Environment-friendly anodic oxidation pretreatment process

Abstract

The invention belongs to the technical field of surface processing, specifically relates to an environment-friendly anodic oxidation pretreatment process, and aims to improve the environment-friendliness and reduce the etching property on the matrix. The process orderly comprises the following steps: oil removing with an organic solvent, oil removing with a chemical method, bright dipping, alkaline etching, and bright dipping; wherein the formula of the bright dipping solution comprises the following components: sulfuric acid with a concentration of 230 to 270 g / L and potassium permanganate with a concentration of 0.8 to 1.2 g / L; and the formula of alkaline etching solution comprises the following components: sodium hydroxide with a concentration of 50 to 60 g / L, and one component with a concentration of 0.1 g / L to 0.5 g / L selected from sodium citrate, sodium tartrate, or sodium gluconate. The pretreatment process adopts low density alkali and an alkaline etching agent as the alkaline etching liquid, and low density sulfuric acid and an oxidant as the bright dipping liquid, and solves the component selection problem of alkaline etching agent and oxidant. The process has a low etching effect on aluminum materials, can remove the uneven passive film on the surface, and effectively avoid the over-etching phenomenon caused by alkaline washing and severe alkaline smog overflow.

Description

technical field [0001] The invention belongs to the technical field of surface treatment, and relates to an environmentally friendly pretreatment method before anodic oxidation of aluminum alloys, in particular to an environmentally friendly anodic oxidation pretreatment process method. Background technique [0002] At present, due to the high concentration of alkali in the pre-treatment of aluminum alloy anodic oxidation, the alkali cleaning is highly corrosive to aluminum-based materials and often damages the surface of parts, especially affecting the brightness of the polished surface; the light-emitting liquid with nitric acid as the main component The treatment effect on aluminum alloys with high Si and Fe content, especially particle-reinforced aluminum-based composite materials, is not good, and the ash on the surface cannot be completely removed, so it is often necessary to add chromic acid and hydrofluoric acid. NO 2 and other toxic gases, and the waste liquid is e...

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Problems solved by technology

[0002] At present, due to the high concentration of alkali in the pre-treatment of aluminum alloy anodic oxidation, the alkali cleaning is highly corrosive to aluminum-based materials and often damages the surface of the parts, especially affecting the brightness of the polished surface; the light-emitting liquid with nitric acid as the main component The treatment effect on aluminum alloys with high Si and Fe content, especially particle-reinforced aluminum-based composite materials, is not good, and the ash on the surface cannot be completely removed, so it is often necessary to add chromic acid and hydrofluoric acid. NO 2 and other toxic gases, and the waste liquid is extremely difficult to deal with, causing serious environmental pollution

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