共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
Qiyi Wei Liang Li Zhen Deng Gengping Wan Ying Zhang Changlong Du Yanran Su Guizhen Wang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(35):2302082
In this work, inspired by the great advantage of the unique “brick-mortar” layered structure as electromagnetic interference (EMI) shielding materials, a multifunctional flexible graphene nanosheets (GNS)/polytetrafluoroethylene (PTFE) composite film with excellent EMI shielding effects, impressive Joule heating performance, and light-to-heat conversion efficiency is fabricated based on the self-emulsifying process of PTFE. Both PTFE microspheres and nanofibers are employed together for the first time as “sand and cement” to build unique nacre-structured EMI shielding materials. Such configuration can obviously enhance the adhesion of composites and improve their mechanical property for the application under extreme environment. Moreover, the simple and effective repetitive roll pressing method can be used for the scalable production in industrialization. The GNS/PTFE composite film shows a high EMI shielding effectiveness (SE) of 50.85 dB. Furthermore, it has a high thermal conductivity of 16.54 W (m K)−1, good flexibility, and recyclable properties. The excellent fire-resistant and hydrophobic properties of GNS/PTFE film also ensure its reliability and safety in practical application. In conclusion, the GNS/PTFE film demonstrates the potential for industrial manufacturing, and outstanding EMI shielding performance with high stability and durability, which has a broad application prospect for electronic devices in practical extreme outdoor environments. 相似文献
4.
The preparation and characterization of pure rare-earth-metal bulks with controllable nanostructures are reported in this paper. A novel 'oxygen-free' in?situ synthesis technique that combines inert-gas condensation with spark plasma sintering (SPS) technology is proposed. Taking into account the special mechanisms of SPS consolidation and the scale effects of nanoparticles, we introduced practical procedures for preparing rare-earth bulks of amorphous, mixed amorphous and nanocrystals, and nanocrystalline microstructures, respectively. Compared with the conventional polycrystalline bulk, these nanostructured bulks exhibit substantially improved physical and mechanical properties. This technique enables comprehensive studies on the microstructures and properties of a large variety of nanostructured metallic materials that are highly reactive in the air. 相似文献
5.
Nanocrystalline metals have many functional and structural applications due to their excellent mechanical properties compared to their coarse-grained counterparts. The atomic-scale understanding of the deformation mechanisms of nanocrystalline metals is important for designing new materials, novel structures and applications. The review presents recent developments in the methods and techniques for in situ deformation mechanism investigations on face-centered-cubic nanocrystalline metals. In the first part, we will briefly introduce some important techniques that have been used for investigating the deformation behaviors of nanomaterials. Then, the size effects and the plasticity behaviors in nanocrystalline metals are discussed as a basis for comparison with the plasticity in bulk materials. In the last part, we show the atomic-scale and time-resolved dynamic deformation processes of nanocrystalline metals using our in-lab developed deformation device. 相似文献
6.
7.
Zhen Li Chao Wu Yanyan Liu Tiebing Liu Zheng Jiao Minghong Wu 《Bulletin of Materials Science》2008,31(6):825-829
A novel method has been developed by electron beam irradiation to prepare PbSe nanoparticles. 2 MeV 10mA GJ-2-II electronic
accelerator was used as radiation source. Nanocrystalline PbSe was prepared rapidly at room temperature under atmospheric
pressure without any kind of toxic reagents. The structure and morphology of prepared PbSe nanoparticles were analysed by
X-ray diffraction, transmission electron microscope and atomic force microscope. The results indicated that the obtained materials
were cubic nanocrystalline PbSe with an average grain size of 30 nm. The optical properties of prepared PbSe nanocrystalline
were characterized by using photoluminescence spectroscopy. The possible mechanism of the PbSe grain growth by electron beam
irradiation method is proposed. 相似文献
8.
高速电弧喷涂FeAlNbB非晶纳米晶涂层的组织与性能 总被引:2,自引:0,他引:2
为了提高钢铁材料的耐磨性和硬度,利用高速电弧喷涂技术在45钢基体上制备了FeAlNbB非晶纳米晶涂层.采用扫描电镜(SEM)、能谱分析仪(EDAX),透射电镜(TEM)和X射线衍射仪等设备对涂层的组织结构和相组成进行了分析,研究了非晶纳米晶的形成机制.实验结果表明:FeAlNbB非晶纳米晶涂层是非晶相、α-Fe、FeAl纳米晶和Fe3Al微晶共存的多相组织,涂层中非晶相含量约36.2%,纳米晶尺寸约14.1 nm;涂层组织均匀,结构致密,平均孔隙率约2.3%;非晶纳米晶涂层具有较高的硬度,其耐磨性是相同实验条件下制备的3Cr13涂层的2.2倍. 相似文献
9.
