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1.
《International Journal of Hydrogen Energy》2022,47(91):38682-38689
A body-centered cubic equiatomic TiZrTaNbAl multi-principal element alloy (MPEA) with elemental fluctuations was investigated to further understand the relationship between the microstructure and hydrogen distribution. In this study, a composition dependence of the hydrogen distribution was observed in the TiZrTaNbAl MPEA. An inhomogeneous electron density distribution of the MPEA was revealed by advanced differential phase-contrast scanning electron microscopy (DPC-STEM) for the first time. The results showed that the electron density has a significant effect on the hydrogen distribution in TiZrTaNbAl MPEAs. This work provides new insight into the design of materials with high hydrogen storage capacity and high hydrogen embrittlement resistance. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(52):22165-22179
Aluminum alloy bipolar plates have unique application potential in proton exchange membrane fuel cell (PEMFC) due to the characteristics of lightweight and low cost. However, extreme susceptibility to corrosion in PEMFC operation condition limits the application. To promote the corrosion resistance of aluminum alloy bipolar plates, a Ni–P/TiNO coating was prepared by electroless plating and closed field unbalanced magnetron sputter ion plating (CFUMSIP) technology on the 6061 Al substrate. The research results show that Ni–P interlayer improves the deposition effect of TiNO outer layer and increase the content of TiN and TiOxNy phases. Compared to Ni–P and TiNO single-layer coatings, the Ni–P/TiNO coating samples exhibited the lowest current density value of (1.10 ± 0.02) × 10?6 A·cm?2 in simulated PEMFC cathode environment. Additionally, potential cyclic polarization measurements were carried out aiming to evaluate the durability of the aluminum alloy bipolar plate during the PEMFC start-up/shut-up process. The results illustrate that the Ni–P/TiNO coating samples exhibit excellent stability and corrosion resistance. 相似文献
3.
《Ceramics International》2021,47(23):33353-33362
High thermal conductivity Si3N4 ceramics were fabricated using a one-step method consisting of reaction-bonded Si3N4 (RBSN) and post-sintering. The influence of Si content on nitridation rate, β/(α+β) phase rate, thermal conductivity and mechanical properties was investigated in this work. It is of special interest to note that the thermal conductivity showed a tendency to increase first and then decrease with increasing Si content. This experimental result shows that the optimal thermal conductivity and fracture toughness were obtained to be 66 W (m K)-1 and 12.0 MPa m1/2, respectively. As a comparison, the nitridation rate and β/(α+β) phase rate in a static pressure nitriding system, i.e., 97% (MS10), 97% (MS15), 97% (MS20) and 8.3% (MS10), 8.3% (MS15), 8.9% (MS20), respectively, have obvious advantages over those in a flowing nitriding system, i.e., 91% (MS10), 91% (MS15), 93% (MS20) and 3.1% (MS10), 3.3% (MS15), 3.3% (MS20), respectively. Moreover, high lattice integrity of the β-Si3N4 phase was observed, which can effectively confine O atoms into the β-Si3N4 lattice using MgO as a sintering additive. This result indicates that one-step sintering can provide a new route to prepare Si3N4 ceramics with a good combination of thermal conductivity and mechanical properties. 相似文献
4.
Grain refinement is critical for fabricating high-quality Al-Si casting components in the application of automobile and aerospace industries,while the well-known Si-poisoning effect makes it difficult.Nbbased refiners offer an effective method to refine Al-Si casting alloys,but their anti Si-poisoning capability is far from being understood.In this work,the grain refining mechanism and the anti Si-poisoning effect in the Al-10 Si/Al-5 Nb-B system were systematically investigated by combining transmission electron microscope,first-principles calculations,and thermodynamic calculations.It is revealed that NbB2provides the main nucleation site in the Al-10 Si ingot inoculated by 0.1 wt.%Nb Al-5 Nb-B refiner.The exposed Nb atoms on the(0001)NbB2and(1-100)NbB2surface can be substituted by Al to form(Al,Nb)B2intermedia layers.In addition,a layer of NbAl3-like compound(NbAl3')can cover the surface of NbB2with the orientation relation of(1-100)[11-20]NbB2//(110)[110]NbAl3'.Both of the(Al,Nb)B2and NbAl3'intermedia layers contribute to enhancing the nucleation potency of NbB2particles.These discoveries provide fundamental insight to the grain refining mechanism of the Nb-B based refiners for Al-Si casting alloys and are expected to guide the future development of stronger refiners for Al-Si casting alloys. 相似文献
5.
A new technique of EDM coring of single crystal silicon carbide (SiC) ingot was proposed in this paper. Currently single crystal SiC devices are still of high cost due to the high cost of bulk crystal SiC material and the difficulty in the fabrication process of SiC. In the manufacturing process of SiC ingot/wafer, localized cracks or defects occasionally occur due to thermal or mechanical causes resulted from fabrication processes which may waste the whole piece of material. To save the part of ingot without defects and maximize the material utilization, the authors proposed EDM coring method to cut out a no defect ingot from a larger diameter ingot which has localized defects. A special experimental setup was developed for EDM coring of SiC ingot in this study and its feasibility and machining performance were investigated. Meanwhile, in order to improve the machining rate, a novel multi-discharge EDM coring method by electrostatic induction feeding was established, which can realize multiple discharges in single pulse duration. Experimental results make it clear that EDM coring of SiC ingot can be carried out stably using the developed experimental setup. Taking advantage of the newly developed multi-discharge EDM method, both the machining speed and surface integrity can be improved. 相似文献
6.
Qi Yang Qilong Wu Yang Liu Shuiping Luo Xiaotong Wu Xixia Zhao Haiyuan Zou Baihua Long Wen Chen Yujia Liao Lanxi Li Pei Kang Shen Lele Duan Zewei Quan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(36):2002822
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO. 相似文献
7.
8.
In this study we analyze the optoelectronic properties and structural characterization of hydrogenated polymorphous silicon thin films as a function of the deposition parameters. The films were grown by plasma enhanced chemical vapor deposition (PECVD) using a gas mixture of argon (Ar), hydrogen (H2) and dichlorosilane (SiH2Cl2). High-resolution transmission electron microscopy images and Raman measurements confirmed the existence of very different internal structures (crystalline fractions from 12% to 54%) depending on the growth parameters. Variations of as much as one order of magnitude were observed in both the photoconductivity and effective absorption coefficient between the samples deposited with different dichlorosilane/hydrogen flow rate ratios. The optical and transport properties of these films depend strongly on their structural characteristics, in particular the average size and densities of silicon nanocrystals embedded in the amorphous silicon matrix. From these results we propose an intrinsic polymorphous silicon bandgap grading thin film to be applied in a p–i–n junction solar cell structure. The different parts of the solar cell structure were proposed based on the experimental optoelectronic properties of the pm-Si:H thin films studied in this work. 相似文献
9.
Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed. 相似文献
10.
《Intermetallics》2015
The structural changes induced in a CoCrCuFeNi multicomponent nano-crystalline high-entropy alloy (HEA) under fast electron irradiation were investigated by in-situ transmission electron microscopy (TEM) using a high voltage electron microscope (HVEM). A fine-grained face centered cubic (fcc) single phase was obtained in the sputtered specimens. The fcc solid solution showed high phase stability against irradiation over a wide temperature range from 298 to 773 K, and remained as the main constituent phase even when the samples were irradiated up to 40 displacement per atom (dpa). Moreover, the irradiation did not seem to induce grain coarsening. This is the first report on the irradiation damage in 5-component HEA under MeV electron irradiation. 相似文献