CN116411235B - Method for preparing in-situ self-generated nano precipitated phase enhanced high-entropy alloy coating by plasma spraying - Google Patents

Abstract

The invention discloses a method for preparing an in-situ self-generated nano precipitated phase enhanced high-entropy alloy coating by plasma spraying, and belongs to the technical field of high-entropy alloy coatings. High-entropy alloy powder Fe by plasma spraying _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 Spraying on a substrate, and carrying out vacuum heat treatment and solution treatment on the obtained coating to obtain an in-situ authigenic nano precipitated phase enhanced high-entropy alloy coating; the parameters in the plasma spraying process are set as follows: the distance between the plasma spray gun and the substrate is 140mm, the spraying voltage is 72.5V, the spraying current is 620A, the powder feeding rate is 35g/min, the argon flow is 30Slpm, and the hydrogen flow is 8Slpm. The method has low cost, further expands the application range of the high-entropy alloy, and has good interlayer combination, compact structure and excellent wear resistance.

Description

A kind of plasma spraying preparation of in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coating Methods

Technical field

The invention belongs to the technical field of high-entropy alloy coatings, and in particular relates to a method for preparing in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coatings by plasma spraying.

Background technique

The development experience of traditional alloys believes that when there are too many metal elements making up an alloy, many brittle intermetallic compounds with complex structures will be formed, which will deteriorate the alloy properties. However, in recent years, researchers have discovered that if five or more metal elements are mixed together in an equimolar or nearly equimolar ratio without distinguishing the main elements, the alloy obtained by smelting will have a simplified microstructure and will not tend to It has structural characteristics such as intermetallic compounds, nano-precipitates and amorphous structure, and has performance characteristics such as high strength, high hardness, resistance to tempering and softening, and wear resistance. This type of alloy was first defined as multi-principal alloy or high-entropy alloy by Ye Junwei and others. There is no existing traditional alloy that can possess the above excellent properties at the same time. Therefore, high-entropy alloys have broad application prospects and can be widely used in the production of high-strength, high-temperature-resistant, and corrosion-resistant cutting tools, molds, and machine parts. Good opportunities in the field of high-performance, high-value-added special alloy materials.

So far, although many scholars have used various methods to prepare high-entropy alloy bulk materials and achieved certain research results, the preparation of bulk materials has inevitable defects such as material waste, component segregation, and shrinkage cavities. Using high-entropy alloy materials as coatings through coating technology can greatly reduce production costs and accelerate its industrialization.

There are currently some methods used to prepare high-entropy alloy coatings, such as laser cladding, magnetron sputtering, hot press sintering, etc., but these methods have high preparation costs and are difficult to apply in industry.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the present invention proposes a method for preparing an in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coating by plasma spraying. The atmospheric plasma spraying process is used to prepare a wear-resistant coating on the surface of a stainless steel substrate. By adjusting the spraying parameters, the micromorphology of the coating is optimized to the greatest extent, and the spraying parameters with the best wear-resistant performance of the coating are obtained. This method is low-cost and further expands the application scope of high-entropy alloys. The coating has good interlayer bonding, dense structure, and excellent wear resistance.

In order to achieve the above objects, the present invention provides the following technical solutions:

A method for preparing an in-situ self-generated nanoprecipitated phase-enhanced high-entropy alloy coating by plasma spraying. The high-entropy alloy powder is sprayed on the substrate by plasma spraying, and the obtained coating is subjected to vacuum heat treatment and solid solution treatment, thereby obtaining In-situ self-generated nano-precipitated phase enhanced high-entropy alloy coating;

The high-entropy alloy powder is Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 ;

The parameters during the plasma spraying process are set as follows: the distance between the plasma spray gun and the substrate is set to 140mm, the spraying voltage is 72.5V, the spraying current is 620A, the powder feeding rate is 35g/min, the argon flow rate is 30Slpm, and the hydrogen flow rate is 8Slpm. .

