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《中国稀土学报(英文版)》2017,(8)
A facile approach was developed to prepare Dy_2Ce_2O_7 nanostructures. Dy_2Ce_2O_7 nanostructures were prepared by applying cerium(IV) ammonium nitrate and dysprosium nitrate as Ce and Dy precursors. It was found that the kind of connecting agent, space-filling template and chelating agent were significant factors for the control in shape and size. Transmission electron microscopy(TEM), X-ray diffraction(XRD), diffuse reflectance UV-vis spectroscopy(DR-UV-vis), field emission scanning electron microscopy(FESEM), photoluminescence spectroscopy(PL) and energy dispersive X-ray microanalysis(EDX) techniques were applied to characterize the Dy_2Ce_2O_7 nanostructures and investigate their optical characteristics. To examine the photocatalytic activity of as-produced Dy_2Ce_2O_7 nanostructures, the photocatalytic degradation of erythrosine dye as water pollutant was carried out. The results of the photocatalytic investigations suggest as-obtained nano-sized Dy_2Ce_2O_7 product as a new, proper and efficient candidate for photocatalytic usages under UV illumination. 相似文献
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Chunfa Liao Shumei Chen Xu Wang Boqing Cai Jueyuan Lin Yunfen Jiao Yanliang Zeng 《中国稀土学报(英文版)》2019,37(2):211-217
Herein, the present paper were attempted to identify ions in LiF-DyF_3 melts according to the law of decreasing primary crystallization temperature and model analysis. Specifically.the primary crystallization temperatures of LiF-DyF_3 and LiF-DyF_3-Dy_2O_3 melts with various DyF_3 and Dy_2O_3 contents were determined by differential scanning calorimetry(DSC), and reactions occurring in the above melts were investigated using ideal dilute solution(Temkin and Flood) models. Moreover, crystal phases produced by rapid solidification of LiF-DyF_3, LiF-Dy_2O_3, DyF_3-Dy_2O_3, and LiF-DyF_3-Dy_2O_3 melts were identified by X-ray diffraction(XRD) analysis. The primary crystallization temperature of LiF-DyF_3 melts exhibits an approximately linear decrease with increasing molar fraction of DyF_3, and the general formula of complex ions in these melts is expressed as DyF_x~((3-x)),e.g., DyF_4~-. Finally, we investigated the dissolution of Dy_2O_3 in LiF-DyF_3 melts, showing that it was chemical in nature and afforded Dy_(1+x)O_(3x)F_(3-3x) and DyOF. 相似文献
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M. J. Cordill A. Taylor J. Schalko G. Dehm 《Metallurgical and Materials Transactions A》2010,41(4):870-875
New emerging technologies in the field of flexible electronic devices require that metal films adhere well and flex with polymer
substrates. Common thin film materials used for these applications include copper (Cu) with an adhesion interlayer of chromium
(Cr). Copper can be quite ductile and easily move with the polymer substrate. However, Cr is more brittle and fractures at
lower strains than Cu. This study aims to examine the fracture and subsequent buckling and delamination of strained Cr films
on polyimide (PI). In-situ scanning electron microscope (SEM) straining is used to systematically study the influence of film thickness on fracture
and buckling strains. Film fracture and delamination depend on film thickness, and increases in crack and buckle density with
decreasing thickness are explored by a shear lag model. 相似文献
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Isothermal oxidation behavior of chromium with and without nanon sol-gel CeO_2 coating is studied at 1 000 ℃ in air. Scanning electron microscopy (SEM)and transmission electron microscopy (TEM)are used to examine the sur-face morphology and mierostructure of the oxide films. It is found that ceria coating greatly improves the anti-oxida-tion property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer (XRD)are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. Secondary ion mass spectrometer (SIMS)is used to examine Cr, O and Ce element distribution in depth in oxide films. Results show that nano-ceria application greatly reduces the growth speed and grain size of Cr_2O_3 film, and this fine grained Cr_2O_3 film probably has better high temperature plasticity, i.e. , oxide film relieves part of the compressive stress by means of creeping. Meanwhile, CeO_2 changes the oxide film growth mechanism from predominant cation outward diffusion to anion in-ward diffusion. XRD and Raman testing results both show the stress declination effect due to nano-CeO_2 application, and their discrepancy in the rare earth effect is analyzed. 相似文献
