High-entropy alloy SiC superhard protective layer and preparation method thereof

Abstract

The invention discloses a high-entropy alloy SiC superhard protective layer and a preparation method thereof. The method comprises the following steps: 1, filling a high-entropy alloy into Si powder, compacting, heating and diffusing to obtain a Si-infiltrated high-entropy alloy; 2, cleaning; thirdly, the cleaned Si-infiltrated high-entropy alloy is loaded into C powder to be compacted, high-temperature thermal activation heating diffusion is carried out, and Si-C binary composite infiltrated high-entropy alloy is obtained; and 4, cleaning the surface of the high-entropy alloy to obtain the SiC superhard protective layer. According to the method, surface treatment, powder coating, high-temperature diffusion and ultrasonic cleaning treatment processes are combined, the principle of binary composite permeation is adopted, Si and C are sequentially diffused and permeated into the surface of the high-entropy alloy for in-situ synthesis of the SiC superhard protective layer, the binding force between the SiC superhard protective layer and a high-entropy alloy matrix is improved, and the strength of the high-entropy alloy is improved. And the service performance of the high-entropy alloy under the service environments of high temperature, high pressure, chemical corrosion, frictional wear and the like is effectively improved, and the method is suitable for various types of high-entropy alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material protection, and in particular to a high entropy alloy SiC superhard protective layer and a preparation method thereof. Background Art

[0002] SiC material itself has the advantages of high hardness, good wear resistance, high chemical stability, high thermal conductivity, and small thermal expansion coefficient. These excellent properties have enabled SiC materials in various forms to be used, such as powder abrasives, high temperature resistant materials, protective coatings, etc. In recent years, high entropy alloys, as a new type of material, have broken the drawback that the performance of traditional alloys is limited by the main elements by virtue of their multi-component characteristics, making their performance controllable window wider and having good comprehensive performance. Therefore, high entropy alloys have great application prospects in aerospace, national defense and military industries. With the increasingly fierce international competition, major equipment in various fields has been rapidly upgraded and iterated, and higher indicators have been put forward for the performance of materials. Therefore, it is necessary to further process and modify high entropy alloys to adapt to the development of high-end equipment. The preparation of SiC protective layer on the surface of high entropy alloy can improve the wear resistance, high temperature oxidation resistance, corrosion resistance, etc. of high entropy alloys, and effectively improve the service stability of high entropy alloys in harsh environments such as high temperature, high pressure and gas high-speed scouring, which has important practical significance for the development of major equipment in aerospace, national defense and military industries.

[0003] Currently, the preparation of SiC protective layer mostly adopts a one-step molding method, which includes sol-gel, burial, chemical vapor deposition, etc. (Paper: Wen ZL, et al. Microstructure and oxidation behavior ofSol-gel mullite coating on SiC-coated carbon / carbon composites[J]. Journal ofthe European ceramic society, 2015, 35(14), 3789-3796; Li L, et al.Comparison of the oxidation behaviors of SiC coatings on C / C compositesprepared by pack cementation and chemical vapor deposition[J]. Surface andcoatings technology, 2016, 302, 56-64. Patent: CN 118326365A, CN 118086818B, etc.), the prepared SiC protective layer often has the disadvantage of poor bonding with the substrate, which will cause peeling and local instability of key components containing SiC protective layer during service, which may eventually lead to catastrophic accidents; and the above method has high requirements on equipment and process. Taking the above problems into consideration, the traditional method of preparing SiC protective layer is questioned in terms of cost and reliability. Therefore, it is urgent to develop a low-cost method that can effectively prepare a strong bonding SiC protective layer on the surface of high entropy alloy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a high entropy alloy SiC superhard protective layer in view of the deficiencies of the above-mentioned prior art. The method combines surface treatment, powder coating, high temperature diffusion, and ultrasonic cleaning processes, and adopts the principle of binary composite infiltration to successively diffuse and infiltrate Si and C on the surface of the high entropy alloy to synthesize the SiC superhard protective layer in situ, thereby improving the bonding force between the SiC superhard protective layer and the high entropy alloy matrix, effectively improving the service performance of the high entropy alloy in service environments such as high temperature and high pressure, chemical corrosion, friction and wear, and solving the problem of poor bonding between the SiC protective layer and the matrix.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high entropy alloy SiC superhard protective layer, characterized in that the method comprises the following steps: Step 1: Mechanically grind and polish the surface of the high entropy alloy, then put it into a mold filled with Si powder, compact it with a hydraulic press, and then put it into a vacuum furnace for heating and diffusion to obtain a high entropy alloy after Si infiltration; Step 2: Place the Si-infiltrated high entropy alloy obtained in step 1 into an ultrasonic cleaning device for cleaning to remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in step 2 into a mold filled with C powder, compact it using a hydraulic press, and then place it in a vacuum furnace for high-temperature thermal activation and heating diffusion to obtain a Si-C binary composite infiltrated high entropy alloy; Step 4: Place the high entropy alloy obtained in step 3 after Si-C binary composite infiltration into an ultrasonic cleaning device for cleaning to remove surface powder, thereby obtaining a SiC superhard protective layer on the surface of the high entropy alloy.

