A method for preparing an aluminum coating on a titanium alloy surface using a friction stir deposition technique

Abstract

The application belongs to the technical field of surface modification of metal materials, and particularly relates to a method for preparing an aluminum coating on a titanium alloy surface by using a friction stir deposition technology, which comprises the following steps: taking a titanium alloy as a substrate, using pure aluminum or an aluminum alloy as a friction deposition rod, and rotating and rubbing the friction deposition rod along the surface of the substrate under the action of an axial pressure so that the friction deposition rod is softened and deposited on the substrate under the action of friction heat and severe plastic deformation, so as to generate an aluminum coating on the titanium alloy surface. In the application, the friction deposition rod is softened and deposited on the substrate to be protected under the action of severe plastic deformation which is jointly generated by friction heat and an axial force between the deposition rod and the titanium alloy substrate to be protected, the prepared coating is well combined with the substrate, the microstructure of the coating is refined, and the high-temperature oxidation resistance of the coating is excellent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface modification of metal materials, and particularly relates to a method for preparing an aluminum coating on a titanium alloy surface by using a friction stir deposition technique. BACKGROUND

[0002] Titanium alloy has high specific strength, low density, good heat resistance and corrosion resistance, and is widely used in aerospace, ocean engineering, energy and chemical industry, and national defense and military industry. In particular in the field of aerospace, the high specific strength of titanium alloy makes it an important material for improving the thrust-to-weight ratio of engines. However, titanium alloy has poor high-temperature oxidation resistance, which greatly limits its application range. In high-temperature oxidation environment, titanium alloy is easy to form a weakly bonded oxide film and an oxygen-rich brittle layer, which affects the mechanical properties and service life of titanium alloy. In an oxidation environment with a service temperature exceeding 500 ℃, a porous TiO2 oxide film is easily formed on the surface of titanium alloy, which cannot effectively resist the further diffusion of oxygen atoms to the titanium alloy substrate. In addition, the formation of an oxygen-rich brittle layer on the surface of titanium alloy leads to brittle fracture of the titanium alloy due to oxidation. Therefore, improving the high-temperature oxidation resistance of titanium alloy is the key to its high-temperature application.

[0003] There are two methods to improve the high-temperature oxidation resistance of titanium alloy, namely alloying and surface modification technology. Alloying can improve the high-temperature oxidation resistance of titanium alloy to a certain extent, but as the oxidation time increases, the improvement effect decreases significantly. Therefore, surface modification technology is the most widely used method to improve the high-temperature oxidation resistance of titanium alloy. Forming a protective coating on the surface of titanium alloy through surface modification technology is one of the most direct and effective methods to improve the high-temperature oxidation resistance of titanium alloy and to improve the service life and reliability of titanium alloy used in aerospace. Currently, the preparation techniques of titanium alloy coating mainly include infiltration, thermal spraying, ion implantation, magnetron sputtering, vapor deposition, and laser cladding. The above techniques can form a protective coating on the surface of titanium alloy, but there are still problems such as poor interfacial bonding strength, environmental pollution, and high energy consumption. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a method for preparing an aluminum coating on a titanium alloy surface by using a friction stir deposition technique, which comprises the following steps:

[0005] Titanium alloy is used as a substrate, and pure aluminum or aluminum alloy is used as a friction deposition rod. Under the action of axial pressure, the friction deposition rod is rotated and advanced along the surface of the substrate, so that the friction deposition rod is softened and deposited on the substrate under the action of friction heat and severe plastic deformation, thereby generating an aluminum coating on the surface of the titanium alloy.

[0006] As a further description of the present application, the method further comprises a pretreatment of the substrate:

[0007] The titanium alloy substrate surface is cleaned with acetone, and then the surface of the titanium alloy substrate is polished with sandpaper to roughen the surface to 25 μm≤Ra≤50 μm.

[0008] As a further description of the present application, the friction deposition rod is driven by a hydraulic system to contact the titanium alloy substrate at a constant penetration speed, and the friction deposition rod is rotated and advanced along the surface of the titanium alloy substrate, and the friction deposition rod and the titanium alloy substrate are deposited on the titanium alloy substrate under the action of thermal coupling to form an aluminum coating.

[0009] The titanium alloy substrate is fixed on the workbench of the friction stir welding equipment, and the pure aluminum or aluminum alloy friction deposition rod is installed at the position of the stirring pin of the friction stir welding equipment;

[0010] The pure aluminum or aluminum alloy friction deposition rod is driven by a hydraulic system to contact the titanium alloy substrate at a constant penetration speed, and the friction deposition rod is rotated and advanced along the surface of the titanium alloy substrate, and the friction deposition rod and the titanium alloy substrate are deposited on the titanium alloy substrate under the action of thermal coupling to form an aluminum coating.