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Rareearthsandtheiralloyshavespecificproperties ,suchasmagnetic ,optical,electricandhydrogenstorage .Theyhavebeenwidelyappliedtovariousfunctionalmaterials .TheLa Fealloyshavebeenappliedasmagneticmaterials .Sincerareearthelementsareveryactive,itisverydifficu… 相似文献
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采用Li2B4O7和LiNO3为熔剂,LiBr作脱膜剂,熔融法制备样品;运用干扰曲线法通过迭次校正Ba,Ti,V,Cr,Mn各元素谱线重叠干扰,理论α系数法校正基体效应,X-射线荧光光谱法(XRF)分析了复杂体系炉渣中Na2O,MgO,Al2O3,SiO2,P2O5,K2O,CaO,TiO2,V2O5,Cr2O3,MnO,TFe,BaO 13种组分。该方法与化学法测定结果符合较好,10次制样测量各组分,相对标准偏差在0.15%~3.79%范围内。 相似文献
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Two kinds of Cu-Al_2O_3 composites(with and without La) were prepared via mechanical alloying-spark plasma sintering(MA-SPS) method. Microstructure, mechanical properties and electrical resistivity were investigated systematically using metallography, scanning electron microscopy, transmission electron microscopy, mechanical and electrical properties testing. The results indicate that an appropriate amount of La can homogenize the distribution of Al_2O_3. As such, yield strength, ultimate tensile strength and elongation of Cu-Al_2O_3-La are greatly increased. Some semi-coherent interface between Cu and Al_2O_3 is found, which means a low interface energy. The grain shape of Cu changes to irregular band with the addition of La. This change results in a density decrease of grain boundary and reduces electrical resistance. Lanthanum may exist in the form of La_2O_3. 相似文献
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《中国稀土学报(英文版)》2020,38(9):941-950
Copper and cobalt oxides supported on CeO_2 were investigated for preferential oxidation of carbon monoxide(CO-PROX) in the presence of excess hydrogen and CO_2.(Cuo)_(1-x)(Co_3 O_4)_(x/3)-(CeO_2)_(2.5)(x=0,0.25,0.50,0.75,0.85 and 1) catalysts were prepared by coprecipitation method.These mixed oxide catalysts were characterized by several physicochemical techniques,such as BET surface area(S_(BET)),X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),temperature programmed reduction(TPR) and X-ray photoelectron spectroscopy(XPS).XRD studies show the peaks related to CuO and Co_3 O_4 phases in copper and cobalt containing CeO_2 catalysts.The average particle size of the CeO_2 crystallites is in the range of 8-10 nm as evaluated from HRTEM studies.XPS studies demonstrate that Cu,Co and Ce in(cuO)_(1-x)(Co_3O_4)_(x/3)-(CeO_2)_(2.5) catalysts are presented in+2 and +1,+3 and +2 and +4 and +3 oxidation states,respectively.The catalyst with x=0.75 shows better activity and selectivity towards CO-PROX.Though the catalyst with only copper(CuO-CeO_2,x=0) shows good activity but reverse water gas shift(RWGS) reaction is noticed at high temperature.On the other hand,RWGS reaction is suppressed on the cobalt containing CuO-ceO_2 catalyst.Cobalt on CeO_2 with x=1 shows hardly any activity for PRoX reaction at low temperatures.No methanation activity is observed on CuO-CeO_2 or Co_3O_4-CeO_2 catalysts.In contrast,combination of copper and cobalt on CeO_2 shows methanation of CO where enhanced activity is observed with increasing in cobalt content. 相似文献
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通过CaO-Bao-CaF_2-CaCl_2渣和Fe-Cr-C-P熔体间的分配平衡实验,研究磷、铬在该渣中的行为。结果表明,在一定范围内,增加渣中的BaO和CaCl_2含量,磷酸盐容量增加,铬酸盐容量的变化则较小。根据实验结果的综合分析说明,该渣对fE-Cr熔体具有较理想的脱磷保铬能力。在此基础上,在实验室内用该渣对含铬30%的Fe-Cr合金进行了氧化脱磷的应用性试验,试验结果表明,适当的低温和BaO和Fe_2O_3添加量可获得大于50%的脱磷率,铬几乎无烧损。 相似文献
