A wear-resistant coating with good adhesion to aluminum alloy surface and its preparation method

Abstract

This invention relates to the field of coating preparation technology, specifically to a wear-resistant coating with good adhesion to the surface of aluminum alloy and its preparation method, comprising the following steps: 1. Pretreatment of aluminum alloy surface; 2. Pre-plating of pure Ti film on aluminum alloy surface; 3. Nitriding by arc discharge plasma in the same furnace; 4. Heat treatment to restore the mechanical properties of the base aluminum alloy, thereby completing the preparation of the wear-resistant coating, solving the problems of low surface hardness and poor friction and wear performance of existing aluminum alloys.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, specifically to a wear-resistant coating with good adhesion to aluminum alloy surfaces and its preparation method. Background Technology

[0002] Aluminum alloys, with their advantages of low specific gravity, high specific strength, excellent comprehensive performance, and abundant reserves, are representative of lightweight alloys and play an important role in the lightweighting of weaponry and equipment. However, due to their low hardness and thin, brittle natural oxide film, aluminum alloys are susceptible to wear and corrosion, making aluminum alloy equipment components prone to failure. This is especially true for iron workpieces, where the high miscibility between aluminum and iron allows aluminum to easily transfer to the iron during friction. In the context of modern military applications, the rapid development of aircraft, armored vehicles, ships, and submarines has placed higher demands on the comprehensive performance of aluminum alloys.

[0003] Due to the diversity and complexity of the service conditions of weapons and equipment, the performance requirements for aluminum alloys often vary greatly. Developing new alloy systems to meet different performance requirements is difficult to complete in the short term and is also very costly. Preparing high-performance protective coatings on the surface of light alloys through surface engineering technology can improve the overall performance of weapons and equipment while significantly reducing costs.

[0004] Currently, commonly used surface modification technologies for improving wear resistance include thermal spraying, laser cladding, plasma nitriding, and arc ion plating. Among these surface modification technologies, thermal spraying and laser cladding often involve enormous heat during coating preparation, leading to thermal deformation of the substrate and making them unsuitable for precision parts. Plasma nitriding has wide applications in the steel industry, but because the solution temperature of aluminum alloys is generally below 550℃, aluminum alloys are prone to "overheating" at high temperatures, limiting the nitriding temperature, which is often lower than the formation temperature of AlN. Furthermore, the low solid solubility of nitrogen atoms in the α-Al lattice makes it very difficult for nitrogen atoms to diffuse from the surface to the interior, preventing the formation of a diffusion layer. In addition, the natural oxide film on the surface of aluminum alloys is very stable and difficult to completely remove by grinding and polishing, which severely hinders the diffusion of nitrogen atoms into the substrate. Arc ion plating technology can deposit nitride hard films on aluminum alloy surfaces to improve surface hardness and wear resistance. However, due to the huge performance difference between the hard coating and the aluminum alloy, the substrate has insufficient load-bearing capacity, resulting in the "eggshell effect". The adhesion between the coating and the substrate is low, and the coating is prone to peeling. For example, in the paper "Corrosion protection of magnetron sputtered TiN coatings deposited on high strength aluminum alloys" (Diesselberg M, Stock HR, Mayr P. Corrosion protection of magnetron sputtered TiN coatings deposited on high strength aluminum alloys[J]. Surface & Coatings Technology. 2004, 177(none)), TiN coatings were directly deposited on the surface of aluminum alloys using magnetron sputtering. However, obvious cracks were observed at the interface between the coating and the substrate, indicating poor film-substrate adhesion. Chinese invention patent CN201511019701.0 uses magnetron sputtering combined with ion nitriding technology to modify the surface of aluminum alloys, achieving a surface hardness of up to 439 Hv, effectively improving the surface hardness and wear resistance of the aluminum alloy. However, the composite process is time-consuming and energy-intensive, failing to meet the requirements of energy conservation and emission reduction. Furthermore, the impact of heat treatment on the aluminum alloy substrate has also attracted attention. Therefore, exploring a method that ensures good adhesion between the modified aluminum alloy layer and the substrate, improves surface hardness, enhances friction and wear performance, and minimizes the impact on the substrate is a direction that materials scientists are striving towards.

[0005] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of low surface hardness and poor wear resistance of existing aluminum alloys, and to provide a wear-resistant coating with good adhesion to the surface of aluminum alloys and its preparation method.

[0007] To achieve the above objectives, this invention discloses a method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface, comprising the following steps:

[0008] S1. The aluminum alloy is polished with SiC sandpaper, then ultrasonically cleaned in anhydrous ethanol for 15-30 minutes, polished after removal, and then ultrasonically cleaned in anhydrous ethanol for 15-30 minutes before being removed and dried to obtain the pretreated aluminum alloy.

