A method for preparing an MCrAlY coating

Abstract

This invention belongs to the field of thermal barrier coating technology, and particularly relates to a method for preparing an MCrAlY coating. The method first uses a powder metallurgy HY3 target and employs multi-arc ion plating technology to prepare an MCrAlY coating on the surface of a high-temperature alloy. The coating is then subjected to vacuum heat treatment, shot peening, and surface conversion layer treatment. The MCrAlY coating prepared by this method has a uniform microstructure, few internal pores and other defects, and a dense surface conversion layer that forms a diffusion barrier layer. This layer resists oxidation and prevents diffusion between the MCrAlY coating and the Pt layer, enabling the study of MCrAlY underlayers with low infrared emissivity and long-term stability.

Description

Technical Field

[0001] This invention belongs to the field of thermal barrier coating technology, and particularly relates to a method for preparing an MCrAlY coating. Background Technology

[0002] Currently, almost all thermal power generation and aircraft propulsion are powered by gas turbines. Improving the efficiency of gas turbines means higher operating temperatures for the gas, which places higher demands on the thermal stability of gas turbine components. To address this issue, thermal barrier coatings (TBCs) technology has emerged. A typical TBC consists of four layers: a substrate, a bond coat, a thermally grown oxide (TGO) layer, and a ceramic coat. MCrAlY coatings are widely used as the bond coat in TBCs, and their diverse composition allows for the design of suitable coating compositions and processes based on different operating environments and substrate materials.

[0003] The MCrAlY coatings prepared in the prior art generally suffer from poor interfacial bonding and internal cracking, which seriously affect the coating's performance and lifespan. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a method for preparing an MCrAlY coating that is resistant to marine corrosion and possesses good interfacial compatibility. This method promotes the phase transformation of the oxide film, resulting in a MCrAlY coating with a uniform microstructure, fewer internal pores and other defects, and a dense surface conversion layer. This provides excellent diffusion resistance, facilitating the coating of noble metals and ultimately leading to a high-temperature protective coating.

[0005] The specific technical solution of the present invention is as follows:

[0006] A method for preparing an MCrAlY coating includes the following steps:

[0007] Step 1: Prepare an MCrAlY coating on a high-temperature alloy substrate;

[0008] Step 2: Perform vacuum heat treatment on the MCrAlY coating;

[0009] Step 3: After vacuum heat treatment, the MCrAlY coating is shot peened.

[0010] Step 4: After shot peening, place the high-temperature alloy substrate with the MCrAlY coating into a vertical furnace. Connect the high-temperature alloy substrate to the negative terminal of the radio frequency power supply, and connect the furnace shell to the positive terminal of the radio frequency power supply. Evacuate the furnace to 0.5-8 Pa, raise the temperature to 870-1050℃, and hold for 1-5 hours. Then, introduce argon and oxygen into the furnace, controlling the oxygen partial pressure to 0.1-10 Pa. Finally, turn on the radio frequency power supply to generate O and Ar plasma, and simultaneously clean and oxidize the MCrAlY coating at a temperature of 870-1050℃.

[0011] Preferably, step 1 specifically includes: using powder metallurgy HY3 target material, and employing multi-arc ion plating technology to prepare an initial MCrAlY coating on a high-temperature alloy substrate, with a preheating temperature of 300-500℃ and a coating thickness of 20-50μm.

[0012] Preferably, the vacuum heat treatment temperature in step 2 is 800-1050℃, and the time is 3-5h.

[0013] Preferably, after vacuum heat treatment in step 2, the roughness of the MCrAlY coating is 1.6-2.4 μm.

[0014] Preferably, the shot peening pressure in step 2 of step 3 is 0.1-1.5 MPa, and the time is 5-15 min.

[0015] Preferably, after shot peening in step 3, the roughness of the MCrAlY coating is 0.4-0.8 μm.

