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1.
The aim of this study was to determine the influence of severe plastic deformation processing and the changes in microstructure resulting therefrom on the corrosion resistance of an Al–Mg–Si alloy. The alloy was processed using incremental equal channel angular pressing, which caused a reduction in grain size from 15 to 0.9 µm. The grain refinement was accompanied by an increase in the number of grain boundaries and dislocations, and by changes in grain orientation. However, there was no change in the size and number of intermetallic particles, which presumably resulted in a constant number of galvanic couplings. Electrochemical experiments revealed only slight differences between the samples before and after processing. Higher potential transients/oscillations upon immersion and increased corrosion currents in the vicinity of corrosion potential point to slightly higher reactivity of the most refined material. This indicates that intermetallic particles are the most crucial microstructural elements in terms of corrosion resistance. Their impact exceeds that of grain boundaries, in particular, at the stage of corrosion initiation. The development of corrosion attack is controlled more by the microstructure of the matrix as the grain refinement resulted in a less pronounced corrosion attack in comparison with the coarse-grained sample. 相似文献
2.
《Ceramics International》2021,47(20):28557-28565
To reduce the energy consumption of cooling in the hot summer days, searching for novel NIR shielding materials for buildings is of great value. In this report, monodispersed F doped TiO2 nanocrystals with an average size of 8.6 nm were synthesized as novel solar shielding materials for energy-saving windows. All the products adopted an anatase TiO2 structure. After doping of F ions, the morphology of TiO2 was transformed from an irregular shape to a pseudospherical shape. The Raman shift and XPS depth analysis confirmed the successful doping of F− ions into the lattice oxygen sites in the TiO2 structure. The introduction of F− ions generated free electrons and bulk Ti3+ in TiO2 crystals, which activated a localized surface plasmon resonance (LSPR) absorption in the NIR region. Correspondingly, the NIR shielding performance of the TiO2 films improved with increasing F doping amounts. The NIR shielding value of the films increased from 1.3% to 43.2% when the molar ratio of F to Ti increased from 0 to 0.3. The reason can be attributed to the enhanced NIR absorption induced by the increased electron concentration after doping of fluorine ions. The F–TiO2 films showed superior visible transmittance (90.1–96.7%). Moreover, the F–TiO2 films lowered the indoor temperature of the heat box by 5.3 °C in the thermal tests. Overall, the prepared F–TiO2 nanocrystals show a great potential to be used for energy-saving windows. 相似文献
3.
For the purpose of developing biodegradable magnesium alloys with suitable properties for biomedical applications, Mg–Zn–Ca–Cu metallic glasses were prepared by copper mold injection methods. In the present work, the effect of Cu doping on mechanical properties, corrosion behavior, and glass-forming ability of Mg66Zn30Ca4 alloy was studied. The experimental findings demonstrated that the incorporation of Cu decreases the corrosion resistance of alloys, but increases the microhardness and degradation rate slightly. However, the addition of a trace amount of Cu can make the samples have antibacterial properties. Therefore, Mg–Zn–Ca–Cu has great advantages in clinical implantation and is the potential implant material. 相似文献
4.
Bing Huang Meng Wang Guodong Xu Lin Hu Lin Chen Yijie Gu 《Ceramics International》2021,47(6):7700-7710
In this study, La was doped into the lithium layer of Li-rich cathode material and formed a layered-spinel hetero-structure. The morphology, crystal structure, element valence and kinetics of lithium ion migration were studied by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The La doped lithium-rich cathode material exhibited similar initial discharge capacity of 262.8 mAh g?1 at 0.1 C compared with the undoped material, but the discharge capacity retention rate can be obviously improved to 90% after 50 cycles at 1.0 C. Besides that, much better rate capability and Li+ diffusion coefficient were observed. The results revealed that La doping not only stabilized the material structure and reduced the Li/Ni mixing degree, but also induced the generation of spinel phase to provide three-dimensional diffusion channels for lithium ion migration. Moreover, the porous structure of the doped samples also contributed to the remarkable excellent electrochemical performance. All of these factors combined to significantly improve the electrochemical performance of the material. 相似文献
5.
Fangjun Zhu You Shi Guorong Hu Zhongdong Peng Yanbing Cao Qian Sun Zhichen Xue Yinjia Zhang Ke Du 《Ceramics International》2021,47(3):3070-3078
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2. 相似文献
6.