[0009] S2, the pretreated aluminum alloy is placed in an arc ion plating furnace, vacuumed, heated and then argon gas is introduced, the surface of the pretreated aluminum alloy is cleaned by glow discharge, then the surface of the aluminum alloy is etched, the arc current is turned off after etching, the coating program is run, the Ti target is turned on, and the aluminum alloy with Ti film is obtained after deposition.

[0010] S3. After the coating process in step S2 is completed, the vacuum chamber temperature is set to 400°C. After the vacuum chamber cools down to 400°C, the nitriding process is started and nitrogen-containing gas is introduced. After the nitriding process is completed, the furnace is cooled to room temperature to complete the preparation of the wear-resistant coating on the aluminum alloy surface.

[0011] S4. After the nitriding process in step S3 is completed, the sample is taken out of the furnace. The aluminum alloy with the coating on the surface is placed in a muffle furnace, the furnace temperature is set to 440℃, and after holding for 1 hour, it is taken out and air-cooled. Then it is placed in an air furnace, the furnace temperature is set to 110℃, and after holding for 8 to 12 hours, it is taken out and air-cooled. The preparation of a wear-resistant coating with good adhesion on the surface of the aluminum alloy is completed.

[0012] In step S1, the SiC sandpaper has a mesh size of 400 to 2000#.

[0013] In step S2, the specific conditions for glow discharge cleaning are: the vacuum degree of the arc ion plating furnace is 5 × 10⁻⁶. -4 mbar, vacuum chamber temperature 420℃, rotation speed 3r / min, argon gas flow rate 300sccm, substrate bias voltage -400V, glow discharge cleaning pretreatment of aluminum alloy surface for 10min.

[0014] In step S2, the specific etching conditions are as follows: the column arc current is 80A, the substrate bias voltage is -30V, gradually adjusted to -180V, and the aluminum alloy surface is etched for 10 minutes.

[0015] In step S2, the specific coating conditions are as follows: the substrate bias voltage is -30V, gradually adjusted to -180V; the Ti target current is 110A to 130A; and the vacuum degree inside the arc ion plating furnace is maintained at 2.5 × 10⁻⁶. -2 mbar was deposited for 2.5 to 4.5 hours under the conditions of substrate bias voltage of -80V and Ti target current of 110A to 130A.

[0016] In step S3, the amount of nitrogen-containing gas introduced is 300 sccm, including 50 sccm of nitrogen and 250 sccm of argon, and the vacuum degree inside the arc ion plating furnace is 3.0 × 10⁻⁶. -2 mbar, substrate bias voltage -30V, gradually adjusted to -300V, column arc current set to 110A, then at temperature 400℃ and vacuum degree 3.0×10 -2 The substrate was kept at a temperature of mbar for 2 hours with a substrate bias of -300V and a column arc current of 110A.

[0017] The present invention also discloses a wear-resistant coating with good adhesion to the surface of an aluminum alloy prepared by the above preparation method.

[0018] The wear-resistant coating has a thickness of 2μm to 4.3μm, a maximum hardness of 460.8HV, a coefficient of friction of 0.49 to 0.55, and an adhesion strength of HF3.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. This invention can obtain a coating with controllable thickness and high hardness on the surface of aluminum alloy, with good adhesion to the aluminum alloy substrate, thereby reducing the wear rate.

[0021] 2. In this invention, the arc discharge plasma nitriding process is carried out at a relatively low temperature (400℃), which meets the requirements of energy saving;

[0022] 3. The aluminum alloy surface strengthening layer prepared by this invention has a gradient structure, with the outer layer being TiN. 0.3 The main phase is a titanium-nitrogen solid solution phase, with an inner layer of intermetallic compound layer composed of aluminum-based intermetallic compounds.

[0023] 4. In this invention, coating and nitriding are carried out in the same furnace, which reduces the complexity of the process, improves efficiency, and can achieve the purpose of energy saving.

[0024] 5. The coating obtained by the present invention after the aluminum alloy surface is plated and infiltrated has high hardness and low friction coefficient, which can effectively improve the use of the treated aluminum alloy in low-speed and light-load transmission applications. Attached Figure Description

[0025] Figure 1X-ray diffraction patterns of untreated aluminum alloys and aluminum alloys with wear-resistant coatings prepared in Examples 1, 4 and 10;

[0026] Figure 2 Cross-sectional microstructure of the aluminum alloy with a wear-resistant coating prepared in Example 1;

[0027] Figure 3 Rockwell indentation test pattern of aluminum alloy with wear-resistant coating prepared in Example 1;

[0028] Figure 4 The graphs show the friction and wear performance test curves. 1 represents the untreated aluminum alloy, and 2 represents the aluminum alloy with a wear-resistant coating prepared in Example 1.