[0011] As a further description of the present application, the deposition is carried out in a straight line in one direction or reciprocatingly and continuously until the preparation of a coating of a specific area is completed.

[0012] As a further description of the present application, the penetration speed of the pure aluminum or aluminum alloy friction deposition rod is 90-160 mm / min.

[0013] As a further description of the present application, the rotation speed of the pure aluminum or aluminum alloy friction deposition rod is 800-1200 rpm.

[0014] As a further description of the present application, the advance speed of the pure aluminum or aluminum alloy friction deposition rod is 240-400 mm / min.

[0015] As a further description of the present application, the thickness of the aluminum coating prepared by the method is 2-10 μm.

[0016] As a further description of the present application, the thickness of the substrate is 3-20 mm, the width is 80-2000 mm, and the length is 100-3000 mm.

[0017] As a further description of the present application, the diameter of the friction deposition rod is 10-40 mm, and the height is 60-100 mm.

[0018] Compared with the prior art, the present application has the following beneficial technical effects:

[0019] (1) The preparation method is simple, easy to operate, environment-friendly and easy to popularize.

[0020] (2) Compared with the coating prepared by the laser cladding technology, the preparation method of the present application does not involve a solidification process, and the coating has no solidification defects such as pores and cracks, and the coating and the substrate have good metallurgical bonding.

[0021] (3) The aluminum coating has similar thermal expansion coefficient with the titanium alloy substrate, and is not prone to cracking, falling off and other problems during service, thereby improving the high temperature oxidation resistance and wear resistance of the titanium alloy under high temperature and long time service.

[0022] (4) The present application is prepared under the action of severe plastic deformation generated by friction heat and axial force between the deposition rod and the titanium alloy substrate to be protected, the deposition rod is softened and deposited on the substrate to be protected, the coating has good bonding with the substrate, the microstructure of the coating is refined, and the high temperature oxidation resistance is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The scanning electron microscope (SEM) image of the cross section of the Ti55 alloy surface deposited with aluminum coating provided in Example 1 of the present application after constant temperature oxidation at 550℃ for 100 hours. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] The present application proposes a method for preparing an aluminum coating on the surface of a titanium alloy by using a friction stir deposition technology, comprising: using titanium alloy as a substrate, using pure aluminum or aluminum alloy as a friction deposition rod, and rotating and advancing along the surface of the substrate under the action of axial pressure, so that the friction deposition rod is softened and deposited on the substrate under the action of friction heat and severe plastic deformation, thereby generating an aluminum coating on the surface of the titanium alloy.

[0026] Specifically, the method comprises the following steps:

[0027] Step 1: Clean the surface of the titanium alloy substrate with acetone to remove oil stains, and then polish the surface of the titanium alloy substrate with sandpaper to roughen the surface to 25μm≤Ra≤50μm, for example, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0028] Step 2: Fix the titanium alloy substrate after the above pretreatment on the workbench of the friction stir welding equipment, and install the pure aluminum or aluminum alloy friction deposition rod on the stir pin position of the friction stir welding equipment.

[0029] Step 3: Drive the pure aluminum or aluminum alloy friction deposition rod to contact the titanium alloy substrate at a constant pressing speed using a hydraulic system, and rotate and advance along the surface of the titanium alloy substrate. The pure aluminum or aluminum alloy friction deposition rod is deposited on the titanium alloy substrate under the action of heat and force to form an aluminum coating.

[0030] Step 4: Take out the deposited titanium alloy plate, and perform surface coating finishing treatment according to specific use requirements, so as to obtain an aluminum coating with high-temperature oxidation resistance on the surface of the titanium alloy.

[0031] Preferably, the deposition in step 3 is performed in a straight line in one direction or reciprocatingly and continuously until the preparation of a coating of a specific area is completed.

[0032] Preferably, in step 3, the pressing speed of the pure aluminum or aluminum alloy friction deposition rod is 90-160 mm / min, for example, it can be 90 mm / min, 100 mm / min, 110 mm / min, 120 mm / min, 130 mm / min, 140 mm / min, 150 mm / min, 160 mm / min, etc. The rotating speed of the pure aluminum or aluminum alloy friction deposition rod is 800-1200 rpm, for example, it can be 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, etc. The advancing speed of the pure aluminum or aluminum alloy friction deposition rod is 240-400 mm / min, for example, it can be 240 mm / min, 250 mm / min, 280 mm / min, 300 mm / min, 350 mm / min, 400 mm / min, etc.

[0033] The aluminum coating prepared by the method has a thickness of 2-10 μm, for example, it can be 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, etc., and the coating has good interface bonding with the substrate.

