Preparation method and application of double-layered silicon carbide particles

Abstract

The present invention discloses a preparation method and application of double-coated silicon carbide particles, comprising: performing surface roughening treatment on silicon carbide particles, drying to obtain roughened silicon carbide particles, adding a dispersant, ball-milling to obtain a uniformly mixed powder, and obtaining SiC powder particles coated with Ti5Si3 / Ti through a vacuum diffusion plating process; dissolving basic copper carbonate into an ammonia solution, stirring and fully dissolving, adding polyacrylamide, mixing evenly, adding SiC powder particles coated with Ti5Si3 / Ti, sealing and keeping still, and obtaining fully coated silicon carbide particles; heating and reducing the preliminarily coated silicon carbide powder in a hydrogen reducing atmosphere, cooling and sieving to obtain double-coated particles. The present invention proposes for the first time a double-coated Cu‑Ti5Si3 / Ti‑SiC powder particle, which significantly improves defects such as holes and gaps formed in the composite material during the hot pressing and sintering process when preparing silicon carbide particle-reinforced aluminum-based composite material by powder metallurgy hot pressing and sintering, and has good interface bonding.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a preparation method of double-layered silicon carbide particles and applications thereof. Background Art

[0002] Silicon carbide particles, as a ceramic reinforcement phase, are often used as reinforcement phase particles in the preparation of metal-based composites, effectively solving the problem of high fiber cost of fiber-reinforced metal-based composites. In addition, the material is isotropic, the preparation process is simple, and the cost is low. It is widely used in aerospace, defense, automobile, high-speed rail and other industries.

[0003] Silicon carbide particles, the reinforcing phase, are ceramic particles with high hardness, a high melting point, and strong corrosion resistance, significantly different from the metal matrix alloy. Therefore, when preparing silicon carbide-reinforced aluminum-based composites, the non-metallic SiC ceramic phase has difficulty wetting the aluminum matrix. This process is plagued by common problems such as interfacial reactions, low density, and poor dispersion uniformity, which severely impact the performance and application of these composites. Improving the wettability of the SiC reinforcing phase particles with the matrix can effectively enhance the interfacial strength between the SiC particles and the aluminum alloy matrix, thereby improving the mechanical properties of the silicon carbide-reinforced metal matrix composite.

[0004] Among existing technologies, surface modification of SiC particles is one of the most effective methods for improving interfacial wettability. Surface modification can also effectively prevent excessive interfacial reactions, further enhancing the performance of composite materials. Surface coating modification involves coating the SiC particles with a layer of metal through physical and chemical methods, significantly improving their wettability with the substrate. Studies have shown that chemically plating metal coatings such as Cu on the SiC surface can significantly improve the mechanical properties and density of aluminum-based composites. During the powder metallurgy hot pressing sintering process with the aluminum matrix, the plated copper coating can form a liquid phase through mutual diffusion at the Al-Cu boundary at a lower sintering temperature, quickly filling most of the powder particle gaps and pores. The generated liquid phase diffuses relatively stably along the aluminum powder boundary during the entire sintering process, and the plated copper coating gradually dissolves in the gaps in the matrix, thereby improving the density of the material. However, during the hot pressing sintering process, the copper coating and the aluminum alloy matrix undergo mutual diffusion. Although the density of the matrix is improved, the copper coating diffuses into the aluminum matrix and the plated copper coating disappears. Therefore, some gaps still exist at the interface. The surface physically deposited copper coating does not effectively solve the problem of poor interface bonding strength. Therefore, a single copper coating is difficult to meet the requirements of composite materials with high density and high interface bonding strength. At the same time, the traditional chemical copper plating process requires complex activation and sensitization treatments. The precious metals such as palladium chloride or silver nitrate used in it greatly increase the production cost, and the treatment process is relatively complicated. At the same time, the plating solution produced by the electroplating industry is complex to handle and causes certain pollution to the environment.

[0005] At the same time, although the surface coating of Ti5Si3 / Ti can effectively improve the wetting of ceramic silicon carbide particles and the aluminum alloy matrix and achieve excellent interface bonding, it cannot avoid defects such as matrix pores during the powder metallurgy sintering process and cannot obtain a highly dense composite material. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing double-layered silicon carbide particles.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing double-layered silicon carbide particles, comprising:

[0010] performing surface roughening treatment on silicon carbide particles and drying to obtain roughened silicon carbide particles;

[0011] The roughened silicon carbide particles were mixed with titanium metal powder, a dispersant was added, and the mixture was ball-milled to obtain a uniformly mixed powder. The SiC powder particles coated with Ti5Si3 / Ti were obtained by a vacuum diffusion coating process.