[0006] The above-mentioned method for preparing a high-entropy alloy SiC superhard protective layer is characterized in that the preparation method of the high-entropy alloy in step one is casting, 3D printing and powder metallurgy.

[0007] The above-mentioned method for preparing a high-entropy alloy SiC superhard protective layer is characterized in that the average particle size of the Si powder in step one is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill stops for 5 min every 40 min of work, and the process control agent in the ball milling is anhydrous ethanol.

[0008] The above-mentioned method for preparing a high-entropy alloy SiC superhard protective layer is characterized in that the heating and diffusion system in step one is: heating to 1100°C at a rate of 5°C / min, keeping warm for 5h~10h, and cooling with the furnace.

[0009] The above-mentioned method for preparing a high entropy alloy SiC superhard protective layer is characterized in that the pressure used for compaction in step 1 and step 3 is 100MPa~400MPa. The present invention increases the contact area between Si powder and high entropy alloy, and between C powder and high entropy alloy after Si infiltration through compaction treatment, which is beneficial to the subsequent corresponding thermal diffusion process.

[0010] The above-mentioned method for preparing a high entropy alloy SiC superhard protective layer is characterized in that the pressure in the vacuum furnace chamber in step 1 and step 3 is 10 -4 Pa level. By controlling the vacuum furnace chamber to a high vacuum, the impurity gas content is reduced and impurity pollution is reduced.

[0011] The above-mentioned method for preparing a high-entropy alloy SiC superhard protective layer is characterized in that the average particle size of the C powder in step three is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill stops for 5 min every 40 min of work, and the process control agent in the ball milling is anhydrous ethanol.

[0012] The above-mentioned method for preparing a high-entropy alloy SiC superhard protective layer is characterized in that the high-temperature thermal activation heating diffusion system described in step three is: first increase the temperature to 1600°C~1800°C at a rate of 5°C / min and keep it for 15min~25min, then slowly cool down to 1300°C at a rate not higher than 2°C / min and keep it for 4h~8h, and cool with the furnace.

[0013] The above-mentioned method for preparing a high entropy alloy SiC superhard protective layer is characterized in that the ultrasonic cleaning medium used for cleaning in step 2 and step 4 is a mixed solution of 90% by volume ethanol and 10% by volume acetone. The ultrasonic cleaning medium has excellent enhanced decontamination ability.

[0014] In addition, the present invention also discloses a high entropy alloy SiC superhard protective layer, which is characterized in that it is prepared by the above method.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The present invention combines surface treatment, powder coating, high-temperature diffusion, and ultrasonic cleaning treatment processes, adopts the principle of binary composite infiltration, and successively diffuses and infiltrates Si and C on the surface of the high-entropy alloy, and in-situ synthesizes a SiC superhard protective layer on the surface of the high-entropy alloy, thereby improving the bonding force between the SiC superhard protective layer and the high-entropy alloy matrix, ensuring the wear resistance, oxidation resistance and corrosion resistance of the high-entropy alloy surface, effectively improving the service stability of the high-entropy alloy in various harsh environments such as high temperature, high pressure and gas high-speed scouring, and avoiding peeling and local instability in key parts of the high-entropy alloy during service.

