TWI467042B - Anticorrosion surface treating for al alloy and articles treated by the same - Google Patents

Description

Aluminum alloy surface anti-corrosion treatment method and product thereof

The invention relates to an anticorrosive treatment method for aluminum alloy surface and a product thereof.

Aluminum alloy has the advantages of light weight and good heat dissipation performance, and is widely used in communications, electronics, transportation, construction and aerospace. An aluminum oxide protective film is formed on the surface of the aluminum alloy in the air. Under normal atmospheric conditions, the aluminum oxide film on the surface of the aluminum alloy can effectively protect the aluminum alloy substrate, but in the moisture containing the electrolyte, such as the surface atmosphere of the ocean. Environment, aluminum alloy surface is prone to pitting corrosion, the appearance of severely broken aluminum alloy products, and at the same time lead to shortened product life.

Salt spray resistance is an important parameter of the corrosion resistance of aluminum alloy. In order to improve the salt spray resistance of aluminum alloy, it is usually necessary to form a surface film on the surface of aluminum alloy. Common treatment methods include anodizing, baking varnish, etc. However, these processes have major environmental pollution problems. The vacuum coating (PVD) technology is a very environmentally friendly coating process, and the coating film can be rich in variety and excellent in wear resistance. However, the film deposited by PVD process tends to grow in the form of columnar crystal, so the film layer exists. A large amount of intercrystalline gaps result in insufficient film densification and cannot effectively prevent salt spray erosion.

In view of this, it is necessary to provide an aluminum alloy surface anticorrosive treatment method which can effectively improve the salt spray resistance of the aluminum alloy.

In addition, it is also necessary to provide an aluminum alloy article obtained by the above method.

An aluminum alloy surface anti-corrosion treatment method comprises the following steps:

Ultrasonic cleaning of aluminum alloy substrate with anhydrous ethanol;

Using pure titanium as a target, argon gas as working gas, nitrogen gas and oxygen as reaction gas, magnetron sputtering method is used to sputter a titanium oxynitride layer on the surface of the aluminum alloy substrate;

A pure chromium is used as a target, argon gas is used as a working gas, nitrogen gas and oxygen gas are used as reaction gases, and a chromium oxynitride layer is sputtered on the titanium oxynitride layer by magnetron sputtering.

An aluminum alloy product comprising an aluminum alloy substrate and a composite film formed on the surface of the aluminum alloy substrate, the composite film comprising a titanium oxynitride layer formed on the surface of the aluminum alloy substrate and formed on the titanium oxynitride layer Layer of chrome oxynitride.

Compared with the prior art, the aluminum alloy article prepared by the above-mentioned aluminum alloy surface anticorrosive treatment method has a composite film composed of a titanium oxynitride layer and a chromium oxynitride layer on the surface thereof, and the composite film is relatively small. The grain composition and the intergranular gap are relatively small, and the surface of the composite film is very dense, which can effectively prevent salt spray erosion, thereby effectively improving the corrosion resistance of the aluminum alloy.

The method for preserving the surface of the aluminum alloy of the invention mainly comprises the following steps:

(1) Ultrasonic cleaning of the aluminum alloy substrate with anhydrous ethanol to remove oil stain on the surface of the sample.

(2) Using pure titanium as the target, argon gas as the working gas, nitrogen and oxygen as the reaction gases, and the surface of the cleaned aluminum alloy substrate was sputtered with a titanium oxynitride (TiON) layer by magnetron sputtering. This step is carried out in a magnetron sputtering apparatus. The sputtering parameters are as follows: the vacuum degree in the vacuum chamber is 5×10 ^-3 Pa~9×10 ^-3 Pa, the cavity temperature is 100-180 ° C, and the rotating speed is 0.5. ~1 rpm, argon flow rate is 150~300sccm (standard state cc/min), oxygen flow rate is 10~100sccm, nitrogen flow rate is 10~80sccm, titanium target power is 6~12kw, bias voltage is -100~- 300V, duty cycle 40%~60%, sputtering 0.5~1.5 hours.

