Papers by Keyword: Pd

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Authors: Ke Jing Yang, Yulia Ivanisenko, J. Markmann, Hans Jorg Fecht
Abstract: In situ tensile tests were conducted on ultra fine grained (UFG) pure Pd and Pd-x% Ag (x=20, 60) alloys of different stacking fault energies (SFEs) with the aim to study the general features of the deformation process of UFG materials as well as the peculiarities brought by the alloying. Grey scale correlation analysis (GSCA) was used to determine the true strain as well as the surface flow within the gauge length. It was shown that the largest values of strength and uniform elongation were obtained in Pd-20% Ag alloy. The GSCA revealed different macroscopic flow processes in this sample as compared with pure Pd and Pd-60% Ag alloy. In particular, pure Pd and Pd-60% Ag alloy demonstrated rapid localization of plastic flow in the neck area, whereas Pd-20% Ag samples showed a large contribution of homogenous deformation even after neck formation. It has been proposed that larger strain hardening capacity of Pd-20% Ag alloy is related to its lower SFE as compared with that of pure Pd: the lower is the SFE, the more difficult is the cross slip and climb of split dislocations, which leads to enhanced dislocation storage and, ultimately, to increased strain hardening. At the same time, further decrease of SFE in Pd-60% Ag sample leads to development of deformation twinning and consequent reduction of strain hardening. The dimpled structure of fracture surfaces in the samples will also be discussed in relationship to these findings.
Authors: Ming Xing Shi, Bi Yu Tang, Ao Peng
Abstract: It’s important to get accurate carrier phase and frequency information when using a standalone GPS receiver. In weak signal applications, to keep a stable tracking is hard to achieve because measuring error will be huge when the SNR is low. Different methods are used to improve the SNR before the detector in a tracking process, such as coherence integration. And this paper keeps eyes on a different viewpoint, on how to refine estimation results. A cascade structure is introduced for weak signal tracking. This structure is divided into two levels. In the first level, raw phase estimation and accurate frequency estimation is provided to achieve stable work in low CNR environment. In the second level, the raw phase estimation is refined to achieve accurate tracking requirement. This cascade structure can also work jointly with any other SNR-improving technology to get a better performance.
Authors: Zhi Yuan Zhang, Fu Shen Zhang
Abstract: In the present study, a green process for cuprous chloride synthesis from waste printed circuit boards (PCBs) was developed. High value-added cuprous chloride (98.7% purity) was obtained by treating metallic particles of waste PCBs with solution of cupric sulfate and sodium chloride. Typical noble metal (Pd) was dissolved by forming a stable chloride complex during the synthesis process as Cu2+ played the role of oxidant or concentrated in the residue. Under the optimum condition (VNaCl/mCuSO4 ratio = 6, [C/[Cu2+] mole ratio = 1.05, treatment time = 30 min, operation temperature = 60 °C), yield of cuprous chloride was 74.0% and approximately 98.5% of the copper could be recovered. It is believed that the process proposed is effective and practical for Cu recovery from waste PCBs.
Authors: Wei Jie Lu, D.T. Shi, T.R. Crenshaw, A. Burger, W.E. Collins
Authors: Li Song Tian, Wei Xuan Chen
Abstract: The partial discharge (PD) detection systems are often vulnerable to strong external interferences, and sometimes the PD signals are submerged in noises (white noise for example) completely. So the signals acquired must be preprocessed to obtain the reliable PD information. While there are many methods for white noise denoising, mostly are not very suitable for partial discharge. The wavelet transform (WT) coefficient of PD and white noises have different spread characteristics in different WT scales. Based on the Information Theory, The Minimum Information Description Length (MDL) criterion is a optimization strategy, a small amount of signal parameter is requried to the PD signals representation, the paper proposes a wavelet spatial correlation algorithm to partial discharge denoising based on MDL criterion: optimal wavelet function is selected based on MDL, then have the white noise reduced in WT, the algorithm has wonderful virtues such as free from any parameters estimation about noise, free from presetting threshhold and threshold chooseing behavior, so the algorithm is highly adaptive. Large amount of experimental results illustrate that the method presented in this paper are efficient and feasible and outperforms other general method of PD noise reduction.
