Modified aluminide coatings and methods for making same

Abstract

The present invention discloses a modified aluminide coating and a method for producing the same. The modified aluminide coating contains 15% to 20% by weight of Al, 0.3% to 1% by weight of Au, and the remainder being base metal elements. The method for producing the modified aluminide coating includes the following steps: (1) pretreating the surface of a workpiece; (2) placing the workpiece in a vacuum ion sputtering system and depositing an Au coating on the workpiece surface using an Au sheet as a sputtering target; and (3) burying the workpiece with the Au coating in Al-containing powder and diffusing it in an argon protective atmosphere to obtain the modified aluminide coating. The coating has excellent high-temperature oxidation resistance, is relatively easy to produce, and is dense and uniform in thickness.

Description

[Technical Field]

[0001] The present invention is in the field of surface engineering and relates to modified aluminide coatings and methods for their manufacture. [Background technology]

[0002] The formation of protective oxide films through selective high-temperature oxidation of alloys is an important basis for the design of high-temperature alloys and their coatings. Selective oxidation of alloys can be promoted by increasing the content of selectively oxidizable elements in the alloy, increasing their diffusion rate, decreasing the oxygen content and diffusion rate, or increasing the oxide nucleation rate. The most oxidation-resistant selective oxide films include Al2O3, SiO2, and Cr2O3 films. However, for titanium alloys, stainless steels with low Cr, Al, and Si contents, and nickel-based alloys, it is impossible to form protective Al2O3, SiO2, and Cr2O3 films during the oxidation process. Therefore, the high-temperature oxidation resistance of metallic materials can only be improved by surface modification. Conventional surface modifications mainly include metal coatings, ceramic coatings, and surface microcrystallization.

[0003] Aluminide coatings provide protection primarily by forming an Al2O3 film on the coating surface at high temperatures. The alumina film is very dense and prevents further oxidation and corrosion. Aluminide coatings provide aluminum elements to form the alumina film, providing continuous protection. Aluminide coatings have excellent high-temperature oxidation resistance but inferior hot corrosion resistance to chromium coatings. Generally, the high-temperature oxidation and hot corrosion resistance of aluminide coatings are improved through two main approaches: first, by improving the bonding strength between the oxide film and the substrate, and second, by reducing the internal diffusion of aluminum within the coating. Specific approaches include (1) modifying the aluminide coating with Cr, Si, Pt, or rare earth elements to improve the bonding strength between the oxide film and the substrate, and (2) creating a diffusion barrier between the coating and the substrate to inhibit the internal diffusion of aluminum.

[0004] Diffusion-type modified aluminide coatings (such as Si-Al, Cr-Al, and Pt-Al coatings) have been widely used overseas. Since their commercial application, modified aluminide coatings have been systematically optimized and developed in terms of manufacturing process and technology, microstructure, and composition control, resulting in the formation of a series of coatings. Taking platinum-aluminum coatings as an example, the typical manufacturing process involves pre-electroplating a platinum layer (3-8 μm) on a high-temperature alloy, followed by aluminizing. However, conventional single-phase platinum-aluminum coatings (mainly β-(Ni,Pt)Al) are prone to phase changes during cyclic oxidation, resulting in volumetric changes and thermal stress due to mismatched thermal expansion coefficients. This results in wrinkles and large irregularities in the surface oxide film, ultimately leading to cracking and peeling.

[0005] In addition to the thermal diffusion manufacturing process, there are many methods for producing modified aluminide coatings, such as composite thermal spraying technology, composite electroplating technology, sintering technology, etc. However, the quality of the coatings produced by these technologies is low, and due to the line-of-sight effect, the coating on the surface of a workpiece with a complex shape will have problems of uneven thickness and lack of density, making it particularly difficult to manufacture devices with complex structures. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide a modified aluminide coating that has excellent high-temperature oxidation resistance, is easy to manufacture, and has a uniform thickness and density, as well as a method for manufacturing the same. [Means for solving the problem]

[0007] To achieve the above object, the modified aluminide coating of the present invention contains 15 to 20 mass % Al, 0.3 to 1 mass % Au, and the balance being base metal elements.

