Corrosion-resistant aluminum alloy composite coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metal corrosion resistance, and particularly discloses a corrosion-resistant aluminum alloy composite coating and a preparation method and application thereof. The aluminum alloy composite coating comprises lithium-aluminum layered double-metal hydroxide film layers and a metal organic framework material layer from inside to outside; and an amino acid corrosion inhibitor is arranged between the lithium-aluminum layered double-metal hydroxide film layers. The preparation method of the aluminum alloy composite coating comprises the following steps: placing an aluminum alloy base material in conversion liquid of the lithium-aluminum layered double-metal hydroxide film layers containing the amino acid corrosion inhibitor, and performing water bath conversion treatment to obtain a semi-finished product; and placing the semi-finished product in conversion liquid of the metal organic framework material layer, and performing hydrothermal conversion treatment to obtain the aluminum alloy composite coating. The grade of adhesive force between the prepared composite coating and the aluminum alloy base material is 0, the corrosion current density can be reduced by two orders of magnitude compared with that of untreated aluminum alloy, and the impedance value can reach 6.6819 x 10<5> to 1.6161 x 10<6> omega.cm<2>.

Description

technical field [0001] The invention belongs to the technical field of metal corrosion resistance, and in particular relates to a corrosion-resistant aluminum alloy composite coating and a preparation method and application thereof. Background technique [0002] Aluminum alloys are widely used in aerospace, automobiles, ships, home building materials and other fields because of their advantages such as high specific strength, low density, and good mechanical properties. Due to the very active chemical properties of aluminum, it can be oxidized to form an inert aluminum oxide film, which can protect the aluminum alloy substrate to a certain extent, but the naturally formed aluminum oxide film is not dense and has poor uniformity, so it often occurs localized corrosion. [0003] In order to improve the corrosion resistance of aluminum alloys, people often carry out surface treatment on them. At present, the preparation methods of corrosion-resistant coatings on the surface o...

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Problems solved by technology

However, the hexavalent chromium in the chromate conversion coating is very toxic and will cause great harm to the human body and the environment. Therefore, people began to look for an environmentally friendly protective film that can replace the chromate conversion coating.

[0004] At present, chromium-free chemical conversion coatings on the surface of aluminum and its alloys mainly include titanium-zirconium conversion coatings, rare earth conversion coatings, silane conversion coatings, and organic acid conversion coatings. In terms of function, it still cannot completely replace the traditional chromate conversion coating, and there is a certain gap, mainly in the weak binding force with the metal substrate, poor corrosion resistance, etc.

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