[0012] Dissolve basic copper carbonate in an ammonia solution, stir and fully dissolve, add polyacrylamide, mix evenly, add SiC powder particles plated with Ti5Si3 / Ti, seal and let it stand to obtain fully coated silicon carbide particles, dry and preliminarily crush to obtain preliminarily coated silicon carbide powder;

[0013] The primary coated silicon carbide powder is heated and reduced in a hydrogen reducing atmosphere, cooled and sieved to obtain double-layered Cu-Ti5Si3 / Ti-SiC powder particles.

[0014] As a preferred embodiment of the preparation method of the present invention, the surface roughening treatment of the silicon carbide particles comprises:

[0015] Add silicon carbide particles to 1-2.5 mol / L NaOH solution at room temperature, boil, stir for 30-60 minutes, precipitate and cool, filter the solution, and wash with distilled water until neutral;

[0016] Then soak it in 0.5-1 mol / L dilute nitric acid, boil and stir for 30-60 minutes, cool the precipitate, filter it, and wash it with distilled water until it is neutral.

[0017] As a preferred embodiment of the preparation method of the present invention, the roughened silicon carbide particles are mixed with metallic titanium powder, wherein the mass ratio of the silicon carbide particles to the metallic titanium powder is 2:1.

[0018] As a preferred embodiment of the preparation method of the present invention, the ball-to-material ratio in the ball milling treatment is 10:1, the ball milling speed is 70 r / min, and the ball milling time is 6 to 10 h.

[0019] As a preferred embodiment of the preparation method of the present invention, the vacuum diffusion plating process includes:

[0020] The mixed powder was placed in a corundum crucible at a temperature of 800-1000°C and a vacuum degree of 1.0×10 -3 Pa conditions, keep warm for 2 to 5 hours, cool, and then sieve to obtain SiC powder particles coated with Ti5Si3 / Ti.

[0021] As a preferred embodiment of the preparation method of the present invention, basic copper carbonate is dissolved in an ammonia solution, stirred and fully dissolved, polyacrylamide is added, mixed evenly, and then SiC powder particles plated with Ti5Si3 / Ti are added, wherein the mass ratio of basic copper carbonate, polyacrylamide and SiC powder particles plated with Ti5Si3 / Ti is 200-300:500-600:400-600.

[0022] As a preferred embodiment of the preparation method of the present invention, the mass ratio of basic copper carbonate, polyacrylamide and Ti5Si3 / Ti-plated SiC powder particles is 300:600:500.

[0023] As a preferred embodiment of the preparation method of the present invention, the preliminary coated silicon carbide powder is heated and reduced in a hydrogen reducing atmosphere, wherein the reduction treatment temperature is 200-400° C. and the reduction time is 2-4 hours.

[0024] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing double-layered silicon carbide particles to produce double-layered silicon carbide particles, wherein the particle size of the double-layered silicon carbide particles is 17 to 20 μm.

[0025] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing aluminum-based composite materials using double-layered silicon carbide particles.

[0026] Beneficial effects of the present invention:

[0027] (1) In view of the problem that the current single copper coating on the SiC surface is difficult to meet the requirements of high-density and high-interface bonding strength composite materials, and at the same time, when the SiC surface is coated with Ti5Si3 / Ti coating, defects such as matrix holes cannot be avoided during the powder metallurgy sintering process, and a high-density composite material cannot be obtained, the present invention proposes for the first time a double-layered Cu-Ti5Si3 / Ti-SiC powder particle. When the double-layered Cu-Ti5Si3 / Ti-SiC particles are used to prepare silicon carbide particle-reinforced aluminum-based composite materials by powder metallurgy hot pressing and sintering, the defects such as holes and gaps formed in the composite materials during the hot pressing and sintering process are significantly improved, the interface bonding is good, and the mechanical properties of the composite materials are greatly improved.

