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Pool Boiling and Thin Film Evaporation
Published in Ralph L. Webb, Nae-Hyun Kim, Principles of Enhanced Heat Transfer, 2004
Other innovative methods have been developed to make porous surfaces. Janowski et al. [1978] have developed a process for making a porous boiling surface (see Figure 11.11d). A tube is wrapped with an open cell polyurethane foam, which is then copper plated. The copper plating provides structural integrity and good thermal conduction. The polyurethane is removed by pyrolysis (300 to 520° C), which forms additional very small pores within the skeletal structure. The structure has 1.5-mm coating thickness, 97% void volume, 4 pores/mm, and 0.12-mm pore size, augmented by 0.02-mm pores within the skeletal structure. Sachar and Silvestri [1983] used vacuum deposition of aluminum in the presence of an inert gas to form a porous surface coating. Zohler [1990] flame-sprayed two dissimilar metals (e.g., zinc and copper) on a tube, and then etched the tube so that one of the metals was etched out. Voids are left where the metal has been etched away. Chang and You [1997] made a “microporous” surface using a paint containing silver flakes (3 to 10 µm). The pores are substantially smaller (0.1 to 1 µm) than for sintered porous surfaces. The paint contained alcohol, which evaporates and epoxy that bonds the silver flakes. They showed performance improvement over a plain surface for FC-72. O’Conner and You [1995] used a dielectric paint made with diamond particles (8 to 12µm) for electronics cooling. They found that the CHF was increased 109% over that of a plain surface. The performance of the Chang and You [1997] and O’Conner and You [1995] painted coatings is not as good as that made by sintered copper particles.
The Cast Zinc Alloy Product
Published in Frank Porter, Zinc Handbook, 1991
Copper plating may be specified either for decorative effects or to provide a highly conductive surface for electrical and electronic application and occasionally to allow soldering. Thickness required will depend on the use. For decorative purposes copper plating is generally lacquered and may be treated to produce an antique bronze effect. Brass finishes can also be applied by plating.
Pre-treatment of dielectrics and technological process for deposition of chemical copper layers from copper solution with improved ecological impact
Published in Transactions of the IMF, 2020
M. Georgieva, V. Chakarova, M. Petrova, D. Lazarova, D. Dobrev
The chemical copper plating ensures uniform deposition of coating with the same thickness on all parts of the surface of the samples, with good electrical conductivity and good elasticity. The major disadvantage of this process is that almost all of the components of the solutions for copper plating are toxic and harmful to the environment. This has stimulated research on direct chemical copper plating.