The substrate is made of 304 stainless steel. Before spraying, the surface of the substrate is cleaned of oil and then sandblasted and textured to achieve uniform surface roughness and no reflection. Finally, it is dried at 90°C for 2 hours and then plasma sprayed.

Further, the particle size of the high-entropy alloy coating powder is 53-150 μm.

Further, the parameters of the vacuum heat treatment are: temperature 780±50°C, time 3-5h; the quenching temperature of the solid solution treatment is 15-25°C.

The invention also provides an in-situ self-generated nano-precipitated phase-reinforced high-entropy alloy coating prepared by the above method.

Compared with the existing technology, the present invention has the following advantages and technical effects:

1) The present invention proposes the feasibility of using atmospheric plasma method to prepare Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 high-entropy alloy coating; in the present invention, plasma spraying technology is used to prepare high-entropy alloy coating, by changing The H ₂ flow is used to control the flame temperature, so that the high-entropy alloy powder is fully melted during the deposition process, enhancing the interface structure between flattened particles, reducing the porosity of the coating and inhibiting the generation of cracks, obtaining Fe _28.0 Co _29.5 Ni _27.5 Al Optimal spraying parameters for _8.5 Ti _6.5 high-entropy alloy coating method.

2) The present invention uses commercial gas atomized high-entropy alloy powder. The powder has good sphericity and ensures good fluidity of the powder during the spraying process. Since the high-entropy alloy has a diffusion hysteresis effect, it is easy to precipitate the second component in a supersaturated solid solution. phase, thus playing a dispersion strengthening effect.

3) The method used in the present invention has a simple preparation process, is easy to prepare, has low cost, and can be industrialized. The prepared Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 high-entropy alloy coating has the characteristics of high hardness and wear resistance. After subsequent heat treatment strengthening, the hardness and wear resistance of the coating have been greatly improved.

4) The method adopted in the present invention has little impact on the substrate, the prepared coating is uniform, and the thickness of the coating is controllable.

Description of the drawings

The drawings that form a part of this application are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an improper limitation of this application. In the attached picture:

Figure 1 shows the morphology of Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 powder, (a) low magnification powder morphology, (b) high magnification powder morphology;

Figure 2 shows the surface and cross-sectional morphology of Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating. (a) Coating surface morphology, (b) Coating cross-sectional morphology;

Figure 3 X-ray diffraction patterns of the sprayed Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating and the heat-treated Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating prepared by the present invention;

Figure 4 is a Vickers hardness diagram before and after heat treatment of the in-situ autogenous nano-precipitated phase-reinforced high-entropy alloy coating prepared by the present invention;

Figure 5 is a graph of the wear coefficient of the sprayed Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating and the heat-treated Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating prepared by the present invention.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range and any other stated value or value intermediate within a stated range is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples are intended to be illustrative only.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

The invention discloses a method for preparing an in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coating by plasma spraying. Plasma thermal spraying is used on the surface of 304 stainless steel to heat pre-set alloy powder (high-entropy alloy coating) under the protection of argon and hydrogen. powder), after high-temperature spraying (the plasma spray flame temperature is as high as several thousand degrees Celsius) and rapid cooling (the plasma spraying time is very short and only stays on the surface for a few seconds, so the coating will quickly return to room temperature from several thousand degrees Celsius and will experience a rapid cooling process (this is due to the plasma spraying process), a high-entropy alloy coating is formed, and a wear-resistant coating can be obtained after solid solution treatment. The high-entropy alloy coating prepared by the invention has good interlayer bonding, dense structure and excellent wear resistance. After testing, it was found that the coating has good wear resistance and is composed of FCC phase, L12 phase and some oxide phases. After heat treatment, the coating is composed of FCC phase, L21 phase and oxide phase, and the wear resistance of the coating is further improved. The coating provided by the invention has a room temperature wear coefficient of 0.35 after testing. The specific technical solutions are as follows:

A method for preparing an in-situ self-generated nanoprecipitated phase-enhanced high-entropy alloy coating by plasma spraying. The high-entropy alloy powder is sprayed on the substrate by plasma spraying, and the obtained coating is subjected to vacuum heat treatment and solid solution treatment, thereby obtaining In-situ self-generated nano-precipitated phase enhanced high-entropy alloy coating;

The high-entropy alloy powder is Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 ;

The parameters during the plasma spraying process are set as follows: the distance between the plasma spray gun and the substrate is set to 140mm, the spraying voltage is 72.5V, the spraying current is 620A, the powder feeding rate is 35g/min, the argon flow rate is 30Slpm, and the hydrogen flow rate is 8Slpm. .