[0016] Preferably, the mixing ratio of argon and oxygen in step 4 is 8:2.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The present invention proposes a method for preparing MCrAlY coatings, which can produce MCrAlY coatings with uniform composition, few internal defects, long life, high reliability, and a good conversion layer with α-Al2O3 as the main component, which can be applied to higher operating temperatures (1150℃) and complex operating conditions (high salinity and heavy corrosion in the ocean), thus meeting the urgent need for the preparation of high-temperature protective coatings for aero-engines. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the vertical furnace structure used in the preparation method of the present invention;

[0021] Figure 2 This is a schematic diagram of the MCrAlY coating structure obtained by the preparation method of the present invention;

[0022] Figure 3 Micrograph of the MCrAlY coating prepared in Example 1;

[0023] Figure 4 The Raman spectrum of the MCrAlY coating obtained in step 4 of Example 1 without plasma-assisted treatment;

[0024] Figure 5 The Raman spectrum of the final MCrAlY coating prepared in Example 1;

[0025] Figure 6 The surface morphology of the samples in step 4 of Example 2, before and after plasma-assisted treatment, was tested for high-temperature oxidation performance at 1000℃ / 20h.

[0026] Figure 7 The surface morphology of the samples in step 4 of Example 2, before and after plasma-assisted treatment, was tested at 40°C for 100 hours using acidic salt spray corrosion.

[0027] In the figure: 1-Vertical furnace, 2-Heating rod, 3-Sample, 4-Negative electrode, 5-RF power supply, 6-Positive electrode, 7-High temperature alloy substrate, 8-MCrAlY coating, 9-Diffusion barrier layer. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0030] This invention proposes a method for preparing an MCrAlY coating, which is essentially a pretreatment process in the preparation of high-temperature protective coatings. First, an MCrAlY coating is prepared on the surface of a high-temperature alloy using a multi-arc ion plating technique with a powder metallurgy HY3 target. The coating is then subjected to vacuum heat treatment, shot peening, and a surface conversion layer treatment.

[0031] Among them, vertical furnaces used for vacuum heat treatment, such as Figure 1 As shown, the vertical furnace 1 is equipped with a heating rod 2 for heating, and a sample 3 with an MCrAlY coating on its surface is located in the vertical furnace and connected to the negative terminal of the radio frequency power supply. The positive terminal of the radio frequency power supply is connected to the outer shell of the vertical furnace. The vertical furnace 1 is also equipped with exhaust and gas supply pipelines.

[0032] The MCrAlY coating structure obtained by the preparation method of this invention is as follows: Figure 2 As shown, from bottom to top, the high-temperature alloy substrate 7, the MCrAlY coating 8, and the diffusion barrier layer 9 are respectively.

[0033] The following two examples will further illustrate this point.

[0034] Example 1

[0035] A method for preparing an MCrAlY coating includes the following steps:

[0036] Step 1: Preparation of MCrAlY coating: MCrAlY coating is prepared on high-temperature alloy using multi-arc ion plating technology with HY3 powder metallurgy target material. The preheating temperature is 300℃ and the coating thickness is 20μm.

[0037] Step 2: Vacuum heat treatment of the MCrAlY coating: Vacuum heat treatment at 900℃ for 5 hours.

[0038] Step 3: Perform shot peening on the MCrAlY coating after vacuum heat treatment: the shot peening material is quartz beads, the pressure is 0.5MPa, and the time is 10min.

[0039] Step 4: Place the high-temperature alloy substrate with the MCrAlY coating into a vertical furnace. First, evacuate to 5 Pa, then raise the temperature to 870℃ and hold for 5 hours. Next, introduce argon and oxygen (mixing ratio Ar:O2 = 8:2), controlling the oxygen partial pressure at 7 Pa. Finally, turn on the radio frequency power supply to obtain plasma, simultaneously cleaning and oxidizing the sample at high temperature.

[0040] Figure 3 A micrograph of the MCrAlY coating prepared in Example 1 is shown. As can be seen from the figure, the obtained microstructure is uniform and has few internal defects. From bottom to top, it is divided into a high-temperature alloy substrate, an MCrAlY coating, and a diffusion barrier layer.

[0041] Among them, Raman spectroscopy analysis was performed on the MCrAlY coating obtained in step 4 of Example 1 without plasma-assisted preparation, and the results are as follows: Figure 4 As shown, it is clear that both α-Al2O3 and θ-Al2O3 exist in the coating.

[0042] Similarly, Raman spectroscopy analysis was performed on the MCrAlY coating finally prepared using plasma assistance in Example 1, and the results are as follows: Figure 5 As shown, the coating contains only α-Al2O3, which indicates that after step 4, all θ-Al2O3 is converted into α-Al2O3.

