溶胶凝胶法SiO2玻璃纤维的制备及其析晶性

研究了水和盐酸加入量对硅酸乙酯溶胶的水解时间ｔ１，可拉丝时间ｔ２，拉丝性以及ＳｉＯ２玻璃纤维析晶性的影响，并确定了其最佳配比。利用Ｒａｍａｎ光谱对纤维结构进行了分析，揭示了纤维内部的网格结构特征和断键程度对胶的拉丝性和ＳｉＯ２玻璃纤维析晶性的作用规律。     

快堆钠池传热流动三维模型与数值模拟

针对快中子增殖反应堆钠池的流动传热特点，以质量、动量、能量守恒定律为基础，建立有关快堆钠池流动传热的三维数学模型。池内流动域中障碍物对流动和传热的影响采用空隙率和穿透率的概念来描述；钠池与其围护结构的传热关系采用耦合计算方法求解。编写了基于压力校正法和交错网格的三维流动传热模拟计算程序ＦＡＳＴＯＲ－３Ｄ。该程序通过了若干经典算例的验证计算，并应用于实际的三维钠池流动传热模拟，获得了大量的预测数据。附属软件ＤＶ以色彩表达流场、温度场等三维物理量的大小强弱，实现了大批量数据的可视化分析。     

基于有限单元和模型降阶的储能飞轮转子动力学建模及分析

针对使用Jeffcott转子模型的集中质量法建立飞轮转子-轴承系统动力学模型时将转子段视为集中质量点,未考虑转子轮盘厚度的问题,提出一种基于有限单元法和模型降阶法的飞轮转子-轴承系统建模方法.以飞轮转子-电机转子-轴承系统为对象,基于此建模方法进行动特性计算,求解飞轮转子在不同轮盘厚度下的固有频率,并与Jeffcott...     

基于数字锁相环的温控变频电路设计

CC4046集成电路锁相环采用RC型压控振荡器,外接RC作为充放电元件,电路简单、成本低廉、实用价值大,可广泛应用于广播电视系统,各种通信系统,以及频率合成,自动控制及时钟同步等技术领域。利用数字集成锁相环组成温控变频电路可以克服常见温控系统可靠性低、抗干扰能力差的缺点,为温度的精确测量及需要进行温度检测控制的设备提供了一种可行的电路设计方案。     

摩擦化学反应对发动机油润滑耐久性能的影响

利用SRV高温摩擦磨损试验机比较了两种分别属于GF-2和GF-3等级，含有MoDTC摩擦改进剂的发动机油的耐久性。结果表明，由于GF-3等级发动机油能使活塞环和缸套试样表面更加平整光滑，且由于Ca清静剂与MoDTC／ZDTP的协同作用，通过摩擦化学反应，在摩擦表面形成良好的摩擦反应膜，从而使它拥有更好的润滑耐久性能。     

Mechanical,dielectric and microwave absorption properties of carbon black (CB) incorporated SiO<Subscript>2f</Subscript>/PI composites

Structural and functional integrated absorbing materials have received extensive attention in recent years. Single-layer absorbing material composites in X and Ku bands (8.2–18 GHz) were prepared by using different proportion of carbon black (CB) incorporated quartz glass fiber reinforced polyimide resin (SiO_2f/PI). The morphology, mechanical, dielectric and microwave absorbing properties of the composites were investigated. Different contents of CB with different distributions were observed according to the fractural morphology of the composites. When the CB content is up to 8 wt%, the flexural strength of the composite reaches a maximum value of 705?±?5 MPa. The real and imaginary parts of complex permittivity both show an increasing trend with the CB content increase. Meanwhile, the real and imaginary parts decrease with the increase of frequency, exhibiting frequency-dependent dielectric response. The reflection loss of the composite was calculated based on the transmission line theory, which is in a good agreement with the experiment.     