The specific method for preparing in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coatings by plasma spraying is as follows:

1) Treat the substrate before spraying;

2) Fix the substrate on the spray frame;

3) Place the high-entropy alloy powder for spraying in the powder feeder;

4) Adjust the spraying distance and determine the running trajectory of the spray gun;

5) Use plasma spraying method to prepare high-entropy alloy coating;

6) Subject the prepared high-entropy alloy coating to vacuum heat treatment and solid solution treatment to obtain the high-entropy alloy coating.

In some embodiments of the present invention, the base body is not specifically limited, but preferably, the base body in the present invention is 304 stainless steel. Before spraying, the surface of the base body is cleaned of oil stains and then sandblasted and textured. Achieve uniform surface roughness and no reflection; finally dry it at 90°C for 2 hours before plasma spraying.

Preferably, in some embodiments of the present invention, the particle size of the high-entropy alloy coating powder is 53-150 μm, because this particle size range can ensure that the powder has good fluidity and is easy to melt. Below this range, it will be detrimental to fluidity and easily cause over-burning, leaving a large number of holes in the coating and the powder is easily blown away by the plasma flame, making it difficult to deposit onto the substrate, resulting in low deposition efficiency. Higher than this range will increase the difficulty of melting, resulting in uneven powder melting and more pores in the coating.

Preferably, in some embodiments of the present invention, the parameters of the vacuum heat treatment are: temperature 780±50°C, time 3-5h; below this temperature, the second phase precipitates in small size and quantity, and above this temperature, the second phase precipitates Phase II will grow larger and decrease in number.

Preferably, in some embodiments of the present invention, the quenching temperature of the solid solution treatment is 15-25°C and the time is 4 hours. Solid solution at this temperature can fully diffuse the alloy elements in the coating and precipitate nano-strengthening phases, thereby improving the hardness of the coating. Below this temperature, the number of precipitated phases is small and the precipitation strengthening effect is poor. Above this temperature, the size of the precipitated phases will grow and their number will decrease.

The invention also provides an in-situ self-generated nano-precipitated phase-reinforced high-entropy alloy coating prepared by the above method.

The raw materials used in the following examples of the present invention were prepared by Ningbo Zhongyuan New Material Technology Co., Ltd. using the aerosolization method.

The following examples serve as further explanations of the technical solutions of the present invention.

Example 1

Step 1: Select the 304 stainless steel workpiece, use ethanol ultrasonic to remove oil stains on its surface, and then sandblast and texturize it to achieve uniform surface roughness and no reflection; finally, dry it at 90°C for 2 hours and set aside.

Step 2: Use Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 (see Figure 1) as the coating raw material, with a particle size of 53-150 μm, and spray it on the surface of the substrate after sandblasting and roughening through atmospheric plasma spraying equipment. The thickness of the Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 high-entropy alloy coating was obtained to be 400 μm. The spraying parameters are: the distance between the plasma spray gun and the substrate is set to 140mm, the spraying voltage is 72.5V, the spraying current is 620A, the powder feeding rate is 35g/min, the argon gas flow rate is 30Slpm, and the hydrogen gas flow rate is 8Slpm.

Step 3: Heat the prepared high-entropy alloy coating in a vacuum heat treatment furnace at 780°C for 4 hours, and then quench (quenching temperature is 15-25°C, time is 4 hours) to obtain an in-situ autogenous nano-precipitated phase-reinforced high-entropy alloy. coating.

Figure 1 shows the morphology of Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 powder. It can be seen from the figure that the sphericity of the high-entropy alloy powder is good, which can ensure good fluidity during the spraying process.