[0008] The method for producing the modified aluminide coating of the present invention comprises: (1) preparing the surface of a workpiece; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing an Au coating on the surface of the workpiece using the Au sheet as a sputtering target; and (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon protective atmosphere to obtain a modified aluminide coating.

[0009] The specific operations in step (1) are as follows: The surface of the workpiece is degreased and derusted, and then treated with a grinding and polishing device to make the roughness of the surface of the workpiece better than 0.8.

[0010] In step (2), the purity of the Au sheet is 99.9% or higher.

[0011] In step (2), the thickness of the Au coating is 1 to 3 microns.

[0012] In step (3), the Al-containing powder contains 1% by mass to 3% by mass of Al powder, 1% by mass to 3% by mass of NH4Cl powder, 1% by mass to 3% by mass of NH4NO3 powder, 30% by mass to 40% by mass of Fe-Al alloy powder, and the balance Al2O3 powder.

[0013] In step (3), the particle size of the Al-containing powder is 200 mesh or less.

[0014] In step (3), the temperature of the diffusion process is 850 to 1050°C.

[0015] In step (3), the diffusion time is 2 to 6 hours.

[0016] The matrix elements are one or more of Fe, Ni, and Co in combination. [Effects of the Invention]

[0017] The present invention has the following beneficial effects.

[0018] The modified aluminide coating and its manufacturing method of the present invention utilize the characteristics of gold, which has good electrical conductivity, ductility, excellent corrosion resistance, and oxidation resistance, to introduce gold and other metal phases into conventional aluminide coatings. This allows the formation of various intermetallic compounds between gold and aluminum, thereby slowing the degradation rate of the aluminide coating. Furthermore, by fully utilizing the advantages of gold, which has excellent thermal stability, the gold modification further improves the high-temperature oxidation resistance of the aluminide coating, slowing the degradation rate of the coating, and achieving a relatively simple manufacturing process with a uniform and dense coating thickness. Furthermore, the present invention is applicable to various devices with complex structures. Compared with the prior art, the manufacturing process of the present invention is simpler and the material adaptability is broader. The coating has stronger oxidation resistance and can be widely used in packaging fields such as advanced integrated circuits and high-end electronic devices. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a schematic diagram of the deposition of an Au coating on the surface of 316L stainless steel in step (2) of Example 1. [Figure 2] 1 is a scanning electron microscope image of a cross section of a modified aluminide coating deposited on the surface of 316L stainless steel in Example 1. [Figure 3] FIG. 1 is an element distribution diagram of the coating of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to help those skilled in the art better understand the solutions of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the disclosure of the present invention. Furthermore, in the following description, descriptions of well-known structures and techniques will be omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative ingenuity should be included within the protection scope of the present invention.

[0021] The drawings show structural schematic diagrams of the embodiments disclosed in the present invention. These drawings are not drawn to scale, and some details may be enlarged or omitted for clarity. The shapes of various regions and layers shown in the drawings, as well as their relative sizes and positions, are merely examples and may actually differ due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can separately design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0022] The modified aluminide coating of the present invention comprises 15% to 20% by weight of Al, 0.3% to 1% by weight of Au, and the balance being base metal elements; The method for producing the modified aluminide coating of the present invention comprises: (1) degreasing and derusting the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece better than 0.8; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 1-3 micron thick Au coating on the surface of the workpiece using a Au sheet with a purity of 99.9% or higher as a sputtering target; (3) embedding the workpiece on which the Au coating has been deposited in Al-containing powder and diffusing it in an argon atmosphere at 850-1050°C for 2-6 hours; The Al-containing powder contains 1% by mass to 3% by mass of Al powder, 1% by mass to 3% by mass of NH4Cl powder, 1% by mass to 3% by mass of NH4NO3 powder, 30% by mass to 40% by mass of Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 200 mesh or less.

