高导热电封装复合材料界面热传导的扫描热显微镜分析

本文利用扫描热显微镜（SThM),以微米级的空间分辨率,测量了SiC/Cu和SiC/Al电封装复合材料增强相－基体的界面特征和界面导热性能,SThM热图显示出材料界面导热性能的差异,对形貌数据和热数据进行统计分析和转换,确定了复合材料的界面宽度和界面导热率。     

激光烧结SiC陶瓷复合材料块体的组织及性能研究

在45钢基体上利用激光烧结技术制备了SiC陶瓷复合材料块体,并利用扫描电子显微镜、能谱仪、显微硬度计等设备,分析了试样的显微组织特征,并对试样硬度和磨损性能进行了测定.结果表明,SiC纳米颗粒作为纳米添加相,一部分弥散在粘结相镍基合金中,使材料的力学性能大大改善,另一部分由于机械混合的不均匀性而形成团簇,并作为微观应力抑制点;而复合材料中的WC微米颗粒在高比能量的激光作用下,被进一步细化和分散在粘结相中;分析同时发现,随着激光功率的增加,材料的硬度和耐磨损性能明显增加,力学性能得到改善.     

纳米压痕和划痕法测定氧化硅薄膜材料的力学特性

为了研究不同制备工艺对材料力学性能的影响,选择了热氧化、LPCVD和PECVD三种典型工艺,在硅片上制备1μm氧化硅薄膜.通过纳米压痕和划痕检测可知,热氧化工艺制备的SiO2薄膜的硬度和模量最大,LPCVD制备的样品界面结合强度高于PECVD.纳米压痕和划痕技术为此提供了丰富的近表面弹塑性变形和断裂等的信息,是评价微米薄膜力学性能的有效手段.     

碳纤维增强铝基复合材料界面的透射电镜研究

纤维增强金属基复合材料的力学性能在很大程度上取决于增强纤维与金属基体之间的界面状况,适中的界面结合可使材料具有较为理想的性能。对复合材料的界面虽已进行了不少研究,但应用透射电镜方法却还只是开始,本文用透射电镜观察了碳—铝复合材料的界面,分析了界面的相组成,并讨论了界面状态对复合材料性能的影响。     

纳米压痕和划痕法测定氧化硅薄膜材料的力学特性

为了研究不同制备工艺对材料力学性能的影响 ,选择了热氧化、LPCVD和PECVD三种典型工艺 ,在硅片上制备 1μm氧化硅薄膜。通过纳米压痕和划痕检测可知 ,热氧化工艺制备的SiO2薄膜的硬度和模量最大 ,LPCVD制备的样品界面结合强度高于PECVD。纳米压痕和划痕技术为此提供了丰富的近表面弹塑性变形和断裂等的信息 ,是评价微米薄膜力学性能的有效手段     

微米硅-石墨-碳负极的制备及在锂离子电池中的应用

硅作为锂离子电池负极的理论比容量是商用碳材料的10倍以上,但是其在循环过程中的巨大体积变化会导致电池负极粉化,形成不稳定的固体电解质界面(SEI)膜,从而阻碍硅负极材料的实际应用.以价格低廉的微米硅作为原材料,石墨和聚丙烯腈作为碳源,采用球磨、液相包覆和热解的方法,制备了微米硅-石墨-碳(Si-G-C)复合材料.所制备...     

