CN107400915A - Have porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat and preparation method thereof concurrently - Google Patents

Abstract

Porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat are had concurrently the invention provides a kind of.The anode oxide film has three-decker, is followed successively by screen layer, porous subsurface stratum and wearing coat outward from alloy matrix aluminum.The anode oxide film substantially increases the anti-wear performance of aluminium alloy, has widened the application field of aluminium alloy.In addition, the present invention uses anodizing, anode and negative electrode using aluminium alloy as anode oxidation process, electrolyte includes sulfuric acid, wide warm oxidant, aluminium ion, by controlling oxidation current density, electrolyte prescription controls the speed of growth and dissolution velocity of anode oxide film, and porous subsurface stratum and the anode oxidation membrane of wearing coat are had concurrently so as to obtain surface.

Description

Aluminum alloy anodized film with porous sub-surface layer and wear-resistant surface layer and preparation method thereof

technical field

The invention relates to the field of aluminum alloy surface treatment, in particular to an aluminum alloy anodized film with a porous subsurface layer and a wear-resistant surface layer and a preparation method thereof.

Background technique

Aluminum alloy has the advantages of low density, high specific strength, good plasticity, and easy processing and forming. It is the second only metal material used in industry after steel. Aluminum alloy has excellent electrical conductivity, thermal conductivity and corrosion resistance, so it is widely used in Aviation, aerospace, automobile, marine, machinery manufacturing, nuclear industry, weapon industry and other fields.

However, at present, there are still deficiencies in the service of aluminum alloys, such as: being susceptible to wear and corrosion and failure, which brings great safety hazards and economic losses to engineering applications; Due to defects, it cannot be directly put into practical application; under natural conditions, an oxide film will be formed on the surface of aluminum alloy, which is about 0.01 μm-0.10 μm. This oxide film is amorphous, thin and porous, and has low mechanical strength. These problems make the aluminum alloy unable to meet the actual working conditions in the application field, so it is necessary to carry out surface treatment on the aluminum alloy substrate.

There are many surface treatment methods for aluminum alloys, and the anodic oxidation method is currently the most widely used and most successful. Anodizing is an electrolytic oxidation process in which an oxide film is formed on the surface of the aluminum alloy substrate. This layer of oxide film is a film layer with a shielding layer (barrier layer) and a porous layer structure located on the aluminum alloy substrate. It has high hardness, good insulation and heat insulation, excellent corrosion resistance, strong bonding, and good adsorption. properties and good optical properties. However, although the oxide film formed by electrochemical reaction on the surface of aluminum alloy through anodic oxidation process can improve the corrosion resistance of aluminum alloy, it does not greatly improve the wear resistance of aluminum alloy. Moreover, after this layer of oxide film is corroded during service, the surface hardness decreases, resulting in a decrease in wear resistance.

Contents of the invention

The present invention provides an anodized film with a novel structure on the surface of an aluminum alloy substrate. As shown in FIG. The surface layer improves the wear resistance of the aluminum alloy anodized film.

That is, the technical solution provided by the present invention is: an aluminum alloy anodized film having both a porous subsurface layer and a wear-resistant surface layer.

Preferably, the thickness of the anodized film is 40 μm-50 μm.

Preferably, the thickness of the wear-resistant surface layer is 2 μm-5 μm.

The wear-resistant surface layer has high hardness and good toughness, and its microhardness is greater than 250Hv, even as high as 450Hv, thus greatly improving the wear resistance of the anodized film. The wear resistance measured by UMT-3 friction and wear testing machine Compared with the wear rate of the aluminum alloy substrate ^{under the same experimental conditions of 1.24×10 -2 mm 3 / Nm} , the wear resistance of the aluminum alloy substrate is significantly improved and the aluminum alloy substrate is broadened. Alloy applications.

