胀性较大、渗透性极低等特性。膨润土在饱和状态与非饱和状态之间转换时,因其湿胀干缩产生的裂缝会导致工程屏障受到破坏。因此,对具有高膨胀性的膨润土的持水特性及微观结构特征进行试验...膨润土作为缓冲或回填材料,具有吸水性极强、膨胀性较大、渗透性极低等特性。膨润土在饱和状态与非饱和状态之间转换时,因其湿胀干缩产生的裂缝会导致工程屏障受到破坏。因此,对具有高膨胀性的膨润土的持水特性及微观结构特征进行试验研究显得非常必要。分别运用滤纸法和饱和盐溶液蒸汽平衡法对膨润土进行了持水特性试验研究,得到了不同吸力范围内膨润土的土-水特征曲线;联合用蒸汽平衡法和扫描电子显微镜(SEM)对特定吸力点(367.54、149.51、71.12、38.00 MPa)的膨润土试样进行扫描电镜试验研究。膨润土的持水特性试验结果表明,滤纸法和饱和盐溶液蒸汽平衡法测得的土-水特征曲线均随吸力的增大而减小。根据滤纸法量测的试验数据,运用origin软件获得了Fredlund and Xing(1994)提出的模型参数,通过建立模型参数与干密度之间的关系,给出了膨润土的土-水特征曲线的预测公式。膨润土的微观定性分析表明:随着吸力的增大,膨润土集聚体逐渐增大,膨润土颗粒之间也越紧密;孔隙数量随着吸力的增大而减少、孔径也随吸力的增大而减小。展开更多
根据摩尔定律,半导体芯片单位面积上的晶体管数量每18个月翻一番,当前量产先工艺节点已经演进到3nm,特征尺寸不断缩小,图案越发复杂,芯片制造过程中出现缺陷的概率升高,对检测技术及其关联设备提出了极高的要求。光刻作为半导体制造中...根据摩尔定律,半导体芯片单位面积上的晶体管数量每18个月翻一番,当前量产先工艺节点已经演进到3nm,特征尺寸不断缩小,图案越发复杂,芯片制造过程中出现缺陷的概率升高,对检测技术及其关联设备提出了极高的要求。光刻作为半导体制造中的核心模块,其工艺质量直接决定了后续工艺准确度,由于图案尺寸小于光源波长,衍射效应显著,导致曝光图案的高频信息丢失,光刻扫描电子显微镜(scanning electron microscope,SEM)图像作为曝光图案的直接表示,基于SEM图像的测量在半导体制造中对于图案化工艺质量的评估和监控显得至关重要。SEM图像不仅能够提供图像的特征宽度和特征-特征间距尺寸测量,同时还提供了其它有关图案质量的丰富信息,然而通过视觉检测在SEM图案质量检测方面留下了相当大的模糊空间。为了缩小模糊范围并获得更多关于图案质量的统计定量信息,通常会提取SEM图像轮廓来进一步计量分析。基于轮廓信息,我们能够估计出曝光图案任何位置的尺度信息,例如侧壁角度,临界尺寸等,这些尺度信息可用于光刻热点检测和光刻OPC模型验证等。基于局部信息的经典轮廓提取算法在处理存在噪声的低对比度光刻SEM图像方面尚有不足,如传统的prewit、log、sobel等算子,利用模板匹配无法获得令人满意的轮廓结果;轮廓提取领域的canny算法因其适用性广和效果较好,被广泛应用,但其梯度图像及阈值先验设置往往具有较大主观性,且没有充分利用待处理场景信息,对于较为复杂场景效果仍有待提升。本文通过结合通过结合光刻SEM图像的灰度、拓扑和轮廓长度先验信息,对canny算法进行优化,利用先验信息获得合适的阈值,完成对伪边缘(轮廓)的有效过滤,最终得到了与光刻SEM图像高度吻合的轮廓结果。展开更多
Unsaturated loess in natural sites loses stability as the overburden load continuously increases.Traditional soil modifiers such as cement and fly ash affect the surrounding environment.A new type of material,i.e.,lig...Unsaturated loess in natural sites loses stability as the overburden load continuously increases.Traditional soil modifiers such as cement and fly ash affect the surrounding environment.A new type of material,i.e.,lignin,is environmentally friendly and able to increase the strength of loess.However,the engineering characteristics of the improved loess under unsaturated conditions are not yet clear.In this study,the soil-water characteristic curves(SWCCs)of lignin-improved loess samples were determined from 0 kPa to 700 kPa using a pressure plate instrument,and then,they were fitted using the van Genuchten(VG)model and the Fredlund and Xing(FX)model.In addition,the effects of the lignin content and sample preparation methods on the SWCCs were investigated to determine the optimal lignin content and a suitable sample preparation method for loess foundations.As the lignin content increases,the matric suction and residual water content of the improved loess increase.The suction stress increases with the increasing lignin contents of 1%–2%.At lignin contents of 3%–4%,the suction stress begins to decrease and the samples prepared using the slurry method has a lower suction stress than that prepared using the wet mixing method.The air entry value(AEV)increases with increasing lignin content.In addition,scanning electron microscopy(SEM)was used to investigate the microstructural variations.It was found that after the addition of lignin,the entrapment of the loess particles by the lignin fibers created some larger particles and smaller pore diameters,which in turn led to poor connectivity of the loess pores.These changes cause the matric suction of the modified loess to increase.展开更多