[0043] Example 2

[0044] A method for preparing an MCrAlY coating includes the following steps:

[0045] Step 1: Preparation of MCrAlY coating: MCrAlY coating is prepared on high-temperature alloy using multi-arc ion plating technology with HY3 powder metallurgy target material. The preheating temperature is 500℃ and the coating thickness is 30μm.

[0046] Step 2: Vacuum heat treatment of the MCrAlY coating: Vacuum heat treatment at 1050℃ for 3 hours.

[0047] Step 3: Perform shot peening on the MCrAlY coating after vacuum heat treatment: the shot peening material is quartz beads, the pressure is 0.2MPa, and the time is 5min.

[0048] Step 4: Place the high-temperature alloy substrate with the MCrAlY coating into a vertical furnace. First, evacuate the tube to 0.5 Pa, raise the temperature to 1050℃, and hold for 2 hours. Then, introduce argon and oxygen (gas mixing ratio of Ar:O2 = 8:2), controlling the oxygen partial pressure at 5 Pa. Finally, turn on the radio frequency power supply to obtain plasma, and simultaneously perform the cleaning and oxidation processes on the sample at high temperature.

[0049] Step 5: Prepare a 1-2 μm Pt layer on the MCrAlY coating shown in Step 4 by magnetron sputtering or electroplating to reduce infrared emissivity.

[0050] Figure 6The surface morphology of the samples prepared in Example 2 and those not treated with plasma were compared after a high-temperature oxidation test at 1000℃ / 20h. The comparison showed that the surface of the plasma-treated sample was brighter and the surface oxidation was weaker than that of the untreated sample (the surface discoloration was obvious, indicating that diffusion had occurred). This indicates that the MCrAlY coating obtained by plasma-assisted treatment has better anti-oxidation performance and prevents the diffusion of the MCrAlY coating and the Pt layer.

[0051] Figure 7 The surface morphology of the samples prepared in Example 2 and those not treated with plasma were compared after a 40°C / 100h acidic salt spray corrosion test. The comparison showed that the surface corrosion of the plasma-treated samples was weaker than that of the untreated samples (which showed pinhole corrosion), indicating that the MCrAlY coating obtained by surface conversion layer treatment has better corrosion resistance and diffusion performance.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0054] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an MCrAlY coating, characterized in that, Includes the following steps: Step 1: Prepare an MCrAlY coating on a high-temperature alloy substrate; Step 2: Perform vacuum heat treatment on the MCrAlY coating; Step 3: After vacuum heat treatment, the MCrAlY coating is shot peened. Step 4: After shot peening, place the high-temperature alloy substrate with MCrAlY coating into a vertical furnace. Connect the high-temperature alloy substrate to the negative terminal of the radio frequency power supply, and connect the furnace shell to the positive terminal of the radio frequency power supply. Evacuate the furnace to 0.5-8 Pa, raise the temperature to 870-1050 ℃, and hold for 1-5 h. Then, introduce argon and oxygen into the furnace, controlling the oxygen partial pressure to 0.1-10 Pa. Finally, turn on the radio frequency power supply to generate O and Ar plasma, and simultaneously clean and oxidize the MCrAlY coating at a temperature of 870-1050 ℃. In step 4, the mixing ratio of argon and oxygen is 8:

2.

2. The preparation method according to claim 1, characterized in that, Step 1 specifically includes: using powder metallurgy HY3 target material, and employing multi-arc ion plating technology to prepare an initial MCrAlY coating on a high-temperature alloy substrate, with a preheating temperature of 300-500 ℃ and a coating thickness of 20-50 μm.

3. The preparation method according to claim 1, characterized in that, The vacuum heat treatment in step 2 is performed at a temperature of 800-1050 ℃ for 3-5 h.

4. The preparation method according to claim 3, characterized in that, After vacuum heat treatment in step 2, the roughness of the MCrAlY coating is 1.6-2.4 μm.

5. The preparation method according to claim 1, characterized in that, The shot peening pressure in step 2 of step 3 is 0.1-1.5 MPa, and the time is 5-15 min.

6. The preparation method according to claim 5, characterized in that, After shot peening in step 3, the roughness of the MCrAlY coating is 0.4-0.8 μm.

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