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赵三团 《工程物理研究院科技年报》2004,(1):406-407
氧化钙材料具有耐火度高,分解压和蒸汽压低,抗热震性能好和抗渣性好等优点,与各种熔融金属几乎不发生反应,是非常好的耐火材料。纯氧化钙在空气中易于与水蒸气发生反应,形成Ca(OH)2,使氧化钙材料开裂与粉化。此外,氧化钙材料的强度很低,纯氧化钙的强度仅有60~70MPa。本文探索了在氧化钙中加入氧化锆纤维,来提高氧化钙的强度与抗水化性能,取得了较好的效果。 相似文献
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本文建立了双层相变材料熔盐斜温层储热系统的传热储热数值模型,分析了相变材料熔点/位置/含量/比例对储热系统斜温层厚度、流固温差和有效热效率等参数的影响规律。结果表明,由于相变材料的存在,储热系统斜温层分为高温斜温层,低温斜温层和相变层,出口温度出现三个平台,储热系统形成热能梯级输出,使有效放热效率升高。相变材料位置直接影响储热系统性能,高熔点相变材料靠近出口,提高了中高温段放热量。下层填充物占罐体高度比为0.15时,有效放热效率比单层时提高3%~10%。 相似文献
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在神光Ⅲ原型激光装置上开展了Al材料在高压(大于10GPa)、高应变率(10^5~10^8s^-1)的情况下材料强度特性实验方法研究。实验采用“有机材料真空间隙一样品”的靶构型(气库靶)对Al样品进行准等熵压缩,从而使Al样品的温度保持在熔点以下,材料仍具有强度特性。为了测量Al样品的RT不稳定性扰动增长,实验采用Ti作面背光材料,通过X光针孔成像获得样品的面向背光照相图像,获得了不同时刻RT不稳定性的增长因子,实验中采用连续相位板(CPP)对激光源进行了优化,提高了背光源和驱动源的均匀性。结果表明在现有高功率激光装置上可进行中z材料的RT不稳定性增长测量,验证了通过RT不稳定性增长测量来研究高压高应变率条件下材料强度的可行性。 相似文献
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我国的建筑节能工作已从寒冷、炎热地区推进到了冬冷夏热地区,品种众多的保温隔热材料不断问世并应用于节能性建筑,因此有关文献众多。但在建筑工程上,有关建筑材料隔热特性研究的大量文献中,仅罗列出一系列特性参数,例如材料的物理力学性能(空心率、导热系数、强度参数等)以及它们与时间、温度等因素的关系,而且只是从实验或经验的方面阐述材料的隔热等特性。本文将从热力学原理出发,来分析隔热材料的特性,以供从事建筑、材料等行业的工作人员参考,同时,对提高全民节能意识也具有积极作用。 相似文献
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钇基重稀土变质处理对高铬铸铁冲击韧度的影响 总被引:2,自引:0,他引:2
高铬白口铸铁由于硬度高且具有一定的冲击韧度,因而成为当前及今后最为实用的抗磨材料之一。研究发现,决定高铬铸铁抗磨性能的不仅是其硬度指标,更为重要的则是其冲击韧度。因此,如何提高高铬铸铁抗磨材料的冲击韧度成为提高材料抗磨性能的关键。通过材料设计、铸造和热处理工艺试验探索了如何提高高铬铸铁抗磨材料的冲击韧度。 相似文献
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运用等离子喷涂技术制备多层屏蔽复合涂层,根据钽、钨、锡材料的物理特性及工艺特点,分别设计了自动喷涂工艺,既保证了涂层的性能,又提高了喷涂工艺的重复性;在喷涂区域使用氩气保护装置制造局部隋性气氛,简便有效地控制了涂层材料在高温等离子体喷射过程中的氧化:综合使用温度测试、力学拉伸、金相组织及化学成分等分析方法,综合考虑优化喷涂功率、喷涂距离等喷涂参数对基体温度、涂层中氧化物含量、涂层密度的影响,优化喷涂工艺参数,制备出厚度均匀、绢织致密的Ta/W/Sn复合涂层。 相似文献
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在材料科学和材料工程领域,对受热材料温度分布测量的需求一直在持续增长。这主要是因为对于材料的各种特性和行为,温度都是其重要参量。本文设计一种新的声表面波测量方法测量在加热或冷却过程中的材料表面的温度梯度。这种方法涉及到超声波回波测量和导热反问题的分析方法来得到材料中沿超声传播方向的一维温度场分布。为了证明方法的可行性,文章使用铝板进行了实验并得到了准确的材料表面温度场分布图像。超声测温技术将作为一种新型的热点技术,将有很大潜力被用在工业材料高温操作过程中的表面温度场成像。 相似文献
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Arash Rahimi-Iman 《Annalen der Physik》2020,532(9):2000015
Technologies employing nanomaterials, such as electronics, optoelectronics, nanobiotechnologies, quantum optics, and nanophotonics, are perceived as the key drivers of investigations on novel and functional materials and their nanostructures for various applications. It is well understood that the study of such materials and structures has been of great importance for the optimization and development of electrical and optical devices. From such devices, one does not only expect higher efficiencies, but also access to the development of completely new concepts, which are strongly demanded by modern information-processing, quantum, or medical technologies, and sensing applications. In this context, a wide range of aspects such as the physics of novel materials, as well as materials engineering, characterization, and applications are summarized here. Novel materials, which can be used, for instance, for energy harvesting or light generation, as well as for future logic devices; material engineering, which can lead to improved device functionality and performance in optoelectronics; material physics, the study of which allows insight to be gained into optical and electrical properties of nanostructured systems and quantum materials; and technologies/devices, addressing progress on the application side of sophisticated material systems and quantum structures, are highlighted using representative examples. 相似文献