[0016] 2. Compared with spherical powders, the present invention effectively increases the contact area between Si powder and C powder and the surface of the corresponding alloy sample by pre-flaking Si powder and C powder, thereby improving the diffusion efficiency.

[0017] 3. The surface hardness of the SiC superhard protective layer prepared in situ on the surface of the high entropy alloy substrate in the present invention is about 1400Hv, which is about 400Hv higher than that of the substrate, effectively improving the service performance of the high entropy alloy in service environments such as high temperature and high pressure, chemical corrosion, friction and wear.

[0018] 4. The preparation method of the present invention is stable, fast and efficient, and is applicable to many types of high entropy alloys, solving the problems of high cost and poor stability in the actual production process.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the X-ray diffraction pattern of the SiC superhard protective layer on the surface of the high entropy alloy prepared in Example 1 of the present invention.

[0021] Figure 2 This is the distribution diagram of Si and C elements in the SiC superhard protective layer on the surface of the high entropy alloy prepared in Example 1 of the present invention.

[0022] Figure 3 This is a graph showing the hardness values ​​of the SiC superhard protective layer on the surface of the high entropy alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] Example 1 This embodiment includes the following steps: Step 1: The composition of Ta in terms of atomic ratio 15 Mo 20 Cr 25 Ti5Al 20 Nb 15 The surface of the cast high entropy alloy was mechanically ground and polished, then loaded into a mold filled with Si powder and compacted using a hydraulic press at a pressure of 400 MPa. It was then placed in a vacuum furnace chamber for heating and diffusion, and the pressure in the vacuum furnace chamber was 10 -4 Pa, heating to 1100℃ at a rate of 5℃ / min and keeping at that temperature for 10h, cooling with the furnace to obtain high entropy alloy after Si infiltration; The average particle size of the Si powder is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 min after working for 40 min. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 2: The Si-infiltrated high entropy alloy obtained in step 1 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in the mold filled with C powder and compact it with a hydraulic press at a pressure of 400 MPa. Then place it in a vacuum furnace chamber for high-temperature thermal activation and heating diffusion. The pressure in the vacuum furnace chamber is 10 -4 Pa, firstly heated to 1800℃ at a rate of 5℃ / min and kept at that temperature for 25min, then slowly cooled to 1300℃ at a rate not higher than 2℃ / min and kept at that temperature for 8h, and then cooled with the furnace to obtain a high entropy alloy after Si-C binary composite infiltration; The average particle size of the C powder is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 hours, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 minutes after every 40 minutes of operation. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 4: Place the Si-C binary composite infiltrated high entropy alloy obtained in step 3 into an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove the surface powder. 15 Mo 20 Cr 25 Ti5Al 20 Nb 15 A SiC superhard protective layer is obtained on the surface of the high entropy alloy.

[0024] The SiC superhard protective layer on the surface of the high entropy alloy prepared in this embodiment was subjected to X-ray diffraction analysis of the phase composition, element distribution and hardness value test. The results are as follows: Figures 1 to 3 shown.

[0025] Figure 1 This is the X-ray diffraction pattern of the SiC superhard protective layer on the surface of the high entropy alloy prepared in this embodiment. Figure 1 It can be seen that in addition to the high entropy alloy matrix phase, a SiC protective layer is formed on the surface of the high entropy alloy after binary composite infiltration.

[0026] Figure 2 The distribution diagram of Si and C elements in the SiC superhard protective layer on the surface of the high entropy alloy prepared in this embodiment is shown in Figure 2. Figure 2 It can be seen that Si and C elements are evenly distributed on the surface of the high entropy alloy, and a dense SiC protective layer is formed on the surface of the high entropy alloy after binary composite infiltration.