[0029] Figure 5 The wear rate diagram of the aluminum alloy with a wear-resistant coating having good adhesion to the surface prepared in Example 1 after tribological testing. Detailed Implementation

[0030] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] A method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface, specifically comprising the following steps:

[0033] 1. Aluminum alloy surface pretreatment: Use 400-2000# SiC sandpaper to polish the aluminum alloy, then place it in anhydrous ethanol for ultrasonic cleaning for 15-30 minutes. After taking it out, use diamond polishing paste to polish the aluminum alloy. Then place it in anhydrous ethanol for ultrasonic cleaning for 15-30 minutes and take it out and blow it dry to obtain the pretreated aluminum alloy.

[0034] The aluminum alloy mentioned is 7075 aluminum alloy;

[0035] 2. Pre-plating of a pure Ti film on the aluminum alloy surface: The pre-treated aluminum alloy is placed in an arc ion plating furnace, and the three-dimensional planetary rotor is adjusted to allow the pre-treated aluminum alloy to rotate in three dimensions. The furnace chamber of the arc ion plating furnace is evacuated to below 5 × 10⁻⁶. -4After mbar, the vacuum chamber was heated to 420℃, and the rotation speed was set to 3 r / min. Then, 300 sccm of argon gas was introduced, and the substrate bias voltage was set to -400V. The pre-treated aluminum alloy surface was cleaned with glow discharge for 10 min. Next, the arc current was set to 80A, and the substrate bias voltage was set to -30V, gradually adjusted to -180V for etching the aluminum alloy surface, held for 10 min. Then, the arc current was turned off, and the coating program was run, with the substrate bias voltage set to -30V, gradually adjusted to -180V. The Ti target current was set to 130A, and the vacuum level inside the arc ion plating furnace was maintained at 2.5 × 10⁻⁶. -2 The aluminum alloy with Ti film was deposited for 4.5 hours under the conditions of substrate bias voltage -80V and Ti target current 130A.

[0036] 3. Simultaneous Arc Discharge Plasma Nitriding: After the coating process is completed, set the vacuum chamber temperature to 400℃. After the vacuum chamber cools down to 400℃, start the nitriding process, introducing 300 sccm of nitrogen-containing gas (50 sccm of nitrogen and 250 sccm of argon) to maintain the vacuum level inside the arc ion plating furnace at 3.0 × 10⁻⁶. -2 The substrate bias voltage was set to -30V and gradually adjusted to -300V. The column arc current was set to 110A. Then, the temperature was set to 400℃ and the vacuum degree to 3.0×10⁻⁶ mbar. -2 Under the conditions of mbar, substrate bias voltage of -300V, and column arc current of 110A, the temperature is maintained for 2 hours. After the program is completed, the furnace is cooled to room temperature to complete the preparation of the wear-resistant coating on the aluminum alloy surface.

[0037] 4. Heat treatment to restore the mechanical properties of the base aluminum alloy: After the nitriding process is completed and the sample is taken out of the furnace, the aluminum alloy with the coating on the surface is placed in a muffle furnace. The furnace temperature is set to 440℃ and held for 1 hour. Then it is taken out and air-cooled. After that, it is placed in an air furnace. The furnace temperature is set to 110℃ and held for 12 hours. Then it is taken out and air-cooled. The mechanical properties of the coated aluminum alloy are restored, which completes the preparation method of wear-resistant coating with good adhesion on the surface of aluminum alloy.

[0038] In this embodiment, arc discharge plasma is obtained by setting the column arc current to 110A.

[0039] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 4.3 μm, a maximum hardness of 460.8 HV, a coefficient of friction of 0.49, and an adhesion strength of HF3. After tribological testing, the wear rate is 4.03 × 10⁻⁶. -13 m 3 ·N -1 ·m -1 .

[0040] Example 2

[0041] The difference between this embodiment 1 and embodiment 1 is that the nitrogen flow rate in the nitrogen-containing gas is 100 sccm and the argon flow rate is 200 sccm, while the rest is the same as in embodiment 1.

[0042] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 4.3 μm, a maximum hardness of 401.2 HV, an adhesion strength of HF3, and a wear rate of 5.29 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0043] Example 3

[0044] The difference between this embodiment and embodiment 1 is that in step 2, the Ti target current is adjusted to 110A and the substrate bias voltage is -80V, and then maintained for 2.5h under the conditions of Ti target current of 110A and substrate bias voltage of -80V. The rest is the same as in embodiment 1.