Figure 2 is an SEM image of the surface and cross-section of the in-situ self-generated nanoprecipitated phase-reinforced high-entropy alloy coating prepared in this embodiment. It can be seen from the image that the interlayer combination is good and the hard phase is evenly distributed.

Figure 3 is the X-ray diffraction pattern of the in-situ autogenous nano-precipitated phase-enhanced high-entropy alloy coating prepared in this example before and after heat treatment. It can be seen from the figure that Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 high-entropy alloy coating During the heat treatment process, a phase transformation occurred, and the coating was composed of FCC phase, L21 phase and oxide phase, which improved the coating performance.

Figure 4 is a Vickers hardness diagram of the in-situ autogenous nano-precipitated phase-reinforced high-entropy alloy coating prepared in this example before and after heat treatment. It can be seen from the figure that the sprayed Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating has The hardness is about 250HV, and the hardness of the coating after heat treatment is about 500HV.

A ball-disc reciprocating friction and wear experiment was conducted on the prepared coating. The friction ball was a cemented carbide ball, the load was 5N, the speed was 220mm/s, and the total sliding distance was 576m. Figure 5 is a graph of the wear coefficient before and after heat treatment of the in-situ autogenous nanoprecipitated phase-enhanced high-entropy alloy coating prepared in this example. It can be seen from the figure that the wear of the sprayed Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 coating The coefficient is about 0.8, and the wear coefficient of the coating after heat treatment is about 0.35.

Comparative example 1

Same as Example 1, except that the spraying parameters are: the distance between the plasma spray gun and the substrate is set to 120mm, the spraying voltage is 71V, the spraying current is 600A, the powder feeding rate is 29g/min, the argon flow rate is 30Slpm, and the hydrogen flow rate is 7Slpm.

It was found that the Vickers hardness value of the coating prepared using this comparative example was about 220HV, and the wear coefficient was about 1.2.

Comparative example 2

Same as Example 1, except that the heat treatment temperature is 900°C;

The results show that the Vickers hardness value of the coating prepared using this comparative example is about 400HV, and the wear coefficient is about 0.6.

The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. All are covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (5)

1. A method for preparing an in-situ autogenous nano-precipitated phase-enhanced high-entropy alloy coating by plasma spraying, which is characterized in that high-entropy alloy powder is sprayed on the substrate by plasma spraying, and the obtained coating is subjected to vacuum heat treatment and Solid solution treatment is used to obtain an in-situ self-generated nano-precipitated phase-enhanced high-entropy alloy coating; The high-entropy alloy powder is Fe _28.0 Co _29.5 Ni _27.5 Al _8.5 Ti _6.5 ; The parameters during the plasma spraying process are set as follows: the distance between the plasma spray gun and the substrate is set to 140mm, the spraying voltage is 72.5V, the spraying current is 620A, the powder feeding rate is 35g/min, the argon flow rate is 30Slpm, and the hydrogen flow rate is 8Slpm. ; The parameters of the vacuum heat treatment are: temperature 780±50°C, time 3-5h. 2. The method for preparing in-situ self-generated nanoprecipitated phase-enhanced high-entropy alloy coating by plasma spraying according to claim 1, characterized in that the particle size of the high-entropy alloy coating powder is 53-150 μm. 3. The method for preparing in-situ self-generated nanoprecipitated phase-enhanced high-entropy alloy coatings by plasma spraying according to claim 1, characterized in that, before plasma spraying, it also includes a process of pretreating the substrate, and the pretreatment method The steps are as follows: remove oil stains on the surface of the substrate, then sandblast and texture it until the surface roughness is uniform and non-reflective; finally, dry it at 90°C for 2 hours. 4. The method for preparing in-situ self-generated nanoprecipitated phase-enhanced high-entropy alloy coating by plasma spraying according to claim 1, characterized in that the quenching temperature of the solid solution treatment is 15-25°C. 5. An in-situ self-generated nano-precipitated phase-reinforced high-entropy alloy coating prepared by the method of any one of claims 1-4.