Fabrication Of Copper Superhydrophilic Composite Wick And Its Wettability And Capillary Performance Study

Wettability of a solid surface is closely related to its physics, chemistry, mechanics, etc. In recent years, it has become a research focus of machinery, materials science, chemistry, thermal physics, and many other subjects. Superhydrophilic surface which is a kind of extreme wetting structure, shows good potential in improving the capillary performance of wicks. This thesis proposed a novel method for the fabrication of superhydrophilic copper surface, with a chemical deposition/heat treatment composite process. A novel groove-deposition composite wick was designed and fabricated based on this process. Moreover, the permeability, stability and capillary performance of the composite wick were investigated. This thesis simply introduced superhydrophilic structure into the groove wicks, which would greatly improve the heat transfer performance of groove heat pipe, and make a contribution to the effective solutions of heat control problem of high heat flux. The main research contents in this thesis were as follows:(1) Fabrication of superhydrophilic copper surface and its wettability studyA novel method of fabrication of superhydrophilic copper surface with high interfacial strength was proposed, combining with electrochemical deposition and heat treatment process. The effects of manufacturing parameters on wettability, morphology, chemical and phase compositions were studied, and the interfacial strength enhancement of heat treatment process was analyzed. Moreover, we made a research on the wetting mechanism of microstructure on copper surface, in order to provide a valuable reference for the study of wettability of micro rough structure on metal surface.(2) Manufacturing of groove-deposition composite wicks with superhydrophilicity on copper surfaceA novel groove-deposition composite wick was designed and manufactured, combining with the machining, electrochemical deposition and heat treatment process. Key parameters of multi-tooth cutter(MTC) was designed and the cutting technical parameters was optimized for the forming of microgrooves on copper surface. The morphology and forming mechanism of micro grooves was analyzed by microscopic observations. Furthermore, combining with the MTC cutting technical and preparation method of superhydrophilic copper surface, a superhydrophilic composite wick was manufactured successfully with a layer of porous microstructure built on the groove surface.(3) Permeability and stability analysis of groove-deposition composite wicksThe effects of manufacturing parameters on the permeability of composite wicks were studied based on the Darcy’s law and the test of liquid flow enforcement, in order to provide significant data for the capillary performance investigations. The permeability of composite wicks reduced with the increase of deposition time, current density and heat treatment temperature, while it has a clearly promotion with the increase of groove depth. In addition, a novel testing method of microstructure anti-scouring performance was put forward, and the effects of heat treatment temperature on it was investigated as well.(4) Capillary performance study of groove-deposition composite wicksThe capillary rise in the composite wicks was accurately recorded by infrared thermal imaging, and the capillary performance was evaluated through the theoretical analysis and data processing. An investigation of the effects of the manufacturing parameters on the capillary performance of the composite wicks was carried out to make an optimization. Comparison with the existing research results shows that the capillary performance of groove-deposition composite wicks was superior to single structure wicks, which provided an excellent wick for the two-phase heat transfer device. Besides, the research results may be a valuable reference for the study of capillary performance of composite microstructures.