[0028] (2) On the one hand, the present invention adopts a vacuum diffusion plating method to plate a titanium coating on the SiC surface. Only pure titanium powder and SiC particles are needed as raw materials. Direct plating is carried out under vacuum conditions. The separation after the reaction is simple, which greatly simplifies the plating method and process flow, and obtains the required SiC particles with complete surface coating. The vacuum thermal reduction copper plating process is used on the silicon carbide surface to improve the high activation and sensitization costs of palladium chloride and silver nitrate in the traditional chemical copper plating process, and at the same time reduces the environmental pollution and other hazards caused by a large amount of plating solution in the chemical copper plating process, effectively simplifies the plating process, reduces costs, realizes full utilization of raw materials, and realizes an environmentally friendly process for plating a copper coating on the surface of silicon carbide particles.

[0029] (3) When the double-layer Cu-Ti5Si3 / Ti-SiC particles prepared by the present invention are used to prepare silicon carbide particle reinforced aluminum matrix composite materials by powder metallurgy hot pressing and sintering, the defects of the composite materials such as holes and gaps formed during the hot pressing and sintering process are significantly improved, so that the SiC P The density of the SiC / Al-based composite material is improved; the Ti5Si3 / Ti coating inside the silicon carbide particles can effectively achieve wetting with the aluminum matrix, making the reinforcement phase particles evenly dispersed and the interface bonding good, which greatly improves the mechanical properties of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0031] Figure 1 Figure 2 shows the macroscopic morphology of silicon carbide powder before and after surface modification of the present invention, where (a) is the macroscopic morphology of original silicon carbide, (b) is the macroscopic morphology of silicon carbide particles after vacuum diffusion coating with Ti5Si3 / Ti coating, and (c) is the macroscopic morphology of Cu-Ti5Si3 / Ti-SiC particle powder prepared by thermal reduction method.

[0032] Figure 2 These are scanning electron microscope micromorphologies of silicon carbide powder coated with Ti5Si3 / Ti coating in Example 1 of the present invention, wherein (a) and (b) are surface micromorphologies of original silicon carbide powder, and (c) and (d) are scanning electron microscope micromorphologies of silicon carbide particles after vacuum diffusion coating with Ti5Si3 / Ti coating.

[0033] Figure 3 XRD pattern of silicon carbide powder for the inner layer Ti5Si3 / Ti coating prepared by vacuum diffusion plating.

[0034] Figure 4 This is the scanning electron microscope morphology of the Cu-Ti5Si3 / Ti-SiC double-layered silicon carbide powder prepared in Example 1 of the present invention.

[0035] Figure 5 The double-layered silicon carbide powder prepared by the powder metallurgy method is SiC P Metallographic photographs of Cu-Ti5Si3 / Ti-SiC / Al-based composites, including (a) original silicon carbide and (b) double-layered Cu-Ti5Si3 / Ti-SiC.

[0036] Figure 6 The double-layered silicon carbide prepared in Example 1 of the present invention has a volume fraction of 17% SiC. P Scanning images of / Al-based composites, including (a) original silicon carbide; (b) Cu-SiC plated; (c) double-layer Cu-Ti5Si3 / Ti-SiC.

[0037] Figure 7 The SiC prepared by the double-layer silicon carbide prepared in Example 1 of the present invention P TEM images of the interface of Cu-Ti5Si3 / Ti-SiC / Al-based composites, including (a) original silicon carbide and (b) Cu-Ti5Si3 / Ti-SiC. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0041] The silicon carbide and titanium powder used in the embodiments of the present invention are both ordinary silicon carbide particles and titanium powder sold on the market. The particle size of the silicon carbide particles is 17-20 μm, and the average particle size of the titanium powder is 100 μm.

[0042] Example 1

[0043] A method for preparing double-layered silicon carbide particles comprises the following steps:

[0044] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0045] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0046] (2) Mix the dried silicon carbide particles with 250 g of titanium powder, add a small amount (100 mL) of alcohol as a dispersant to the mixed powder, and ball mill the mixture for 10 h;

[0047] (3) The mixed powder was placed in a corundum crucible at a temperature of 800°C and a vacuum degree of 1.0×10 -3 Pa conditions, the mixture was kept warm for 3 h, cooled, and sieved to obtain SiC powder coated with Ti5Si3 / Ti, and the color of the powder changed from green to black.

[0048] (4) Weigh 300 g of basic copper carbonate and dissolve it in 300 mL of ammonia water at room temperature. Stir continuously to dissolve it. At the same time, add 600 g of polyacrylamide and mix well. Then, add the SiC powder coated with Ti5Si3 / Ti obtained above under strong stirring to fully soak the silicon carbide particles in the solution and ensure that their surface is completely coated with basic copper carbonate.

