通讯机构：
[Wang, Qingliang] U;Univ South China, Sch Resource & Environm & Safety Engn, Hengyang 421001, Peoples R China.;Univ South China, Cooperat Innovat Ctr Nucl Fuel Cycle Technol & Eq, Hengyang 421001, Peoples R China.
关键词：
Uranium-beryllium ore;Selective leaching;Uranium and beryllium separation;Kinetics
摘要：
Both uranium and beryllium are very important strategic metals and have been applied to many fields, such as nuclear industries, atomic energy, metallurgical industries and telecommunications industries. When uranium and beryllium in the ore were leached simultaneously, a complicated downstream separation process was needed. Based on the different chemical stabilities of uranium and beryllium, an acid leaching method was employed in this work to selectively extract uranium from uranium-beryllium ore. The effects of sulfuric acid concentration, temperature, liquid-solid ratio and leaching time on the leaching efficiency were studied experimentally. Results indicated that treatment of the ores in 0.2 M sulfuric acid at 348.5 K for 50 min with the solid-liquid ratio of 0.25 g/mL is optimum. Under optimal conditions, the leaching efficiencies of uranium is 97.4% and the leaching efficiencies of beryllium is 1.78%, and the standard deviation of them are less than 2% and 0.06%, respectively. Results of kinetic study suggest that the leaching process of uranium was thermodynamically favorable and was controlled by the diffusion of the product layer, whereas the rate-determining step for beryllium leaching is the surface chemical reaction.
通讯机构：
[Xiao, Weiwei] U;[Deng, Hua] C;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;CNNC Jianzhong Nucl Fuel Corp, Yibin 644000, Sichuan, Peoples R China.
关键词：
High temperature oxidation;Mechanical properties;Sputtered TiN coating;Substrate bias
摘要：
This study is aimed to investigate the influence of substrate bias on mechanical properties and high temperature oxidation of sputtered TiN coating which is prepared on the surface of Zr-4 alloy. The microstructures of coatings were characterized by using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The thicknesses of coatings were detected by examining the cross-sectional SEM image. The adhesion property was tested by using scratch testing. The residual stress was measured by using the XRD method. The tensile property was evaluated by standard tensile test. And the high temperature oxidation performance in air condition was also assessed. It was revealed that substrate bias has a significant influence on crystalline structure, surface micromorphology, thickness, adhesion strength, and residual stress. Nevertheless, tensile property and high temperature oxidation performance are affected by substrate bias indistinctively. From the cross-sectional SEM image, it can be found that thicker coating can be obtained in unit time with a lower substrate bias. The adhesion property does not vary monotonically with increasing negative substrate bias and the coating deposited with -100 V possesses highest critical load. The sputtered TiN coatings demonstrate a compressive residual stress and the magnitude of residual stress of coatings prepared with -200 V and -300 V is higher than that of coatings prepared with -50 V and -100 V. The tensile test reveals that there is no obvious difference between tensile properties of TiN-coated specimens prepared with different substrate bias and the Zr-4 alloy specimen. And the weight gains of high temperature oxidation of TiN-coated specimens with different substrate bias are almost the same and are lower than uncoated Zr-4 alloy specimen. The XRD and EDS results show that TiN coating is oxidized and cracked and the internal Zr-4 substrate is also oxidized when the specimen is exposed to high temperature circumstance for a long time. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
We investigate the isospin properties of the strange quark matter (SQM) and quark stars (QSs) in the framework of the isospin-dependent confining quark matter (ICQM) model and confined-isospin and density-dependent mass (CIDDM) model. Within these two isospin-dependent quark mass phenomenological models, we study the quark matter symmetry energy, the stability of strange quark matter, the quark fractions, the isospin asymmetry, and the quark mass asymmetry in SQM, and the mass-radius relation of quark stars. We find that including isospin dependence of the quark mass can significantly influence the isospin properties of the quark matter. Recently, the LIGO-Virgo collaboration reported their detection of gravitational wave (GW) signals GW170817, which are originating from a binary compact star merger. Using the ICQM model and CIDDM model, we describe the compact stars with the new maximum mass limits 2.01−0.04+0.04≤M/M⊙≤2.16−0.15+0.17 as quark stars, and the dimensionless tidal deformabilities of QSs are also investigated in this work.