纳米压痕和划痕法测定氧化硅薄膜材料的力学特性

为了研究不同制备工艺对材料力学性能的影响，选择了热氧化、LPCVD和PECVD三种典型工艺，在硅片上制备1μm氧化硅薄膜。通过纳米压痕和划痕检测可知，热氧化工艺制备的SiO2薄膜的硬度和模量最大，LPCVD制备的样品界面结合强度高于PECVD。纳米压痕和划痕技术为此提供了丰富的近表面弹塑性变形和断裂等的信息，是评价微米薄膜力学性能的有效手段。     

SiCp/A390复合材料中析出相的形貌及界面结构演变

采用快速凝固的A390铝合金粉体和SiC颗粒,通过粉末冶金法+热挤压工艺制备了SiCp/A390复合材料,并对复合材料进行了T6处理,利用扫描电镜(SEM)、透射电镜(TEM)及高分辨透射电镜(HRTEM)对复合材料时效过程中第二相的析出形貌及界面结构进行了表征,测定了复合材料的力学性能,探讨了析出相的演变规律、析出相与基体的界面结构及其对力学性能的影响.结果表明:SiCp/A390复合材料经固溶+时效处理后,合金元素从基体中析出形成GP区,然后转变为颗粒状的δ″相.随着时效时间的延长,这些颗粒状δ″相继续长大成δ′相和δ相;同时,时效析出相与基体之间界面结构随时效时间的延长发生着转变,其转变规律为:完全共格界面GP区→共格界面的δ″相→半共格界面δ′相→非共格界面δ相;SiCp/A390复合材料的抗拉强度随着时效时间延长先增加后降低,在时效6h时,复合材料的力学性能达到最大值.     

形变镁合金微观组织与织构的EBSD研究

镁合金具有密排六方结构,变形时易形成基面织构,室温塑性差。研究镁合金变形过程中微观组织及织构的演变规律是解决以上问题的关键。近几年发展起来的电子背散射衍射（EBSD）自动分析技术是研究材料微观组织及织构的一种非常有效的分析手段。本文分别举例介绍了EBSD技术在形变镁合金轧制过程微观组织与织构演变、拉伸孪晶界面和动态再结晶研究中的应用。     

扫描电镜法研究PP／CaCO3复合材料的微观形态

采用CaCO3等无机填料对PP进行增韧改性是近几年发展起来的技术，其改性关键在于新型偶联技术，解决了树脂与填料界面相容问题。利用扫描电镜可以清晰地观察到复合材料的两相界面情况、偶联剂作用产生的微观形态结果、复合材料随CaCO3用量改变其脆韧性的变化情况，对深入了解复合材料的微观形态结构与力学性能之间的关系发挥了重要作用。     

不同取样方向对AZ31镁合金高周疲劳性能的影响

在轧制镁板材沿TD和RD方向分别切取疲劳试样,并对它们进行室温下的高温疲劳变形。 EBSD分析方法应用于样品的微观组织及织构变化的表征方面。发现经高周应力疲劳变形后,由于应变量非常小,RD与TD方向整体孪晶数量都不多,疲劳后相比疲劳前孪生体积分数有所增加,沿TD方向的孪生体积分数高于RD方向。经拉压循环变形后除{1012}拉伸孪生外还出现了少量的{1011}压缩孪生与{1011}－{1012}二次孪生,导致屈服强度增加,TD方向的抗拉强度与延伸率均高于RD方向。分析其断口形貌发现TD方向疲劳辉纹较小,解理断裂的区域更少,韧窝比较深,故TD试样的高周疲劳性能以及材料的塑性略优于RD试样。由于轧制织构在轧制面内基本对称,所以二者的差别并不太显著。     

电解电容器高压阳极用高纯铝箔织构研究

采用蚀坑法、EBSD微观取向分析法,研究了电解电容器高压阳极用高纯铝箔制备过程中的织构演变。结果表明:热轧高纯铝板织构主要类型是高斯织构、立方织构和铜织构。随着冷轧变形率的增加,冷轧织构中的立方织构含量增加,冷轧变形率为96.3%时,立方织构体积分数为14%。再结晶织构中的立方织构含量随再结晶退火温度的增加而增加,再结晶退火温度为530℃时,立方织构体积分数为86%。     

Processing and Characterization of Ni Base Coated Superconductor Substrate Tapes With Layered Architecture