(3) Using pure chromium as the target, argon gas as working gas, nitrogen and oxygen as reaction gases, and chromium oxide-oxygen compound (CrON) layer were sputtered on the surface of titanium oxynitride film by magnetron sputtering. This step is carried out in a magnetron sputtering apparatus. The sputtering parameters are as follows: the vacuum degree in the vacuum chamber is 5×10 ^-3 Pa~9×10 ^-3 Pa, the cavity temperature is 100-180 ° C, and the rotating speed is 0.5. ~1 rpm, argon flow rate is 150~300sccm, oxygen flow rate is 10~150sccm, nitrogen flow rate is 10~100sccm, chrome target power is 6~12kw, bias voltage is -100~-300V, duty cycle is 40 %~60%, sputtering for 0.5~3 hours. Thus, a composite film composed of a titanium oxynitride layer and a chromium oxynitride layer was obtained on the surface of the aluminum alloy substrate. The composite film has a thickness of about 0.6 to 2.5 μm.

Preferably, step (2) and step (3) are carried out in the same magnetron sputtering apparatus.

Preferably, the total gas pressure in the above step (3) (that is, when the titanium oxynitride layer is sputtered) is greater than the total gas pressure in the above step (2) (that is, when the chromium oxynitride layer is sputtered).

Preferably, the ratio of the nitrogen flow rate to the oxygen flow rate in steps (2) and (3) is about 1:1 to 1:3.

Referring to FIG. 1 , an aluminum alloy article 10 obtained by the above aluminum alloy surface anti-corrosion treatment method includes an aluminum alloy substrate 11 and a composite film 13 formed on the surface of the aluminum alloy substrate 11 , and the composite film 13 is directly formed on the aluminum alloy substrate 11 . A titanyl compound layer 131 on the surface of the aluminum alloy substrate 11 and a chromium oxynitride layer 132 formed on the titanyl compound layer 131. The titanium oxynitride layer 131 has a percentage of titanium atoms of 40% to 65%, an oxygen atom percentage of 25% to 50%, and a nitrogen atom percentage of 10% to 20%. The chromium oxynitride layer 132 has a percentage of chromium atoms of 50% to 70%, a percentage of oxygen atoms of 20% to 45%, and a percentage of nitrogen atoms of 5% to 10%. The composite film 13 is composed of crystal grains having a diameter of about 4 to 7 nm.

The invention will now be specifically described by way of examples.

Example 1

The aluminum alloy sample was ultrasonically cleaned with absolute ethanol for about 30 minutes. The cleaned aluminum alloy sample is placed in a vacuum chamber of an intermediate frequency magnetron sputtering coating machine. The intermediate frequency magnetron sputtering coating machine used in this embodiment is produced by Shenzhen Nanfang Innovation Vacuum Technology Co., Ltd., and the model number is SM-1100H.

Open the vacuum pump and vacuum the vacuum chamber and set the vacuum to 8×10 ^-3 Pa. Turn on the rotating frame and set the rotation speed to 0.5 rpm. Turn on the vacuum chamber and set the vacuum chamber temperature to 120 °C.

After the vacuum of the vacuum chamber is pumped to the above set value, the working gas argon gas and the reaction gas oxygen and nitrogen are introduced, the flow rate of the argon gas is 150 sccm, the oxygen flow rate is 30 sccm, the nitrogen flow rate is 20 sccm, the titanium target is turned on and the titanium target power is adjusted. For 8 kW, the titanium target was biased at -200 V, the duty cycle was 50%, and sputtering was carried out for 0.5 hours to form a layer of titanium oxynitride on the surface of the aluminum alloy.