[0034] In the method, the thickness of the titanium alloy substrate is 3-20 mm, for example, it can be 3 mm, 5 mm, 10 mm, 15 mm, 20 mm, etc.; the width is 80-2000 mm, for example, it can be 80 mm, 120 mm, 160 mm, 200 mm, 500 mm, 1000 mm, 2000 mm, etc.; and the length is 100-3000 mm, for example, it can be 100 mm, 150 mm, 200 mm, 500 mm, 1000 mm, 3000 mm, etc.

[0035] The diameter of the friction deposition rod in the method is 10-40 mm, for example, 10 mm, 20 mm, 30 mm, or 40 mm; and the height is 60-100 mm, for example, 60 mm, 70 mm, 80 mm, 90 mm, or 100 mm.

[0036] The following is described in several preferred embodiments: Example 1

[0037] In this example, a common Ti55 alloy is used as a metal plate to prepare an aluminum coating layer with high-temperature oxidation resistance. The specific steps are as follows:

[0038] Step 1: Take a piece of Ti55 alloy plate with a size of 100 mm x 80 mm x 10 mm, clean the surface of the titanium alloy substrate with acetone, and then polish the surface of the titanium alloy substrate with sandpaper to roughen the surface to 40 μm.

[0039] Step 2: Fix the pretreated Ti55 alloy substrate on the workbench of the friction stir welding equipment, and install the pure aluminum friction deposition rod on the stirring needle position of the equipment. The pure aluminum friction deposition rod is cylindrical in shape, with a diameter of 10 mm and a height of 70 mm.

[0040] Step 3: Use the hydraulic system to drive the pure aluminum friction deposition rod to contact the Ti55 alloy substrate at a constant axial pressing speed, and rotate and advance along the surface of the substrate. Under the action of heat and force coupling, the aluminum coating layer is generated on the Ti55 alloy substrate, forming a protective coating layer. The deposition method is repeated in a straight line in one direction until the preparation of the coating layer of a specific area is completed. The axial pressing speed of the friction deposition rod is 120 mm / min, the rotating speed is 1100 rpm, and the advancing speed is 260 mm / min.

[0041] Step 4: Take off the deposited Ti55 alloy plate, and perform surface coating finishing treatment according to specific use requirements, so that an aluminum coating layer with high-temperature oxidation resistance is obtained on the surface of the Ti55 alloy. The coating layer obtained by the method has a thickness of 8 μm.

[0042] Example 1 successfully realizes the process of preparing an aluminum coating layer with high-temperature oxidation resistance on a Ti55 alloy plate. As shown in FIG. 1, the Ti55 alloy plate is prepared by the method of the present application, and the surface of the Ti55 alloy plate is coated with an aluminum coating layer with high-temperature oxidation resistance. Figure 1The image shows scanning electron microscope (SEM) images of the cross-sections of the prepared aluminum coating and substrate on the Ti55 alloy surface after oxidation at 550℃ for 100 h. It can be seen that the prepared aluminum coating has good interfacial bonding with the Ti55 alloy substrate, with the deposited aluminum coating on top and the Ti55 alloy substrate below. After oxidation at 550℃ for 100 h, a 2-3 μm oxide intermediate layer is formed between the coating and the Ti55 alloy substrate. This oxide intermediate layer is dense, without obvious pores, cracks, or other defects, and exhibits good interfacial bonding with the substrate. Therefore, this coating can effectively prevent oxygen from entering the Ti55 substrate and causing oxidation, thereby significantly improving the high-temperature oxidation resistance of the Ti55 alloy substrate. These results indicate that preparing an aluminum coating with good interfacial bonding on a Ti55 alloy substrate using friction stir deposition significantly improves the high-temperature oxidation resistance of the Ti55 alloy substrate. Example 2

[0043] This embodiment uses a common TC4 alloy as the metal sheet to prepare a surface anti-oxidation aluminum coating. The specific steps are as follows:

[0044] Step 1: Take a 1000 mm × 1000 mm × 5 mm TC4 alloy plate, clean the oil stains on the surface of the TC4 alloy substrate with acetone, and then use sandpaper to polish the surface of the TC4 alloy substrate to roughen the surface to 50 μm.

[0045] Step 2: Fix the pretreated TC4 alloy substrate onto the worktable of the friction stir welding equipment, and install the 6061 aluminum alloy friction deposition rod at the stirring pin position of the equipment. The 6061 aluminum alloy friction deposition rod is cylindrical in shape, with a diameter of 30 mm and a height of 80 mm.