Ni/Ni-5at.%Mo and Ni/Ni-5at.%Mo/Ni multilayer tapes were prepared from elemental powders by a powder metallurgy route for coated superconductor substrate applications. The development of cube texture $({001}langle 100rangle)$ following heavy cold rolling ($sim$ 95%) and annealing has been studied in the Ni side(s) of these multilayer tapes and compared to a nonalloyed Ni tape. Although the deformation textures in the Ni side(s) of these multilayer tapes appear quite similar to that of the nonalloyed Ni tape cold rolled to a similar deformation level, the volume fraction of the cube grains in the Ni side(s) of the multilayer tapes following annealing shows marked improvement as compared to the nonalloyed Ni tape after different annealing treatments. X-ray area mapping from typical cross-sectional areas of the multilayer compacts in the sintered condition reveals significant diffusion of the alloying element Mo from the alloy side(s) to the Ni side. These facts amply corroborate the earlier observation on the beneficial role of Mo on the development of cube texture in Ni. The yield strength of the annealed multilayer tapes shows marked improvement over nonalloyed Ni tapes.      

Optimal design of periodic surface texture for thin‐film a‐Si:H solar cells

Optical analysis of hydrogenated amorphous silicon (a‐Si:H) solar cells with a periodic texture applied to the interfaces was carried out by two‐dimensional optical simulator. The optical simulator solves the electromagnetic wave equations by means of finite element method using triangular elements for the discretization of space. The periodic texture with rectangular‐like shape acts as a diffraction grating which scatters light into selective angles and thus gives a potential for significant prolongation of optical paths in thin absorber layers of the cells. Optimization of the geometrical parameters (period, height and duty‐cycle) of the periodic texture was carried out in order to obtain the highest photocurrent from a‐Si:H solar cells. The a‐Si:H solar cell with the optimal periodic texture parameters (period of 300 nm, height of 300 nm and duty cycle of 50%) and the absorber layer thickness of 300 nm generates up to 35% more photocurrent in comparison to the cell with flat interfaces. The optical analysis demonstrates that the optimal periodic texture in the a‐Si:H solar cell results in the best trade‐off between the antireflection effect at front interfaces, light scattering efficiency and the absorption losses at realistic metal back contact. Copyright © 2010 John Wiley & Sons, Ltd.     

多层片式LC滤波器中间层复合材料的研究

为了解决多层片式LC滤波器制造中的介电体与铁氧体的共烧问题,采取了在两种材料之间加入中间层复合材料的方法来实现异种材料之间的共烧。制备了由Pb(Ni1/3Nb2/3)O3-PbTiO3基介电体和NiZnCu铁氧体构成的中间层复合材料,研究了其显微组织、成分分布以及其与介电体和铁氧体的共烧界面等,结果表明中间层复合材料中介电体与铁氧体各自保持独立的相结构,没有新相生成;介电体晶粒与铁氧体晶粒相间分布于中间层中,且它们之间存在着离子的相互扩散;中间层能够有效地减小异种材料共烧界面上的应力。     

热轧对N18合金板材显微组织及织构的影响

本文以我国自主开发的Zr-Sn-Nb系N18锆合金为研究对象,利用配备在扫描电镜中的EBSD自动分析技术,研究了该合金板材在750℃、780℃、820℃下热轧过程中的晶粒组织、晶界特征及微织构的演化规律。结果表明,N18合金板材在热轧过程中发生了动态回复及局部动态再结晶,并产生了大量的小角度晶界及亚结构等缺陷,且热轧温度越高其动态再结晶晶核的密度越高,缺陷密度有所增加。N18合金板材的织构类型主要为（0002）[12 10]和（0002）[10 10]基面织构以及（10 14）[12 10]锥面织构。热轧样品中观察到了（10 11）[1012]压型孪生,说明压型孪生变形促进了N18合金热轧变形。     