摘要：
The hybrid architectures comprising different types of nano-structured WO(3 )particles were prepared via facile surfactant-and template-free hydrothermal synthesis process. We demonstrate that morphology of the fabricated hybrid nanomaterials can be manipulated but the phases of those nanomaterials are still monoclinic and hexagonal hybrid structure via tuning the proportion of the reagents. The synthesis mechanism and the gas-sensing properties of the harvested nanomaterials have also been investigated. The as prepared WO3 nano-particles with hybrid architectures exhibit excellent gas-sensing functions to ethanol gas at the optimal temperature as low as 350 degrees C under the low concentration of 35 ppm, rendering them a promising sensing material for the on-site detection of ethanol. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
6061 aluminum alloy T-joints were welded by double-pulsed MIG welding process. Then, the post-weld heat treatment was performed on the welded T-joints. The weld microstructure under different aging temperature and time was investigated by transmission electron microscopy and scanning electron microscopy. The mechanical properties were examined by hardness test and tensile test. The results showed that the micro-hardness was sensitive to heat treatment temperature and time. Increasing temperature was beneficial to the shortening of peak aging time. There were a large number of dislocations and few precipitates in the welded joints. With the increase of post-weld heat treatment temperature and time, the density of dislocation decreased. Meanwhile, the strengthening phase precipitated and grew up gradually. When the post-weld heat treatment temperature increased up to 200 degrees C, large Q' phases were observed. And they were responsible for the peak value of the micro-hardness in the welded joints.
摘要：
We report a new organics cladding pretreatment technique to fabricate the austenitic steel coating via the laser remanufacturing technology and demonstrate that the organics cladding pretreatment could refine the grains and alleviate defects of the coating remarkably, which consequently enhances significantly the mechanical property. In addition, a new synchronous lateral powder feeding device is employed to prevent the nozzle from being blocked by organics coated powder and also protect the surface of the molten pool from being oxidized. This new organics cladding pretreatment technique may be important for the technological improvement in the mechanical property of coating fabricated via laser remanufacturing method.
摘要：
The coatings are fabricated using austenitic stainless steel powder with various contents of carbon and boron via laser remanufacturing technique. A new synchronous lateral powder feeding device is adopted to avoid surface oxidation of molten pool. The authors find that the strength can be increased but plasticity is decreased of with the rise of boron content due to the formation of lamellar borides phase structures, which are very brittle and have high hardness. In addition, the authors also find that the tensile strength and hardness are enhanced by increasing the content of carbon, while the plasticity is deteriorated due to the formed carbide in the grain of the austenitic stainless steel coating. The coatings of austenitic stainless steel powder with various contents of carbon and boron are fabricated using laser remanufacturing technique. A new synchronous lateral powder feeding device is adopted to avoid surface oxidation of molten pool. The tensile strength and hardness are enhanced by increasing the content of carbon and boron, while the plasticity is deteriorated.
摘要：
As a candidate technology for accident tolerant fuel (ATF), surface modified Zr cladding has captured the interest of an army of nuclear workers in the past few years. In this paper, three coatings (TiN, Cr, and TiN/Cr) were deposited on Zr-4 by direct current magnetron sputtering. The microstructural properties of the three coatings were detected by using scanning electron microscope (SEM) and X-ray diffraction (XRD). The thickness of coating was determined by examining the cross sectional SEM image. The adhesion properties of was characterized by using scratch testing. The thermal shock resistance (TSR) tests were carried out in three temperature variations, that is, Delta T = 800 degrees C, 1000 degrees C, and 1200 degrees C, respectively. After the TSR test, the surface morphology of the tested specimens was observed, XRD, SEM and energy dispersive spectrometer (EDS) were used to examine the microstructural properties of the tested specimens, and scratch testing was executed to determine the adhesion properties. The results show that TiN coating was partially peeled off and the inner zirconium alloy was oxidized. And the thickness of the generated ZrO2 layer is about 50 mm. The specimens coated with single Cr coating remained intact. The cross-sectional analysis result show that only about 30% of Cr coating is oxidized, and the residual Cr coating and inner zirconium alloy are not oxidized. It is mainly due to the dense and uniform structure of Cr2O3 formed by the oxidation of the outermost layer of Cr coating, which prevents the further penetration of oxygen into the interior and plays a very prominent protective role. For the bilayer TiN/Cr-coated specimens, the coefficient of thermal expansion (CTE) of intermediate TiN layer is different from that of zirconium alloy substrate. After TSR test, cracks and a large number of pores appear, and there are obvious gaps between the bulk oxidation products, which leads to poor protection of the internal materials. It indicates that the zirconium alloy coated with a single Cr coating has excellent TSR property. (C) 2019 Elsevier B.V. All rights reserved.