[0049] After the fully soaked silicon carbide powder particles are sealed with plastic wrap and stored, they are left to stand for 4 hours to allow the basic copper carbonate to fully dissolve in the ammonia solution to ensure the integrity of the coating.

[0050] (5) The silicon carbide particles fully coated with basic copper carbonate were dried at 90° C. for 3 h, and then crushed to obtain pretreated silicon carbide powder particles.

[0051] (6) The preliminarily coated silicon carbide powder was heated and reduced at 200°C in a hydrogen reduction furnace for 4 hours. After reduction, it was cooled and sieved in a hydrogen atmosphere to obtain double-layer Cu-Ti5Si3 / Ti-SiC powder particles with complete surface coating performance. The powder color changed from black to red.

[0052] The macroscopic morphology of silicon carbide powder before and after surface modification of the present invention is shown in Figure 1, (a) is the macroscopic morphology of the original silicon carbide, (b) is the macroscopic morphology of the silicon carbide particles after vacuum diffusion coating with Ti5Si3 / Ti coating, and (c) is the macroscopic morphology of the Cu-Ti5Si3 / Ti-SiC particle powder prepared by thermal reduction method.

[0053] The scanning electron microscope micromorphology of the silicon carbide powder coated with Ti5Si3 / Ti in this embodiment is shown in Figure 2 Among them, (a) and (b) are the surface micromorphologies of the original silicon carbide powder, and (c) and (d) are the scanning electron microscope micromorphologies of the silicon carbide particles after vacuum diffusion coating with Ti5Si3 / Ti coating.

[0054] The XRD pattern of silicon carbide powder with inner Ti5Si3 / Ti coating prepared by vacuum diffusion plating is shown in Figure 3 , SEM micromorphology of prepared Cu-Ti5Si3 / Ti-SiC double-layered silicon carbide powder, see Figure 4 .

[0055] Example 2

[0056] A method for preparing double-layered silicon carbide particles comprises the following steps:

[0057] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0058] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0059] (2) Mix the dried silicon carbide particles with 250 g of titanium powder, add a small amount of alcohol as a dispersant to the mixed powder, and ball mill the mixture for 10 h;

[0060] (3) The mixed powder was placed in a corundum crucible at a temperature of 950°C and a vacuum degree of 1.0×10 -3 Pa conditions, the mixture was kept warm for 2.5 h, cooled, and sieved to obtain SiC powder coated with Ti5Si3 / Ti, the color of the powder changing from green to black.

[0061] (4) Weigh 200 g of basic copper carbonate and dissolve it in 300 mL of ammonia water at room temperature. Stir continuously to dissolve. At the same time, add 600 g of polyacrylamide and mix well. Then, add the SiC powder coated with Ti5Si3 / Ti obtained above under strong stirring to fully soak the silicon carbide particles in the solution and ensure that their surface is completely coated with basic copper carbonate.

[0062] The fully soaked silicon carbide powder particles were sealed with plastic wrap and left to stand for 5 hours to allow the basic copper carbonate to fully dissolve in the ammonia solution to ensure the integrity of the coating.

[0063] (5) The silicon carbide particles fully coated with basic copper carbonate were dried at 90° C. for 3 h, and then crushed to obtain pretreated silicon carbide powder particles.

[0064] (6) The preliminarily coated silicon carbide powder was heated and reduced at 300°C in a hydrogen reduction furnace for 3 hours. After reduction, it was cooled and sieved in a hydrogen atmosphere to obtain double-layer Cu-Ti5Si3 / Ti-SiC powder particles with complete surface coating performance. The powder color changed from black to red.

[0065] Example 3

[0066] A method for preparing double-layered silicon carbide particles comprises the following steps:

[0067] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0068] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0069] (2) Mix the dried silicon carbide particles with 250 g of titanium powder, add a small amount of alcohol as a dispersant to the mixed powder, and ball mill the mixture for 10 h;

[0070] (3) The mixed powder was placed in a corundum crucible at a temperature of 1000°C and a vacuum degree of 1.0×10 -3 Pa conditions, the mixture was kept warm for 2 h, cooled, and sieved to obtain SiC powder coated with Ti5Si3 / Ti, and the color of the powder changed from green to black.