[0027] Figure 3 The hardness value result diagram of the SiC superhard protective layer on the surface of the high entropy alloy prepared in this embodiment is shown in FIG. Figure 3It can be seen that a dense SiC protective layer is formed on the surface of the high entropy alloy after binary composite infiltration, with a hardness of about 1400Hv, which is higher than Ta 15 Mo 20 Cr 25 Ti5Al 20 Nb 15 The high entropy alloy matrix is ​​about 400Hv.

[0028] In this embodiment, the preparation method of the high entropy alloy can also be 3D printing or powder metallurgy.

[0029] Example 2 This embodiment includes the following steps: Step 1: The composition of Ta in terms of atomic ratio 20 Mo 20 Cr 20 Ti 20 Al 20 The surface of the cast high entropy alloy was mechanically ground and polished, then loaded into a mold filled with Si powder and compacted using a hydraulic press at a pressure of 100 MPa. It was then placed in a vacuum furnace chamber for heating and diffusion, and the pressure in the vacuum furnace chamber was 10 -4 Pa, heating to 1100℃ at a rate of 5℃ / min and keeping at that temperature for 5h, cooling with the furnace to obtain the high entropy alloy after Si infiltration; The average particle size of the Si powder is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 min after working for 40 min. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 2: The Si-infiltrated high entropy alloy obtained in step 1 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in the mold filled with C powder and compact it with a hydraulic press at a pressure of 100 MPa. Then place it in a vacuum furnace chamber for high-temperature thermal activation and heating diffusion. The pressure in the vacuum furnace chamber is 10 -4 Pa, firstly heated to 1600℃ at a rate of 5℃ / min and kept at that temperature for 15min, then slowly cooled to 1300℃ at a rate not higher than 2℃ / min and kept at that temperature for 4h, and then cooled with the furnace to obtain a high entropy alloy after Si-C binary composite infiltration; The average particle size of the C powder is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 hours, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 minutes after every 40 minutes of operation. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 4: Place the Si-C binary composite infiltrated high entropy alloy obtained in step 3 into an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove the surface powder. 20 Mo 20 Cr 20 Ti 20 Al 20 A SiC superhard protective layer is obtained on the surface of the high entropy alloy.

[0030] After testing, it was found that the present embodiment adopts a binary composite infiltration process to form a uniform and dense SiC superhard protective layer on the surface of the high entropy alloy, and the Si and C elements are evenly distributed on the surface of the high entropy alloy. The hardness of the SiC superhard protective layer is significantly higher than that of the high entropy alloy matrix.

[0031] In this embodiment, the preparation method of the high entropy alloy can also be 3D printing or powder metallurgy.

[0032] Example 3 This embodiment includes the following steps: Step 1: The composition of Ta in terms of atomic ratio 25 Mo 25 Cr 25 Al 25 The surface of the cast high entropy alloy was mechanically ground and polished, then loaded into a mold filled with Si powder and compacted using a hydraulic press at a pressure of 200 MPa. It was then placed in a vacuum furnace chamber for heating and diffusion, and the pressure in the vacuum furnace chamber was 10 -4 Pa, heating to 1100℃ at a rate of 5℃ / min and keeping at that temperature for 6h, cooling with the furnace to obtain high entropy alloy after Si infiltration; The average particle size of the Si powder is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 min after working for 40 min. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 2: The Si-infiltrated high entropy alloy obtained in step 1 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in the mold filled with C powder and compact it with a hydraulic press at a pressure of 100 MPa. Then place it in a vacuum furnace chamber for high-temperature thermal activation and heating diffusion. The pressure in the vacuum furnace chamber is 10 -4 Pa, firstly heated to 1700℃ at a rate of 5℃ / min and kept at that temperature for 20min, then slowly cooled to 1300℃ at a rate not higher than 2℃ / min and kept at that temperature for 6h, and then cooled with the furnace to obtain a high entropy alloy after Si-C binary composite infiltration; The average particle size of the C powder is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 hours, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 minutes after every 40 minutes of operation. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 4: Place the Si-C binary composite infiltrated high entropy alloy obtained in step 3 into an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove the surface powder. 25 Mo 25 Cr 25 Al 25 A SiC superhard protective layer is obtained on the surface of the high entropy alloy.

