云南镇源难处理金精矿工艺矿物学研究

利用X射线衍射、X射线荧光光谱（XRF）、X射线能谱分析（EDX）和矿物解离分析（MLA）等检测手段对云南镇源难处理金精矿的化学组成、矿物组成、硫化物特征以及金的分布情况进行了详细的工艺矿物学研究。结果显示：该金矿以硫化矿、碳酸盐和硅酸盐类矿物为主，含有3.18%的有机碳和2.37%的无机碳。通过金的诊断浸出发现96.16%的金被硫化物包裹，少量金以单体形式存在。通过对主要载金矿物黄铁矿、辉锑矿和毒砂的粒度、包裹及裸露情况进行分析，得出大部分硫化矿以解离单体的形式存在，少部分与其他矿物共生。根据MLA测试及金的诊断浸出，认为大部分金被硫化矿完全包裹，处理该矿石时应先进行硫化物包裹层的氧化处理，再进行金矿的浸出。     

Hydrogen embrittlement and associated surface crack growth in fine-grained equiatomic CoCrFeMnNi high-entropy alloys with different annealing temperatures evaluated by tensile testing under in situ hydrogen charging

The effect of the annealing temperature after cold rolling on hydrogen embrittlement resistance was investigated with a face-centered cubic (FCC) equiatomic CoCrFeMnNi high-entropy alloy using tensile testing under electrochemical hydrogen charging. Decreasing annealing temperature from 800 °C to 750 °C decreased grain sizes from 3.2 to 2.1 μm, and resulted in the σ phase formation. Interestingly, the specimen annealed at 800 °C, which had coarser grains, showed a lower hydrogen embrittlement susceptibility than the specimen annealed at 750 °C, although hydrogen-assisted intergranular fracture was observed in both annealing conditions. Because the interface between the FCC matrix and σ was more susceptible to hydrogen than the grain boundary, the presence of the matrix/σ interface significantly assisted hydrogen-induced mechanical degradation. In terms of intergranular cracking, crack growth occurred via small crack initiation near a larger crack tip and subsequent crack coalescence, which has been observed in various steels and FCC alloys that contained hydrogen.     

基于BS值的钢中多相组织分相技术

为了对钢中双相或多相组织进行分相定量表征，利用场发射扫描电镜(FE SEM)与电子背散射衍射技术(EBSD)中的BS值对其进行了详细的研究与讨论。结果表明，对于单相的铁素体、贝氏体或马氏体，其BS灰度分布图呈近似的正态分布，BS图可以呈现出类似于组织的图像。利用BS值可以很好地对结构相近的双相或多相组织进行分相定量。在分相定量时，需选择适合的拟合函数，定量结果才更为准确。     

Maximization of quadruple phase boundary for alkaline membrane fuel cell using non-stoichiometric α-MnO2 as cathode catalyst

Oxygen can only be reduced at the quadruple phase boundary (catalyst, carbon support, ionomer and oxygen) of the cathode catalyst layer with non-conducting electrocatalyst. To maximize the quadruple phase boundary sites is crucial to increase the peak power density of each membrane electrode assembly. The quadruple phase boundary is depending on the ratio of catalyst, carbon support and ionomer. The loading of catalyst layer is also crucial to the fuel cell performance. In this study, non-stoichiometric α-MnO₂ manganese dioxide nanorod material has been synthesized and the ratios of carbon, ionomer and catalyst loadings were optimized in alkaline membrane fuel cell. In total, ten membrane electrode assemblies have been manufactured and tested. Taguchi design method has been applied in order to understand the effect of each parameter. The conclusion finds out the ionomer has more influence on the alkaline membrane fuel cell peak power performance than carbon and loading.     

Low voltage operating organic light emitting transistors with efficient charge blocking layer

Charge injection/blocking layers play important roles in the performances of organic electronic devices. Their incorporation into organic light emitting transistors has been limitted, due to generally high operating voltages (above 60 V) of these devices. In this work, two hole blocking molecules are integrated into tris-(8-hydroxyquinoline) aluminum (Alq₃) based light emitting transistors under operating voltage as low as 5 V. The effects of hole blocking and electron injection are decoupled through the differences in the energy levels. Significantly improved optical performance is achieved with the molecule of suitable energy level for electron injection. Surprisingly, a decreased performance is observed in the case of another hole blocking molecule evidencing that charge injection overweighs charge blocking in this device architecture.     

Structural transformation in Mn-substituted Sr2Bi2Ta2TiO12 Aurivillius phase synthesized by hydrothermal method: A comparative study and dielectric properties

In this study, a hydrothermal method was applied to synthesize the three-layer Aurivillius phase Sr₂Bi₂Ta₂TiO₁₂ (SBTTO) and Mn-substituted Sr_1·5Bi_2·5Ta₂Ti_0·5Mn_0·5O₁₂ (SBTTMO), with the use of NaOH as a mineralizer. The crystal structure, morphology, dielectric properties, and the correlation between the structural transformation and dielectric properties were investigated. The XRD data reveal that the SBTTO sample adopts a tetragonal crystal structure with the I4/mmm space group and is then transformed into an orthorhombic structure with the B2cb space group for SBTTMO. The morphology of both samples was observed by SEM, which showed anisotropic plate-like grains. With the Mn substitution, the ferroelectric transition temperature (T_c) significantly increases as the influence of the 6s² lone pair of Bi³⁺ increases, and this in turn further induces the relaxor-ferroelectric behavior. Consequently, the increase in T_c confirms the structural transformation from the paraelectric-tetragonal to the ferroelectric-orthorhombic phase.     

