共查询到18条相似文献,搜索用时 171 毫秒
1.
2.
3.
The influence of size effect of conductivity on the microwave absorption properties of thin Al films
采用中频磁控溅射法制备不同厚度的Al膜。利用直线型四探针法测量不同厚度Al膜的电导率,研究薄膜直流电导率随厚度的变化关系(尺寸效应);并利用网络矢量分析仪测量Al膜与FR4-epoxy环氧树脂玻璃板复合结构微波吸收率,研究电导率尺寸效应对Al膜微波吸收性能的影响。实验结果表明:薄膜厚度对金属Al膜的电导率产生主要影响;在Al膜和FR4-epoxy环氧树脂玻璃板复合结构中,Al膜电导率变化对复合结构的最大吸收峰值以及吸收峰值对应的Al膜厚度会产生显著影响。实验结果利用传输矩阵方法计算得到了验证。 相似文献
4.
5.
采用离子束溅射沉积了不同厚度的Co膜和Cu膜,利用四电极法测量了薄膜的电阻率,从而得到了Co膜和Cu膜的电导率随薄膜厚度的变化关系。实验结果表明,Co膜和Cu膜的电学特性都具有明显的尺寸效应。比较了同时考虑表面散射和晶界散射的电导理论得到的电导率公式与实验结果,不同薄膜厚度电导率的理论结果与实验结果符合较好。提出了厚度作为金属薄膜生长从不连续膜进入连续膜的一个特征判据,并利用原子力显微镜(AFM)观测了膜厚在特征厚度附近的Co膜和Cu膜的表面形貌。 相似文献
6.
7.
选用金属Mo作为红外反射层,Mo-Al_2O_3作为吸收层,Al_2O_3作为减反射层,利用磁控溅射镀膜技术,在抛光的316L不锈钢片上制备具有双吸收层的Mo/Mo-Al_2O_3/Al_2O_3太阳能选择吸收膜系,研究减反射层和高、低金属吸收层的厚度及其金属体积分数对膜系选择吸收性能的影响。结果表明,当减反层厚度为50 nm时,所得膜系的选择吸收性能最佳。高金属吸收层厚度的增加会使薄膜反射率的骤升阈值发生红移,薄膜的发射率升高,但其厚度过高,则会影响薄膜的干涉效应。低金属吸收层厚度的增加会导致可见光波段的吸收率增加,红外波段的发射率上升,薄膜反射率的骤升阈值红移。高金属吸收层中金属体积分数增加会导致它的方块电阻降低,使薄膜的红外发射率下降。低金属吸收层中金属体积分数的增加,会导致薄膜的红外干涉下降,使其发射率升高,获得薄膜的最佳吸收率为0.922,发射率为0.029。 相似文献
8.
通过建立纳米铝膜/电介质复合材料的计算模型,用有限元软件Ansoft's HFSS TM模拟纳米铝膜/电介质复合结构的电磁散射参数(S参数),并利用S参数反演得到纳米金属Al膜的等效介电常数和磁导率.模拟和计算结果表明:在纳米金属膜/电介质复合结构中,反射率随薄膜厚度的增加而增加,透射率则随之减少;吸收率的峰位与薄膜厚度的变化没有关系,只与电介质厚度和介电常数有关;在X波段,随频率增加,薄膜等效介电常数实部逐渐增加,虚部逐渐减小;磁导率实部先出现振荡,后逐渐增加;虚部则先减小,后增加,再减小;薄膜厚度的变化对等效介电常数实部和磁导率影响不大,但对等效介电常数虚部的影响显著. 相似文献
9.
10.
11.
超薄板的CMT冷金属过渡技术 总被引:5,自引:0,他引:5
CMT(cold Metal Transfer)冷金属过渡技术是在MIG/MAG焊接工艺基础上开发的一种革新技术,热输入极低,可焊接薄至0.3mE的板材,并可实现钢与铝的异种连接。介绍了CMT焊接工艺的原理、特点及其应用前景。 相似文献
12.
