无铅易切削硒铋黄铜的研究

介绍了无铅易切削硒铋黄铜的制备工艺，于中频感应炉中制备了无铅易切削硒铋黄铜铸锭，并对其组织和力学性能以及抗腐蚀性进行了测定。结果表明，铋以铜铋中间合金形式在1200℃加入时，铋均匀分布在铜合金中。该工艺制备的无铅易切削硒铋黄铜具有较HPb59-1好的力学性能、机加工性能和抗脱锌腐蚀性能。通过物相与组织形貌分析，解释了铋改善铜合金切削性能的机理。     

Effect of wall wettability condition on drift-flux parameters in lead–bismuth two-phase flow in circular and annular bubble columns

Lead–bismuth two-phase flow in a cylindrical vessel and annulus was experimentally investigated by varying the surface wettability of the vessel wall. The test section used in this study was a cylindrical stainless vessel with/without inner sleeve to change the hydraulic diameter. Volume-averaged void fraction was measured by varying the surface wettability of the test section, which was enhanced by using a soldering flux. Measured void fraction was compared with existing two-phase flow correlations and with one-dimensional theoretical simulations assuming one-dimensional drift-flux model. From experimental results, measured distribution parameters of the lead–bismuth two-phase flow are much larger than that of ordinary two-phase flow regardless of the surface wettability. In the present work, the one-dimensional analysis was carried out for the cylindrical vessel to reproduce the distribution parameter. From the simulation results, predicted value for the cylindrical vessel showed good agreement with experimental results. However, in annulus, the distribution parameters in annulus were underestimated by the present model. It was suggested that, in case of annulus, steeper void fraction profile might be formed near the inner surface for poor wettability condition.     

Fe/Bi0.5Sb1.5Te3热电元件高温稳定性研究

热电元件的界面高温稳定性是决定热电器件服役性能和应用前景的重要因素,而阻挡层和热电材料之间的界面扩散和界面电阻则是评价热电元件高温稳定性的主要标准.为了进一步提升P型碲化铋热电器件的界面稳定性,本研究采用高通量筛选的方法选定适用于P型碲化铋的Fe阻挡层材料.通过一步烧结的方法制备了Fe/P-BT的热电元件,并系统研究了...     

钛酸铋钠基无铅压电陶瓷研究近期进展

钛酸铋钠(分子式是Bi0.5Na0.5TiO3,简写为BNT)基无铅压电陶瓷性能优良,但与铅基陶瓷相比还有相当的差距,其性能有待进一步提高.从BNT基陶瓷改性、陶瓷新体系以及陶瓷制备技术等多方面,分析了提高BNT基陶瓷性能的原理、途径和方法,指出了发明陶瓷新体系的有关思路,讨论了陶瓷制备技术与陶瓷性能的关系.同时,列举了近期在BNT基陶瓷性能改善研究中的若干新进展和新结果、性能良好的BNT基陶瓷新体系及制备工艺和制备新技术对陶瓷性能的影响,并对今后的相关研究进行了展望.     

ICP—AES法测定黄铜中的铅铁铋镍铝锑

用电感耦合等离子体发射光谱法可直接测定黄铜中的铅铁铋镍铝锑6种元素的含量．通过试验优化出各元素的分析波长和分析条件，且用基体匹配补偿基体效应．该法流程简单，分析快速，回收率为95％～105％，相对标准偏差小于2．5％。     

Natural circulation studies in a lead bismuth eutectic loop

Lead Bismuth Eutectic (LBE) is increasingly getting more attraction as the coolant for advanced reactor systems. It is also the primary coolant of the Compact High Temperature Reactor (CHTR), being designed at BARC. A loop has been set up for thermal hydraulics, instrument development and material related studies relevant to CHTR. Steady state natural circulation experimental studies were carried out for different power levels. Transient studies for start-up of natural circulation in the loop, loss of heat sink and step power change have also been carried out. An 1D code named LeBENC has been developed at BARC to simulate the natural circulation characteristics in closed loops. The salient features of the code include ability to handle non-uniform diameter components, axial thermal conduction in fluid and heat losses from the piping to the environment. This paper deals with the experimental studies carried out in the loop. Detailed validation of the LeBENC code with the experimental data is also discussed in the paper.     

Safety design of Pb–Bi-cooled direct contact boiling water fast reactor (PBWFR)

In Pb–Bi-cooled direct contact boiling water small fast reactor (PBWFR), steam is generated by direct contact of feedwater with primary Pb–Bi coolant above the core, and Pb–Bi coolant is circulated by steam lift pump in chimneys. Safety design has been developed to show safety features of PBWFR. Negative void reactivity is inserted even if whole of the core and upper plenum are voided hypothetically by steam intrusion from above. The control rod ejection due to coolant pressure is prevented using in-vessel type control rod driving mechanism. At coolant leak from reactor vessel and feedwater pipes, Pb–Bi coolant level in the reactor vessel required for decay heat removal is kept using closed guard vessel. Dual pipes for feedwater are employed to avoid leak of water. Although there is no concern of loss of flow accident due to primary pump trip, feedwater pump trip initiates loss of coolant flow (LOF). Injection of high pressure water slows down the flow coast down of feedwater at the LOF event. The unprotected loss of flow and heat sink (ATWS) has been evaluated, which shows that the fuel temperatures are kept lower than the safety limits.     

One-Step Phase Separation for Core-Shell Carbon@Indium Oxide@Bismuth Microspheres with Enhanced Activity for CO2 Electroreduction to Formate

It is a substantial challenge to construct electrocatalysts with high activity, good selectivity, and long-term stability for electrocatalytic reduction of carbon dioxide to formic acid. Herein, bismuth and indium species are innovatively integrated into a uniform heterogeneous spherical structure by a neoteric quasi-microemulsion method, and a novel C@In₂O₃@Bi₅₀ core-shell structure is constructed through a subsequent one-step phase separation strategy due to melting point difference and Kirkendall effect with the nano-limiting effect of the carbon structure. This core-shell C@In₂O₃@Bi₅₀ catalyst can selectively reduce CO₂ to formate with high selectivity (≈90% faradaic efficiency), large partial current density (24.53 mA cm⁻² at −1.36 V), and long-term stability (up to 14.5 h), superior to most of the Bi-based catalysts. The hybrid Bi/In₂O₃ interfaces of core-shell C@In₂O₃@Bi will stabilize the key intermediate HCOO* and suppress CO poisoning, benefiting the CO₂RR selectivity and stability, while the internal cavity of core-shell structure will improve the reaction kinetics because of the large specific surface area and the enhancement of ion shuttle and electron transfer. Furthermore, the nano-limited domain effect of outmost carbon prevent active components from oxidation and agglomeration, helpful for stabilizing the catalyst. This work offers valuable insights into core-shell structure engineering to promote practical CO₂ conversion technology.     

中国首例缓倾铋铜金矿脉--曙光(小西南岔)铜金矿床研究新进展

据现场深入研究，结合多年生产实践，首次系统地描述了小西南岔矿床北山矿段缓倾斜铋铜金支矿脉的地质产状、规模、铜和金品位、自然铋与自然金的交生关系。在此基础上，进一步阐述了缓倾铋铜金矿脉对理论、应用研究及矿山确保铜和金入选品位的重要意义。     

Study on Ferroelectric and Dielectric Properties of La-Doped CaBi4Ti4O15-Based Ceramics

Research on bismuthlayer structuredferroelectricceramics as piezoelectric material with high Curie tem-perature ,strong anisotropic characters ,lowdielectricdissipationfactor and lowaging rate has attracted in-creasing interest[1,2].It can be used to manu…