Authors: Dao Hua Sun, Peng Yao Li, Xue Liang Li
Abstract: We report the facile synthesis of triangular Pd nanoplates using aqueous extract of Syzygium Samarangense leaf. The morphology and structure of the obtained Pd nanoplates were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. FTIR spectra indicated that C=C, COH, and OCOH were mainly responsible for the formation of the Pd nanoplates.
Authors: You Ming Cao
Abstract: Pd catalyst is very active in Suzuki reaction. As a heterogeneous catalyst, SWNTs/Pd shows highly catalytic ability with Suzuki reaction. We will demonstrate the effect of catalyst’s amount, the reaction time and temperature on Suzuki reaction in this work. In comparison, a control experiment used commercial Pd/C as catalyst in Suzuki reaction has been done. An optimum reaction condition of about reacting 60 min at 50°C with 5% (mass%) catalyst is confirmed finally, and a better catalytic ability of SWNTs/Pd than commercial Pd/C is also observed.
Authors: Samantha Zimnik, Christian Piochacz, Sebastian Vohburger, Christoph Hugenschmidt
Abstract: We report on time-dependent Positron annihilation induced Auger Electron Spectroscopy (PAES) study on 0.5 monolayers (ML) Ni on polycrystalline Pd accompanied by complementary X-ray induced Photoelectron Spectroscopy (XPS). The normalized PAES spectra showed a significant decrease in the Ni intensity and an increase in the Pd intensity as a function of time. To rule out varying influence on the elements e.g. from surface contaminates due to the residual gas, a time-dependent XPS analysis was performed on pure Ni and Pd as well as to analyze the main contaminants C and O. The O fraction was found to be constant within the measurement time and the time constants for C significantly differ from those of Ni and Pd in the PAES data. Consequently, it was concluded that the PAES data show a superposition of C contamination and structural changes at the surface of Ni/Pd.
Authors: Yulia Ivanisenko, Hans Jörg Fecht
Abstract: Instrumented high pressure torsion, i.e. mechanical test in a torsion mode under high pressure, allows interesting possibility of materials testing, because materials mechanical response can be studied in a practically unlimited shear strain range. We have studied microstructures formed in initially coarse crystalline and nanocrystalline (nc) Pd and its alloys after instrumented HPT up to shear strain 300, and revealed signatures of similar processes occurring in all these materials. In particular, we found traces of cooperative grain boundary sliding in the form of aligned in parallel segments of boundaries of several grains with straightened triple points. Fracture surfaces contained shear bands. Texture measurements revealed lower dislocation activity in nanocrystalline state as compared with coarse crystalline one. Therefore we argue that cooperative grain boundary sliding is an important deformation mechanism at large strain which develops in both ultrafine grained (ufg) and nanocrystalline materials. In nc and ufg materials planes of cooperative grain boundary sliding act as precursors of shear bands and shear occurs along planes formed by numerous grain boundaries.
Authors: Ichiro Yamanaka, Yuta Nabae
Abstract: Steady generation of electricity (360 mW cm-2 at 1173 K) with dry methane fuel was successfully performed in solid oxide fuel cells (SOFC) by Pd-Ni bimetallic catalyst on porous composite anode prepared from La0.8Sr0.2CrO3 (LSCr) and Ce0.8Sm0.2O1.9 (SDC) (50:50 wt%). The amounts of carbon deposition were quite small under the open and closed circuit conditions. Synergy of Pd and Ni electrocatalysts was observed on the LSCr-SDC anode for the oxidation of dry methane. A small amount of carbon deposition over the anode during the open circuit conditions could be easily and quickly removed by gasification with steam. Data of detailed kinetic studies and electrochemical analysis strongly suggest that (i) methane decompose to hydrogen and carbon over the Pd-Ni catalyst, (ii) hydrogen is electrochemically oxidized with O2- to water, and (iii) carbon is quickly reformed with water to hydrogen and carbon oxides.
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