Investigation of electroless copper plating on polyurethane foam,as an initial step of open cell foam production process

Abstract

Coating of polymeric foams is known as a method for production of metallic foams, which produces foams with high volume of porosity and controllable pore size. In this research, this method was employed to produce open cell copper foam by use of polyurethane foam with an average pore size of 0.4?mm as the substrate. Since polyurethane foam as a non-conductive material is not able to be coated directly by electrolytic deposition, the substrate was initially metallised by electroless copper plating. In the electroless plating process, the effects of the main parameters such as bath chemical composition, solution pH and temperature on deposition rate and thickness of the coatings obtained were investigated. The results showed that the optimum condition of the process is obtained when CuSO₄ concentration in the deposition bath is 12?g?L^??1, pH is 13 and plating temperature range is 55–60°C.     

Comparison of the Electrical Characteristics of PZT and SBT Thin Films

The electrical properties of lead zirconate titanate (PZT) and strontium bismuth tantalate (SBT) thin films are compared for nonvolatile random access memory applications. PZT thin films have high switchable polarization with poor fatigue resistance and higher leakage current densities as compared to SBT thin films deposited on platinized silicon substrates. Characterization of these films in terms of their domain dynamics under application of sub-switchable and switchable electric fields give valuable insight about the observed differences in the electrical behavior. In the present work the dielectric behaviors of SBT and PZT thin films at sub-switchable electric field were analyzed in terms of Rayleigh law. The reversible and irreversible polarization component of switchable polarization was separated by the measurement of capacitance-voltage (C-V) and polarization hysteresis loops. The conduction mechanisms in these films were evaluated by measuring field dependence of leakage current densities at various temperatures. The observed differences in electrical properties are explained in terms of the intrinsic defects and defect-domain interaction of these two materials.     

Structural effects on trends in the deposition and dissolution of metal-supported metal adstructures

A simple thermodynamic formalism is combined with Density Functional Theory calculations to determine periodic trends in the reversible deposition/dissolution potentials of admetals on a variety of transition metal substrates. For each admetal/substrate combination (81 in total), the deposition/dissolution potential shift (referenced to the corresponding potential of the admetal in its bulk, elemental form) is calculated for isolated adatoms, for dimers, and for more extended kink structures. Clear periodic trends are found for the potential shifts across the space of different admetals and substrates. In addition, for the significant majority of these admetal/substrate systems, the structural effects are found to be a strong function of the local coordination number of the metal atoms, thereby verifying an important assumption that has been widely used in semiempirical models of deposition and dissolution.     

Tuning peculiar antimony micro- and nano-morphology via a novel electrodeposition approach

Antimony (Sb) microspheres composed of antimony nanoplates or nanoparticles were synthesized via a novel electrodeposition technique onto the top surface of porous anodic alumina membrane (AAM) after the growth of antimony nanowires. The two kinds of morphologies could be controlled by altering the experimental parameters, and the size of the nanoplates could also be tuned by adjusting the deposition potential. Besides, the micro- and nano-structure had relative narrow size distribution. Based on the experimental results, the possible growth mechanism was also proposed briefly. The method demonstrated here extends the application of AAM and can be used to synthesize other micro- and nano-structured materials.     

Influence of Stratification and Shoreline Erosion on Reservoir Sedimentation Patterns

Sedimentation in the main pool of a deep (maximum depth: 50?m), 227?km2 hydropower reservoir was modeled using a three-dimensional numerical model of hydrodynamics and sedimentation for different wind, inflow, and outflow conditions. Short-term velocity measurements made in the reservoir were used to validate some aspects of the hydrodynamic model. The effects of thermal stratification on sedimentation patterns were investigated, since the reservoir is periodically strongly stratified. Stratification alters velocity profiles and thus affects sedimentation in the reservoir. Sedimentation of reservoirs is often modeled considering only the deposition of sediments delivered by tributaries. However, the sediments eroding from the shorelines can contribute significantly to sedimentation if the shorelines of the reservoir erode at sufficiently high rates or if sediment delivery via tributary inflow is small. Thus, shoreline erosion rates for a reservoir were quantified based on measured fetch, parameterized beach profile shape, and measured wind vectors, and the eroded sediments treated as a source within the sedimentation modeling scheme. The methodology for the prediction of shoreline erosion was calibrated and validated using digital aerial photos of the reservoir taken in different years and indicated approximately 1?m/year of shoreline retreat for several locations. This study revealed likely zones of sediment deposition in a thermally stratified reservoir and presented a methodology for integration of shoreline erosion into sedimentation studies that can be used in any reservoir.     