Then the titanium target was turned off, the oxygen flow rate was adjusted to 40 sccm, the nitrogen flow rate was 30 sccm, the chromium target was turned on and the chromium target power was adjusted to 8 kw, the chromium target bias was -200 V, the duty ratio was 50%, and sputtering was performed for 1 hour to A layer of chromium oxynitride is formed on the nitrogen compound layer to obtain a composite film composed of a titanium oxynitride layer and a chromia oxynitride layer on the surface of the aluminum alloy substrate.

Example 2

The second embodiment is similar to the first embodiment except that the oxygen flow rate is adjusted to 80 sccm when the chromium target is turned on, and the nitrogen flow rate is adjusted to 50 sccm, and other conditions are the same as in the first embodiment. According to Example 2, an aluminum alloy article having a composite film formed of a titanium oxynitride layer and a chromium oxynitride layer on its surface was also obtained.

The composite films of the aluminum alloy articles prepared in Example 1 and Example 2 have similar morphology and structure, and have similar corrosion resistance.

Comparative example

The aluminum alloy sample was sputtered by the same intermediate frequency magnetron sputtering coater as in Example 1. The target target different from Example 1 was a chromium target, the reaction gas was nitrogen, the nitrogen flow rate was 60 sccm, and the chromium target power was used. It was 8 kw, the chromium target was biased at -200 V, the duty ratio was 50%, and sputtering was performed for 0.5 hours, and a one-component chromium nitride (CrN) film was sputtered on the surface of the aluminum alloy sample.

The surface morphology of the titanium oxynitride compound and the chromium oxynitride composite film and the comparatively plated chromium nitride (CrN) film plated in Example 1 were observed by scanning electron microscopy. The scanning electron microscope used was produced by Japan Electronics. The field emission scanning electron microscope model of the model JSM-6701F. 2 is a scanning electron micrograph of a titanium oxynitride compound and a chromium oxynitride composite film plated in Example 1 of the present invention, and FIG. 3 is a scanning electron micrograph of a chromium nitride (CrN) film plated in a comparative example. Compared with FIG. 2, the one-component chromium nitride (CrN) film shown in FIG. 3 is composed of relatively coarse crystal grains, and a large amount of intergranular gap exists on the surface; and the titanium oxynitride layer and chrome oxide are formed. The composite film composed of the nitrogen compound layer is composed of very fine crystal grains, and the average crystal grain diameter is about 4 to 7 nm, and the intergranular gap is relatively small, and the surface of the composite film is very dense.

The aluminum alloy sample coated with the composite film prepared by the method of the present invention and the aluminum alloy sample coated with the chromium nitride (CrN) film prepared in the comparative example were subjected to a neutral salt spray of 35 ° C (NaCl). The concentration is 5%) tested. As a result, it was found that the aluminum alloy sample of the surface-plated chromium nitride (CrN) film prepared in the comparative example was significantly corroded after 4 hours; and the surface prepared by the method of the present invention was plated with the composite film aluminum. The alloy samples showed corrosion after 72 hours.

It can be seen that the aluminum alloy article prepared by the aluminum alloy surface anti-corrosion treatment method of the present invention has a composite film composed of a titanium oxynitride layer and a chromium oxynitride layer on the surface thereof, and the composite film can effectively prevent salt spray erosion, thereby Improve the corrosion resistance of aluminum alloys.

10. . . Aluminum alloy products

11. . . Aluminum alloy substrate

13. . . Composite film

131. . . Titanium oxynitride layer

132. . . Chromium oxynitride layer

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an aluminum alloy article obtained by a method for preserving an aluminum alloy surface according to a preferred embodiment of the present invention.

2 is a scanning electron micrograph of a composite film prepared according to an embodiment of the present invention at an magnification of 100,000 times.

Figure 3 is a scanning electron micrograph of a 50,000-fold magnification of a chromium nitride film prepared by magnetron sputtering.