[0071] (4) Weigh 350 g of basic copper carbonate and dissolve it in 300 mL of ammonia water at room temperature. Stir continuously to dissolve it. At the same time, add 600 g of polyacrylamide and mix well. Then, add the SiC powder coated with Ti5Si3 / Ti obtained above under strong stirring to fully soak the silicon carbide particles in the solution and ensure that their surface is completely covered by the basic copper carbonate.

[0072] The fully soaked silicon carbide powder particles were sealed with plastic wrap and left to stand for 6 hours to allow the basic copper carbonate to fully dissolve in the ammonia solution to ensure the integrity of the coating.

[0073] (5) The silicon carbide particles fully coated with basic copper carbonate were dried at 90° C. for 3 h, and then crushed to obtain pretreated silicon carbide powder particles.

[0074] (6) The preliminarily coated silicon carbide powder was heated and reduced at 350°C in a hydrogen reduction furnace for 2 hours. After reduction, it was cooled and sieved in a hydrogen atmosphere to obtain double-layer Cu-Ti5Si3 / Ti-SiC powder particles with complete surface coating performance. The powder color changed from black to red.

[0075] Example 4

[0076] A method for preparing double-layered silicon carbide particles comprises the following steps:

[0077] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0078] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0079] (2) Mix the dried silicon carbide particles with 250 g of titanium powder, add a small amount of alcohol as a dispersant to the mixed powder, and ball mill the mixture for 10 h;

[0080] (3) The mixed powder was placed in a corundum crucible at a temperature of 850°C and a vacuum degree of 1.0×10 -3 Pa conditions, the mixture was kept warm for 3 h, cooled, and sieved to obtain SiC powder coated with Ti5Si3 / Ti, and the color of the powder changed from green to black.

[0081] (4) Weigh 250 g of basic copper carbonate and dissolve it in 300 mL of ammonia water at room temperature. Stir continuously to dissolve it. At the same time, add 600 g of polyacrylamide and mix well. Then, add the SiC powder coated with Ti5Si3 / Ti obtained above under strong stirring to fully soak the silicon carbide particles in the solution and ensure that their surface is completely covered by the basic copper carbonate.

[0082] The fully soaked silicon carbide powder particles were sealed with plastic wrap and left to stand for 4 hours to allow the basic copper carbonate to fully dissolve in the ammonia solution to ensure the integrity of the coating.

[0083] (5) The silicon carbide particles fully coated with basic copper carbonate were dried at 90° C. for 3 h, and then crushed to obtain pretreated silicon carbide powder particles.

[0084] (6) The preliminarily coated silicon carbide powder was heated and reduced at 320°C in a hydrogen reduction furnace for 2.5 hours. After reduction, it was cooled and sieved in a hydrogen atmosphere to obtain double-layer Cu-Ti5Si3 / Ti-SiC powder particles with complete surface coating performance. The powder color changed from black to red.

[0085] Comparative Example 1 (Preparation Process of Cu-SiC Powder Particles)

[0086] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0087] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0088] (2) Weigh 300 g of basic copper carbonate and dissolve it in 300 mL of ammonia water at room temperature, stirring continuously to dissolve, and add 600 g of polyacrylamide at the same time. After mixing evenly, add the above-obtained SiC powder under the action of strong stirring to fully soak the silicon carbide particles in the solution and ensure that their surface is completely coated with basic copper carbonate;

[0089] The fully soaked silicon carbide powder particles were sealed with plastic wrap and left to stand for 4 hours to allow the basic copper carbonate to fully dissolve in the ammonia solution to ensure the integrity of the coating.

[0090] (3) The silicon carbide particles fully coated with basic copper carbonate were dried at 90° C. for 3 h, and then crushed to obtain pretreated silicon carbide powder particles.

[0091] (4) The preliminarily coated silicon carbide powder is placed in a hydrogen reduction furnace at 200°C for heating and reduction treatment for 4 hours. After reduction, it is cooled and sieved in a hydrogen atmosphere to obtain Cu-SiC powder particles with complete surface coating performance.

