Method for preparing differential arc oxidation coating with high solar absorptivity and high emissivity

Abstract

The invention provides a method for preparing a micro-arc oxidized coating with high solar absorptivity and high emissivity. The invention solves such a problem associated with prior Al-alloy coating that the solar-absorptivity, emissivity and bond, etc. can't meet the requirements from such fields as aerospace and decoration. The procedures are: placing a cleaned Al alloy in a stainless steel electrolytic tank as an anode, taking the stainless steel electrolytic tank as a cathode, supplying power by a pulse micro-arc oxidizing power supply, controlling the current density to be 0.5- 30A / dm<2>, positive voltage 240-1000 V, power supply frequency 50-3000 Hz, duty rate 10-50%, and controlling the electrolyte by a cooling circulating water to be no more than 30 DEG C, pH value of the electrolyte 8-12, carrying out micro-arc oxidization for 5-180 min., and then obtaining a ceramic coating. The invention reduces the cost and improves the product performance. The invention obtains a ceramic coating that has a solar absorptivity on Al alloy surface more than 0.90 and emissivity more than 0.80, in addition, the coating is of high hardness (more than 1000 Hv) and good bond with the substrate.

Description

technical field

[0001] The invention relates to a coating method, in particular to a micro-arc oxidation ceramic coating with high solar absorption rate and high emissivity prepared on the surface of an aluminum alloy by using a micro-arc oxidation technology. technical background

[0002] High solar absorptivity and high emissivity coatings, as an important class of thermal control coatings, are widely used in aviation, aerospace, decoration and other fields to control temperature and eliminate stray light. They have two important properties: high solar absorptivity (generally greater than 0.8) and higher emissivity (emissivity is generally greater than 0.8). At present, the high-absorption and high-emission coatings mainly used include two types: one is a coating based on anodized film obtained by anodic oxidation coloring or electrolytic coloring; the other is a binder plus black fuel (graphite, etc. ) mixed and applied to the surface of the substrate. Although these tw...

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