A method for preparing a porous structure Al2O3 / Al ceramic metal coating on the surface of an aluminum matrix composite

Abstract

The application relates to a method for preparing a porous structure Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material, and belongs to the technical field of surface treatment of aluminum-based composite materials. The application aims to solve the problems of the prior art, such as complicated preparation of ceramic-metal composite materials, uncontrollability, high cost, difficulty in balancing the strength and toughness of the composite material, and insufficient regulation of the thermal conductivity. The method comprises the following steps: I, pretreating the surface of the aluminum-based composite material; II, preparing a porous micro-arc oxidation coating; and III, preparing an Al2O3 / Al ceramic coating with a complete structure. The multilayer structure composite material prepared by the application has more excellent mechanical properties (high resistance to friction and wear, high thermal shock resistance, adjustable thermal expansion coefficient, high fracture toughness) and high thermal conductivity (>=100 W / mK), and has important significance for the upgrading of future packaging substrate materials and the development of composite materials for harsh deep-sea, deep-space and deep-earth environments.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment of aluminum-based composite materials, and particularly relates to a method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material. Background Art

[0002] Compared to ceramics, metals generally exhibit superior ductility and fracture toughness, with aluminum alloys offering outstanding specific strength and specific stiffness. However, the absolute strength, stiffness, and fracture toughness of metals are relatively low, which, to a certain extent, limits their widespread application. With the increasing demand for productivity, single metals or single ceramics are unable to meet the increasingly stringent operating conditions of components. Ceramic-metal composites offer advantages such as diverse composition, high specific strength and modulus, high fatigue strength, and good fracture toughness. They can achieve complementary performance between different materials and present broad application prospects. However, current preparation methods for ceramic-metal composites are complex and uncontrollable, strength and toughness are difficult to balance, and thermal conductivity is insufficiently regulated. Furthermore, research has found that there are no reports on the preparation of multilayer composites consisting of metal-based composites and ceramic-metal composite coatings. Such multilayer composites exhibit superior mechanical properties (friction and wear resistance, high thermal shock resistance, adjustable thermal expansion coefficient, and high fracture toughness) as well as high thermal conductivity (≥100 W / mK), which is of great significance for the future upgrading of packaging substrate materials and the development of composite materials for harsh environments such as deep sea, deep space, and deep Earth. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems of the existing methods for preparing ceramic-metal composite materials, which are complex, uncontrollable, and costly, and the difficulty in balancing the strength and toughness of the composite materials and insufficient regulation of thermal conductivity, and to provide a method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material.

[0004] A method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material is specifically completed by the following steps:

[0005] 1. Pretreatment of the surface of aluminum-based composite materials:

[0006] Removing impurities and oil stains on the surface of the aluminum-based composite material to obtain a pretreated substrate;

[0007] 2. Preparation of porous micro-arc oxidation coating:

[0008] ① Dissolve sodium silicate, sodium aluminate, sodium phosphate and sodium hydroxide in deionized water to obtain an electrolyte;

[0009] ②, immersing the pretreated substrate in a stainless steel electrolytic cell filled with an electrolyte, connecting the pretreated substrate to the positive electrode of a power supply, connecting the stainless steel electrolytic cell to the negative electrode of the power supply, and micro-arc oxidation for a period of time under the conditions of an electrolyte temperature of 30°C to 50°C, an applied voltage of 400V to 600V, a frequency of 200Hz to 1000Hz, and a duty cycle of 4% to 30%, to obtain an aluminum-based composite material with an alumina ceramic coating having a porous structure;

[0010] 3. Preparation of Al2O3 / Al ceramic coating with complete structure:

[0011] The aluminum-based composite material with a porous alumina ceramic coating is placed in a high-temperature furnace, heated to 550°C to 650°C, and kept at 550°C to 650°C for a period of time to obtain an aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating on the surface.