The thermal shock resistance of ceramics depends on the materials mechanical and thermal properties, also is affected by component geometry and external factors and so on. Therefore, the thermal shock resistance of ceramic materials is the comprehensive performance of their mechanical and thermal properties corresponding to the various heat conditions and external constraints. In the present work, a thermal shock resistance model of the ultra-high temperature ceramics which considered the effects of thermal environment and constraints was established. With this model, the influence of constraints on the thermal shock resistance and critical fracture temperature difference had been studied and an effective idea to improve thermal shock resistance for ceramic material and structure was found. Furthermore, the model was validated by finite element method. 相似文献
10.
对不同灰粉比的苯丙乳液基水泥复合材料进行定伸、拉伸和剪切试验,通过测量弹性恢复率、拉伸剪切力学性能指标、变形性能指标、能耗性能指标和负荷位移,研究了灰粉比对苯丙乳液基水泥复合材料定伸黏结性能、拉伸力学性能、剪切力学性能及破坏形态的影响,结合FESEM试验和压汞测孔(MIP)试验结果,分析了灰粉比对苯丙乳液基水泥复合材料力学性能及破坏形态影响规律的微观机制。结果表明:适当增大灰粉比能够改善苯丙乳液基水泥复合材料的微观形貌,优化孔隙结构,提高密实度,显著增强了复合材料的力学性能;随着灰粉比的增大,苯丙乳液基水泥复合材料的定伸黏结性能逐渐降低,拉伸剪切力学性能不断增强,拉伸剪切变形性能和能耗性能均先提升后降低。灰粉比为30%~35%时,苯丙乳液基水泥复合材料的拉伸剪切力学性能最佳;灰粉比为45%时,苯丙乳液基水泥复合材料的拉伸剪切变形性能和能耗性能均低于灰粉比为20%的苯丙乳液基水泥复合材料。随着灰粉比的增大,苯丙乳液基水泥复合材料能够承受的拉伸和剪切负荷位移均先增大后减小,其破坏形态逐步由“内聚破坏”转为“黏结破坏”。 相似文献
11.
Structural nanocrystalline materials: an overview 总被引:1,自引:0,他引:1
Carl C. Koch 《Journal of Materials Science》2007,42(5):1403-1414
This paper presents a brief overview of the field of structural nanocrystalline materials. These are materials in either bulk,
coating, or thin film form whose function is for structural applications. The major processing methods for production of bulk
nanocrystalline materials are reviewed. These methods include inert gas condensation, chemical reaction methods, electrodeposition,
mechanical attrition, and severe plastic deformation. The stability of the nanocrystalline microstructure is discussed in
terms of strategies for retardation of grain growth. Selected mechanical properties of nanocrystalline materials are described;
specifically strength and ductility. Corrosion resistance is briefly addressed. Examples of present or potential applications
for structural nanocrystalline materials are given. 相似文献
12.
Xiangbao Li Fengling Yue Wenchao Pang Jialiang Wu Beibei Kong 《Fullerenes, Nanotubes and Carbon Nanostructures》2019,27(5):459-467
In this study, the effects of incorporating graphene oxide (GO) and γ irradiation on the mechanical and wear properties of ultra-high-molecular-weight polyethylene (UHMWPE) were investigated. Moreover, the crystallinity and oxidation index of irradiated GO/UHMWPE composites were studied. The results indicated that the crystallinity, compression performance, and hardness of UHMWPE were improved owing to the incorporation of GO and γ irradiation treatment. Furthermore, the incorporation of GO and γ irradiation treatment could effectively reduce the wear rate of UHMWPE. In addition, the incorporation of GO could improve the oxidative resistance of irradiated and aged UHMWPE. 相似文献
13.
As structural materials, cementitious materials are quasi-brittle and susceptible to cracking, and have no functional properties. Nanotechnology is introduced into cementitious materials to address these issues. Nano materials, especially nano carbon materials (NCMs) were found to be able to improve/modify the mechanical property, durability and functional properties of cementitious materials due to their excellent intrinsic properties and composite effects. Here, this review focuses on the recent progress of fabrication, properties, and structural applications of high-performance and multifunctional cementitious composites with NCMs including carbon nanofibers, carbon nanotubes and nano graphite platelets. The improvement/modification mechanisms of these NCMs to composites are also discussed. 相似文献
14.
A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with cerium salt particles was vulcanized via in situ coordination for the first time. The resulting materials exhibit good mechanical properties. Curing characteristics analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of the composite. The results in this paper indicate that the composite is a kind of elastomer based on the in situ coordination crosslinking interactions between the nitrile groups (–CN) of NBR and cerium ions. The mechanical properties of vulcanized cerium salt/ NBR rubber are altered when changing the sorts of cerium salt. Moreover, these materials show good irradiation resistance because of the introduction of the cerium salt. 相似文献
15.