[0045] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 2.1 μm, a maximum hardness of 234.1 HV, an adhesion strength of HF3, and a wear rate of 12.74 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0046] Example 4

[0047] The difference between this embodiment and embodiment 1 is that in step 2, the Ti target current is adjusted to 130A and the substrate bias voltage is -80V, and then maintained for 2.5h under the conditions of Ti target current of 130A and substrate bias voltage of -80V. The rest is the same as in embodiment 1.

[0048] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 2.2 μm, a maximum hardness of 251.1 HV, an adhesion strength of HF3, and a wear rate of 12.14 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0049] Example 5

[0050] The difference between this embodiment and embodiment 1 is that in step 2, the Ti target current is adjusted to 110A and the substrate bias voltage is -80V, and then maintained for 3.5h under the conditions of Ti target current of 110A and substrate bias voltage of -80V. The rest is the same as in embodiment 1.

[0051] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 3.1 μm, a maximum hardness of 325.5 HV, an adhesion strength of HF3, and a wear rate of 7.11 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0052] Example 6

[0053] The difference between this embodiment and embodiment 1 is that in step 2, the Ti target current is adjusted to 130A and the substrate bias voltage is -80V, and then maintained for 3.5h under the conditions of Ti target current of 130A and substrate bias voltage of -80V. The rest is the same as in embodiment 1.

[0054] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 3.3 μm, a maximum hardness of 348.1 HV, an adhesion strength of HF3, and a wear rate of 6.82 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0055] Example 7

[0056] The difference between this embodiment and embodiment 1 is that in step 2, the Ti target current is adjusted to 110A and the substrate bias voltage is -80V, and then maintained for 4.5h under the conditions of Ti target current of 110A and substrate bias voltage of -80V. The rest is the same as in embodiment 1.

[0057] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 4.1 μm, a maximum hardness of 448.8 HV, an adhesion strength of HF3, and a wear rate of 4.33 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0058] Example 8

[0059] The difference between this embodiment and embodiment 1 is that in step 4, the furnace temperature of the air furnace is set to 110°C, and after holding at that temperature for 8 hours, the furnace is taken out and air-cooled. The rest is the same as in embodiment 1.

[0060] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 4.3 μm, a maximum hardness of 436.8 HV, an adhesion strength of HF3, and a wear rate of 4.74 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0061] Example 9

[0062] The difference between this embodiment and embodiment 2 is that: in step 2, the Ti target current is adjusted to 110A and the substrate bias voltage is -80V, and then maintained for 4.5h under the conditions of Ti target current of 110A and substrate bias voltage of -80V; in step 4, the air furnace temperature is set to 110℃, and after holding for 8h, it is taken out and air-cooled. The rest is the same as in embodiment 1.

[0063] In this embodiment, the wear-resistant coating obtained on the aluminum alloy surface has a thickness of 4.1 μm, a maximum hardness of 417.8 HV, an adhesion strength of HF3, and a wear rate of 5.03 × 10⁻⁶ after tribological testing. -13 m 3 ·N -1 ·m -1 .

[0064] Figure 1 The X-ray diffraction patterns of the wear-resistant coatings with good surface adhesion prepared in Examples 1, 4 and 6 are shown in the figures. As can be seen from the figures, the coatings contain a titanium nitride solid solution phase and an aluminum-based intermetallic compound phase.

[0065] Figure 2 The cross-sectional microstructure of the aluminum alloy with a wear-resistant coating that has good adhesion to the surface prepared in Example 1 is shown in the figure. As can be seen from the figure, the coating and the substrate have good interfacial bonding.

[0066] Figure 3 The image shows a Rockwell indentation test result of the wear-resistant coating with good adhesion to the surface prepared in Example 1. Test conditions: Rockwell hardness tester, load 150g. The Rockwell indentation results show that the adhesion between the coating and the substrate reaches HF3.

[0067] The wear resistance properties of the aluminum alloy with the wear-resistant coating with good adhesion prepared in Example 1 and the aluminum alloy without the treatment of this embodiment were tested. Test conditions: on a ball-and-disc tribolab tribotester, the test disc was a 7075 aluminum alloy sample strengthened by the method of this embodiment. The grinding test ball of the mating parts was made of GCr15 steel with a diameter of 6.35 mm. The test was carried out under dry friction conditions with a load of 2 N, a turntable speed of 144 r / min, and a test time of 1000 s.

