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排序方式: 共有640条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2021,47(23):33057-33063
In this study, a chelating agent is introduced to prepare CeO2–ZrO2 nano-composite through a precipitation process. The physicochemical properties of the oxide precursors, nano composite materials are strongly dependent on the preparation method and whether a chelating agent is used. Adding an appropriate quantity of chelating agent SO42− can facilitate thermal stability and phase structure uniformity of CeO2–ZrO2 mixed oxides. The calculation results showed that the Gibbs free energy of chelating complex of [ZrSO4]2+ (ΔG = −127.2469 kJ/mol) is higher than the [Ce(III)SO4]+ (ΔG = -29.8279 kJ/mol). The precipitation chemical potential of Zr4+ moves close to the precipitation chemical potential of Ce3+. The novel and low-cost chelating precipitation method can modify the homogeneity of the compounds at the atomic scale, which can offer a powerful opportunity for, and provide direction in, the design of materials with exceptional properties. 相似文献
2.
《Calphad》2021
Sb2S3 and CuSbS2 have been proposed as alternative earth-abundant absorber materials for thin-film solar cells. However, no thermodynamic study of the S−Sb binary system and the Cu−S−Sb ternary system were investigated. In this paper, The S−Sb system and the Cu−S−Sb system are calculated utilizing the so-called CALPHAD (CALculation of PHAse Diagrams) technique. Using TEM-EDS and XRD, Cu0.9Sb1S2 is experimentally confirmed at the Cu1Sb1S2 and Sb2S3 two-phases region in the isothermal section at 673 K of the Cu−S−Sb ternary system. Given the asymmetric shape and miscibility gap of the liquidus in the S−Sb phase diagram, the associate solution model for the liquid phase is adopted. The solution phases (liquid, bcc, fcc) are treated with the Redlich–Kister equation. The compounds S3Sb2, Cu3SbS3, Cu12Sb4S13, CuSbS2, and Cu3SbS4 are described as a stoichiometric compound. A set of self-consistent thermodynamic parameters of the S−Sb binary system and the Cu−S−Sb ternary system are obtained. The calculated results are in good agreement with the experimental data. This study provides a set of reliable thermodynamic parameters to the Cu−Sb−S thermodynamic database, and a cost-effective tool to design material synthesis experiments and manufacturing processes. 相似文献
3.
为进一步优化电解制备Al-Cu-Y合金的热、动力学条件,对AlF3-(Li, Na)F-(Al2O3-Y2O3)熔盐体系的密度、黏度及电导率变化规律进行研究。分别采用阿基米德法、连续变化电导池常数法和旋转法测定AlF3-(Li, Na)F-(Al2O3-Y2O3)熔盐体系在温度为900~1 000 ℃范围内,n((Li, Na)F): n(AlF3)=2.5时的密度(ρ)、电导率(σ)、黏度(η)随温度和组分的变化规律,结果表明:在温度900~1 000 ℃范围内,AlF3-(Li, Na)F-(Al2O3-Y2O3)体系中Al2O3和Y2O3的含量一定,密度-温度、黏度-温度和电导率-温度之间均呈线性关系。在温度为950 ℃条件下,熔盐体系的密度随Al2O3含量的增加而线性减小,随Y2O3含量的增加而线性增加; 电导率随Y2O3或Al2O3含量的增加而线性减小; 体系的黏度则随Y2O3或Al2O3含量的增加而线性增加。 相似文献
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6.