The present invention also provides a method for preparing the aluminum alloy anodic oxidation film having both a porous subsurface layer and a wear-resistant surface layer. The anodic oxidation method is adopted, the aluminum alloy substrate is used as the anode, the aluminum alloy is used as the cathode, and the electrolyte includes sulfuric acid, The wide temperature oxidant and aluminum ions control the growth rate and dissolution rate of the anodic oxide film by controlling the anodic oxidation current density and the electrolyte formula, so as to obtain an anodic oxide film with a porous subsurface layer and a wear-resistant surface layer.

Preferably, the aluminum alloy substrate is cleaned and pretreated before the anodic oxidation treatment to remove surface impurities. As an implementation method, firstly, the surface of the aluminum alloy substrate is mechanically polished, and then degreasing treatment is performed to remove the surface grease, followed by water washing, and then a neutralization reaction is performed to neutralize the alkaline solution remaining on the surface of the aluminum alloy during the degreasing process, and then Ultrasonic cleaning is carried out in absolute ethanol so that no other impurities remain on the surface of the aluminum alloy. Finally, the cleaned aluminum alloy is blown dry with nitrogen. During the drying process, contact with the aluminum alloy surface should be avoided to prevent surface contamination.

Preferably, the anodic oxidation current is a direct current constant current, and more preferably, the oxidation current density is adjusted to 4-10A/dm ² .

Preferably, the oxidation time is 30-60min.

Preferably, the oxidation temperature is room temperature.

Preferably, during the anodic oxidation process, the electrolyte formula is: 45-180g/L sulfuric acid, 10-16g/L wide temperature oxidant, 5-10g/L aluminum ion. The wide-temperature oxidizing agent is not limited, and includes one or a combination of two or more of phosphoric acid, oxalic acid, tartaric acid, pyruvic acid, and the like. The aluminum ion source is not limited, and includes one or more of aluminum hydroxide, aluminum sulfate, metaaluminate and the like.

Preferably, after the anodic oxidation reaction, it should be washed with deionized water, and then dried.

In summary, the present invention adopts the anodic oxidation method. On the one hand, in the anodic oxidation process, the aluminum alloy is used as the cathode and aluminum ions are added in the electrolyte to control the dissolution process of the oxide film in the anodic oxidation process; Adding a wide-temperature oxidant to the electrolyte widens the temperature range of anodic oxidation, reducing the influence of temperature on the growth of anodic oxide film during the anodic oxidation process. The combination of the two realizes the preparation of an anodic oxidation film layer having both a porous subsurface layer and a wear-resistant surface layer on the surface of the aluminum alloy substrate. The method is simple and easy to operate, and the obtained anodized film has good bonding, low friction coefficient and good mechanical properties, and can significantly improve the wear resistance of the aluminum alloy.

Description of drawings

Fig. 1 is the structural representation of the aluminum alloy anodic oxidation film that has porous subsurface layer and wear-resistant surface layer concurrently of the present invention;

Fig. 2 is a three-dimensional structural schematic diagram of the structure shown in Fig. 1;

Fig. 3 is the scanning electron micrograph of the aluminum alloy anodized film that makes in the embodiment 1 of the present invention;

Figure 4 is an enlarged view of the framed area in Figure 3;

Fig. 5 is the scanning electron micrograph of the longitudinal section of the aluminum alloy anodized film obtained in Example 1 of the present invention;

FIG. 6 is an enlarged view of the framed portion in FIG. 5 .

detailed description

The present invention will be further described in detail below with reference to the embodiments of the accompanying drawings. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but have no limiting effect on it.

Reference numerals in Fig. 1-2 are: 1 - wear-resistant surface layer; 2 - porous subsurface layer; 3 - shielding layer.

Example 1:

In this embodiment, the anodized film on the surface of the aluminum alloy substrate has a three-layer structure. As shown in FIG. Fig. 2 is a schematic diagram of the three-dimensional structure of the anodized film.