[0023] As can be seen from the Au-Al phase diagram, various intermetallic compounds can be formed between Au and Al, and the phase represented by Au8Al3 has relatively good high-temperature stability and can slow the degradation rate of aluminide coatings.

[0024] The present invention is applicable to iron-based, nickel-based, and cobalt-based alloy workpieces, where the base metal elements are one or more of the following in combination: Fe, Ni, Co. [Example]

[0025] Example 1 The method for producing the modified aluminide coating of the present invention for a 316L stainless steel workpiece comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; Referring to FIG. 1, step (2) is to place the workpiece in a vacuum ion sputtering apparatus and deposit a 1.2 micron thick Au coating on the surface of the workpiece using a 99.97% pure Au sheet as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 860°C for 6 hours; The Al-containing powder contains 1.2 mass% Al powder, 1.1 mass% NH4Cl powder, 1 mass% NH4NO3 powder, 35 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0026] The modified aluminide coating produced in this example was metallurgically bonded to the substrate and had a thickness of 38 microns. The coating composition, by mass, was 16.5% Al, 0.48% Au, and the balance of the substrate elements (Fe, Ni, and Cr). The cross-sectional morphology of the coating is shown in Figure 2, and the component distribution is shown in Figure 3.

[0027] Example 2 The method for producing the modified aluminide coating of the present invention for a 316L stainless steel workpiece comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 2.95 micron thick Au coating on the surface of the workpiece using a 99.97% pure Au sheet as a sputtering target; (3) embedding the workpiece on which the Au coating has been deposited in an Al-containing powder and diffusing it at 1050°C for 2 hours in an argon atmosphere; The Al-containing powder contains 3 mass% Al powder, 3 mass% NH4Cl powder, 3 mass% NH4NO3 powder, 30 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0028] The resulting modified aluminide coating in this example was metallurgically bonded to the substrate and had a thickness of 116 microns. The coating composition, by mass, was 19.5% Al, 0.88% Au, and the balance the substrate elements (Fe+Ni+Cr).

[0029] Example 3 The method for producing the modified aluminide coating of the present invention for a 316L stainless steel workpiece comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 1.8 micron thick Au coating on the surface of the workpiece using a Au sheet with a purity of 99.97% or higher as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 980°C for 4 hours; The Al-containing powder contains 1.8 mass% Al powder, 1.8 mass% NH4Cl powder, 2.1 mass% NH4NO3 powder, 40 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0030] The modified aluminide coating produced in this example was metallurgically bonded to the substrate and had a thickness of 76 microns. The coating composition, by mass, was 18% Al, 0.68% Au, and the balance the substrate elements (Fe, Ni, and Cr).

[0031] Example 4 The method of producing the modified aluminide coating of the present invention, intended for workpieces made of K417G nickel-base high temperature alloy, comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 1.8 micron thick Au coating on the surface of the workpiece using a Au sheet with a purity of 99.97% or higher as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 1000°C for 4 hours; The Al-containing powder contains 1.8 mass% Al powder, 1.8 mass% NH4Cl powder, 2.1 mass% NH4NO3 powder, 40 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0032] The modified aluminide coating produced in this example was metallurgically bonded to the substrate and had a thickness of 68 microns. The coating composition, by mass, was 17% Al, 0.65% Au, and the balance substrate elements (Ni+Cr).

[0033] Example 5 The method of producing the modified aluminide coating of the present invention, intended for workpieces made of DZ40M cobalt-based high temperature alloy, comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 1.8 micron thick Au coating on the surface of the workpiece using a Au sheet with a purity of 99.97% or higher as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 1000°C for 4 hours; The Al-containing powder contains 1.8 mass% Al powder, 1.8 mass% NH4Cl powder, 2.1 mass% NH4NO3 powder, 40 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0034] The modified aluminide coating produced in this example was metallurgically bonded to the base metal and had a thickness of 59 microns. The coating composition, by mass, was 16.8% Al, 0.55% Au, and the balance base metal elements (Co, Cr, W, etc.).