In this paper,a new method combining focused ion beam(FIB)and scanning electron microscope(SEM)Moirétechnique for the measurement of residual stress at micro scale is proposed.The FIB is employed to introduce str...In this paper,a new method combining focused ion beam(FIB)and scanning electron microscope(SEM)Moirétechnique for the measurement of residual stress at micro scale is proposed.The FIB is employed to introduce stress relief like the macro ring-core method and fabricate gratings with a frequency of 5000 lines/mm on the measured area of the sample surface.Three groups of gratings in different radial directions are manufactured in order to form a micro-scale strain rosette.After milling ring-core by FIB,the deformation incurred by relief of the stress will be recorded with the strain rosette.The displacement/strain field can be measured using SEM scanning Moiréwith random phase-shifting algorithm.In this study,the Nickel alloy GH4169 sample(which was processed by laser shock peening)is selected as a study object to determine its residual stress.The results showed that the components of the in-plane principal stresses were-359 MPa and-207 MPa,respectively,which show good agreement with the results obtained from the available literature.展开更多
叔丁醇冻结干燥法用于植物材料,获得了良好的效果。经常规固定的样品完成脱水以后浸泡在叔丁醇中,然后将含醇样品放入电冰箱中冷冻,待叔丁醇凝固后再转移到真空镀膜机的钟罩里,用机械泵抽真空,冻结的醇在低真空中升华后样品得到了干燥。...叔丁醇冻结干燥法用于植物材料,获得了良好的效果。经常规固定的样品完成脱水以后浸泡在叔丁醇中,然后将含醇样品放入电冰箱中冷冻,待叔丁醇凝固后再转移到真空镀膜机的钟罩里,用机械泵抽真空,冻结的醇在低真空中升华后样品得到了干燥。SEM 镜检表明,样品的表面和细胞断裂面及其深层(可见到内质网的双层膜、线粒体的嵴、高尔基体潴泡叠层、核糖体颗粒等细胞器)的三维图象均优于用临界点干燥法所得到的样品图象,叔丁醇冻结干燥法用于植物 SEM 样品制备,是一种操作简单,干燥质量可靠、值得推广的方法。展开更多
文摘It is very important to measure local deformations for an in-depth understanding of mechanical properties and fracture mechanism of structural and functional materials. In this paper, different types of model grid fabrication methods and many types of electron Moire methods using an electron beam drawing system, a scanning electron microscope or a focus ion beam are reported, together with their applications in the measurement of deformations occurring in various engineerings and materials science research.
文摘膨润土作为缓冲或回填材料,具有吸水性极强、膨胀性较大、渗透性极低等特性。膨润土在饱和状态与非饱和状态之间转换时,因其湿胀干缩产生的裂缝会导致工程屏障受到破坏。因此,对具有高膨胀性的膨润土的持水特性及微观结构特征进行试验研究显得非常必要。分别运用滤纸法和饱和盐溶液蒸汽平衡法对膨润土进行了持水特性试验研究,得到了不同吸力范围内膨润土的土-水特征曲线;联合用蒸汽平衡法和扫描电子显微镜(SEM)对特定吸力点(367.54、149.51、71.12、38.00 MPa)的膨润土试样进行扫描电镜试验研究。膨润土的持水特性试验结果表明,滤纸法和饱和盐溶液蒸汽平衡法测得的土-水特征曲线均随吸力的增大而减小。根据滤纸法量测的试验数据,运用origin软件获得了Fredlund and Xing(1994)提出的模型参数,通过建立模型参数与干密度之间的关系,给出了膨润土的土-水特征曲线的预测公式。膨润土的微观定性分析表明:随着吸力的增大,膨润土集聚体逐渐增大,膨润土颗粒之间也越紧密;孔隙数量随着吸力的增大而减少、孔径也随吸力的增大而减小。
文摘根据摩尔定律,半导体芯片单位面积上的晶体管数量每18个月翻一番,当前量产先工艺节点已经演进到3nm,特征尺寸不断缩小,图案越发复杂,芯片制造过程中出现缺陷的概率升高,对检测技术及其关联设备提出了极高的要求。光刻作为半导体制造中的核心模块,其工艺质量直接决定了后续工艺准确度,由于图案尺寸小于光源波长,衍射效应显著,导致曝光图案的高频信息丢失,光刻扫描电子显微镜(scanning electron microscope,SEM)图像作为曝光图案的直接表示,基于SEM图像的测量在半导体制造中对于图案化工艺质量的评估和监控显得至关重要。SEM图像不仅能够提供图像的特征宽度和特征-特征间距尺寸测量,同时还提供了其它有关图案质量的丰富信息,然而通过视觉检测在SEM图案质量检测方面留下了相当大的模糊空间。为了缩小模糊范围并获得更多关于图案质量的统计定量信息,通常会提取SEM图像轮廓来进一步计量分析。基于轮廓信息,我们能够估计出曝光图案任何位置的尺度信息,例如侧壁角度,临界尺寸等,这些尺度信息可用于光刻热点检测和光刻OPC模型验证等。基于局部信息的经典轮廓提取算法在处理存在噪声的低对比度光刻SEM图像方面尚有不足,如传统的prewit、log、sobel等算子,利用模板匹配无法获得令人满意的轮廓结果;轮廓提取领域的canny算法因其适用性广和效果较好,被广泛应用,但其梯度图像及阈值先验设置往往具有较大主观性,且没有充分利用待处理场景信息,对于较为复杂场景效果仍有待提升。本文通过结合通过结合光刻SEM图像的灰度、拓扑和轮廓长度先验信息,对canny算法进行优化,利用先验信息获得合适的阈值,完成对伪边缘(轮廓)的有效过滤,最终得到了与光刻SEM图像高度吻合的轮廓结果。
基金funded by the Natural Science Foundation of the Inner Mongolia Autonomous Region(Grant No.2020BS04003)the Project of High-Level Talent Research in Inner Mongolia University(Grant No.12000-15031942)the National Natural Science Foundation of China(Grant No.51778590,51879131).