[0092] Comparative Example 2

[0093] (1) Weigh 500 g of silicon carbide particles at room temperature, slowly add them to a 2.5 mol / L NaOH solution under vigorous stirring, boil and stir for 30 min, cool the precipitate, filter the solution, and rinse with distilled water until neutral;

[0094] Then, the SiC particles were soaked in 0.5 mol / L dilute nitric acid and boiled and stirred for 30 minutes. After the precipitate was cooled, it was filtered and washed with distilled water until it was neutral. The SiC particles were then placed in a vacuum drying oven at 80°C for drying.

[0095] (2) Mix the dried silicon carbide particles with 250 g of titanium powder, add a small amount (100 mL) of alcohol as a dispersant to the mixed powder, and ball mill the mixture for 10 h;

[0096] (3) The mixed powder was placed in a corundum crucible at a temperature of 800°C and a vacuum degree of 1.0×10 -3 Pa conditions, the mixture was kept warm for 3 h, cooled, and sieved to obtain SiC powder coated with Ti5Si3 / Ti. The color of the powder changed from green to black, and Ti5Si3 / Ti-SiC powder was obtained.

[0097] The powder particles obtained in the embodiment and the comparative example were respectively used to prepare composite materials, and the specific process was as follows:

[0098] (1) A 17% volume fraction of double-layer Cu-Ti5Si3 / Ti-SiC powder particles (including the powder particles of the comparative example) and Al-12Si aluminum alloy powder were fully mixed and placed in a cemented carbide mold for cold pressing. Then, hot pressing and sintering were performed in a protective atmosphere at a sintering temperature of 550°C and a sintering pressure of 200 MPa to prepare a SiC reinforced aluminum matrix composite material;

[0099] (2) The prepared samples were kept at 505°C for 1 h and then quenched in cold water;

[0100] (3) The composite material was then aged at 190 °C for 12 h and then air-cooled to obtain the final composite material.

[0101] The obtained double-layered silicon carbide particles (Example 1) are uniformly dispersed in the matrix (as shown below) Figure 5 As shown), the interface is tightly bonded (as shown Figure 6 As shown in the SEM picture, Figure 7 TEM interface image), the density reaches 99.5% (the density of the original silicon carbide is 93.3%; the single-layer copper coating is 97%; the single-layer Ti5Si3 / Ti-SiC coating is 96.1%), and the tensile strength is 413MPa (the original silicon carbide is 207MPa; the single-layer copper coating is 298MPa; the single-layer Ti5Si3 / Ti-SiC coating is 286MPa).

[0102] In the present invention, SiC is prepared according to the Archimedean method. PDensity of the aluminum / Al-based composites was measured; tensile strength was measured according to the national standard for tensile specimens for metallic materials (GBT 228.1-2010). Specimens were 3 cm thick and polished smooth. Room-temperature tensile tests were conducted on an Instron MTS 810 mechanical testing machine at a loading rate of 0.2 mm / min. The deformed specimens had a rectangular cross-section, a 5 mm diameter at the parallel ends, and a gauge length of 15 mm. Five measurements were performed for each test, and the average value was calculated. The results are shown in Table 1.

[0103] Table 1

[0104] Density (%) Tensile strength (MPa) Example 1 99.5 413 Example 2 98.8 382 Example 3 99.7 390 Example 4 99.0 402 Comparative Example 1 97.0 298 Comparative Example 2 96.1 286 Raw silicon carbide 93.3 207

[0105] The present invention develops a double-layered Cu-Ti5Si3 / Ti-SiC particle that can be directly hot-pressed to form a silicon carbide-reinforced aluminum-based composite material with high density, high interfacial bonding strength, and uniform distribution of the reinforcing phase through a powder metallurgy process. A stable Ti5Si3 / Ti coating is applied to the surface of the silicon carbide particles using vacuum diffusion, effectively achieving interfacial wetting between the reinforcing phase particles and the aluminum matrix. Simultaneously, the copper coating, deposited using a low-cost solid-state thermal reduction method, allows the Al-Cu boundary to form a liquid phase through interdiffusion at a relatively low sintering temperature during the powder metallurgy hot-pressing sintering process. This liquid phase promptly fills the pores and gaps formed during the hot-pressing sintering of the composite material, significantly improving its density. The formed second phase also effectively strengthens the composite material, significantly enhancing its mechanical properties.

