Nano particle strengthened composite coating layer for realizing dropwise condensation heat transfer

Abstract

The invention relates to a nano particle strengthened composite coating layer for realizing dropwise condensation heat transfer, which is amorphous. The thickness of the coating layer is 20-30 mum, and the surface energy is 25-30 mN / m. A preparation method of the nano particle strengthened composite coating layer comprises the following main steps of: preparing a coating liquid, adding nano SiO2 particles, and performing chemical composite coating. The invention has the characteristics that the composite coating liquid containing suspended SiO2 particles is prepared through ultrasonic stirring, a chemical composite coating layer containing SiO2 particles is successfully obtained on the surface of a metal test specimen, the binding force between the coating layer and the metal matrix is good, the surface energy is low, the heat resistance of an accessory is small, and the stable dropwise condensation of steam at normal pressure is realized on the surface.

Description

【Technical field】 [0001] The present invention relates to the preparation of nanoparticle-reinforced metal-matrix composite materials and their condensation heat transfer performance. Specifically, it is a method for preparing composite electroless coatings reinforced by nano-silica particles. Silicon oxide particles reduce the surface energy of the coating and form a stable drop-like condensation heat transfer form on its surface. 【Background technique】 [0002] Since the discovery of the droplet condensation heat transfer phenomenon in the 1930s, many heat transfer researchers have conducted a lot of research on the method of droplet condensation because its heat transfer coefficient is several times or even ten times higher than that of film condensation. The methods for successfully realizing dropwise condensation include coating precious metals, coating organic accelerators, and molecular self-assembled films, etc., but these methods have defects of varying degrees. For...

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Problems solved by technology

[0002] Since the discovery of the droplet condensation heat transfer phenomenon in the 1930s, many heat transfer researchers have conducted a lot of research on the method of droplet condensation because its heat transfer coefficient is several times or even ten times higher than that of film condensation. The methods for successfully realizing dropwise condensation include coating precious metals, coating organic accelerators, and molecular self-assembled films, etc., but these methods have defects of varying degrees. For example, the cost of coating precious metals is too high, which limits its large-scale industrialization; the service life of the organic accelerator is not long, and it is easy to cause pollution; the molecular self-assembled film has the disadvantages of poor bonding with the substrate and easy to fall off

[0003] Because the amorphous electroless coating has the advantages of low surface energy, good bonding force with the substrate, good corrosion resistance, low cost, and simple process, it has a good application prospect in realizing droplet condensation, but it is currently used at home and abroad. There are not many studies on the enhancement of condensation heat transfer by nickel-based electroless plating technology

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