The preparation method of the anodic oxidation film on the surface of the above-mentioned aluminum alloy substrate comprises the following steps:

(1) mechanical polishing

The aluminum alloy substrate is polished in three stages. Firstly, the aluminum alloy is roughly polished, then finely polished, and finally finely polished to obtain a mirror effect.

(2) Degreasing treatment

Degreasing the polished aluminum alloy, the degreasing agent is lye with a mass fraction of 10%, and the lye is at least one of sodium hydroxide, sodium carbonate and sodium phosphate, and is treated at 20° C. for 15 minutes.

(3) Anodizing

Put the degreased aluminum alloy substrate into the anodic oxidation bath for anodic oxidation treatment, the cathode is aluminum alloy, the oxidation current density is 4A/dm ² , the oxidation current is DC constant current, the oxidation temperature is room temperature, and the oxidation time is 60min ;

The electrolyte composition is as follows:

Sulfuric acid 45g/L;

Wide temperature oxidant 15g/L;

Aluminum ion 5g/L;

The rest is water.

(4) Washing and drying

The aluminum alloy substrate after the anodic oxidation treatment was washed with deionized water, and then dried. The temperature of the drying treatment was 80° C., and the drying treatment time was 30 minutes.

The scanning electron microscope image of the anodized film on the surface of the aluminum alloy substrate after the above treatment is shown in FIG. 3 , and FIG. 4 is an enlarged view of the boxed area in FIG. 3 . Fig. 5 is a scanning electron micrograph of the longitudinal section of the anodized film on the surface of the aluminum alloy substrate after the above treatment, and Fig. 6 is an enlarged view of the framed part in Fig. 5 . It can be seen from FIG. 3 that the surface layer of the anodized film prepared by the anodic oxidation method of this embodiment is uniform and flat, and has good gloss. It can be seen from Fig. 4 that under the wear-resistant surface layer of the anodized film is a honeycomb porous subsurface layer. The anodized film has a three-layer structure as measured by a scanning electron microscope, including a shielding layer, a porous sublayer, and a wear-resistant surface layer.

The surface layer of the anodized film prepared on the surface of the aluminum alloy after the above treatment is amorphous Al ₂ O ₃ through XPS spectrum and XRD spectrum analysis. The microhardness of the anodized film measured by a microhardness tester reaches 250-300Hv, the wear rate is 3.2×10 ^-4 -6.41×10 ^-4 mm ³ /Nm, and the wear resistance and corrosion resistance are good. The film is darker in color while still having a good gloss.

Example 2:

In this embodiment, the anodized film on the surface of the aluminum alloy substrate has a three-layer structure, that is, from the aluminum alloy substrate to the surface, there are a shielding layer, a porous subsurface layer, and a wear-resistant surface layer.

The preparation method of the anodic oxidation film on the surface of the above-mentioned aluminum alloy substrate comprises the following steps:

(1) mechanical polishing

The aluminum alloy substrate is polished in three stages. Firstly, the aluminum alloy is roughly polished, then finely polished, and finally finely polished to obtain a mirror effect.

(2) Degreasing treatment

Degreasing the polished aluminum alloy, the degreasing agent is lye with a mass fraction of 15%, and the lye is at least one of sodium hydroxide, sodium carbonate and sodium phosphate, and is treated at 30° C. for 13 minutes.

(3) Anodizing

Put the degreased aluminum alloy substrate into the anodic oxidation bath for anodic oxidation treatment, the cathode is aluminum alloy, the oxidation current density is 6A/dm ² , the oxidation current is DC constant current, the oxidation temperature is room temperature, and the oxidation time is 50min ;

The electrolyte composition is as follows:

Sulfuric acid 90g/L;

Wide temperature oxidant 12g/L;

Aluminum ion 10g/L;

The rest is water.

(4) Washing and drying

The aluminum alloy substrate after the anodic oxidation treatment was washed with deionized water, and then dried. The temperature of the drying treatment was 60° C., and the drying treatment time was 35 minutes.