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自蔓延高温合成是制备材料的一种新工艺。通过热力学和显微结构分析研究了Al-Cr2O3-ZrO2系统,结果表明:在Al:Cr2O3:ZrO2=1:2.8:1.43(wt)时,可以自蔓延高温合成Al2O3-ZrO2-Cr复合材料,ZrO2不与Al发生反应,产物孔隙度达35%-45%。 相似文献
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S. K. Datta S. N. Tewari J. E. Gatica W. Shih L. Bentsen 《Metallurgical and Materials Transactions A》1999,30(1):175-181
Porous carbon-carbon preforms, based on three-dimensional networks of PAN (Polyacrylonitrile)-based carbon fibers and various
volume fractions of chemical vapor-deposited (CVD) carbon, were impregnated by oxygen-free, high-conductivity (OFHC) Cu, Cu-6Si-0.9Cr,
and Cu-0.3Si-0.3Cr (wt pct) alloys by pressure infiltration casting. The obtained composites were characterized for their
coefficient of thermal expansion (CTE) and thermal conductivity (K) along the through-thickness and two in-plane directions. One composite, with a 28 vol pct Cu-0.3Si-0.3Cr alloy, showed outstanding
potential for thermal management applications in electronic applications. This composite exhibited approximately isotropic
thermal expansion properties (CTE=4 to 6.5 ppm/K) and thermal conductivities (k≥260 W/m K). 相似文献
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通过粉末冶金法制备了Ti-xCr、Ti-yCu及Ti-xCr-yCu钛基材料,研究了Cr、Cu含量对其相组成、显微组织、压缩屈服强度、弹性模量以及切削加工性能的影响规律。结果表明:随Cr含量的增加,Ti-xCr钛基材料依次出现了Ti_4Cr、TiCr_2及Cr相,其压缩屈服强度表现出先增大后减小的趋势,当Cr含量为10%时其屈服强度达到最大值(710 MPa),同时,添加Cr元素有利于降低钛基材料的弹性模量,最低可达25 GPa。添加Cu元素的钛基材料,随Cu含量的增加,Ti_2Cu相增加,并且显微组织细化,屈服强度降低;弹性模量受Cu含量影响较小而受烧结温度影响较大。添加Cr和Cu元素的钛基材料,其显微组织主要为网篮组织,弹性模量低于纯钛,其中添加Cu元素有利于细化层片,添加Cr元素有利于细化等轴组织。此外,Cr含量为5%时,钛基材料具有较佳的切削加工性能。 相似文献
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S. Floreen 《Metallurgical and Materials Transactions A》1982,13(11):2003-2013
A series of lower Cr stainless steels containing various levels of Mo, Si, Cu, V, N, and Ni were examined. In less severe
environments it was possible to achieve corrosion resistance comparable to 18-8 type stainless steels in alloys containing
about 9 pct Cr, along with additions of Ni, Mo, Cu, and V. The hot working behavior, weldability, and mechanical properties
appear comparable to conventional grades of stainless. Alloys of this type could be used in decorative, aqueous, and some
industrial applications, but should not be adequate for more severe environments. 相似文献
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In order to investigate the effect of different B-site additions on phase structure and electrochemical properties of cobalt-free La-Mg-Ni based alloys, La0.80Mg0.20Ni2.85Al0.11M0.53 (M=Ni, Si, Cr, Cu, Fe) hydrogen storage alloys were prepared and studied systemati-cally. X-ray powder diffraction showed that the alloys consisted mainly of LaNi3 phase and LaNi5 phase except that Cr addition caused a minor Cr phase. Electrochemical testing indicated that alloys with additional Ni, Cr, Cu or Fe were activated within only 1-2 cycles, while that with Si addition needed 4 cycles. Adding Si, Cu and Fe increased cycling stability of La-Mg-Ni based alloys. However, maximum discharge capacity decreased from 362 mAh/g to 215 mAh/g in the order of Ni>Fe>Cu>Cr>Si. In addition, electrochemical kinetics of alloy electrodes was also researched by measuring high rate discharge ability (HRD), hydrogen diffusion coefficient (D) and limiting current density (IL). 相似文献
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铅基弛豫铁电体陶瓷材料PMN-PT制备及研究进展 总被引:3,自引:3,他引:0
铅基弛豫铁电陶瓷材料Pb(Mg1/33Nb2/3)O3-PbTiO3(PMN—PT)具有优异的介电、压电性能,其单晶更具有潜在的应用前景.综述了近年来国际上铅基弛豫铁电陶瓷材料PMN—PT的合成及研究进展,并对近年来出现的颇有应用价值的几种制备技术及其特点进行了综合评述,同时指出目前研究中存在的主要问题,并提出了今后研究的方向。 相似文献
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CSP流程薄板坯及热轧板卷氧化皮组织演变 总被引:1,自引:0,他引:1
采用SEM和XRD方法对CSP冷轧冲压用钢薄板坯和热轧板氧化皮进行了研究。结果表明:覆盖在板坯表面的氧化皮对氧化性炉气的高温腐蚀有明显保护作用,均热前后Fe2O3:Fe3O4:FeO为5:35:60,新鲜基体腐蚀严重些,Fe2O3和Fe3O4含量增加到28%和64%;卷取后快冷钢的氧化皮以2层结构为主,Fe2O3:Fe3O4:FeO为6:31:63,缓冷钢的氧化皮中析出了弥散或薄片状的Fe相,Fe2O3:Fe3O4:FeO:Fe为8:73:15:4,二者厚度相差不大;卷取温度升高,快冷钢的Fe2O3和Fe3O4的含量略有降低,但缓冷钢中残余FeO含量明显减少,不利于酸洗。 相似文献