[0068] Figure 4The graph shows the friction coefficient curves obtained from the tribological tests. 1 represents the untreated aluminum alloy, and 2 represents the aluminum alloy with a wear-resistant coating having good adhesion prepared in Example 10. As can be seen from the graph, the friction coefficient of the aluminum alloy treated in Example 1 gradually increases with the extension of wear time. After the wear time is extended to 400 s, the friction coefficient tends to stabilize, with an average friction coefficient of approximately 0.49, which is lower than that of the untreated aluminum alloy substrate.

[0069] Figure 5 The image shows the wear rate of the aluminum alloy with a wear-resistant coating that has good adhesion to the surface, prepared in Example 1, after tribological testing. As can be seen from the image, the wear rate of the aluminum alloy treated in Example 1 is significantly lower than that of the untreated aluminum alloy substrate.

[0070] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface, characterized in that, Includes the following steps: S1. The aluminum alloy is polished with SiC sandpaper, then ultrasonically cleaned in anhydrous ethanol for 15 to 30 minutes, polished after removal, and then ultrasonically cleaned in anhydrous ethanol for 15 to 30 minutes before being removed and dried to obtain the pretreated aluminum alloy. S2, the pretreated aluminum alloy is placed in an arc ion plating furnace, vacuumed, heated and then argon gas is introduced, the surface of the pretreated aluminum alloy is cleaned by glow discharge, then the surface of the aluminum alloy is etched, the arc current is turned off after etching, the coating program is run, the Ti target is turned on, and the aluminum alloy with Ti film is obtained after deposition. S3. After the coating process in step S2 is completed, the vacuum chamber temperature is set to 400 ℃. After the vacuum chamber is cooled to 400 ℃, the nitriding process is started and nitrogen-containing gas is introduced. After the nitriding process is completed, the furnace is cooled to room temperature to complete the preparation of the wear-resistant coating on the aluminum alloy surface. S4. After the nitriding process in step S3 is completed, the sample is taken out of the furnace. The aluminum alloy with the coating on the surface is placed in a muffle furnace, the furnace temperature is set to 440 ℃, and after holding for 1 h, it is taken out and air-cooled. Then it is placed in an air furnace, the furnace temperature is set to 110 ℃, and after holding for 8~12 h, it is taken out and air-cooled. The preparation of a wear-resistant coating with good adhesion on the surface of the aluminum alloy is completed.

2. The method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface as described in claim 1, characterized in that, In step S1, the SiC sandpaper has a mesh size of 400 to 2000#.

3. The method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface as described in claim 1, characterized in that, In step S2, the specific conditions for glow discharge cleaning are: the vacuum degree of the arc ion plating furnace is 5 × 10⁻⁶. -4 mbar, vacuum chamber temperature 420℃, rotation speed 3r / min, argon gas flow rate 300 sccm, substrate bias voltage -400 V, glow discharge cleaning pretreatment of aluminum alloy surface for 10 min.

4. The method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface as described in claim 1, characterized in that, In step S2, the specific etching conditions are as follows: the column arc current is 80 A, the substrate bias voltage is -30 V, gradually adjusted to -180 V, and the aluminum alloy surface is etched for 10 min.

5. The method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface as described in claim 1, characterized in that, In step S2, the specific coating conditions are as follows: the substrate bias voltage is -30 V, gradually adjusted to -180 V; the Ti target current is 110 A ~ 130 A; and the vacuum degree inside the arc ion plating furnace is maintained at 2.5 × 10⁻⁶. -2 mbar was deposited for 2.5 to 4.5 h under the conditions of substrate bias of -80V and Ti target current of 110 A to 130 A.

6. The method for preparing a wear-resistant coating with good adhesion to an aluminum alloy surface as described in claim 1, characterized in that, In step S3, the amount of nitrogen-containing gas introduced is 300 sccm, including 50 sccm of nitrogen and 250 sccm of argon, and the vacuum degree inside the arc ion plating furnace is 3.0 × 10⁻⁶. -2 mbar, substrate bias voltage -30 V, gradually adjusted to -300 V, column arc current set to 110 A, then at temperature 400 ℃ and vacuum degree 3.0×10 -2 The substrate was kept at a temperature of mbar for 2 hours with a substrate bias of -300 V and a column arc current of 110 A.

7. A wear-resistant coating with good adhesion to the surface of an aluminum alloy, prepared by the preparation method according to any one of claims 1 to 6.

8. The wear-resistant coating with good adhesion to the surface of an aluminum alloy as described in claim 7, characterized in that, The wear-resistant coating has a thickness of 2μm to 4.3μm, a maximum hardness of 460.8HV, a coefficient of friction of 0.49 to 0.55, and an adhesion strength of HF3.

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