The scanning electron micrograph of the anodized film prepared on the surface of the aluminum alloy after the above treatment is similar to that shown in Figure 3, and the scanning electron micrograph of its cross section is similar to that shown in Figure 5 and Figure 6, showing the aluminum alloy substrate obtained by the anodic oxidation method of this embodiment The anodized film on the surface is thick and uniform, with good gloss. The anodized film has a three-layer structure as measured by a scanning electron microscope, including a shielding layer, a porous sublayer, and a wear-resistant surface layer.

The surface layer of the anodized film prepared on the surface of the aluminum alloy after the above treatment is amorphous Al ₂ O ₃ through XPS spectrum and XRD spectrum analysis. The microhardness of the anodized film measured by the microhardness tester reaches 410-450Hv, the wear rate is low 6.21×10 ^-5 -9.1×10 ^-5 mm ³ /Nm, and the wear resistance and corrosion resistance are good. Layers are lighter in color while having a nice sheen.

Example 3

In this embodiment, the anodized film on the surface of the aluminum alloy substrate has a three-layer structure, that is, from the aluminum alloy substrate to the surface, there are a shielding layer, a porous subsurface layer, and a wear-resistant surface layer.

The preparation method of the anodic oxidation film on the surface of the above-mentioned aluminum alloy substrate comprises the following steps:

(1) mechanical polishing

The aluminum alloy substrate is polished in three stages. Firstly, the aluminum alloy is roughly polished, then finely polished, and finally finely polished to obtain a mirror effect.

(2) Degreasing treatment

Degreasing the polished aluminum alloy, the degreasing agent is lye with a mass fraction of 15%, and the lye is at least one of sodium hydroxide, sodium carbonate and sodium phosphate, and is treated at 40° C. for 10 minutes.

(3) Anodizing

Put the degreased aluminum alloy substrate into the anodic oxidation bath for anodic oxidation treatment, the cathode is aluminum alloy, the oxidation current density is 8A/dm ² , the oxidation current is DC constant current, the oxidation temperature is room temperature, and the oxidation time is 40min ;

The electrolyte composition is as follows:

Sulfuric acid 180g/L;

Wide temperature oxidant 14g/L;

Aluminum ion 6g/L;

The rest is water.

(4) Washing and drying

The aluminum alloy substrate after the anodic oxidation treatment was washed with deionized water, and then dried. The temperature of the drying treatment was 80° C., and the drying treatment time was 30 minutes.

The scanning electron micrograph of the anodized film prepared on the surface of the aluminum alloy after the above treatment is similar to that shown in Figure 3, and the scanning electron micrograph of its cross section is similar to that shown in Figure 5 and Figure 6, showing the aluminum alloy substrate obtained by the anodic oxidation method of this embodiment The anodized film on the surface is thick and uniform, with good gloss. The anodized film has a three-layer structure as measured by a scanning electron microscope, including a shielding layer, a porous sublayer, and a wear-resistant surface layer.

The surface layer of the anodized film prepared on the surface of the aluminum alloy after the above treatment is amorphous Al ₂ O ₃ through XPS spectrum and XRD spectrum analysis. The microhardness of the anodized film is measured by a microhardness tester to reach 380-420Hv, and the wear rate is as low as 9.21×10 ^-5 -1.1×10 ^-4 mm ³ /Nm, with good wear resistance and corrosion resistance. Has a nice sheen.

Example 4

In this embodiment, the anodized film on the surface of the aluminum alloy substrate has a three-layer structure, that is, from the aluminum alloy substrate to the surface, there are a shielding layer, a porous subsurface layer, and a wear-resistant surface layer.

The preparation method of the anodic oxidation film on the surface of the above-mentioned aluminum alloy substrate comprises the following steps:

(1) mechanical polishing

The aluminum alloy substrate is polished in three stages. Firstly, the aluminum alloy is roughly polished, then finely polished, and finally finely polished to obtain a mirror effect.