[0033] After testing, it was found that the present embodiment adopts a binary composite infiltration process to form a uniform and dense SiC superhard protective layer on the surface of the high entropy alloy, and the Si and C elements are evenly distributed on the surface of the high entropy alloy. The hardness of the SiC superhard protective layer is significantly higher than that of the high entropy alloy matrix.

[0034] In this embodiment, the preparation method of the high entropy alloy can also be 3D printing or powder metallurgy.

[0035] Example 4 This embodiment includes the following steps: Step 1: The composition of Ta in terms of atomic ratio 20 Mo 20 Nb 20 Ti 20 Al 20 The surface of the cast high entropy alloy was mechanically ground and polished, then loaded into a mold filled with Si powder and compacted using a hydraulic press at a pressure of 300 MPa. It was then placed in a vacuum furnace chamber for heating and diffusion, and the pressure in the vacuum furnace chamber was 10-4 Pa, heating to 1100℃ at a rate of 5℃ / min and keeping at that temperature for 7h, cooling with the furnace to obtain high entropy alloy after Si infiltration; The average particle size of the Si powder is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 min after working for 40 min. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 2: The Si-infiltrated high entropy alloy obtained in step 1 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in the mold filled with C powder and compact it with a hydraulic press at a pressure of 100 MPa. Then place it in a vacuum furnace chamber for high-temperature thermal activation and heating diffusion. The pressure in the vacuum furnace chamber is 10 -4 Pa, firstly heated to 1700℃ at a rate of 5℃ / min and kept at that temperature for 25min, then slowly cooled to 1300℃ at a rate not higher than 2℃ / min and kept at that temperature for 7h, and then cooled with the furnace to obtain a high entropy alloy after Si-C binary composite infiltration; The average particle size of the C powder is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 hours, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 minutes after every 40 minutes of operation. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 4: Place the Si-C binary composite infiltrated high entropy alloy obtained in step 3 into an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove the surface powder. 20 Mo 20 Nb 20 Ti 20 Al 20 A SiC superhard protective layer is obtained on the surface of the high entropy alloy.

[0036] After testing, it was found that the present embodiment adopts a binary composite infiltration process to form a uniform and dense SiC superhard protective layer on the surface of the high entropy alloy, and the Si and C elements are evenly distributed on the surface of the high entropy alloy. The hardness of the SiC superhard protective layer is significantly higher than that of the high entropy alloy matrix.

[0037] In this embodiment, the preparation method of the high entropy alloy can also be 3D printing or powder metallurgy.

[0038] Example 5 This embodiment includes the following steps: Step 1: The composition of Nb in terms of atomic ratio 25 Mo 25 Ta 25 W 25 The surface of the cast high entropy alloy was mechanically ground and polished, then loaded into a mold filled with Si powder and compacted using a hydraulic press at a pressure of 250 MPa. It was then placed in a vacuum furnace chamber for heating and diffusion, and the pressure in the vacuum furnace chamber was 10 -4 Pa, heating to 1100℃ at a rate of 5℃ / min and keeping at that temperature for 10h, cooling with the furnace to obtain high entropy alloy after Si infiltration; The average particle size of the Si powder is 50 μm, and the Si powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 min after working for 40 min. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 2: The Si-infiltrated high entropy alloy obtained in step 1 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in the mold filled with C powder and compact it with a hydraulic press at a pressure of 100 MPa. Then place it in a vacuum furnace chamber for high-temperature thermal activation and heating diffusion. The pressure in the vacuum furnace chamber is 10 -4 Pa, firstly heated to 1800℃ at a rate of 5℃ / min and kept at that temperature for 20min, then slowly cooled to 1300℃ at a rate not higher than 2℃ / min and kept at that temperature for 8h, and then cooled with the furnace to obtain a high entropy alloy after Si-C binary composite infiltration; The average particle size of the C powder is 50 μm, and the C powder is pre-flaked by a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 hours, the ball milling speed is 400 r / min, and the ball mill is stopped for 5 minutes after every 40 minutes of operation. The process control agent in the ball milling is anhydrous ethanol, and the amount of the process control agent added is 40 mL; Step 4: The Si-C binary composite infiltrated high entropy alloy obtained in step 3 is placed in an ultrasonic cleaning device containing a mixed solution of 90% by volume ethanol and 10% by volume acetone to clean and remove the surface powder. 25 Mo 25 Ta25 W 25 A SiC superhard protective layer is obtained on the surface of the high entropy alloy.

