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101.
Zubair Ahmad Tianyu Ma Shan TaoMi Yan 《Journal of magnetism and magnetic materials》2012,324(8):1534-1538
The Fe63B23Nd7Y3Nb3Cr1 nanocomposite magnets in the form of sheets have been prepared by copper mold casting technique. The phase evolution, crystal structure, microstructural and magnetic properties have been investigated in the as-cast and annealed states. The as-cast sheets show magnetically soft behaviors which become magnetically hard by thermal annealing. The optimal annealed microstructure was composed of nanosize soft magnetic α-Fe (19-29 nm) and hard magnetic Nd2Fe14B (45-55 nm) grains. The best hard magnetic properties such as intrinsic coercivity, jHc of 1119 kA/m, remanence, Br of 0.44 T, magnetic induction to saturation magnetization ratio, Mr/Ms=0.61 and maximum energy product, (BH)max of 55 kJ/m3 was obtained after annealing at 680 °C for 15 min. The annealing treatment above 680 °C results in non-ideal phase grains growth, which degrade the magnetic properties. 相似文献
102.
H. Yako T. Kanomata K. Endo R.Y. Umetsu A. FujitaR. Kainuma H. NishiharaK.R.A. Ziebeck 《Physica B: Condensed Matter》2012,407(3):311-315
X-ray powder diffraction and magnetization measurements have been carried out on Rh2Mn1+xSn1−x (0≤x≤0.3) alloys. The alloys, which crystallize in the L21 structure, were found to exhibit ferromagnetic behavior. The lattice constant a at room temperature decreases with increasing x, whereas the Curie temperature TC decreases linearly. At 5 K the magnetic moment per formula unit first increases with increasing x and then saturates for x≥0.2. The experimental results are discussed in terms of the influence of the Mn-Mn exchange interactions between the Mn atoms on the Sn and Mn sites. 相似文献
103.
将平均晶粒尺寸为4.6 nm的金粒子通过静电作用粘附于聚苯乙烯(PS)微球表面用于化学镀,化学镀金后PS表面的金沉积层几乎达到完全包覆,厚度70~90 nm;在Au/PS表面进行化学镀银,沉积的银颗粒堆积紧密,颗粒大小较先前沉积的金颗粒大,镀覆层厚度增厚至200~400 nm;模板去除后,获得了完全自支撑的Au40Ag60空心微球结构的圆柱状泡沫材料。制备的金银合金泡沫由直径约10 m的空心球壳组成,圆柱体直径约5 mm,密度约1.2 g/cm3。 相似文献
104.
In this paper, we investigated the electrochemical and surface behavior of hydroxyapatite (HA)/Ti films on the nanotubular Ti-35Nb-xZr alloy. The Ti-35Nb-xZr ternary alloys with 3-10 wt.% Zr content were made by an arc melting method. The nanotubular oxide layers were developed on the Ti-35Nb-xZr alloys by an anodic oxidation method in 1 M H3PO4 electrolyte containing 0.8 wt% NaF at room temperature. The HA/Ti composite films on the nanotubular oxide surfaces were deposited by a magnetron sputtering method. Their surface characteristics were analyzed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and an X-ray diffractometer (XRD). The corrosion behavior of the specimens was examined through potentiodynamic and AC impedance tests in 0.9% NaCl solution. From the results, the Ti-35Nb-xZr alloys showed a solely β phase microstructure that resulted from the addition of Zr. The nanotubular structure formed with a diameter of about 200 nm, and the HA/Ti thin film was deposited on the nanotubular structure. The HA/Ti thin film-coated nanotubular Ti-35Nb-xZr alloys showed good corrosion resistance in 0.9% NaCl solution. 相似文献
105.
高择优锌-镍合金电沉积的现场ECSTM研究 总被引:1,自引:0,他引:1
采用"二步包封"法制备了性能良好的电化学STM针尖.以此为基础采用ECSTM现场研究了工艺条件下HOPG上高择优锌-镍合金的电沉积过程.研究结果表明这种高择优沉积层以侧向生长方式生长,而表面上电化学活性差的晶面构成了晶体生长过程的保留面,从而进一步形成了与基底表面方向一致的高择优沉积层,X射线研究表明这一择优面为(100)晶面. 相似文献
106.