多级多孔硅酸镍微球的合成及其对碱性品红的高效吸附

层状硅酸镍因其独特的结构, 在电化学和催化等领域展现出良好的应用前景, 其合成与性能研究近年来受到广泛关注。本研究以氯化镍和正硅酸乙酯为原料, 采用水热法合成了硅酸镍微球, 并详细探究了镍硅比和碱源对产物组成、形貌及孔结构的影响。在优化条件下, 产物呈现由纳米片组装的、平均直径约为2.5 μm的微球形貌, 比表面积为119.6 m²·g^-1, 孔容为0.673 cm³·g^-1。Zeta电位分析表明, 该微球在pH=3~10范围内保持表面电负性。将硅酸镍微球用于处理碱性品红溶液, 吸附过程符合准二级动力学模型。在初始浓度为50 mg·L^-1的条件下, 吸附容量可达120.7 mg·g^-1, 脱除率达96.6%, 远优于改性粘土及近年来报道的多种材料。吸附量与平衡浓度的数据表明, 碱性品红在硅酸镍微球上的吸附符合Freundlich吸附模型, 1/n=0.1678, 表明该吸附为多层非均相吸附且吸附作用力强。     

二烷基二硫代甲酸钼(MoDTC)摩擦改进剂对GF-3等级全配方发动机油摩擦学性能的影响

利用SRV高温摩擦磨损试验机研究了二烷基二硫代甲酸钼(MoDTC)对渗氮活塞环／铸铁缸套在ILSACGF-3发动机油润滑条件下的摩擦学性能的影响。结果表明，MoDTC能与GF-3全配方发动机油中的ZDTP／磺酸钙添加剂体系产生协同作用，在活塞环和缸套表面生成减摩和抗磨的摩擦反应膜，从而显著降低并在较长时间内保持低摩擦系数(最低0．03)，同时缸套的磨损降低50％以上。     

Dielectric Properties in the Microwave Range of K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>NbO<Subscript>3</Subscript> Ceramics

Dielectric properties of a potassium sodium niobate (KNN) system in the microwave range up to GHz have rarely been studied. Since K_0.5Na_0.5NbO₃ is the most common and typical type of KNN materials, non-doped K_0.5Na_0.5 NbO₃ ceramics were synthesized at different temperatures (1080°C, 1090°C, 1100°C, and 1110°C) by a traditional solid reaction method for further characterization and analysis. The ceramics were in perovskite phase with orthorhombic symmetry. A small quantity of second phase was found in the 1110°C sintered specimen, which resulted from the volatilization of alkali oxides as the temperature increased. The complex permittivity was measured for the first time in the microwave range (8.2–12.4 GHz) and in the temperature range from 100°C to 220°C, and the effects of annealing on the dielectric properties were studied. The results indicate that the complex permittivity of KNN ceramics over the microwave range increases mainly due to high bulk density and the additional dielectric contributions of oxygen vacancies at high temperature.     

Solid-State Reaction Mechanism and Deliquescence Phenomenon of K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>Nb<Subscript>0.7</Subscript>Al<Subscript>0.3</Subscript>O<Subscript>3</Subscript> Ceramic

Development of (K,Na)NbO₃-based ceramics has attracted much attention in recent decades. In this work, K_0.5Na_0.5Nb_0.7Al_0.3O₃ ceramic was prepared using conventional solid-state processing. A deliquescence phenomenon was observed when the specimen was exposed to moist atmosphere. The reaction mechanism and cause of deliquescence were investigated using x-ray diffraction analysis, scanning electron microscopy, energy-dispersive spectrometry, electron microprobe analysis, inductively coupled plasma mass spectrometry, and thermogravimetric/differential scanning calorimetric analysis. The results revealed interactions mainly amongst the raw materials K₂CO₃, Na₂CO₃, and Nb₂O₅ as well as K₂CO₃, Na₂CO₃, and Al₂O₃, which can influence the sintering behavior of the mixture. (K,Na)NbO₃ and (K,Na)AlO₂ were present in the sintered K_0.5Na_0.5Nb_0.7Al_0.3O₃ ceramic, with the latter leading to deliquescence. During the sintering process, Al₂O₃ reacts with alkali oxides (Na₂O and K₂O), which are the decomposition products of carbonates, to form (K,Na)AlO₂. In addition, Al₂O₃ is more likely to react with K₂O compared with Na₂O.