《Calphad》2023
Iron oxides and silica are the major components of copper smelting slag. The oxides of aluminum, calcium and magnesium are also present in the slag that is introduced through copper concentrate, flux and refractories. Liquidus temperatures of the copper smelting slags are usually controlled by Fe/SiO2. The concentrations of Al2O3, CaO and MgO, and FeO/Fe2O3 in the slag can also affect the liquidus temperatures where FeO/Fe2O3 is a function of oxygen partial pressure. High temperature equilibration under controlled oxygen partial pressure followed by quenching and electron probe microanalysis were used to determine the compositions of the liquid and solid phases at 1200 °C and Po2 10-8 atm. The experimental results are presented in the forms of pseudo-ternary sections “FeO”-CaO-SiO2 at fixed 2, 4 and 6 wt pct MgO, and 2 + 2, 4 + 4 and 6 + 6 wt pct MgO + Al2O3. Spinel and tridymite are the major primary phases in the composition range investigated. In addition, CaSiO3, pyroxene, olivine, and melilite are also present. The isotherms in the spinel and tridymite primary phase fields move towards higher SiO2 concentration directions with increasing CaO, Al2O3, and MgO concentrations. The experimentally determined results are compared with the FactSage calculations. 相似文献
7.
《Calphad》2023
Mg-Sr alloys are promising to fabricate orthopedic implants. The alloying of rare earth elements such as Gd may improve the comprehensive mechanical properties of Mg-Sr alloys. The information on the phase diagram and the microstructure development are required to design chemical composition and microstructure of Gd alloyed Mg-Sr alloys. The phase equilibria and the microstructure development in Mg-rich Mg-Gd-Sr alloys (Gd, Sr < 30 at. %) are experimentally investigated via phase identification, chemical analysis, and microstructure observation with respect to the annealed ternary alloys. The onset temperatures of liquid formation are measured by differential scanning calorimetry. A thermodynamic database of the Mg-rich Mg–Gd–Sr ternary system is developed for the first time via CALPHAD (CALculation of PHAse Diagram) approach assisted by First-Principles calculations. The thermodynamic calculations with the developed database enable a well reproduction of the experimental findings and the physical-metallurgical understanding of the microstructure formation in solidification and annealing. 相似文献
8.
We show that biogeography-based optimization (BBO) is a generalization of a genetic algorithm with global uniform recombination (GA/GUR). Based on the common features of BBO and GA/GUR, we use a previously-derived BBO Markov model to obtain a GA/GUR Markov model. One BBO characteristic which makes it distinctive from GA/GUR is its migration mechanism, which affects selection pressure (i.e., the probability of retaining certain features in the population from one generation to the next). We compare the BBO and GA/GUR algorithms using results from analytical Markov models and continuous optimization benchmark problems. We show that the unique selection pressure provided by BBO generally results in better optimization results for a set of standard benchmark problems. We also present comparisons between BBO and GA/GUR for combinatorial optimization problems, include the traveling salesman, the graph coloring, and the bin packing problems. 相似文献
9.
《Materials Research Bulletin》2006,41(7):1364-1369
In situ polymerization of pyrrole was carried out in the presence of γ–Fe2O3 (FE) to synthesize polypyrrole–γ–Fe2O3 composites (PPy/FE) by chemical oxidation method. The PPy/FE composites have been synthesized with various compositions viz., 10, 20, 30, 40 and 50 wt.% of γ–Fe2O3 in pyrrole. The AC conductivity was studied in the frequency range 102–107 Hz. The dielectric behaviour was also investigated in the frequency range 102–107 Hz. The dimensions of γ–Fe2O3 particles in the matrix have a greater influence on the conductivity values and the observed dielectric values. 相似文献
10.
TiC-dispersion-strengthened Cu alloys were prepared by a two-step ball-milling (BM) process followed by sparks plasma sintering (SPS), heat treatment and hot rolling in sequence. The two-step BM process is composed of a pre-ball-milling (pre-BM) on both Ti and graphite powders as well as a subsequent homogenizing by BM together with Cu powder. Microstructure evolution analysis was performed to evaluate the effects of BM conditions on the electrical and mechanical properties of Cu-based alloys. The X-ray results revealed that titanium carbide (TiC) formed from Ti and C under high impact energy BM. Moreover, the formation of TiC during the SPS and heat treatment processes was found to more beneficial in enhancing the mechanical properties of alloy. The residual Ti in Cu matrix was found to be the predominant factor lowering the electrical conductivity of Cu–Ti–C alloys. 相似文献