10. . . Aluminum alloy products

11. . . Aluminum alloy substrate

13. . . Composite film

131. . . Titanium oxynitride layer

132. . . Chromium oxynitride layer

Claims (12)

An aluminum alloy surface anti-corrosion treatment method comprises the following steps:
Ultrasonic cleaning of aluminum alloy substrate with anhydrous ethanol;
Using pure titanium as a target, argon gas as working gas, nitrogen gas and oxygen as reaction gas, magnetron sputtering method is used to sputter a titanium oxynitride layer on the surface of the aluminum alloy substrate;
A pure chromium is used as a target, argon gas is used as a working gas, nitrogen gas and oxygen gas are used as reaction gases, and a chromium oxynitride layer is sputtered on the titanium oxynitride layer by magnetron sputtering. The method for preserving an aluminum alloy surface according to claim 1, wherein in the step of sputtering a titanate layer and the step of sputtering the layer of oxynitride, a ratio of a nitrogen flow rate to an oxygen flow rate is 1:1~1:3. The method for preserving the surface of an aluminum alloy according to the second aspect of the invention, wherein the step of sputtering the titanium oxynitride layer has an oxygen flow rate of 10 to 100 sccm and a nitrogen flow rate of 10 to 80 sccm. The method for preserving an aluminum alloy surface according to claim 3, wherein the step of sputtering the titanium oxynitride layer is further performed under the following parameter conditions: a vacuum degree in the vacuum chamber is 5×10 ^-3 to 9× 10 ^-3 Pa, the cavity temperature is 100~180°C, the rotating speed is 0.5~1 rev/min, the titanium target power is 6~12kw, the argon flow rate is 150~300sccm, and the titanium target bias is -100~- 300V, duty cycle 40%~60%, sputtering 0.5~1.5 hours. The method for preserving the surface of an aluminum alloy according to claim 2, wherein the step of sputtering the chromium oxide compound layer has an oxygen flow rate of 10 to 150 sccm and a nitrogen flow rate of 10 to 100 sccm. The method for preserving an aluminum alloy surface according to claim 5, wherein the step of sputtering the chromium oxide compound layer is performed under the following parameter conditions: a vacuum degree in the vacuum chamber is 5×10 ^-3 to 9× 10 ^-3 Pa, the cavity temperature is 100~180 °C, the rotating speed is 0.5~1 rev / min, the titanium target power is 6~12kw, the argon flow rate is 150~300sccm, and the chrome target bias is -100~- 300V, duty cycle is 40%~60%, sputtering is 0.5~3 hours. The method for preserving an aluminum alloy surface according to claim 1, wherein the titanium oxynitride layer has a percentage of titanium atoms of 40% to 65%, and the number of oxygen atoms is 25% to 50%. The percentage of nitrogen atoms is 10% to 20%; the percentage of chromium atoms in the chromium-oxygen compound layer is 50% to 70%, the percentage of oxygen atoms is 20% to 45%, and the percentage of nitrogen atoms is 5 %~10%. The method for preserving an aluminum alloy surface according to claim 1, wherein the titanium oxynitride layer and the chromium oxynitride layer are composed of crystal grains having a diameter of 4 to 7 nm. An aluminum alloy product comprising an aluminum alloy substrate and a composite film formed on the surface of the aluminum alloy substrate, wherein the composite film comprises: a titanium oxynitride layer formed on the surface of the aluminum alloy substrate and formed on the titanium a chromium oxynitride layer on the oxynitride layer. The aluminum alloy article according to claim 9, wherein the titanium oxynitride layer has a percentage of titanium atoms of 40% to 65%, and the number of oxygen atoms is 25% to 50%, and the nitrogen atom The percentage of the number is 10% to 20%; the percentage of chromium atoms in the chromium-oxygen compound layer is 50% to 70%, the percentage of oxygen atoms is 20% to 45%, and the percentage of nitrogen atoms is 5%~ 10%. The aluminum alloy article according to claim 9, wherein the composite film is composed of crystal grains having a diameter of 4 to 7 nm. The aluminum alloy article according to claim 9, wherein the composite film has a thickness of 0.6 to 2.5 μm.