Understanding the relationship between the acceptor dopant size and proton conductivity in barium zirconate, BaZrO3, is important for maximizing efficiency in this promising fuel cell material. While proton conduction pathways with larger YZr′ and smaller AlZr′ defects have been explored, proton pathways with ScZr′, a defect of comparable size to the replaced ion, have not been investigated using centrality measures, periodic pathway searches, and kinetic Monte Carlo (KMC). Centrality measures in BaSc0.125Zr0.875O3 highlight a trapping region by ScZr′ and scattered high centrality regions on undoped planes. Connected long-range high centrality regions are found mainly in undoped planes for BaAl0.125Zr0.875O3 and in the dopant planes for BaY0.125Zr0.875O3. The best long-range proton conduction periodic pathways in AlZr′ and ScZr′ systems travel between dopant planes, while those for yttrium-doped BaZrO3 remained on dopant planes. KMC trajectories at 1000 K show long-range proton conduction barriers of 0.86 eV, 0.52 eV, and 0.25 eV for AlZr′, ScZr′, and YZr′ systems, respectively. Long-range periodic conduction highway limiting barrier averages correlate well with the connectivity of the most central regions in each system but ignore diffusion around the dopant and through other high centrality regions. BaSc0.125Zr0.875O3 shows an intermediate overall conduction barrier limited by trapping, which earlier experiments and simulations suggest that it can be mitigated with increased oxygen vacancy concentration.
AbstractAbstractNiCrAl/20%WC coatings were prepared by laser cladding on 45 steel under different technological parameters. The effects of technological parameters on the microstructure, microstructure, hardness and wear resistance were investigated. The results show that with the increase of the scanning speed, the height, width, depth and dilution rate of the cladding layer gradually decrease, the microstructure becomes smaller and smaller, the hardness gradually increases, and the wear amount decreases first and then increases, and the wear amount is the least when the scanning speed is 600 mm/min. With the increase of laser power, the height, width, depth and dilution rate of cladding layer gradually increase. The hardness gradually decreases; The wear decreases first and then increases, and the wear is the least when the laser power is 1.2 kW.Keywords: Laser claddingprocess parameterswear-resisting performance Additional informationFundingThe work was supported by Xi’an Science and Technology Project No. 22GXFW0120-5, and the Team of Shaanxi Intelligent Remanufacturing Technology; Natural Science Basic Research Program of Shaanxi No.2022JM-187.
The site preference of co-alloying elements pair W-X (Cr, Mo, W, Re and Ru) in Ni3Al system and the co-alloying elements pair strengthen the shear deformation resistance of Ni3Al were investigated using the first principles density functional theory. It was found that the atom pair preferred Al-Al site. The shear resistance of Ni3Al was significantly improved by alloying atom pairs, where W-Re and W-W were most beneficial for ideal shear strength, respectively. The result of electronic structure shown that the strong interaction between the alloy atoms and their common FNN Ni atoms was the strengthening mechanism.
AbstractNiCrAl/20%WC/MoS2 composite coatings with different MoS2 additions were prepared on the surface of 45 steel by laser cladding technology. The effects of MoS2 content on the microstructure, hardness and antifriction and wear resistance of the cladding layer were mainly studied. The results show that the content of lubricating phase has a certain influence on the hardness, anti-friction and wear resistance. With the increase of MoS2 content, the microstructure is gradually refined; the hardness gradually increases; the friction coefficient first decreases and then increases, and when the MoS2 content is 5%, the friction coefficient is at least 0.55; the wear volume first decreases and then increases, and the MoS2 addition amount is 5% When the wear volume is the smallest, the wear resistance is increased by 79% compared with the 45 steel substrate. Comprehensive analysis shows that the optimum addition amount of MoS2 is 5%.Keywords: Laser claddingNi-based composite coatinganti-friction and wear-resistance AcknowledgmentsSincere thanks to the Team of Shaanxi Intelligent Remanufacturing Technology for its support.
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