期刊：
Journal of Superconductivity and Novel Magnetism,2019年32(12):3831-3835 ISSN：1557-1939
通讯作者：
Liu, Min;Li, Duxin
作者机构：
[Zhang, Ge; Liu, Min; Xia, Yanfang] Univ South China, Coll Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Li, Duxin; Xia, Yanfang] Cent S Univ, Natl Key Lab Powder Met, Changsha 410006, Peoples R China.;[Zhang, Ge; Liu, Min; Xia, Yanfang] Univ South China, Cooperat Innovat Ctr Nucl Fuel Cycle Technol & Eq, Hengyang, Peoples R China.
通讯机构：
[Liu, Min] U;[Li, Duxin] C;Univ South China, Coll Nucl Sci & Technol, Hengyang 421001, Peoples R China.;Cent S Univ, Natl Key Lab Powder Met, Changsha 410006, Peoples R China.;Univ South China, Cooperat Innovat Ctr Nucl Fuel Cycle Technol & Eq, Hengyang, Peoples R China.
关键词：
The mixed magnetic property;Prussian blue analogs;Spin frustration
摘要：
In this work, polycrystalline powder samples of Cu0.64Mn0.86[Fe(CN)(6)]center dot 7.2H(2)O and Cu0.84Mn0.66[Fe(CN)(6)]center dot 7.1 H2O have been synthesized by a coprecipitation method. The lattice parameter a is 10.053(8) angstrom and 10.083 angstrom for Cu0.64Mn0.86[Fe(CN)(6)]center dot 7.2H(2)O and Cu0.84Mn0.66[Fe(CN)(6)]center dot 7.1H(2)O, respectively. When the temperature reaches to 5 K, the magnetization is 7.262 emu/g and 0.142 emu/g for Cu0.64Mn0.86[Fe(CN)(6)]center dot 7.2H(2)O and Cu0.84Mn0.66[Fe(CN)(6)]center dot 7.1H(2)O, respectively. The coercive field and the remanent magnetization of Cu0.64Mn0.86[Fe(CN)(6)]center dot 7.2H(2)O are 1204 Oe and 0.382 mu(B)/fu, respectively. The coercive field and the remanent magnetization of Cu0.84Mn0.66[Fe(CN)(6)]center dot 7.1H(2)O are 833 Oe and 0.681 mu(B)/fu, respectively. In the initial magnetization curve, under the external magnetic field of 7 T, the magnetization of Cu0.64Mn0.86[Fe(CN)(6)]center dot 7.2H(2)O and Cu0.84Mn0.66[Fe(CN)(6)]center dot 7.1H(2)O is 2.13 mu(B)/fu and 2.44 mu(B)/fu, respectively. The difference between the calculated magnetic moment and the theoretical magnetic moment is quite large, which may be due to spin frustration.
作者机构：
[Luo, Biao] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Li, Wei] Univ Sci & Technol Beijing, Sch Mech Engn, Beijing 100083, Peoples R China.
通讯机构：
[Luo, Biao] U;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Thermal dynamic characteristics;Tooth profile modification;Thermoelastic coupling condition;Gear transmission system
摘要：
The tooth profile modification was considered as a part of the static error of a gear transmission system. Subsequently, the thermodynamic equation of the system after the tooth profile modification was derived by introducing the equivalent static transmission error and thermal meshing stiffness. The effect of the tooth profile modification on the dynamic characteristics of the gear transmission system under the thermoelastic coupling condition was systematically analysed. Then the optimal thermal tooth profile modification method of gear which considered the thermal dynamic characteristics was obtained. The results indicate that the tooth profile modification is equivalent to increasing the load excitation of the system, and the load increment is equal to the sum of the products of the meshing stiffness and modification amount of each related single tooth pair. After modification, the response of the system dynamic error tends to be constant, and the dynamic load coefficient is approximately 1.0.
