RESUMEN
Nacre-inspired metal matrix composites have received much attention due to their excellent deformation coordination ability, which can achieve the synergy of strength and ductility. The preparation of nacre-like Al matrix composites by freeze casting has been a promising application, but the continuous ceramic-rich layer affects the corrosion resistance of the composites, facing complex corrosion problems during service. In this work, the microstructure and corrosion behavior of the nacre-inspired (TiBw-TiB2)/Al composites fabricated by freeze casting and squeeze casting were systematically studied. The results indicated that the Al layers and ceramic-rich layers had little change, about 35 µm and 31 µm, respectively, with an increasing ratio of the Ti/TiB2. Meanwhile, a high Ti/TiB2 ratio resulted in an increase in the Fe-Ti intermetallic phases, which was detrimental to the corrosion performance of the composites and was prone to pitting. The electrochemical test results showed that the 3Ti7TiB2 composite had the lowest corrosion current density (15.9 µA) and intergranular corrosion depth (231 µm), indicating that it had the best corrosion resistance, which can be attributable to its stable and dense passivation film. Two different corrosion phenomena during the intergranular corrosion test existed in the present nacre-inspired (TiBw-TiB2)/Al composites: intergranular corrosion in the Al matrix layer and pitting corrosion in the ceramic-rich layer. Among all the composites, the corrosion depth of the 3Ti7TiB2 composite was the smallest and significantly less than that of the 2024Al alloy. In addition, the continuous ceramic-rich layer acted as a corrosion channel during corrosion, significantly degrading the corrosion resistance of the nacre-like Al composites.
RESUMEN
The distribution of reinforcements and interfacial bonding state with the metal matrix are crucial factors in achieving excellent comprehensive mechanical properties for aluminum (Al) matrix composites. Normally, after heat treatment, graphene nanosheets (GNSs)/Al composites experience a significant loss of strength. Here, better performance of GNS/Al was explored with a hybrid strategy by introducing 0.9 vol.% silicon carbide nanoparticles (SiCnp) into the composite. Pre-ball milling of Al powders and 0.9 vol.% SiCnp gained Al flakes that provided a large dispersion area for 3.0 vol.% GNS during the shift speed ball milling process, leading to uniformly dispersed GNS for both as-sintered and as-extruded (0.9 vol.% SiCnp + 3.0 vol.% GNS)/Al. High-temperature heat treatment at 600 °C for 60 min was performed on the as-extruded composite, giving rise to intragranular distribution of SiCnp due to recrystallization and grain growth of the Al matrix. Meanwhile, nanoscale Al4C3, which can act as an additional reinforcing nanoparticle, was generated because of an appropriate interfacial reaction between GNS and Al. The intragranular distribution of both nanoparticles improves the Al matrix continuity of composites and plays a key role in ensuring the plasticity of composites. As a result, the work hardening ability of the heat-treated hybrid (0.9 vol.% SiCnp + 3.0 vol.% GNS)/Al composite was well improved, and the tensile elongation increased by 42.7% with little loss of the strength. The present work provides a new strategy in achieving coordination on strength-plasticity of Al matrix composites.
RESUMEN
In the past decade, in the context of the carbon peaking and carbon neutrality era, the rapid development of new energy vehicles has led to higher requirements for the performance of strike forces such as battery cycle life, energy density, and cost. Lithium-ion batteries have gradually become mainstream in electric vehicle power batteries due to their excellent energy density, rate performance, and cycle life. At present, the most widely used cathode materials for power batteries are lithium iron phosphate (LFP) and LixNiyMnzCo1-y-zO2 cathodes (NCM). However, these materials exhibit bottlenecks that limit the improvement and promotion of power battery performance. In this review, the performance characteristics, cycle life attenuation mechanism (including structural damage, gas generation, and active lithium loss, etc.), and improvement methods (including surface coating and element-doping modification) of LFP and NCM batteries are reviewed. Finally, the development prospects of this field are proposed.
RESUMEN
LiNi0.8Co0.1Mn0.1O2 (LNCMO) cathode materials for lithium-ion batteries (LIBs) were prepared by the hydrothermal synthesis of precursors and high-temperature calcination. The effect of precursor hydrothermal synthesis temperature on the microstructures and electrochemical cycling performances of the Ni-rich LNCMO cathode materials were investigated by SEM, XRD, XPS and electrochemical tests. The results showed that the cathode material prepared using the precursor synthesized at a hydrothermal temperature of 220 °C exhibited the best charge/discharge cycle stability, whose specific capacity retention rate reached 81.94% after 50 cycles. Such enhanced cyclic stability of LNCMO was directly related to the small grain size, high crystallinity and structural stability inherited from the precursor obtained at 220 °C.
RESUMEN
As an alternative anode to graphene, molybdenum disulfide (MoS2) has attracted much attention due to its layered structure and high specific capacity. Moreover, MoS2can be synthesized by hydrothermal method with low cost and the size of its layer spacing can be controlled. In this work, the results of experiment and calculation proved that the presence of intercalated Mo atoms, leading to the expansion of MoS2layer spacing and weakening of Mo-S bonding. For the electrochemical properties, the presence of intercalated Mo atoms causes the lower reduction potentials for the Li+intercalation and Li2S formation. In addition, the effective reduction of diffusion resistance and charge transfer resistance in Mo1+xS2leads to the acquisition of high specific capacity for battery applications.
RESUMEN
To achieve the goal of "dual-carbon", induction furnaces with high efficiency and energy-saving advantages are paid more attention in the foundry and metallurgy industries. The service life and safety of induction furnaces strongly depended on the lining because expansion and forward sintering could result in the erosion and slag resistance of the lining. Focusing on the tailoring properties of alumina-magnesia-based dry ramming mixes, calcined magnesia particles were replaced with the novel multi-component materials of calcium magnesium aluminate (CaO-MgO-Al2O3, CMA) with a size of 200 mesh. Properties such as the bulk density, apparent porosity, strength, and slag corrosion resistance of alumina-magnesia-based dry ramming mix containing CMA were evaluated contrastively. The results demonstrate that the penetration index of manganese-bearing slag in dry ramming mixes first decreased and then slightly increased with the addition of CMA. Meanwhile, the permanent linear change in dry ramming mixes was gradually reduced. When the addition of CMA reached 4 wt%, the strength of the dry ramming mixes was slightly greater than the reference, and the slag penetration index was just 75% of the latter.
RESUMEN
The dataset presented in this paper is supporting the research article "Enhanced magnetic refrigeration capacity in Ni-Mn-Ga micro-particles" (Qian, et al., 2018) [1]. The martensite transformation temperature (Ms ) and the Curie point (Tc ) of the annealed alloys with nominal composition Ni55-xMn20+xGa25 (x = 0, 0.25, 0.5, 1, atomic percent, labeled as A1, A2, A3 and A4, respectively) varied with x, yielding a temperature difference Tc -Mc of 7.2â¯K at x = 0.5 (A3). The magnetization difference (ΔM) between the austenite and martensite, the field dependence of transformation temperature (ΔT/ΔH) and the thermal hysteresis loss of A3 and the according stress relief annealing (SRA) particles were demonstrated. The isothermal magnetization curves of A3 and the SRA particles were measured in order to determine the magnetocaloric effect.