Changes of the electrochemical corrosion behavior and the mechanical properties of C/Al-composites due to SiC and pyrolytic carbon fiber coatings The following contribution describes the modification of the electrochemical and mechanical behavior of carbon fiber reinforced pure aluminum (C/Al-composite) due to two different fiber coatings. Tests include potentiodynamic corrosion tests, Transmission electron microscopy, bending tests and single fiber-“push in”-tests. The potentiodynamic corrosion tests were carried out in 3,5 wt.% NaCl solution. The results give evidence of a considerable decrease of the corrosion resistance of the C/Al-composites due to the application of the pyrolytic fiber coating. The SiC coating improves the corrosion resistance of the composite. However, the mechanical properties of the composites were harmed by the SiC coating. The pyrolytic carbon coating leads to a remarkable energy dissipation due to “stick-slip” effects on the interface under load. Consequently, the application of suitable multilayers of pyrolytic carbon and SiC fiber coatings could result in improved electrochemical and optimized mechanical properties of the C/Al-composite. 相似文献
16.
M.R.M. Aliha S.M.N. Ghoreishi D.M. Imani Y. Fotoohi F. Berto 《Fatigue & Fracture of Engineering Materials & Structures》2020,43(7):1514-1528
Butt welding of AA6063 aluminium cylindrical shells was performed using the orbital friction stir welding (FSW) method. Tool rotation speed and orbital speed (i.e., traverse speed of rotating cylinder during welding) were considered as variable, and the strength and the mechanical properties including tensile strength, microhardness, mode I fracture energy and mode I crack growth behaviour of manufactured cylinders were investigated experimentally. A novel and subsized test specimen was designed and manufactured for fracture testing of specimens extracted from both base metal and weld zone region of cylinders. The initial precrack was introduced along (i) the tool penetration through the pipe thickness (i.e., T‐direction) and (ii) along the tool travelling direction (i.e., L‐direction). It was found that the crack growth resistance and fracture energy values of FSW samples are greater than the corresponding values of base aluminium material along both “L”‐ and “T”‐directions. Also, the fracture resistance value in T‐direction was higher than the L‐direction for the whole tested FSW samples with different welding speeds. 相似文献
17.
18.
25th Anniversary Article: Semiconductor Nanowires – Synthesis,Characterization, and Applications
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jianwei Sun Chong Liu Sarah Brittman Sean C. Andrews Jongwoo Lim Peidong Yang 《Advanced materials (Deerfield Beach, Fla.)》2014,26(14):2137-2184
Semiconductor nanowires (NWs) have been studied extensively for over two decades for their novel electronic, photonic, thermal, electrochemical and mechanical properties. This comprehensive review article summarizes major advances in the synthesis, characterization, and application of these materials in the past decade. Developments in the understanding of the fundamental principles of “bottom‐up” growth mechanisms are presented, with an emphasis on rational control of the morphology, stoichiometry, and crystal structure of the materials. This is followed by a discussion of the application of nanowires in i) electronic, ii) sensor, iii) photonic, iv) thermoelectric, v) photovoltaic, vi) photoelectrochemical, vii) battery, viii) mechanical, and ix) biological applications. Throughout the discussion, a detailed explanation of the unique properties associated with the one‐dimensional nanowire geometry will be presented, and the benefits of these properties for the various applications will be highlighted. The review concludes with a brief perspective on future research directions, and remaining barriers which must be overcome for the successful commercial application of these technologies. 相似文献
19.
S. Varalakshmi G. Appa Rao M. Kamaraj B. S. Murty 《Journal of Materials Science》2010,45(19):5158-5163
The present study is aimed to investigate the consolidation behaviour and mechanical properties of nanocrystalline equiatomic
AlFeTiCrZnCu high entropy alloy after mechanical alloying. The consolidation was achieved by cold pressing with conventional
sintering, vacuum hot pressing and hot isostatic pressing techniques. The microstructure and mechanical properties were evaluated.
The hardness and compressive strength of nanocrystalline equiatomic AlFeTiCrZnCu high entropy alloy after vacuum hot pressing
are 9.50 and 2.19 GPa and those after hot isostatic pressing are 10.04 and 2.83 GPa, respectively. The wear resistance is
found to be higher than the commercially used materials such as Ni-hard faced alloy. 相似文献
20.
《材料与设计》2015
New hybrid materials with no phase separation up to nanometric level were obtained by performing the in situ co-reticulation of an aluminosilicate source (metakaolin), a mixture of dialkylsiloxane oligomers with different degrees of polymerization and an alkaline solution. As supported by SEM and NMR analyses, these hybrid materials are characterized by a highly interpenetrated structure due to the chemical similarity between the components, resulting in excellent physical and mechanical properties compared to neat geopolymers. These promising results represent a further step in developing alternative “low-carbon” binders (as also geopolymers) with improved engineering properties in the concrete technology. The enhanced mechanical properties, along with the high fire resistance, also suggest their utilization for structural applications as heat insulating and heat-resistant panels for the construction industry, and in the production of heat-resistant protective coatings or adhesives for technologically advanced uses. 相似文献