(2) Degreasing treatment

Degreasing the polished aluminum alloy, the degreasing agent is lye with a mass fraction of 20%, and the lye is at least one of sodium hydroxide, sodium carbonate and sodium phosphate, and is treated at 50° C. for 5 minutes.

(3) Anodizing

Put the degreased aluminum alloy substrate into the anodic oxidation bath for anodic oxidation treatment, the cathode is aluminum alloy, the oxidation current density is 10A/dm ² , the oxidation current is DC constant current, the oxidation temperature is room temperature, and the oxidation time is 30min ;

The electrolyte composition is as follows:

Sulfuric acid 180g/L;

Wide temperature oxidant 15g/L;

Aluminum ion 6g/L;

The rest is water.

(4) Washing and drying

The aluminum alloy substrate after the anodic oxidation treatment was washed with deionized water, and then dried. The temperature of the drying treatment was 60° C., and the drying treatment time was 35 minutes.

The scanning electron micrograph of the anodized film prepared on the surface of the aluminum alloy after the above treatment is similar to that shown in Figure 3, and the scanning electron micrograph of its cross section is similar to that shown in Figure 5 and Figure 6, showing the aluminum alloy substrate obtained by the anodic oxidation method of this embodiment The anodized film on the surface is thick and uniform, with good gloss. The anodized film has a three-layer structure as measured by a scanning electron microscope, including a shielding layer, a porous sublayer, and a wear-resistant surface layer.

The surface layer of the anodized film prepared on the surface of the aluminum alloy after the above treatment is amorphous Al ₂ O ₃ through XPS spectrum and XRD spectrum analysis. The microhardness of the anodized film is measured by a microhardness tester to reach 290-360Hv, the wear rate is 1.23×10 ^-4 -4.3×10 ^-4 mm ³ /Nm, the wear resistance and corrosion resistance are good, and it also has good of gloss.

The above-mentioned embodiments have systematically and detailedly described the technical solutions of the present invention. It should be understood that the above-mentioned examples are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, supplement or equivalent replacement made within the principle scope of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. a kind of have porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently, it is characterized in that：Described anode Oxide-film is followed successively by screen layer, porous subsurface stratum and wearing coat from matrix outward.

2. have porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 1, its feature It is：The thickness of described anode oxide film is 40 μm -50 μm.

3. have porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 1 or 2, its It is characterized in：The microhardness of described wearing coat is more than 250Hv, and abrasion is measured through UMT-3 friction wear testing machines Rate is 6.41 × 10^-4mm³/ below Nm.

4. have the system of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 1 or 2 Preparation Method, it is characterized in that：Using anodizing, using alloy matrix aluminum as anode, using aluminium alloy as negative electrode, electricity Solving liquid includes sulfuric acid, wide warm oxidant and aluminium ion, by controlling oxidation current density, electrolyte prescription control sun The speed of growth and dissolution velocity of pole oxide-film.

5. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：Alloy matrix aluminum is pre-processed before anodized.

6. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：Oxidation current is direct current constant current, oxidate current 4-10A/dm²。

7. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：The electrolyte prescription is：The wide temperature oxidant of 45-180g/L sulfuric acid, 10-15g/L, 5-10g/L Aluminium ion.

8. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：Oxidization time is 30-60min, and oxidizing temperature is preferably room temperature.

9. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：Described wide temperature oxidant be phosphoric acid, oxalic acid, tartaric acid, in pyruvic acid it is one or two kinds of with On mixing.

10. have the preparation side of porous subsurface stratum and the aluminium alloy anode oxide film of wearing coat concurrently as claimed in claim 4 Method, it is characterized in that：Described source of aluminum ion include aluminium hydroxide, aluminum sulfate, in meta-aluminate it is one or two kinds of with On mixing.