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Thermoelectric devices have gained importance in recent years as viable solutions for applications such as spot cooling of electronic components, remote power generation in space stations and satellites etc. These solid-state devices have long been known for their reliability rather than their efficiency; they contain no moving parts, and their performance relies primarily on material selection, which has not generated many excellent candidates. Research in recent years has been focused on developing both thermoelectric structures and materials that have high efficiency. In general, thermoelectric research is two-pronged with (1) experiments focused on finding new materials and structures with enhanced thermoelectric performance and (2) analytical models that predict thermoelectric behavior to enable better design and optimization of materials and structures. While numerous reviews have discussed the importance of and dependence on materials for thermoelectric performance, an overview of how to predict the performance of various materials and structures based on fundamental quantities is lacking. In this paper we present a review of the theoretical models that were developed since thermoelectricity was first observed in 1821 by Seebeck and how these models have guided experimental material search for improved thermoelectric devices. A new quantum model is also presented, which provides opportunities for the optimization of nanoscale materials to enhance thermoelectric performance. 相似文献
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Recent progress on integrating two-dimensional materials with ferroelectrics for memory devices and photodetectors
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Two-dimensional(2D) materials, such as graphene and Mo S2 related transition metal dichalcogenides(TMDC), have attracted much attention for their potential applications. Ferroelectrics, one of the special and traditional dielectric materials,possess a spontaneous electric polarization that can be reversed by the application of an external electric field. In recent years, a new type of device, combining 2D materials with ferroelectrics, has been fabricated. Many novel devices have been fabricated, such as low power consumption memory devices, highly sensitive photo-transistors, etc. using this technique of hybrid systems incorporating ferroelectrics and 2D materials. This paper reviews two types of devices based on field effect transistor(FET) structures with ferroelectric gate dielectric construction(termed Fe FET). One type of device is for logic applications, such as a graphene and TMDC Fe FET for fabricating memory units. Another device is for optoelectric applications, such as high performance phototransistors using a graphene p-n junction. Finally, we discuss the prospects for future applications of 2D material Fe FET. 相似文献
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A.S. SEKHARB.N. SRINIVAS 《Journal of sound and vibration》2002,251(4):621-630
The dynamics of asymmetric rotors has been investigated in the literature. However, considering the importance in the practical fields, the vibration characteristics of slotted shafts are not studied in detail. It needs more attention particularly with the emerging of new materials, such as composites for shafts. The present study aims at the analysis of the slotted shafts including the compensatory inertia slots. Also, the slotted composite shaft has been modelled based on first order shear deformation theory using finite element method with shell elements. Different materials such as, Boron epoxy, Carbon epoxy and Graphite epoxy have been tried for various stacking sequences. The slot parameters, stacking sequences and material properties have found to influence to great extent on the vibrational characteristics of rotors. The results are compared with those of isotropic slotted shaft. 相似文献
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自从石墨烯被发现以来,机械解理技术已经成为制备高质量二维材料的重要方法之一,在二维材料本征物性的研究方面展现出了独特的优势.然而传统机械解理方法存在明显的不足,如制备效率低、样品尺寸小等,阻碍了二维材料领域的研究进展.近些年我们在机械解理技术方面取得了一系列的突破,独立发展了一套具有普适性的新型机械解理方法.这种新型机械解理方法的核心在于通过改变解理过程中的多个参数,增强层状材料与基底之间的范德瓦耳斯相互作用,从而提高单层样品的产率和面积.本文着重以石墨烯为例,介绍了该技术的过程和机理.相比于传统机械解理方法,石墨烯的尺寸从微米量级提高到毫米量级,面积提高了十万倍以上,产率大于95%,同时石墨烯依然保持着非常高的质量.这种新型机械解理方法具有良好的普适性,目前已经在包括MoS2,WSe2,MoTe2,Bi2212等几十种材料体系中得到了毫米量级以上的高质量单层样品.更重要的是,在解理过程中,通过调控不同的参数,可以在层状材料中实现一些特殊结构的制备,如气泡、褶皱结构等,为研究这些特殊材料体系提供了重要的物质保障.未来机械解理技术还有很多值得深入研究的科学问题,该技术的突破将会极大地推动二维材料领域的研究进展. 相似文献