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1.
Nickel–phosphorus alloys were codeposited with boron carbide particles. Two compositions of nickel-phosphorus, one presenting a low phosphorus content in the order of 4% wt. and another one presenting a high phosphorus content of about 12% wt., were deposited from modified Watts nickel electrolytes using both direct and pulse plating. A strong influence of the deposition method was observed on the phosphorus content in the matrix and on the quantity of codeposited particles. Pulse plating was found to significantly increase both of them. Nucleation of the pure nickel–phosphorus alloy and of the codeposit were studied using chronoamperometry and AFM in potentiostatic mode. An instantaneous nucleation mechanism was evidenced on iron and gold substrates. Microhardness was measured and linked to the phosphorous and particle contents. 相似文献
2.
The formation of CoSi2 on strained epitaxial Si0.8Ge0.2/Si(100) films has been studied as a function of the deposition method and annealing temperature. Two types of deposition processes were used: a direct method, where 5 nm of pure Co metal were deposited at room temperature onto a strained 80 nm thick Si0.8Ge0.2 layer; and a co-deposition method, where 5 nm Co and 18.2 nm Si were simultaneously deposited in a 1:2 ratio onto a strained Si0.8Ge0.2 layer at 450°C. Samples were then annealed at temperatures ranging from 500 to 800°C. Extended X-ray absorbance fine structure spectroscopy (EXAFS) and X-ray diffraction (XRD) were used to characterize the structure of the resulting films. It was found that the samples prepared via the direct deposition method did not convert to CoSi2 at any annealing temperature up to 800°C, while the co-deposited samples formed epitaxial CoSi2 at even the lowest annealing temperature of 500°C. These results are discussed in terms of proposed reaction mechanisms of the different deposition methods, based on consideration of the Co–Si–Ge ternary phase diagram. 相似文献
3.
Thermodynamic study on co-deposition of ZrB2-SiC from ZrCl4-BCl3-CH3SiCl3-H2-Ar system 总被引:1,自引:0,他引:1
Thermodynamics phase diagram of ZrB2-SiC co-deposited from precursors of ZrCl4-BCl3-CH3SiCl3 (methyltrichlorosilane, MTS)-H2-Ar has been investigated in detail by using the FactSage code and its embedded database (130 species being involved). The yields of condensed phases in the co-deposition process have been examined as the functions of the inject reactant ratios of BCl3 / (BCl3 + MTS) and H2 / (ZrCl4 + BCl3 + MTS), and the temperature at a fixed pressure of 5 kPa. The results show that their yields strongly depend on the molar ratios of the inject reactants and the temperature. Consequently, the pure ZrB2-SiC composite without free C, B4C, ZrC and ZrSi can be co-deposited under the ideal condition by adjusting the reactant ratios and the temperature. The gas-phase equilibrium concentration distribution shows that the high input amount of H2 is favorable for the co-deposition of ZrB2 and SiC at a fixed ratio of ZrCl4:BCl3:MTS:Ar. In the end, the theoretical results can lay down guidelines for increasing the experimental yields of ZrB2 and SiC. 相似文献
4.
E. T. Croke R. J. Hauenstein C. W. Nieh T. C. McGill 《Journal of Electronic Materials》1989,18(6):757-761
A study of the growth parameters governing the nucleation of metastable superconducting A15 V3Si on Si and A12O3 is presented. Nominally, 500Å films of V1-xSix were produced through codeposition of V and Si onto heated (111) Si and (1102) A12O3 substrates. Samples were prepared in a custom-built ultrahigh vacuum (UHV) chamber containing dual e-beam evaporation sources and a high temperature substrate heater. V and Si fluxes were adjusted to result in the desired average film composition. V0.75Si0.25 films prepared at temperatures in excess of 550° C on Si show significant reaction with the substrate and are nonsuperconducting while similar films grown on A12O3 exhibit superconducting transition temperatures(@#@ Tc @#@) approaching bulk values for V3Si (16.6-17.1 K). Codeposition at temperatures between 350 and 550° C results in superconducting films on Si substrates while growth at lower temperatures results in nonsuperconducting films. Lowering the growth temperature to 400° C has been shown throughex situ transmission electron microscopy (TEM) and Auger compositional profiling to minimize the reaction with the Si substrate while still activating the surface migration processes needed to nucleate A15 V3Si. Variation of film composition aboutx = 0.25 is shown to result in nonsuperconducting films for highx and superconducting films with Tc approaching the bulk V value (5.4 K) for lowx. Finally, lowering the V0.75Si0.25 deposition rate is shown to raise Tc. 相似文献
5.
