煤矸石粉/聚酯纤维沥青混合料盐冻损伤研究EI北大核心CSCD

针对煤矸石粉替代率50%、聚酯纤维掺量0.4%的沥青混合料,开展盐冻耦合作用(NaCl溶液质量分数为0%、7.0%、13.0%、26.5%,冻融循环次数为0、2、4、6、8)下的半圆弯曲(SCB)试验,分析了盐冻耦合作用对SCB试件内部损伤劣化过程的影响.结果表明:NaCl溶液质量分数为13.0%、冻融循环为8次时,盐冻耦合作用对沥青混合料的侵蚀破坏作用最强,试件内部损伤最严重;在煤矸石粉与矿粉质量比为1∶1、聚酯纤维掺量为0.4%的条件下,沥青混合料能够形成高黏性、致密、厚实的沥青膜以及由纤维形成的三维网状结构,从而显著降低盐冻侵蚀对沥青混合料的损伤.通过Poly2D模型对SCB试件的极限拉应力损伤量进行拟合,拟合系数为0.944.     

基于组合赋权-改进可拓云的装甲车辆PHM系统性能评估

针对装甲车辆PHM系统性能评估过程中主观性强、评语等级界限分明等问题，采用主客观组合赋权和改进可拓云理论相结合的评估方法，增强了评估结果的客观性和准确性；首先介绍了装甲车辆PHM系统组成及其性能评估指标体系，然后采用基于“AHP-熵值”的组合赋权法确定指标权重系数，采用基于最优云熵的改进可拓云理论确定各指标云关联度值，最后采用模糊综合评判方法计算了4套装甲车辆PHM系统性能。结果表明，改进评估方法在不失准确性的同时，能够有效克服评估主观性和评语等级界限分明性，为装甲车辆PHM系统性能的优化提供了借鉴和参考。     

Uniform α-Fe2O3 nanoparticles with narrow gap immobilized on CNTs through N-doped carbon as high-performance lithium-ion batteries anode

Fe₂O₃ with high theoretical capacity, low cost, and environmental friendliness has been attracted great attention in lithium-ion batteries (LIBs), which however is limited by low rate capability and fast capacity fading owing to low electronic conductivity, self-aggregation, and sever volume expansion. CNTs with excellent conductivity and unique 3D interconnected network are ideal matrices for composite electrochemical materials, but it is difficult to meet the demand of high capacity. Here, uniform α-Fe₂O₃ nanoparticles with narrow gap (~1.4 nm) were immobilized on CNTs through N-doped carbon (α-Fe₂O₃/CNTs-NC) that can address these issues. As an advanced LIBs anode, the electrode displays unprecedented specific capacity (1173 mAh/g at 0.2 A/g) and outstanding rate behavior (716.4 mAh/g at 5.0 A/g after 1200 cycles), which are even superior to the theoretical capacity (1007 mAh/g) and the performance of most reported Fe₂O₃-based anodes. Homogeneous nano-sized α-Fe₂O₃ with a narrow gap highly shortens the diffusion path for Li⁺ transport, exposes quite sufficient active sites, and prevents the volume change. Moreover, the 3D backbone of CNTs with a more homogeneously distributed electric field can enhance conductivity, and tightly contact with α-Fe₂O₃ by NC, then obtain robust structural stability, which boosts LIBs in storage capacity, rate capability, and cycling stability.     

Effect of Y concentration and film thickness on microstructure and electrical properties of HfO2 based thin films

In this work, we introduced a simple solution processing method to prepare yttrium (Y) doped hafnium oxide (HfO₂) based dielectric films. The films had high densities, low surface roughness, maximum permittivity of about 32, leakage current < 1.0 × 10^?7 A/cm² at 2 MV/cm, and breakdown field >5.0 MV/cm. In addition to dielectric performance, we investigated the influence of YO_1.5 fraction on the electronic structure between Y doped HfO₂ thin films and silicon (Si) substrates. The valence band electronic structure, energy gap and conduction band structure changed linearly with YO_1.5 fraction. Given this cost-effective deposition technique and excellent dielectric performance, solution-processed Y doped HfO₂ based thin films have the potential for insulator applications.     

Crushing behavior of alumina inclusions with different porosity during hot compression

Alumina inclusions in commercial as-cast 2.25Cr1Mo0.25V aluminum deoxidized steel exhibited a feature of porous structure. In order to investigate the crushing characteristics of alumina inclusion during hot working, a series of alumina blocks with different porosity whose properties are similar to the alumina inclusions in ingots were prepared using spark plasma sintering. The crushing behavior of alumina blocks during hot compression with quasi-static load was studied. A prediction model of compressive strength of alumina inclusions considering apparent porosity was established on basis of hyperbolic sine Arrhenius equation. A novel crushing mode diagram for alumina inclusions characterized by Z parameter was proposed. The crushing mechanism of alumina inclusions under different deformation parameters was clarified by fracture characteristics. The results showed that the hot compression process of alumina presented a typical brittle fracture, the compressive strength was more sensitive to deformation conditions at lower apparent porosity as compared with the conditions of higher apparent porosity. With the increase of Z, the crushing mode of alumina inclusions gradually changed from intergranular fracture to transgranular fracture.     

A selective organosilica membrane for ethyl acetate dehydration by pervaporation

Organosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H₂O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m⁻².h⁻¹ with a selectivity of >10,000 for EA/H₂O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H₂O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n-propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost-effective, quick, and efficient synthesis route for practical membrane based applications.     

Inhibiting effect of heterogeneous cations aggregation enhanced by oxygen deficiency on glass formation of BaTi2O5 melts

Although remarkable development of titanate-based glasses has been achieved, challenge remains to elucidate the correlation between structure and glass-forming properties in these systems due to their complex structure that is inconsistent with the classic Zachariasen's model. In this work, we aim to correlate the structural evolution of titanate melts to their glass-forming ability (GFA). The prototypical material barium dititanate (BaTi₂O₅, BT2) melts with different GFA were rendered by controlled melting atmospheres, and the corresponding structural changes were determined using in situ high-energy synchrotron X-ray diffraction combined with empirical potential structure refinement and ab initio molecular dynamics. The results show that BT2 melt in reducing atmosphere shows poor GFA but that in oxidizing atmosphere presents good GFA. Structural analysis demonstrates the mean coordination number of [TiO_m] polyhedra is analogous in the melt under two different atmospheres but an enhanced heterogeneous cations aggregation takes place in the melt under reducing atmosphere, which is closely related to oxygen-deficiencies. Furthermore, we reveal that the enhanced heterogeneous cations aggregation promotes crystallization (and therefore hinders glass formation) through disordering the distribution of [TiO_m] and [BaO_n] polyhedra, changing the connectivity between these polyhedra, creating more crystal-like Ti-Ti clusters, and decreasing topological disorder of BT2 melt. Our work provides a new viewpoint to understand the GFA of titanates melt from structural heterogeneity beyond the previous perspectives that only focus on [TiO_m] polyhedra.