[0039] After testing, it was found that the present embodiment adopts a binary composite infiltration process to form a uniform and dense SiC superhard protective layer on the surface of the high entropy alloy, and the Si and C elements are evenly distributed on the surface of the high entropy alloy. The hardness of the SiC superhard protective layer is significantly higher than that of the high entropy alloy matrix.

[0040] In this embodiment, the preparation method of the high entropy alloy can also be 3D printing or powder metallurgy.

[0041] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high entropy alloy SiC superhard protective layer, characterized in that: The method comprises the following steps: Step 1: Mechanically grind and polish the surface of the high entropy alloy, then put it into a mold filled with Si powder, compact it with a hydraulic press, and then put it into a vacuum furnace for heating and diffusion to obtain a high entropy alloy after Si infiltration; Step 2: Place the Si-infiltrated high entropy alloy obtained in step 1 into an ultrasonic cleaning device for cleaning to remove surface powder; Step 3: Place the cleaned Si-infiltrated high entropy alloy in step 2 into a mold filled with C powder, compact it using a hydraulic press, and then place it in a vacuum furnace for high-temperature thermal activation and heating diffusion to obtain a Si-C binary composite infiltrated high entropy alloy; Step 4: Place the high entropy alloy obtained in step 3 after Si-C binary composite infiltration into an ultrasonic cleaning device for cleaning to remove surface powder, thereby obtaining a SiC superhard protective layer on the surface of the high entropy alloy.

2. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The preparation methods of the high entropy alloy described in step 1 are casting, 3D printing and powder metallurgy.

3. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The average particle size of the Si powder in step 1 is 50 μm, and the Si powder is pre-flaked using a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to Si powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill is rested for 5 min every 40 min of operation. The process control agent in the ball milling is anhydrous ethanol.

4. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The heating diffusion system in step 1 is: heating to 1100°C at a rate of 5°C / min, keeping the temperature for 5h~10h, and cooling with the furnace.

5. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The compaction pressures used in step 1 and step 3 are both 100 MPa to 400 MPa.

6. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The pressure in the vacuum furnace chamber in step 1 and step 3 is 10 -4 Pa level.

7. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The average particle size of the C powder in step three is 50 μm, and the C powder is pre-flaked using a ball mill. During the flaking process, the mass ratio of stainless steel grinding balls to C powder is 10:1, the diameter of the stainless steel grinding balls is 8 mm, the ball milling time is 6 h, the ball milling speed is 400 r / min, and the ball mill stops for 5 min after every 40 min of operation. The process control agent in the ball milling is anhydrous ethanol.

8. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The high temperature thermal activation heating diffusion system described in step three is: first increase the temperature to 1600℃~1800℃ at a rate of 5℃ / min and keep it for 15min~25min, then slowly cool it to 1300℃ at a rate not higher than 2℃ / min and keep it for 4h~8h, and cool it with the furnace.

9. The method for preparing a high entropy alloy SiC superhard protective layer according to claim 1, characterized in that: The ultrasonic cleaning medium used in the cleaning in step 2 and step 4 is a mixed solution of 90% by volume ethanol and 10% by volume acetone.

10. A high entropy alloy SiC superhard protective layer, characterized in that: The method is prepared by any one of claims 1 to 9.

Images