Codeposited PtSb/C catalysts for direct formic acid fuel cells 总被引:1,自引:0,他引:1
Xingwen YuPeter G. Pickup 《Journal of power sources》2011,196(19):7951-7956
Carbon supported PtSb catalysts were synthesized by codeposition of platinum and antimony on Vulcan® carbon black. X-ray diffraction (XRD) analysis revealed that the Sb was alloyed with the Pt while XPS indicated that a large fraction of the Sb was in an oxidized state, with only partial alloying. The performances of catalysts with a range of compositions were compared in a multi-anode direct formic acid fuel cell (DFAFC). A 0.29 mol fraction of Sb was found to provide the best performance with a maximum specific power output of 280 W g−1 Pt. CO stripping results indicated that the addition of Sb at this optimum level greatly suppressed both CO adsorption and H adsorption/desorption, as well as promoting oxidative stripping of CO. The results are compared with those for previously studied catalysts prepared by the reductive deposition of Sb on a carbon supported Pt catalyst. 相似文献
6.
DMF中电沉积制备Yb—Ni合金膜 总被引:2,自引:0,他引:2
研究了室温下含有少量水的YbCl3-NiCl2-DMF溶液中电沉积制备Yb-Ni合金膜。EDAX和XRD分析表明,在适当浓度的YbCl2-NiCl2的DMF电镀液中,控制电位进行恒电位电镀;控制电流密度进行恒电流电镀或进行脉冲电镀,可得到不同形态和Yb含量的共沉积合金膜。 相似文献
7.
碳纤维增强C—SiC梯度基复合材料研究 总被引:3,自引:0,他引:3
采用CVI工艺均热法共沉积技术制备了碳纤维增强C-SiC梯度基复合材料。C和SiC的原料氛分别是C2H2t CH3SiCl3,Ar和H2分别是载流和稀释气体。基体微观结构的变化通过控制原料气体的成分配比藜得。测试了材料的力学性能、抗氧化性能和摩擦磨损性能。利用金相技术、电子探针成分分析技术、TEM和SEM技术观察和分析了材料的微观结构。试验结果表明,这种材料的组织结构特点是:在微观上是梯度的,即围 相似文献
8.
Porous PbO2 electrodes have been prepared by anodic codeposition of PbO2 particles with an electrochemically grown PbO2 matrix, with the aim of illustrating how composite deposition may be a suitable method for obtaining electrodes of large and controlled surface roughness. By exploiting the different crystal structures of PbO2, the composition of α-PbO2+β-PbO2 composites (i.e. composites with an α matrix and a β dispersed phase) has been determined by X-ray diffraction. It has been found that reliable indications on composition of deposits may be also obtained by measuring the current efficiency of the deposition process, which largely exceeds unity in the case of composites. This way, the dependence of the dispersed phase concentration in the deposits on current density and suspended particles concentration has been determined. The surface roughness of the composite electrodes has been estimated by electrochemical impedance spectroscopy. It was found to increase almost linearly with the deposition charge and reach limiting values as either the deposition current density or the suspended particles concentration are increased. 相似文献
9.
《International Heat Treatment & Surface Engineering》2013,7(4):178-184
AbstractCr and Cr–Al2O3 coatings were electrodeposited from Cr(III) bath with both pulsating and direct current onto copper substrates. Pulsating current resulted in homogeneous films of higher Al2O3 content and lower particle agglomeration than the direct current. Differences were more tangible at shorter duty cycles and pulse frequencies. Pulsating current improved both microhardness and corrosion resistance. The presence of alumina nanoparticles resulted in greater current efficiency, higher film microhardness and better corrosion resistance. Maximum current efficiency, highest microhardness and densest electrodeposited coatings were achieved at current density of 20 A dm?2, duty cycle of 40% and pulse frequency of 10 Hz. 相似文献
10.
The thin films of AlxNb1 − x (95 ≥ x ≥ 20), AlxMox (90 ≥ x ≥ 20) and AlxTa1 − x (95 ≥ x ≥ 20) were prepared by magnetron codeposition at room temperature. The average film thickness was from 325 to 400 nm, depending on the film composition. The structure of the as-deposited films was examined by the X-ray diffraction. The stress of the films was determined from the substrate deformation by the profilometer, and the microhardness (load 2 mN) was examined by the micro- and nano-hardness device. For the purpose of the examination of the hardness, the samples were deposited onto the sapphire wafers, while the examination of the film stress, was performed by using thin glass substrates. For all the Al-(Nb, Mo, Ta) alloy compositions, the microhardness is predominantly under the influence of the harder element, and monotonically decreases with the increase of the aluminum content. However, the microhardness of the amorphous AlTa films was higher than the bulk value of a harder element (Ta) in the alloy. A simple empirical linear relationship between the Vickers hardness, the bulk value hardness of the transition metal (harder element) and the elastic energy fraction of the identation deformation, was established. The elastic energy fraction in the microhardness is also linearly correlated with the stress in films. 相似文献