CN111020452A

CN111020452A - Surface treatment method for improving corrosion resistance of aluminum alloy

Info

Publication number: CN111020452A
Application number: CN201911252770.4A
Authority: CN
Inventors: 王存发
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-09
Filing date: 2019-12-09
Publication date: 2020-04-17

Abstract

The invention discloses a surface treatment method for improving the corrosion resistance of aluminum alloy, which comprises the following steps of firstly carrying out sand blasting treatment on the surface of the aluminum alloy to remove foreign matters and non-compact oxide skins adhered to the surface of the aluminum alloy so as to expose the fresh surface of the aluminum alloy; secondly, the surface of the aluminum alloy is treated with oxygen-enriched ions on the surface of high-temperature plasma by adopting a plasma spraying method, namely Ar and H are sprayed on the surface of the aluminum alloy by adopting the traditional plasma spraying method₂Adding O to the plasma gas₂，O₂Ionized at high temperature and reacted with the aluminum alloy to form compact corrosion-resistant Al on the surface of the aluminum alloy₂O₃Compared with the traditional aluminum alloy corrosion protection technology, the invention has the advantages of high efficiency, low cost, no wastewater and waste gas pollution and the like.

Description

Surface treatment method for improving corrosion resistance of aluminum alloy

Technical Field

The invention relates to an aluminum alloy surface treatment method, in particular to a method for obtaining compact Al on the surface of the aluminum alloy₂O₃A surface treatment method for improving the corrosion resistance of aluminum alloy by an oxide film.

Background

The aluminum content is only after oxygen and silicon elements in the crust, and accounts for more than about 8 percent of the crust substance, and is the metal material which has the largest usage amount, the largest yield and the most extensive application in nonferrous metals. China is a large country for aluminum production and consumption. The aluminum material has the advantages of small specific gravity, good thermal conductivity, easy processing, low price and the like, and is widely applied to the fields of aerospace, transportation, light industry building materials and the like. However, the unstable three-electron structure of the aluminum outer layer makes it exhibit active metallic properties in corrosive media. Although aluminum can form an oxide film by self-passivation, the passivation film is loose and hardly takes advantage of its corrosion resistance, which increases the potential risk of the aluminum alloy in use.

The Chinese acremon is wide, the coastline is tens of thousands of kilometers long, the ocean economy is developed, and the development of ocean resources has great strategic significance on the economic construction of China. The aluminum alloy has wide application value in ocean traffic, such as an outer shell of a ship, the bottom of a hull of a yacht, a torpedo shell, a torpedo water tank and the like. Aluminum is one of the more active metals in chemistry, and the environment has an important influence on the general corrosion of aluminum by the chemical action of aluminum. In the marine environment, the corrosion reaction of aluminum and alloys is enhanced due to the presence of contaminants such as sulfates, sulfites and chlorides to varying degrees. The corrosion of aluminum in the ocean atmosphere can take various forms, such as stress corrosion, galvanic corrosion, crevice corrosion, local corrosion and the like, and the damage effect on a matrix is particularly strong. Since the surface of the aluminum alloy is very easy to corrode in the marine environment with chloride ions, which greatly limits the application range of the aluminum alloy, how to improve the corrosion resistance of the aluminum alloy in media such as seawater is one of important research subjects related to the aluminum alloy.

At present, the surface treatment is an effective protective measure aiming at the defects of the aluminum alloy surface in the aspect of corrosion performance. The most widely used surface protection treatment technology for aluminum alloy industrialization is chemical conversion, anodic oxidation, electroplating, chemical plating, organic polymer coating treatment and the like. (1) Chemical oxidation method: the technology for generating a passivated insoluble oxide film on the surface of an aluminum alloy by the chemical reaction of metal aluminum and an oxidizing solution at a certain temperature, such as chromate treatment and phosphorus chromate treatment, but the technology has the harmful influence of hexavalent chromium on the environment and is difficult to meet the requirement of environmental protection. (2) An anodic oxidation method: the anodic oxidation is a universal surface treatment of aluminum, and is a process of taking aluminum or aluminum alloy as an anode in an electrolysis process and generating an oxide film on the surface of the aluminum, wherein the surface of the aluminum is subjected to anodic oxidation to generate a porous anodic oxide film which can be subjected to coloring treatment, and in order to meet the requirement of corrosion resistance, hole sealing treatment of a porous film is usually performed, so that different functionalities and decorative properties are obtained, but the method has huge power consumption and high cost. (3) Organic matter coating treatment: the coating technology comprises the processes of brushing, dipping, spraying, electrophoresis and the like, but the method is easy to cause marine microorganism adhesion in the marine environment and increases the friction force between the ship body and seawater. (4) Electroplating or chemical plating: electroplating or electroless plating can give a beautiful metallic appearance, but this method cannot give protection to large-sized workpieces.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a surface treatment method for improving the corrosion resistance of an aluminum alloy, which comprises the following steps:

(1) pretreating the surface of the aluminum alloy to remove foreign matters and non-compact oxide scales adhered to the surface of the aluminum alloy;

(2) carrying out high-temperature plasma surface oxygen-enriched ion treatment on the surface of the aluminum alloy treated in the step (1) by adopting a plasma spraying method;

in the step (2), the plasma spraying parameters are as follows: spraying distance is 60-120 mm, current is 630-680A, Ar flow is 45-65L/min, H₂Flow rate of 4-8L/min, O₂The flow rate is 2-6L/min, the moving speed of the spray gun is 300-600 mm/s, and the spraying instantaneous high temperature is more than 2000 ℃.

