再加工工艺对N18锆合金板残余应力的影响

采用“热轧+冷轧+退火”工艺对N18锆合金板进行再加工,通过X射线法分析板的表面残余应力,采用EBSD技术分析晶界取向差角分布和大小角度晶界。结果表明,热轧后N18锆合金板的表面残余应力呈现无规律分布状态;冷轧后板的表面残余应力均为压应力,其大小随着冷轧变形量的增加而增加;退火后板的表面残余应力值处于较低水平,当退火制度为500 ℃×2 h时,残余应力处于最低水平;退火后,板的微观结构以小角度晶界为主,且随着退火温度的升高,小角度晶界的密度先增加后趋于稳定。     

Easy access to pharmaceutically relevant heterocycles by catalytic reactions involving α-imino gold carbene intermediates

This review summarizes recent advances in the field of gold-catalyzed synthesis of pharmaceutically relevant aza-heterocycles via in situ generated α-imino gold carbene complexes as intermediates.     

柔性夹具技术研究

为适应快速多变的市场需求,制造企业需要设计并应用柔性夹具。介绍了柔性夹具的发展及特点,给出了柔性夹具的设计依据,并从零件结构及工艺、组成元件确定、强度与精度保证等方面分析了柔性夹具的设计方法。     

Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants

With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn–3Ag–0.5Cu–xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m^?1 and 6.30 mN·m^?1 for SnAgCu and SnAgCu–P, respectively. The surface tension of SnAgCu–xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn₄P₃ intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.     

A transient fluid–structure interaction analysis strategy and validation of a pressurized reactor with regard to loss-of-coolant accidents

Nuclear Science and Techniques - Rare event search experiments are one of the most important topics in the field of fundamental physics, and high-purity germanium (HPGe) detectors with an ultra-low...     

新型常温捕收剂DN-6对磷灰石的捕收性能研究

为降低北方磷矿厂的选矿成本，提高浮选指标，东北大学研制了一种常温磷灰石捕收剂DN-6。为检测DN-6的浮选性能，进行了单矿物浮选试验，并通过Zeta电位检测和傅里叶变换红外光谱分析对该捕收剂在磷灰石表面的作用机理进行了研究。单矿物浮选试验结果表明，在矿浆pH=7.6，矿浆温度28 ℃，DN-6用量为166.7 mg/L的浮选条件下，捕收剂DN-6对磷灰石单矿物的浮选回收率可达97.59%。Zeta电位和傅里叶变换红外光谱分析表明，pH＜4时，DN-6在磷灰石表面发生键合吸附。     

FCM燃料堆内行为模拟及结构设计研究

本文采用二维特征模型模拟不同无燃料区厚度全陶瓷微封装弥散（FCM）燃料的热力学行为，在保证堆芯装载要求的条件下，研究不同结构FCM燃料SiC基体和包覆燃料颗粒SiC层的应力状态。通过优化无燃料区厚度，调整TRISO颗粒间的间距，保证无燃料区和SiC层同时具有较低的应力水平。分析了无燃料区厚度为100 ~ 500 μm时基体SiC、无燃料区以及SiC层的应力分布，结果表明，基体SiC和SiC层最大应力随无燃料区厚度增大而增大，而无燃料区的最大应力则随其厚度增大而降低。当无燃料区厚度为400 μm时，无燃料区和SiC层均处于较低的应力状态，无燃料区SiC基体应力约为400 MPa，而SiC层的最大环向应力约为200 MPa，其失效概率约为2.5×10-4。因此，当无燃料区厚度为400 μm时，FCM燃料既能维持芯块结构完整，又能保证SiC层具有较低的失效概率。结构优化为FCM燃料的应用提供了基础。