《Electroanalysis》2006,18(1):35-43
A new method is presented for the determination of electrochemically labile iron in estuarine and coastal seawater. The method is based on differential pulse anodic stripping voltammetry (DPASV) at a rotating silver‐alloy disk electrode. The voltammetric parameters include a plating potential of ?1.5 V and an activation potential of ?5 V for 10s; the seawater is at the original sample pH. The main finding is the presence of a peak for low nmol L?1 levels of iron at ?0.55 V ascribed to elemental iron deposited on the bare silver alloy electrode. The peak increased linearly with the iron concentration between <1 and 14 nmol L?1 using a 900 s plating time. At higher concentrations an additional iron peak appeared at ?0.7 V which was also found to increase linearly with the iron concentration but at a higher concentration range from ca. 15 to 90 nmol L?1 using a 300 s plating time. The second peak was ascribed to iron deposited on iron. Additions of chelating agents (EDTA and a siderophore) to seawater caused the iron peak to be masked indicating that this method is suitable for iron speciation as only the electrochemically labile fraction is determined. The detection limit was 0.3 nmol L?1 using a 900 s plating time. The method was used to determine iron in the range of 5 to 50 nmol L?1 in samples from the Mersey estuary near Liverpool and its potential use for in situ monitoring was demonstrated by using it to monitor labile iron (at 2–3 nmol L?1) over a period of 4 days at 1 h intervals in coastal waters in the Trondheim fjord, Norway. 相似文献
107.
Troy A. Lowe Gordon G. Wallace Aaron K. Neufeld 《Journal of Solid State Electrochemistry》2009,13(4):619-631
Electrochemical polarisation experiments have shown that anodic dissolution processes on Al–40% Zn alloys are significantly
enhanced in chloride compared to sulfate-based electrolytes. The aluminium content of the alloys allowed passive behaviour
to be observed in sulfate electrolyte even in the presence of zinc-rich precipitates on the surface. Electrolyte pH affected
cathodic processes, which was attributed to the rate of proton reduction and the passivity of the surface. Monitoring the
OCP of the alloy band during polarisation of neighbouring zinc electrodes in band microelectrode (BME) arrays showed that
generation of alkaline pH at the zinc electrodes affected the OCP of the alloy when the inter-electrode spacing was 10, 50,
and 200 μm. Where elements of a BME array were close enough to interact via mass transport, the overall galvanic behaviour
of the cell was found to be anodic or cathodic, whereas the alloy was consistently cathodic with respect to zinc in galvanic
cells at larger separations.
Dedicated to the 80th birthday of Keith B. Oldham. 相似文献
108.
《Electroanalysis》2004,16(7):532-538
The cathodic reduction of NO in 1.0 M HClO4 is investigated by voltammetry at pure Ni and Cu electrodes, and three Cu‐Ni alloy electrodes of varying composition, all configured as rotated disks. Voltammetric data obtained using these hydrodynamic electrodes demonstrate significantly improved activity for NO reduction at Cu‐Ni alloy electrodes as compared to the pure Ni and Cu electrodes. This observation is explained on the basis of the synergistic benefit of different surface sites for adsorption of H‐atoms, generated by cathodic discharge of H+ at Ni‐sites, and adsorption of NO at Cu‐sites on these binary alloy electrodes. Koutecky‐Levich plots indicate that the cathodic response for NO at a Cu75Ni25 electrode corresponds to an 8‐electron reduction, which is consistent with production of NH3. In comparison, the cathodic response at Cu50Ni50 and Cu25Ni75 electrodes corresponds to a 6‐electron reduction, which is consistent with production of NH2OH. Flow injection data obtained using Cu50Ni50 and Cu25Ni75 electrodes with 100‐μL injections exhibit detection limits for NO of ca. 0.95 μM (ca. 95 pmol) and 0.60 μM (ca. 60 pmol), respectively. 相似文献
109.
110.
EXAFS研究Ni-B和Ni-Ce-B超细非晶态合金的退火晶化 总被引:1,自引:0,他引:1
采用同步辐射EXAFS技术定量地研究化学还原法制备的Ni-B和Ni-Ce-B超细非晶态合金中Ni原子的局域环境结构随退火温度升高而产生的变化,结果表明,对于Ni-B和Ni-Ce-B超细非晶态合金初始样品:Ni-Ni最邻近配位壳层的平均键长RNi-Ni、配位数N、热无序σT、结构无序σs分别为0.275nm,11.9.0.0069nm,0.034nm;0.276nm,12.4,0.0067nm,0.035nm,Ni-B最邻近配位壳层的RNi-B,N, σT,σs分别为0.215nm,2.7,0.0055nm,0.0048nm;0.214nm,2.0,0.0058nm,0.0042nm,Ni-Ni配位的σs很大,是其σT的4-5倍,比Ni-B配位的σs大近一个数量级,在300℃退火后,Ni-B样品开始发生晶化生成晶态Ni3B,其RNi-Ni和σs分别为0.254nm和0.011nm,σs降低近2倍;而.3%原子比的Ce掺入后使Ni-Ce-B超细非晶态合金的晶化温度升高100℃左右。在500℃退火后,Ni-B样品的结构参数与Ni箔的相近,但Ni-Ce-B样品中的Ni-Ni配位的σs仍为0.0073nm,Ni-B配位的N为1.2,表明稀土元素Ce(以CeO2)显著增强了Ni与B的相互作用,且同时使退火晶化成的Ni晶结构产生畸变。 相似文献