[0035] Example 6 The modified aluminide coating of the present invention comprises 15% by weight Al, 0.3% by weight Au, and the balance being base metal elements; The method for producing the modified aluminide coating of the present invention comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.7; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 1 micron thick Au coating on the surface of the workpiece using an Au sheet with a purity of 99.95% or higher as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 850°C for 2 hours; The Al-containing powder contains 1 mass% Al powder, 1 mass% NH4Cl powder, 1 mass% NH4NO3 powder, 30 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 250 mesh.

[0036] Example 7 The modified aluminide coating of the present invention comprises 20% by weight Al, 1% by weight Au, and the balance being base metal elements; The method for producing the modified aluminide coating of the present invention comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.65; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 3 micron thick Au coating on the surface of the workpiece using an Au sheet with a purity of 99.96% or higher as a sputtering target; (3) embedding the workpiece on which the Au coating has been deposited in an Al-containing powder and diffusing it at 1050°C for 6 hours in an argon atmosphere; The Al-containing powder contains 3 mass% Al powder, 3 mass% NH4Cl powder, 3 mass% NH4NO3 powder, 40 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 350 mesh.

[0037] Example 8 The modified aluminide coating of the present invention comprises 17.5% by weight Al, 0.6% by weight Au, and the balance being base metal elements; The method for producing the modified aluminide coating of the present invention comprises: Step (1) of degreasing and removing rust from the surface of the workpiece, and treating the surface of the workpiece with a grinding and polishing device to make the surface roughness of the workpiece 0.6; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing a 2 micron thick Au coating on the surface of the workpiece using a 99.97% pure Au sheet as a sputtering target; (3) embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon atmosphere at 950°C for 4.5 hours; The Al-containing powder contains 2 mass% Al powder, 2 mass% NH4Cl powder, 2 mass% NH4NO3 powder, 35 mass% Fe-Al alloy powder, and the balance Al2O3 powder, and the particle size of the Al-containing powder is 300 mesh.

[0038] Finally, the above examples are only used to illustrate the technical solutions of the present invention, and are not intended to limit the same. Although the present invention has been described in detail with reference to the above examples, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A modified aluminide coating comprising 15% to 20% by weight of Al, 0.3% to 1% by weight of Au, and the balance being base metal elements.

2. (1) preparing the surface of a workpiece; (2) placing the workpiece in a vacuum ion sputtering apparatus and depositing an Au coating on the surface of the workpiece using the Au sheet as a sputtering target; Step (3) of embedding the workpiece with the deposited Au coating in Al-containing powder and diffusing it in an argon protective atmosphere to obtain a modified aluminide coating; 1. A method for producing a modified aluminide coating comprising:

3. The specific operation of step (1) is as follows:

2. The method for producing the modified aluminide coating of claim 1, characterized in that the surface of the workpiece is degreased and derusted, and then treated with a grinding and polishing device to make the surface roughness of the workpiece better than 0.

8.

4. 2. The method for producing a modified aluminide coating according to claim 1, wherein in step (2), the purity of the Au sheet is 99.9% or more.

5. 2. The method for producing a modified aluminide coating according to claim 1, wherein in step (2), the thickness of the Au coating is 1-3 microns.

6. In step (3), the Al-containing powder is prepared by mixing 1 mass % to 3 mass % of Al powder and NH ４ Cl powder in an amount of 1 mass % to 3 mass % and NH ４ NO ３ 1% by mass to 3% by mass of Fe—Al alloy powder, 30% by mass to 40% by mass of Fe—Al alloy powder, and the remaining amount of Al ２ O ３ and a powder.

7. 4. The method for producing a modified aluminide coating according to claim 3, wherein in step (3), the particle size of the Al-containing powder is 200 mesh or less.

8. The method for producing modified aluminide coating according to claim 1, characterized in that in step (3), the temperature of the diffusion process is 850-1050°C.

9. 2. The method for producing modified aluminide coating according to claim 1, wherein in step (3), the diffusion time is 2 to 6 hours.

10. 2. The method of claim 1, wherein the base metal element is one or a combination of Fe, Ni, and Co.

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