Interface growth morphologies in pulsed laser deposited, room temperature grown multilayer hard coatings

The mechanical behaviour - hardness, elasticity, and adhesion - of multilayer coatings is strongly influenced by the type of the formed interfaces between the different layers. In industrially applied tribological coatings the interface region is predominantly not a perfect sudden change of the chemical composition of the adjacent crystal planes, but a transition zone of a thickness, which is strongly dependent on the energetic conditions during deposition. Multilayer coatings grown by high-energetic deposition techniques always struggle with high atomic mixing of both adjacent coating materials due to high energetic ion implantation.One of these high-energetic deposition techniques is the Pulsed Laser Deposition (PLD), characterized by pulsed and within one pulse alternating high- and low-energetic particle fractions, hitting successively the substrate surface. Such deposition conditions were shown to be highly advantageous for low temperature deposition by the densification of the growth structures due to activated diffusion and re-sputtering, but increases the difficulty in depositing multilayer structures.The current paper addresses these specific growth conditions based on Ti/TiN and Cr/CrN multilayer coatings. High resolution transmission electron microscopy results show that the atomic mixing at the interface is not highly critical for the deposition of multilayer coatings and that extremely dense growth structures are forming even in the interface regions.     

Influence of processing variables on the structure and properties of ZnO films

Zinc oxide films of high optical quality have been deposited onto both silica and silicon substrates using reactive sputtering, pulsed laser deposition, and an aqueous solution based technique. Films have been characterized with respect to crystalline phase and phase stability, surface morphology, and optical response by means of X-ray diffraction, Raman spectroscopy, atomic force microscopy, optical transmission and ellipsometry measurements. All films studied were of the wurtzite phase, fine-grained, and exhibited varying degrees of c-axis orientation with respect to the substrate normal depending upon deposition conditions. Films showed some degree of residual tensile stress which was inferred from the E₂ Raman line shift relative to the single-crystal frequency. The wurtzite phase was found to be stable to temperatures near 800 °C, but at higher temperatures, reaction with silica led to evolution of Zn₂SiO₄ at the interface. Variations in Raman line intensities upon post-deposition annealing have been correlated with oxidation of excess zinc in the lattice.     

吐哈油田生产井蜡沉积物系统分析及蜡沉积机理探讨

用溶剂萃取分离，气相色谱，红外光谱、核磁共振等方法分析研究了吐哈油田特别是鄯善油田生产井的蜡沉积物，吐哈原油中的蜡按烷烃碳数分布有Ｃ１３－Ｃ３５和Ｃ３０－Ｃ６５两个峰区，其中第二峰区的高碳石蜡含量超过蜡总含量的５０％，蜡熔点很高，为８４－１００℃，基本上是不带支链的纯粹正构烷烃，极易从原油中析出。对蜡沉积作了初步探讨和推论。     

Thermophoretic deposition of small particles in a direct numerical simulation of turbulent channel flow

This paper presents results for the deposition rate of small particles on the walls of a turbulent channel flow. The results were obtained by direct numerical simulation of a horizontal turbulent channel flow. A temperature profile typical of ceramic oxide aerosol reactors was imposed across the channel. Thermophoresis played an important role in the deposition of particles for the range of conditions that were studied. An interaction between turbophoresis and thermophoresis was found to play an important role in the deposition process.     

中国含油气盆地的演化

本文从中国各个地质时期的地壳运动和沉积古地理出发，综合分析了晚古生代以来中国陆相含油气盆地的演化特点，提出了二叠纪湖盆发育于新疆北部，晚三叠纪湖盆主要发育于陕甘宁地区，侏罗纪时期中国西部大面积沉降，发育众多的大型湖盆，水域面积大，西部湖盆较东部发育。早白垩纪晚期以后，中国西部上升而东部开始沉降，早白垩纪晚期发育了松辽湖盆，早第三纪发育了渤海湾、苏北、江汉和海上大陆架诸多湖盆。以上这些大型古湖盆都是油气生成的有利场所。