文摘Unsaturated loess in natural sites loses stability as the overburden load continuously increases.Traditional soil modifiers such as cement and fly ash affect the surrounding environment.A new type of material,i.e.,lignin,is environmentally friendly and able to increase the strength of loess.However,the engineering characteristics of the improved loess under unsaturated conditions are not yet clear.In this study,the soil-water characteristic curves(SWCCs)of lignin-improved loess samples were determined from 0 kPa to 700 kPa using a pressure plate instrument,and then,they were fitted using the van Genuchten(VG)model and the Fredlund and Xing(FX)model.In addition,the effects of the lignin content and sample preparation methods on the SWCCs were investigated to determine the optimal lignin content and a suitable sample preparation method for loess foundations.As the lignin content increases,the matric suction and residual water content of the improved loess increase.The suction stress increases with the increasing lignin contents of 1%–2%.At lignin contents of 3%–4%,the suction stress begins to decrease and the samples prepared using the slurry method has a lower suction stress than that prepared using the wet mixing method.The air entry value(AEV)increases with increasing lignin content.In addition,scanning electron microscopy(SEM)was used to investigate the microstructural variations.It was found that after the addition of lignin,the entrapment of the loess particles by the lignin fibers created some larger particles and smaller pore diameters,which in turn led to poor connectivity of the loess pores.These changes cause the matric suction of the modified loess to increase.
基金supported by the National Basic Research Program of China(Grant Nos.2010CB631005 and 2011CB606105)the National Natural Science Foundation of China(Grant Nos.90916010,11172151 and 11232008)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20090002110048)Tsinghua University Initiative Scientific Research Program
文摘In this paper,a new method combining focused ion beam(FIB)and scanning electron microscope(SEM)Moirétechnique for the measurement of residual stress at micro scale is proposed.The FIB is employed to introduce stress relief like the macro ring-core method and fabricate gratings with a frequency of 5000 lines/mm on the measured area of the sample surface.Three groups of gratings in different radial directions are manufactured in order to form a micro-scale strain rosette.After milling ring-core by FIB,the deformation incurred by relief of the stress will be recorded with the strain rosette.The displacement/strain field can be measured using SEM scanning Moiréwith random phase-shifting algorithm.In this study,the Nickel alloy GH4169 sample(which was processed by laser shock peening)is selected as a study object to determine its residual stress.The results showed that the components of the in-plane principal stresses were-359 MPa and-207 MPa,respectively,which show good agreement with the results obtained from the available literature.
文摘叔丁醇冻结干燥法用于植物材料,获得了良好的效果。经常规固定的样品完成脱水以后浸泡在叔丁醇中,然后将含醇样品放入电冰箱中冷冻,待叔丁醇凝固后再转移到真空镀膜机的钟罩里,用机械泵抽真空,冻结的醇在低真空中升华后样品得到了干燥。SEM 镜检表明,样品的表面和细胞断裂面及其深层(可见到内质网的双层膜、线粒体的嵴、高尔基体潴泡叠层、核糖体颗粒等细胞器)的三维图象均优于用临界点干燥法所得到的样品图象,叔丁醇冻结干燥法用于植物 SEM 样品制备,是一种操作简单,干燥质量可靠、值得推广的方法。