Propagation modeling of periodic laminated composite structures

A new model based on filament-current and thin-current assumptions is proposed to analyze the propagation problem associated with the lossy periodic multilayer structure of conducting fibers situated in a dielectric matrix. To discuss the combined effect of fibers and dielectric matrix, reflection and transmission matrices at the air-matrix, and grating interfaces together with suitable phase correction are incorporated in the model in which the fiber grating is regarded as a thin Floquet layer. To reduce the central processing unit (CPU) time, an extended filament-current model for the same multilayer structure is also examined. In this study, numerical results for the graphite/epoxy (G/E) fiber-reinforced planar laminated composite materials are presented and discussed. In particular, the parameters that influence their shielding and reflection characteristics are investigated in detail. The new model is useful in characterizing the G/E fiber-reinforced laminated composites even up to the frequency of 100 GHz     

A Competitive Reaction Strategy toward Binary Metal Sulfides for Tailoring Electromagnetic Wave Absorption

The development of multicomponent dielectric composites has become a mainstream approach for obtaining excellent electromagnetic wave (EMW) absorbers. However, conventional component introduction is often performed blindly and based only on semiempirical rules, lacking precise modulation of components, interfaces, and defects during the reaction process. Herein, a competitive reaction mechanism is proposed for the first time, in which not only the metal ion concentration but also its characteristic are two feasible parameters to control the components, interfaces, and defects to tailor the EMW absorption performances of Cu-based binary metal sulfides. The appropriate heterogeneous interfaces and components and the abundant defects can synergistically benefit the EMW absorption capacity by forming perfect impedance matching and multiple dielectric polarizations. As a result, combined with these advantages, an effective absorption band) of 6.80 GHz (6.3–13.1 GHz) is achieved at 2.80 mm for Cu–Co binary metal sulfide, showing the sole middle-frequency broadband absorption of reported sulfide-based absorbers to date. Other Cu-based binary metal sulfides deliver different EMW absorption behaviors. This work breaks through the limitation of traditional component design, opening up a novel methodology for designing multicomponent composites beyond sulfides with broadband absorption.     

梯度纹理直方图与多层感知器船舶快速检测

在动态的复杂环境中,受背景建模失效影响,传统船舶目标检测方法的精度较低。针对该问题,提出一种基于梯度纹理直方图特征与多层感知器的船舶快速检测算法。该算法利用多层感知器将目标的梯度与纹理的直方图进行特征融合,为船舶目标构建特征空间。首先,基于二值梯度的特征训练船舶候选区模型,以快速生成具有高召回率的少量船舶候选窗口,并在每个候选窗口提取梯度纹理直方图特征;其次,设计一个多层感知器作为船舶分类器,对提取到的梯度纹理直方图特征进行判别。实验结果表明,该算法在多个海上场景中船舶检测平均精确率达90.0%,平均执行时间为20.4 ms/frame,有效实现海上船舶精确与快速的检测。     

高纯钽交叉轧制过程中微观结构和织构梯度的演变

高纯钽板在交叉轧制过程中,通过控制轧制的道次,得到了70％,82％和87％变形量的样品.应用X-射线衍射(XRD)技术测量了轧制样品1/8厚度层,1/4厚度层和中间层的宏观织构,并对样品沿厚度方向上的变形组织与微织构进行电子背散射衍射(EBSD)表征.结果表明,随着交叉轧制变形量的增加,{111} 和{100}取向晶粒的取向分裂程度增加,并且{111}取向的晶粒分裂程度高于{100}取向的晶粒.变形量为70％时,高纯钽板沿厚度方向存在强烈的微观组织和织构梯度,中间层具有强烈的{111}取向晶粒,而1/8厚度层主要为{100} 取向.随着变形量增加,高纯钽板沿厚度方向的微观组织和织构均匀性得到改善.当变形量达到87％时,表面和中心的{100} 和{111} 取向晶粒都为长条状且交互分布在一起,使得钽板沿厚度方向织构梯度得到减弱,同时获得均一的晶粒尺寸.