[0106] At present, a large number of defects such as holes and gaps are commonly found in the sample matrix after powder hot pressing and sintering. This is because even pure aluminum powder is difficult to achieve densification during the powder metallurgy hot pressing and sintering process. When SiC particles are added to the matrix, the presence of SiC particles further hinders the formation of powder sintering necks during the powder metallurgy process, resulting in the presence of inevitable defects such as holes and gaps in the matrix due to the lack of liquid phase replenishment. The densification of the mixed powder of aluminum and SiC is even more difficult to achieve. At the same time, chemically plating metal coatings such as Cu on the SiC surface can significantly improve the mechanical properties and density of aluminum-based composite materials. When the plated copper coating is subjected to powder metallurgy hot pressing and sintering with the aluminum matrix, the Al-Cu boundary can form a liquid phase through mutual diffusion at a lower sintering temperature, quickly filling most of the powder particle gaps and holes. The generated liquid phase diffuses relatively stably along the aluminum powder boundary during the entire sintering process, and the plated copper coating gradually dissolves in the gaps in the matrix, thereby improving the density of the material.

[0107] However, during the hot pressing sintering process, the copper coating and the aluminum alloy substrate diffuse into each other. Although the density of the substrate is improved, the copper coating diffuses into the aluminum substrate and the plated copper coating disappears. Therefore, some gaps still exist at the interface. The problem of poor interface bonding strength caused by the physically deposited copper coating on the surface has not been effectively solved.

[0108] In view of this, the present invention proposes for the first time a double-layered Cu-Ti5Si3 / Ti-SiC powder particle. When the double-layered Cu-Ti5Si3 / Ti-SiC particles are used in powder metallurgy hot pressing and sintering to prepare silicon carbide particle-reinforced aluminum-based composite materials, the defects such as holes and gaps formed in the composite materials during the hot pressing and sintering process are significantly improved, the interface bonding is good, and the mechanical properties of the composite materials are greatly improved.

[0109] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A method for preparing double-layered silicon carbide particles, characterized in that: include, performing surface roughening treatment on silicon carbide particles and drying to obtain roughened silicon carbide particles; The roughened silicon carbide particles were mixed with titanium powder, a dispersant was added, and the mixture was ball-milled to obtain a uniformly mixed powder. The SiC powder particles coated with Ti5Si3 / Ti were prepared by a vacuum diffusion coating process, wherein the mass ratio of silicon carbide particles to titanium powder was 2:

1. Dissolve basic copper carbonate in an ammonia solution, stir and fully dissolve, add polyacrylamide, mix well, add SiC powder particles coated with Ti5Si3 / Ti, seal and allow to stand to obtain fully coated silicon carbide particles, dry and preliminarily crush to obtain preliminarily coated silicon carbide powder, wherein the mass ratio of basic copper carbonate, polyacrylamide and SiC powder particles coated with Ti5Si3 / Ti is 200-300:500-600:400-600; The preliminarily coated silicon carbide powder is heated and reduced in a hydrogen reducing atmosphere, cooled and sieved to obtain double-layered Cu-Ti5Si3 / Ti-SiC powder particles, wherein the reduction treatment temperature is 200-400°C and the reduction time is 2-4h.

2. The preparation method according to claim 1, wherein: The surface roughening treatment of the silicon carbide particles comprises: Add silicon carbide particles to 1-2.5 mol / L NaOH solution at room temperature, boil, stir for 30-60 minutes, precipitate and cool, filter the solution, and wash with distilled water until neutral; Then soak it in 0.5-1 mol / L dilute nitric acid, boil and stir for 30-60 minutes, cool the precipitate, filter it, and wash it with distilled water until it is neutral.

3. The preparation method according to claim 1, wherein: The ball milling process comprises a ball-to-material ratio of 10:1, a ball milling speed of 70 r / min, and a ball milling time of 6 to 10 h.

4. The preparation method according to claim 1, wherein: The vacuum diffusion plating process includes: The mixed powder was placed in a corundum crucible at a temperature of 800-1000°C and a vacuum degree of 1.0×10 -3 Pa conditions, keep warm for 2 to 5 hours, cool, and then sieve to obtain SiC powder particles coated with Ti5Si3 / Ti.

5. The preparation method according to claim 1, wherein: The mass ratio of basic copper carbonate, polyacrylamide and Ti5Si3 / Ti-plated SiC powder particles is 300:600:

500.

6. Double-layered silicon carbide particles prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The particle size of the double-layered silicon carbide particles is 17 to 20 μm.

7. Use of the double-coated silicon carbide particles according to claim 6 in the preparation of aluminum-based composite materials.

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