Ultrahigh and field-independent energy storage efficiency of (1-x)(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-xBi(Mg0.5Ti0.5)O3 ceramics

Relaxor ferroelectrics are attracting an increasing interest in the application of pulse power systems due to their excellent energy storage performance. In this paper, the (1-x)(Ba_0·85Ca_0.15)(Zr_0·1Ti_0.9)O₃-xBi(Mg_0·5Ti_0.5)O₃ ((1-x)BCZT-xBMT, x ≤ 0.2) relaxor ceramics are prepared by the solid state method. The influence of BMT on the microstructure, dielectric and energy storage properties of the prepared ceramics is investigated. The XRD results show that the peak intensity of impurities (Bi₂O₃, TiO₂ and Ba₂Bi₄Ti₅O₁₈) is gradually stronger than that of BCZT phase with x increasing. Meanwhile, the grain size of (1-x)BCZT-xBMT ceramics gradually increases on account of the appearance of impurities Bi₂O₃. Influenced by the impurities and BMT, the dielectric constant of prepared ceramics gradually decreases with x increasing. A large W_rec value of 0.65 J/cm³ with an ultrahigh η value of 97.89% is achieved at x = 0.15 due to the high breakdown strength and slim P-E hysteresis loop. Meanwhile, the η is insensitive to the electric field. The ultrahigh η leads to lesser energy loss during the charge and discharge process. It makes the 0.85BCZT-0.15BMT ceramic more attractive in the application of pulse power systems.     

Influence of the stoichiometry,microstructure, and metallization method on the dielectric properties of 0.94 Na0.5Bi0.5TiO3-0.06 BaTiO3

The morphotropic composition of the lead-free solid solution between Na_0.5Bi_0.5TiO₃ and BaTiO₃ (0.94 Na_0.5Bi_0.5TiO₃-0.06 BaTiO₃ or NBT-6BT) is of particular interest for the next generation of high-temperature capacitors but remains plagued by the diversity of dielectric properties reported in the literature. In order to explain the apparent inconsistencies among the reported dielectric properties of NBT-6BT, we examine the influence of stoichiometry, phase separation, and metallization method. We show that the nominal stoichiometry has a crucial effect, since increasing the nominal Na/Bi ratio increases conductivity and dielectric losses (tan δ). It also increases the real part of the permittivity (ε’) and the frequency dispersion of both ε’ and tan δ, thereby altering the shape of the evolution with temperature of the dielectric properties. Moreover it increases the depolarization temperature (T_d) and decreases the temperature of maximum permittivity (T_m). Phase separation also occurs during the synthesis of NBT-6BT as Na evaporation leads to the formation of secondary Ba-containing phases. We report that these phases can have a positive impact on the dielectric properties: a moderate volume fraction (2.5 to 3.0%) and average grain surface (0.9 to 3.0 µm²) of these secondary Ba-containing phases increase the relative permittivity, decrease the dielectric losses, and increase the insulation resistance. We also show that the metallization method impacts the dielectric properties and therefore may contribute to the differences between various reports. The dielectric properties of NBT-6BT samples are measured during successive heating/cooling cycles and reveal that the permittivity value is lower during the first heating when silver paste, even cured, is used. These three components contribute to explaining the diversity of the reported dielectric properties of NBT-6BT.     

Development of vibration damping materials based on butyl rubber: A study of the phase equilibrium,rheological, and dynamic properties of compositions

A detailed study of butyl rubber-based vibration damping formulations linking their composition, morphology, phase structure, viscosity, mechanical loss factor, and other characteristics is presented for the first time. High performance of the compositions including aromatic petroleum oil is explained by limited solubility of the plasticizer that leads to the formation of a highly-viscous emulsion (η_20°C ≈ 1000 Pa·s) consisting of a swollen butyl rubber matrix and dispersed oil droplets in the broad composition range. Chalk is found to be the best inorganic filler as its spherical particles provide strong adhesion to the reinforcing layer of aluminum foil. Aiming to eliminate ecologically unfriendly aromatic compounds, a new low-cost binding agent formulation based on butyl rubber mixed with polyisobutylene and highly refined mineral oil is suggested. Being environmentally safe, it possesses high viscosity of 1000–3000 Pa·s, cohesion strength of 3.5–5.0 N/cm, penetration of 4.5–6.0 mm, and mechanical loss factor up to 0.34 at room temperature, which are as good as, or even better than, the properties of currently produced vibration damping materials containing aromatic compounds. New materials can be used in car and aircraft parts for effective vibration isolation.