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1.
化学还原法制备纳米铜粉的研究   总被引:18,自引:1,他引:17  
本文采用KBH4在液相中化学还原CuSO4,并加入KOH和络合剂EDTA ,制得了纳米级的纯净的铜粉 ,通过调整反应物的浓度 ,可以消除Cu2 O等杂质。制备的纳米铜粉还存在一定程度的团聚 ,需试验加入分散剂来改善。  相似文献   
2.
用正电子湮没方法研究了新型超微晶软磁合金的微观结构缺陷,样品选用的是在不同温度下退火的Fe81P12C3Cu1Mo0.5Si2.5合金,结果表明,合金的微观结构构陷大小,密度随退火温度有规律地变化,这种现象可能与非晶的晶化过程有关。  相似文献   
3.
According to Maxwell's theory, the optical transmission characteristics in GeSi/Si superlattice nanocrystalline layer have been analyzed and calculated. The calculated result shows that when the total thickness L is 340 nm, the single mode lightwave can be transmitted only at periodic number M≥15.5. In addition, at the direction of transmission, when the transmission distance is larger than 500 μm, the lightwave intensity is decreased greatly. Based on the above parameters, the design and manufacture of GeSi/Si superlattice nanocrystalline photodetector are carried out.  相似文献   
4.
We have used x-ray phase analysis to study the composition of the products of reaction between oxygen and nanocrystalline powders with particle sizes 15, 40, 55, and 80 nm, and also specimens pressed (and sintered) from them. The powders were oxidized in air at 100°C (400 h) to 500°C (5 min), while the sintered specimens were oxidized at 600–900°C for 15, 120, and 240 min. In all cases, in the initial oxidation step the oxynitride Ti(OxNy) is formed, which over time is oxidized to TiO, Ti2O3, Ti3O5, TiO2 (anatase) and TiO2 (rutile). In the range 600–800°C, formation of a continuous oxide layer and conversion of anatase to rutile slows down diffusion of oxygen in the scale. We have established that at 900°C, the growth rate of the scale thickness increases and so the reflections from the oxynitride are barely noticeable on the diffraction patterns taken from the surface of the oxidized specimen. In these diffraction patterns, along with strong reflections from the rutile, we also observed weak reflections from lower oxides and anatase, which may be due to reaction between oxygen and the titanium ions diffused to the scale surface. We have concluded that at T > 850°C, the mechanism for oxidation of TiN changes. This is due to superposition of counterdiffusion of titanium ions on the diffusion of oxygen. __________ Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 72–78, March–April, 2006.  相似文献   
5.
综述了纳米晶体材料和纳米碳管材料的力学性能研究的最新进展。实验数据表明纳米晶体材料的强度与其晶粒尺寸大小的关系并不遵循Hall-Petch方程。相对于常规晶体材料 ,纳米材料的超塑性发生在更低的温度和更高的应变速率下。理论计算和实验数据表明 :纳米碳管是一种有着高刚性、高强度、高韧性和低密度的材料。纳米晶体材料和纳米碳管的异常的力学性能已经有了一些应用实例  相似文献   
6.
7.
溶胶-凝胶法制备(Sr,Pb)TiO3纳米晶粉及表征   总被引:5,自引:1,他引:4  
采用溶胶-凝胶法成功地合成了(Sr,Pb)TiO3纳米晶粉,并利用FTIR技术对凝胶的形成过程及350℃,1.5h煅烧获得的粉体材料进行了表征。实验以TG-DSC分析作为拟定煅烧温度的依据,以XRD作为煅烧产物的分析手段,最佳煅烧温度为600℃,所合成的(Sr,Pb)TiO3纳米晶粉的平均晶粒尺寸约为21nm,属钙钛矿型立方顺电相结构。  相似文献   
8.
Deposition of nanocrystalline TiO2 coating at low temperature is becoming more attractive due to the possibility for continuous roll production of the coating for assembly lines of dye-sensitized solar cell (DSC) at a low cost. In this study, porous nano-TiO2 coating was deposited by vacuum cold spraying (VCS) at room temperature on a conducting glass substrate using commercial P25 nanocrystalline TiO2 powder. The microstructure of TiO2 coating was characterized by field emission scanning electron microscopy (FESEM) and nitrogen adsorption test. A commercial dye (N719) was adsorbed on the surface of TiO2 particles within the coating to assemble a DSC. The cell performance was evaluated by employing simulated solar light at an intensity of 100 mW/cm2. The results showed that TiO2 coating was deposited by the agglomerates of nano-TiO2 powders. The Brunauer-Emmett-Teller (BET) test of the as-sprayed TiO2 coating yielded a porosity of 49% and an average pore size of 17 nm. The assembled solar cell yielded a short-circuit current density of 7.3 mA/cm2 and an energy conversion efficiency of 2.4%. The test results indicate that VCS was a promising method to deposit nanocrystalline TiO2 coatings at low temperature applied to DSCs. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.  相似文献   
9.
纳米晶体Se的微观结构特征   总被引:2,自引:0,他引:2  
张皓月  卢柯  胡壮麒 《金属学报》1995,31(15):123-128
本文采用X射线衍射和透射电子显微镜研究了纳米晶体Se的微观结构特征.通过测定不同晶粒尺寸的纳米晶体Se的点阵参数a和c,发现纳米晶体Se中存在晶格畸变,畸变量与晶粒尺寸有关.得到了纳米晶体Se中晶胞体积变化与晶粒尺寸的关系.并由点阵参数计算出纳米晶体Se的键长.用非晶态Se中的无规链折叠的晶化机制解释了纳米晶体Se中晶格畸变现象.  相似文献   
10.
Nanocrystalline Nd2Fe14B/α—Fe permanent magnet   总被引:2,自引:0,他引:2  
Nd8.5Fe75Co5Cu1Zr3Nb1B6.5bonded magnet was prepared by melt-spinning(vs=18m/s)and subsequent heat treatment(670℃,4min).Excellent magnetic properties of the bonded magnet were achieved:Br=0.68T,iHc=620.3kA/m,(BH)max=74kJ/m^3.The addition of Cu and Zr elements shows to be advantageous in improving an intrinsic coercivity and squareness of hysteresis loop,as well as energy product.In has a remarkable remanence enhancement and the isotropic saturation remanence ratio Mr/Ms is 0.83.  相似文献   
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