7.
《中国有色金属学会会刊》2021,31(10):2939-2948
The uniaxial tensile test of the 5A06-O aluminium–magnesium (Al–Mg) alloy sheet was performed in the temperature range of 20–300 °C to obtain the true stress–true strain curves at different temperatures and strain rates. The constitutive model of 5A06-O Al–Mg alloy sheet with the temperature range from 150 to 300°C was established. Based on the test results, a unique finite element simulation platform for warm hydroforming of 5A06-O Al–Mg alloy was set up using the general finite element software MSC.Marc to simulate warm hydroforming of classic specimen, and a coupled thermo-mechanical finite element model for warm hydroforming of cylindrical cup was built up. Combined with the experiment, the influence of the temperature field distribution and loading conditions on the sheet formability was studied. The results show that the non-isothermal temperature distribution conditions can significantly improve the forming performance of the material. As the temperature increases, the impact of the punching speed on the forming becomes particularly obvious; the optimal values of the fluid pressure and blank holder force required for forming are reduced. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(67):29172-29183
To improve the safety of wet dust removal systems for processing magnesium-based alloys, a new method is proposed for preventing hydrogen generation. In this paper, hydrogen generation by Mg–Zn alloy dust was inhibited with six common metal corrosion inhibitors. The results showed that sodium dodecylbenzene sulfonate was the best hydrogen inhibitor, while CeCl3 enhanced hydrogen precipitation. The film-forming stability of sodium dodecylbenzene sulfonate was tested with different contents, temperatures, Cl? concentrations and perturbation rates. The results showed that this inhibitor formed stable protective films on the surfaces of Mg–Zn alloy particles, and adsorption followed the Langmuir adsorption model. 相似文献
9.
《Ceramics International》2022,48(14):19971-19977
Molybdenum diboride is unique among transition metal diborides because it exists in both hexagonal (AlB2-type) and rhombohedral structures. However, it is difficult to stabilize the superconducting AlB2-type phase, which requires either extreme synthesis condition or suitable chemical doping. Here we report the structural and physical properties of Sc-doped nonstoichiometric molybdenum diborides (Mo0.95Sc0.05)1-xB2 and (Mo1-yScy)0.71B2 prepared by the common arc melting method. The AlB2-type phase is found to form over wide ranges of 0 ≤ x ≤ 0.29 and 0.025 ≤ y ≤ 0.30 for the first time, and bulk superconductivity with Tc up to 7.9 K is observed. Tc increases with increasing x in the (Mo0.95Sc0.05)1-xB2 series, but evolves nonmonotonically with varying y in the (Mo1-yScy)0.71B2 series. Despite this contrast, Tc of both borides follows nearly the same linear dependence on the electron-phonon coupling constant, suggesting that it is mainly controlled by the electron-phonon interaction. In addition, the stabilization of AlB2-type structure is attributed to the decrease in the number of d electrons as a consequence of Sc doping, which suggests that a similar effect may be achieved by substituting Mo with other d electron-poorer metal elements. 相似文献
10.
《International Journal of Hydrogen Energy》2022,47(26):12829-12840
In the present work, nitrogen doped hierarchically activated porous carbon (APC) samples have been synthesized via single step scalable method using ethylene di-amine tetra acetic acid (EDTA) as precursor and KOH as activating agent. Activated porous carbons with different pore sizes have been developed by varying the activation temperature. SEM, TEM and SAXS analysis suggest that with variation of activation temperature, a hierarchical porous structure with interconnected meso-pore and micro pores has been achieved. The sufficiently high surface area of the synthesized materials provides active sites to enhance the diffusion of ions between the electrolyte and the carbon electrodes. The electrode prepared at 800 °C activated sample exhibited highest specific capacitance of 274 Fg-1 in two electrode setup, at a current density of 0.1 Ag-1 in 1 M aqueous H2SO4. Along with this, it showed maximum energy density of 9.5 Whkg?1 at a power density of 64.5 Wkg-1. The remarkable electrochemical performance reveals that the synthesized nitrogen doped activated carbon electrodes derived from EDTA can be tuned to have optimum pore structure and pore size distribution for better electrochemical performance, so it can be considered as a potential electrode material for applications in electrochemical energy storage. 相似文献