[0046] Step 3: A hydraulic system drives a 6061 aluminum alloy deposition rod to contact the TC4 alloy substrate at a constant axial pressing speed, and rotates and advances along the substrate surface. Under the thermal coupling effect, an aluminum coating is formed between the 6061 aluminum alloy deposition rod and the TC4 alloy substrate, covering the surface of the TC4 alloy substrate to form a protective coating. The deposition process is repeated in a straight line in one direction until a coating of a specific area is prepared. The axial pressing speed of the friction deposition rod is 90 mm / min, the rotation speed is 1200 rpm, and the forward speed is 300 mm / min.

[0047] Step 4: Remove the deposited TC4 alloy plate and perform surface coating finishing treatment according to specific application requirements. This will result in an aluminum coating with high-temperature oxidation resistance on the TC4 alloy surface. The coating thickness obtained by this method is 5μm. Example 3

[0048] The embodiment takes the common Ti153 alloy as the metal plate to prepare the surface aluminum coating with oxidation resistance, and the specific steps are as follows:

[0049] Step 1, taking a piece of Ti153 alloy plate with a size of 2000 mm*800 mm*20 mm, the surface oil dirt of the Ti153 alloy substrate is cleaned by using acetone, and then the surface of the Ti153 alloy substrate is polished by using sandpaper, so that the surface is roughened to 25 μm.

[0050] Step 2, the pretreated Ti153 alloy substrate is fixed on the workbench of the friction stir welding equipment, and the 6063 aluminum alloy friction deposition rod is installed at the position of the stirring needle. The 6063 aluminum alloy friction deposition rod is in the shape of a cylinder with a diameter of 40 mm and a height of 100 mm.

[0051] Step 3, the 6063 aluminum alloy friction deposition rod is driven by the hydraulic system to contact the Ti153 alloy substrate at a constant axial pressing speed, and rotates and advances along the surface of the substrate, so that the aluminum coating is generated under the thermal coupling between the 6063 aluminum alloy friction deposition rod and the Ti153 alloy substrate, and a protective coating is formed on the surface of the Ti153 alloy substrate. The deposition mode is repeated in a straight line in one direction until the preparation of the coating of a specific area is completed. The axial pressing speed of the friction deposition rod is 150 mm / min, the rotating speed is 800 rpm, and the advancing speed is 400 mm / min.

[0052] Step 4, the deposited Ti153 alloy plate is taken down, and the surface coating finishing treatment is carried out according to the specific use requirement, so that an aluminum coating with high-temperature oxidation resistance is obtained on the surface of the Ti153 alloy. The coating obtained by the method has a thickness of 3 μm.

[0053] It should be noted that in this paper, terms such as "including", "containing" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0054] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an aluminum coating on a titanium alloy surface using friction stir deposition, characterized in that, include: Using titanium alloy as a substrate, friction stir deposition technology is employed, with pure aluminum or aluminum alloy as the friction deposition rod. Under axial pressure, the rod rotates and advances along the substrate surface, causing it to soften and deposit onto the substrate under frictional heat and intense plastic deformation, thereby forming an aluminum coating on the titanium alloy surface. Specifically, this includes: A titanium alloy substrate is fixed on the worktable of a friction stir welding equipment, and a pure aluminum or aluminum alloy friction deposition rod is installed at the stirring pin position of the friction stir welding equipment. A hydraulic system is used to drive a pure aluminum or aluminum alloy friction deposition rod to contact the titanium alloy substrate at a constant pressing speed, and to rotate and advance along the surface of the titanium alloy substrate. Under the effect of thermal coupling, the pure aluminum or aluminum alloy friction deposition rod deposits an aluminum coating on the titanium alloy substrate. The pressing speed of the pure aluminum or aluminum alloy friction deposition rod is 90~160 mm / min, the rotation speed is 800~1200 rpm, and the advancing speed is 240~400 mm / min. The thickness of the aluminum coating prepared by the method is 2~10 μm.

2. The method for preparing an aluminum coating on a titanium alloy surface using friction stir deposition as described in claim 1, characterized in that, The method further includes substrate pretreatment: The surface of the titanium alloy substrate was cleaned with acetone to remove oil stains, and then the surface of the titanium alloy substrate was roughened with sandpaper to a roughness of 25μm≤Ra≤50μm.

3. The method for preparing an aluminum coating on a titanium alloy surface using friction stir deposition as described in claim 1, characterized in that, The deposition process is carried out in a linear unidirectional or reciprocating continuous manner until a coating of a specific area is prepared.

4. The method for preparing an aluminum coating on a titanium alloy surface using friction stir deposition as described in claim 1, characterized in that, The substrate has a thickness of 3-20 mm, a width of 80-2000 mm, and a length of 100-3000 mm.

5. The method for preparing an aluminum coating on a titanium alloy surface using friction stir deposition as described in claim 1, characterized in that, The diameter of the triboelectric deposition rod is 10-40 mm and the height is 60-100 mm.

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