Search Results (6)

To improve the electrochemical activity and discharge performance of an aluminum-air (Al-air) battery, a commercial 6061 alloy (Al6061) was selected as the anode, and CeO₂ was also added inside the anode to enhance its performance. The CeO₂/Al6061 composite was prepared using selective laser melting (SLM) technology. The influence of hatch spacing on the forming quality, corrosion resistance, and discharge performance of the anode was studied in detail. The results showed that with an increase in hatch spacing, the density, corrosion resistance, and discharge performance of the anode first increased and then decreased. When the hatch spacing is 0.13 mm, the anode has the best forming quality. At this point, the density reaches 98.39%, and the self-corrosion rate (SCR) decreases to 2.596 × 10⁻⁴ g·cm⁻²·min⁻¹. Meanwhile, the anode exhibits its highest electrochemical activity and discharge voltage, which is up to −1.570 V. The change in anode performance is related to the defects generated during the SLM forming process. For samples with fewer defects, the anode can dissolve uniformly, while for samples with more defects, the electrode solution is prone to penetrate the defects, causing uneven corrosion and reducing electrochemical and discharge activity. Full article

To improve the discharge performance of aluminum–air batteries, CeO₂/Al6061 composites were prepared as an anode using selective laser melting (SLM). Response surface methodology (RSM) was employed, and the test results were linearly fitted. A prediction model for the forming quality of the composite anode was established, and the reliability of the model and the interaction between process parameters were explored based on variance analysis and significance testing. On this basis, with corrosion potential, self-corrosion rate, and discharge voltage as optimization objectives, the optimal solution set of the SLM forming CeO₂/Al6061 anode process parameter was solved through a genetic algorithm, and experimental verification was conducted. The results indicate that the optimal process range for the forming quality and various properties of composite materials is laser power of 265~285 W, scanning speed of 985~1025 mm/s, and scanning spacing of 0.116~0.140 mm. The optimized process parameters were selected for reliability testing, and the errors were all within 3.0%, verifying the accuracy and reliability of the model. Full article

This investigation presents results on the improvement of the corrosion-protective effect of consecutive sealing treatments of anodized Al 1050 (Al_Anod). The treatments were performed in cerium-containing and mixed NaH₂PO₄ + Ca(NO₃)₂ solutions. The changes of the surface morphology, structure and chemical composition, chemical state of the elements, and basic corrosion parameters of the studied systems were investigated by SEM, EDXS, XRD, XPS, and a complex of electrochemical techniques (PDP, E_OCP vs. timeplot, chronoamperometric transients, Rp and CR at E_OCP, etc.). The results obtained show that the basic components of the obtained sealing conversion layers (before and after exposure to model Cl⁻-containing corrosion media) are characterized by Ca₁₀(PO₄)₆(OH)₂, AlO(OH), CePO₄, and CeAlO₃ (after the corrosion tests, they are converted to insoluble Me-PO₃ and Me-P₄O₁₀). We conclude that the observed decrease in the corrosion rate of Al and the corresponding increase in the polarization resistance are accomplished by the two-step sealing treatment, which fills up the Al_Anod pores with insoluble deposits. Full article

The direct utilization of anhydrous ethanol in solid oxide fuel cells (SOFC), with oxygen-storage anode materials of the type Cu-(ZrxCe_1−xY_0.2O_2−δ-Al₂O₃), is presented. The ceramic processing of CeO₂-Al₂O₃ and 8YSZ (8% mol yttria stabilized zirconia) favors the reaction between Ceria and 8YSZ. Therefore, anode materials composed of active solid solutions, such as (Zr_0.25Ce_0.75)_0.8Y_0.2O_1.9 (cubic) and (Zr_0.50Ce_0.50)_0.8Y_0.2O_1.9 (tetragonal), in addition to the Al₂O₃ phase, are produced and prevent the formation of CeAlO₃. The anodes exhibited an excellent oxygen storage capacity, OSC, between 415 to 446 µmolg⁻¹. This occurred due to the replacement of Ce⁴⁺ by Zr⁴⁺, generating structural defects that increase the oxygen ion mobility and the activity of the Ce⁴⁺/Ce³⁺ redox pair. The anode material presenting the cubic phase showed a better electrochemical performance. The Al₂O₃ phase provided thermal stability and prevented the coarsening of the solid solution and loss of Ceria’s redox activity. It allowed for SOFC operation at high temperatures, since the yield increased as the operating temperature rose from 750 to 950 °C. An analysis of the results before and after the SOFC operation at 950 °C for 200 h revealed that there was no significant copper grains coarsening since the performance increased with the temperature. The redox behavior during the SOFC operation is also explained through a theoretical physical–chemical mechanism. Full article

Two perovskite materials with SrMo_1−xAl_xO_3−δ (x = 0.1, 0.2) compositions have been synthesized by reduction from the corresponding scheelite phases, with SrMo_1−xAl_xO_4−δ stoichiometry; the pertinent characterization shows that the defective perovskites can be used as anode materials in solid oxide fuel cells, providing maximum output power densities of 633 mW/cm² for x = 0.2. To correlate structure and properties, a neutron powder diffraction investigation was carried out for both perovskite and scheelite phases. Both perovskites are cubic, defined in the Pm-3m space group, displaying a random distribution of Mo and Al cations over the 1a sites of the structure. The introduction of Al at Mo positions produced conspicuous amounts of oxygen vacancies in the perovskite, detected by neutrons. This is essential to induce ionic diffusion, providing a mixed ionic and electronic conduction (MIEC), since in MIEC electrodes, charge carriers are combined in one single phase and the ionic conductivity can be one order of magnitude higher than in a conventional material. The thermal expansion coefficients of the reduced and oxidized samples demonstrated that these materials perfectly match with the La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ electrolyte, La_0.4Ce_0.6O_2−δ buffer layer and other components of the cell. Scanning electron microscopy after the test in a real solid oxide fuel cell showed a very dense electrolyte and porous electrodes, essential requirements for this type of fuel. SrMo_1−xAl_xO_3−δ perovskites are, thus, a good replacement of conventional biphasic cermet anodes in solid oxide fuel cells. Full article

Sn-0.7Cu-0.075Al solder alloy adding with Ce and La had been successfully prepared by applying ball-milling and vacuum arc remelting. The influence of Ce and La on microstructure and corrosion behavior of Sn-0.7Cu-0.075Al solder alloy was investigated. The results showed that Ce (La)-containing solders had refined grains and obvious directional tendency due to the dispersive refiner (CeO₂ and La₂O₃). Electrochemical potentiodynamic curves revealed three different stages of the reaction, including anodic and cathodic processes, prepassivation section, and stable passivation stages. The self-corrosion potential (E_corr) of alloys with Ce and La addition were a little bit more negative, hardly making a difference on corrosion occurrence. However, the corrosion current density (I_corr) and passivation current density (I_p) decreased by two-thirds and one-half respectively, which indicated a better corrosion resistant after adding rare earths. The recorded micrographs of corroded surface at different polarized points witnessed the formation of corrosion product film both on prepassivation and passivation stage. Moreover, the cross section of corrosion product film showed the coarse, loose film in Sn-0.7Cu-0.075Al solder and adherent, compact film in Ce (La)-containing solders, which further indicated an excellent anti-corrosion property. Full article