| C/Cu composites have good comprehensive properties because they can combine the high electrical and heat conductivity of copper and the high heat resistance, good self-lubrication property and high arc corrosive resistance of graphite. The composites are widely used in electrical, electronic and mechanical applications and spaceflight and aviation. As the rapid development of science and technology, the use of C/Cu composites further extends from mechanical areas to integrate circuits, electronic encapsulation bases, heat sink materials, heat radiation and other applications. In some applications, there also have requirements for C/Cu composites with special shapes such as flake and thin tapes. On the other hand, the use of new carbon materials such as carbon fibers and carbon nanotubes can further improve the properties of C/Cu composites. In new energy area, to realize the practical use of solid oxide fuel cells, it is desirable to develop effective preparation methods for planar cells with large area (e.g. NiO/YSZ anode supports). Tape rolling or calendering is now a widely used method for manufacturing ceramic parts with plate shapes. However, there are still some theoretical and technical problems to be studied and solved. In this dissertation, C/Cu composites and NiO/YSZ materials for anode supports of solid oxide fuel cells were manufactured by the tape calendering method and macrostructure and properties of the materials were investigated.In the experimental, green tapes of grapithe/Cu, carbon nanotubes/Cu and NiO/YSZ were prepared by the tape calendering method using natural scalelike graphite, carbon nanotubes, electrolysis copper, NiO and YSZ powders as main raw materials with suitable organic binder, plasticizer and dispersant. The green tapes were then sintered to obtain grapithe/Cu and carbon nanotubes/Cu composites and NiO/YSZ materials. Effects of the composition of the raw materials, the parameters of tape calendaring and sintering on the microstructure and properties of the composites and the anode supports were systemically investigated. Following is the main results obtained in this dissertation.(1)Graphite/Cu (3wt.%graphite) green tapes with about0.7mm in thickness were prepared by tape calendering using natural scalelike graphite and electrolysis copper powder as raw materials, PVB as binder and cyclohexanone as plasticizer. Graphite/Cu composites were obtained by sintering the green tapes in H2at970℃for1h. Graphite/Cu composites have relative density of91.4%, electrical conductivity of44.4%IACS, and Vickers hardness of72.2HV.(2)The composition of the flan materials during tape rolling have obvious influence on the rolling process and the properties of the green tapes. When the PVB binder exceeds4wt.%and cyclohexanone plasticizer exceeds10wt.%, the green tapes show good formability. Increase of the PVB binder is beneficial to rolling, and increases the green density. The green density of the tapes with4wt.%of binder and8wt.%of plasticizer is5.51g/cm3and4.48g/cm3, respectively, and the relatively density is88.1%and96.4%, respectively. The thickness of the green tapes also has influence on the green density. When the thickness increases from0.1mm to0.7mm, the green density decreases about0.2g/cm3.(3)Graphite/Cu (3wt.%graphite) and carbon nanotubes/Cu composites were prepared from graphite electroplated with Cu powders, carbon nanotubes and electrolysis Cu powders by the tape calendaring method. The surface treatment by electroplating Cu can improve the property of graphite/Cu composites, and the composites have electrical conductivity of53.2%IACS and Vickers hardness of77.8HV. The amount of carbon nanotubes in the carbon nanotubes/Cu composites has influence on the properties of the composites. The materials with3wt.%carbon nanotubes show best properties in the experiments have relative density of89.09%, electrical conductivity of41.36%IACS,and Vickers hardness of88.2HV.(4) NiO/YSZ (40:60) anode supporting materials for planar solid oxide fuel cells were prepared by the organic based tape calendering process. Thickness of the green tapes is about1mm and the relative density is about73.6%. The anode materials show good comprehensive properties after sintering at1450℃for2h, which meet the requirements for anode materials of solid oxide fuel cells. |
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