如何配置SMT生产线

目前SMT生产线已被广泛应用于大规模电子组装生产上,对SMT设备选择、组线设计等问题作了实用性论述,希望对企业选择SMT设备有一定的帮助。     

Effect of Copper on Solid Electrolytes (Ce0.8Sm0.2)1 ? xCuxO2 ? δ and Composite Cathodes Based on La0.8Sr0.2MnO3

The phase composition and electroconduction in air of solid electrolytes (Ce_0.8Sm_0.2)_{1 − x} Cu_xO_{2 − δ} (CSCu), where x = 0, 2, 5, 10, and 20 mol % and which are synthesized using the ceramic technology, are studied. Adding an additive of CuO lowers the CSCu sintering temperature by 100– 200°C and leads to the formation of single-phase solid solutions of a fluorite type up to x = 10 mol %. The electroconductivity of the CSCu electrolytes remains practically invariant upon adding up to 5 mol % Cu and equals 0.089–0.095 and 0.017–0.021 S cm⁻¹ at 800 and 600°C. The sintering, adhesion, and electroconductance of composite cathodes based on La_0.8Sr_0.2MnO₃ with 40% CSCu and their electrochemical behavior in air in the temperature interval 900–1000°C on carrying electrolyte Zr^0.9Y_0.1O_1.95 with a CSCu sublayer containing 2 mol % Cu are studied.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 656–661.Original Russian Text Copyright © 2005 by Bogdanovich, Gorelov, Balakireva, Dem’yanenko.     

静电纺丝法和气流-静电纺丝法制备聚砜纳米纤维

应用电纺法制备了聚砜纳米纤维.设计了一种新型的气流静电纺丝装置,其特点是在喷丝头上添加了喷气组件.电纺过程中所用聚砜的特性粘数为0.97dLg,溶剂为二甲基乙酰胺,载气为氮气.研究了聚砜纳米纤维的平均直径与过程参数之间的关系.研究表明影响聚砜纳米纤维的平均直径的主要因素为电压、纺丝液的流速、喷丝头与收集器之间的距离、操作温度以及纺丝液的性质(如粘度、表面张力和电导率).纳米纤维的平均直径和直径分布用扫描电镜表征.应用这种气流静电纺丝法制备的纳米纤维的直径范围是50～500nm.所得纳米纤维的直径依赖于电压、喷丝头与收集器之间的距离以及喷丝液的浓度.结果表明,采用气流静电纺丝不仅能制备较细而且均匀的纳米纤维,而且产量更高.     

旋转流体实验设备改造

论述了旋转流体实验装置改造所存在的问题及改进的措施。     

电子设备故障诊断专家系统的设计

介绍了大型电子设备故障诊断专家系统的作用 ,阐述了该系统的软件设计、具体要求、功能及任务     

The preparation of PLZT ceramics from a sol-gel process

Sol-gel process is employed to prepare PLZT ceramic with the composition 9/56/44 (La/Zr/Ti). Complete crystallization of the sol-gel derived powders is achieved after 600°, 1 hr. calcination. The sintered density of the PLZT pellet decreases as the sintering time increases. A ninety-nine percent theoretical density is obtained for samples sintered at 1250° for one hour. The dielectric properties and optical transmission of the sol-gel derived samples are measured and compared with those of the hot-pressed PLZT ceramics reported in the literature. Sol-gel derived powders, when properly sintered, possess sufficient optical transparency for optoelectrical device applications.     

An assessment of a parallel,finite element method for three‐dimensional,moving‐boundary flows driven by capillarity for simulation of viscous sintering

A parallel, finite element method is presented for the computation of three‐dimensional, free‐surface flows where surface tension effects are significant. The method employs an unstructured tetrahedral mesh, a front‐tracking arbitrary Lagrangian–Eulerian formulation, and fully implicit time integration. Interior mesh motion is accomplished via pseudo‐solid mesh deformation. Surface tension effects are incorporated directly into the momentum equation boundary conditions using surface identities that circumvent the need to compute second derivatives of the surface shape, resulting in a robust representation of capillary phenomena. Sample results are shown for the viscous sintering of glassy ceramic particles. The most serious performance issue is error arising from mesh distortion when boundary motion is significant. This effect can be severe enough to stop the calculations; some simple strategies for improving performance are tested. Copyright © 2001 John Wiley & Sons, Ltd.     

激光直接快速成形金属零件的机理分析

以Cu粉和Sn粉的混合粉末为对象分析双组元金属粉末的激光烧结成形机理,分析了材料特性和工艺参数对成形机理的影响,设计了双组元金属粉末的烧结机理实验,并对实验结果进行了分析。     

浅析退锡铅制程

文章主要介绍退锡铅制程的原理、制程问题的解决方法以及设备的设计的注意事项。     

Apatite type lanthanum silicate and composite anode half cells

Apatite type rare earth silicates are being extensively studied as electrolyte material for intermediate temperature solid oxide fuel cells (SOFC). In this paper we presents results on synthesis of Al and/or Fe-doped ATLS, the design of compatible anode materials, thermal expansion properties and co-sintering of half-cells from expansion matched materials using the advanced pulsed electric current sintering (PECS) technique. The issues related to the co-sintering of half cells have been addressed successfully by the combined use of nano powders and PECS.