LY12铝合金微弧氧化的尺寸变化规律 总被引:43,自引:1,他引:43
研究了LY12铝合金微弧氧化过程中工件尺寸变化规律,并初步分析了氧化膜生长机理。氧化膜经过一段时间的线性增长后,生长速度逐渐降低。氧化初始阶段向外生长为主,氧化膜达到一定厚度后,工件外部尺寸不再增加,而逐渐转向基体内部生长。氧化膜分为疏松层和致密层两层结构,致密层最终可占到总膜厚的75%以上,打磨掉表面疏松层后,工件基本上能保持原始尺寸。 相似文献
13.
通过磁控溅射技术在玻璃基体上制备了晶粒尺寸在400 nm左右微晶铝膜.利用动电位极化曲线及电化学噪声技术研究了微晶铝在酸性氯化钠溶液的腐蚀行为.结果表明,微晶铝自腐蚀电位升高,自腐蚀电流明显减小,维钝电流、点蚀击破电位显著升高;微晶化对纯铝点蚀行为有两方面的影响,一方面点蚀孕育速度增大,另一方面点蚀牛长速度降低,导致微晶化后纯铝的耐点蚀性能增强. 相似文献
14.
C.X. Jiang ) J.P. Tu) S.Y. Guo) M.F. Fu) X.B. Zhao) ) Department of Materials Science Engineering Zhejiang University Hangzho u China ) Department of Mechanical Electronic Engineering Nanchang University Nan chang China ) Department of Mechanical Engineering Zhejiang Institute of Science Techn ology Hangzhou China 《金属学报(英文版)》2005,18(3):249-253
1. IntroductionA lum inum and its alloys are used in m any engineering applications because of their highstrength-to-w eightratio and high therm alconductivities.H ow ever,high friction coefficient,poorw earresistance and low seizure load ofalum inum allo… 相似文献
15.
Ta/NiFe/Ta ultrathin films with and without nano-oxide layers (NOLs) were prepared by magnetron sputtering followed by a vacuum
annealing process. The influence of NOLs on the magnetoresistance (MR) ratio of ultrathin permalloy films was studied. The
results show that the influence of grain size and textures on the MR ratio becomes weak when the thickness of the NiFe layer
is below 15 nm. A higher MR ratio was observed for the thinner (< 15 nm) NiFe film with NOLs. The MR ratio of a 10 nm NiFe
film can be remarkably enhanced by NOLs. The enhanced MR ratio for these ultrathin films can be attributed to the enhanced
specular reflection of conduction electrons. 相似文献
16.
White anodized thermal control coating on LY12 aluminum alloy 总被引:1,自引:0,他引:1
Wu Xiaohong Qin Wei Cui Bo Jiang Zhaohua Lu Weiqiang He Weidong 《Journal of Materials Processing Technology》2008,200(1-3):405-409
The thermal control coating with low solar absorptance that can be used in the thermal control system of the spacecraft are gained by in situ growth on the LY12 aluminum alloy. In this article, the optical properties, thickness and microstructure of the anodized coating were studied by spectrophotometer, thickness gauge and AFM, respectively. The influence of various operating parameters, viz., temperature, current density, and anodizing time, on the optical properties of the coating was investigated. Results show that the thicknesses of the coating, size and density of micropores have important influence on the optical properties of the coating. Less size and density of micropores, higher reflectance could be gained on the base of enough thickness of the coating. Therefore, white anodized thermal control coating could be prepared by optimizing the process parameters. 相似文献
17.
18.
In their pioneering experimental work, Liu et al. have given the data related to the in situ sheet resistance measurements of polycrystalline ultrathin Cu films, where the resistivity ρ, was determined as a function of film thickness d.The aim of this paper is to show that the size effects in polycrystalline ultrathin Cu films can be easily reinterpreted by using a simple analytical expression of the electrical conductivity, earlier proposed in the framework of the multidimensional conduction models. The electronic transport parameters obtained in this study are in good agreement with our previous theoretical works. For this purpose, the study given by the authors which has been interpreted by using the Namba's model is reconsidered. 相似文献