In the technical scheme, the step (1) is used for pretreating the surface of the aluminum alloy, and specifically, 46 # corundum sand is used for carrying out sand blasting treatment on the surface of the aluminum alloy.

The method for improving the corrosion resistance of the aluminum alloy is a high-temperature plasma surface treatment technology, the spraying instantaneous high temperature is more than 2000 ℃, active particles (such as charged particles, ultraviolet photons and the like) generated in plasma are used for bombard and clean the surface of the aluminum alloy, and a plurality of atomic layers adsorbed on the surface are removed, so that the surface chemical activity of the aluminum alloy is improved. Because the plasma torch has high power and high plasma temperature, the plasma torch is different from the traditional low-temperature plasma surface treatment, and the plasma torch has higher surface treatment moving speed in order not to damage an aluminum alloy matrix. In the present invention, O is charged₂Under the action of high-temperature plasma₂Is ionized and reacts with high-activity Al atoms on the surface of the aluminum alloy to form compact Al in situ₂O₃And (3) a membrane. Because the high-temperature plasma contains a large amount of high-energy active particles, compared with the traditional method, the method has high efficiency and low costCost, no waste water and gas pollution and the like.

Drawings

FIG. 1 scanning electron micrograph of a cross section of the plasma surface-treated aluminum alloy of example 1;

in the figure: 1. an aluminum alloy substrate; 2. al formed in situ₂O₃A film; 3. epoxy resin mounting.

Detailed Description

The preparation process of the present invention will be further described with reference to the following specific examples.

Example 1

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: spraying distance is 60mm, current is 630A, Ar flow is 45L/min, H₂Flow 4L/min, O₂The flow rate is 2L/min, and the moving speed of the spray gun is 600 mm/s.

Example 2

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: spraying distance is 120mm, current is 680A, Ar flow is 65L/min, H₂Flow rate of 8L/min, O₂The flow rate is 6L/min, and the moving speed of the spray gun is 300 mm/s.

Example 3

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: spraying distance is 70mm, current is 640A, Ar flow is 50L/min, H₂Flow 5L/min, O₂The flow rate is 3L/min, and the moving speed of the spray gun is 400 mm/s.

Example 4

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: spraying distance of 80mm, current of 650A, Ar flow rate of 55L/min, H₂Flow rate of 6L/min, O₂The flow rate is 4L/min, and the moving speed of the spray gun is 500 mm/s.

Example 5

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: spraying distance is 100mm, current is 660A, Ar flow is 60L/min, H₂Flow 7L/min, O₂The flow rate is 5L/min, and the moving speed of the spray gun is 500 mm/s.

Example 6

Carrying out sand blasting treatment on the surface of the aluminum alloy by using No. 46 corundum sand, and removing foreign matters and non-compact oxide skin adhered to the surface of the aluminum alloy to expose the fresh surface of the aluminum alloy; carrying out high-temperature plasma oxygen-enriched ion surface treatment on the surface of the aluminum alloy by using a plasma spraying technology, wherein the surface treatment parameters are as follows: the spraying distance is 110mm, the current is 670A, the Ar flow is 60L/min, H₂Flow 7L/min, O₂The flow rate was 6L/min, and the moving speed of the lance was 600 mm/s.

In the above embodiment, the plasma spraying method is adopted to perform high-temperature plasma surface oxygen-enriched ion treatment on the aluminum alloy surface, and the spraying instantaneous high temperature is greater than 2000 ℃.

Claims

1. A surface treatment method for improving the corrosion resistance of aluminum alloy, aiming at obtaining compact Al on the surface of the aluminum alloy₂O₃An oxide film, characterized by comprising the steps of:

in the step (2), the plasma spraying parameters are as follows: spraying distance is 60-120 mm, current is 630-680A, Ar flow is 45-65L/min, H₂Flow rate of 4-8L/min, O₂The flow rate is 2-6L/min, the moving speed of a spray gun is 300-600 mm/s, and the spraying instantaneous high temperature is more than 2000 ℃; the method comprises the following steps that (1) the surface of the aluminum alloy is pretreated, and concretely, 46 # corundum sand is used for carrying out sand blasting treatment on the surface of the aluminum alloy.