[0012] Principle of the present invention:

[0013] The present invention utilizes micro-arc oxidation technology to prepare porous alumina on the surface of a pretreated aluminum-based composite material for the following purposes: 1. Maintaining a high porosity (including through-holes) provides a channel for subsequent high-temperature diffusion of aluminum in the composite material, thereby achieving diffusion of aluminum into the ceramic layer and on its surface; 2. Filling the pores well during the high-temperature diffusion of aluminum, thereby rapidly forming a ceramic-metal composite material, and finally forming a multilayer structure composite material consisting of an Al2O3 / Al ceramic-metal outer layer + an aluminum-based composite material substrate; the multilayer structure composite material has more excellent mechanical properties (friction and wear resistance, high thermal shock resistance, adjustable thermal expansion coefficient, and high fracture toughness) and high thermal conductivity (≥100W / mK).

[0014] Advantages of the present invention:

[0015] The present invention obtains a ceramic-metal composite coating with excellent mechanical strength and high thermal conductivity on the surface of an aluminum-based composite material at low cost and lower temperature conditions, which is of great significance to the future upgrading of packaging substrate materials and the development of composite materials for harsh deep-sea, deep-space, and deep-earth environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments;

[0017] Figure 2 This is a macroscopic image of the aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0018] Figure 3This is a SEM image of the aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0019] Figure 4 XRD pattern of the aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0020] Figure 5 Thermal conductivity data of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments;

[0021] Figure 6 The friction coefficient of the aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in different embodiments;

[0022] Figure 7 Thermal expansion coefficient of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments;

[0023] Figure 8 The room temperature compressive strength of the aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating prepared in different embodiments;

[0024] Figure 9 The fracture toughness of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments. DETAILED DESCRIPTION

[0025] Specific embodiment 1: This embodiment is a method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material, which is specifically completed by the following steps:

[0026] 1. Pretreatment of the surface of aluminum-based composite materials:

[0027] Removing impurities and oil stains on the surface of the aluminum-based composite material to obtain a pretreated substrate;

[0028] 2. Preparation of porous micro-arc oxidation coating:

[0029] ① Dissolve sodium silicate, sodium aluminate, sodium phosphate and sodium hydroxide in deionized water to obtain an electrolyte;

[0030] ②, immersing the pretreated substrate in a stainless steel electrolytic cell filled with an electrolyte, connecting the pretreated substrate to the positive electrode of a power supply, connecting the stainless steel electrolytic cell to the negative electrode of the power supply, and micro-arc oxidation for a period of time under the conditions of an electrolyte temperature of 30°C to 50°C, an applied voltage of 400V to 600V, a frequency of 200Hz to 1000Hz, and a duty cycle of 4% to 30%, to obtain an aluminum-based composite material with an alumina ceramic coating having a porous structure;

[0031] 3. Preparation of Al2O3 / Al ceramic coating with complete structure:

[0032] The aluminum-based composite material with a porous alumina ceramic coating is placed in a high-temperature furnace, heated to 550°C to 650°C, and kept at 550°C to 650°C for a period of time to obtain an aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating on the surface.

[0033] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the aluminum-based composite material described in step 1 is SiC-reinforced aluminum alloy, wherein the mass fraction of SiC is 10% to 50%. The other steps are the same as those in specific embodiment 1.

[0034] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the aluminum alloy described in step 1 is 2024 aluminum alloy, 6061 aluminum alloy, or 1050 aluminum alloy. The other steps are the same as specific embodiment 1 or 2.

[0035] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the concentration of sodium silicate in the electrolyte described in step 2 (1) is 1 g / L to 20 g / L, the concentration of sodium aluminate is 1 g / L to 20 g / L, the concentration of sodium phosphate is 1 g / L to 40 g / L, and the concentration of sodium hydroxide is 1 g / L to 20 g / L. The other steps are the same as specific embodiments 1 to 3.

[0036] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the time for micro-arc oxidation in step 2② is 10 to 80 minutes. The other steps are the same as those in specific embodiments 1 to 4.

[0037] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the thickness of the porous alumina ceramic coating in step 2 ② is 10 μm to 100 μm and the porosity is 10% to 40%. The other steps are the same as specific embodiments 1 to 5.

[0038] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the heating rate in step 3 is 5°C / min to 8°C / min. The other steps are the same as those in specific embodiments 1 to 6.

[0039] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the insulation time in step 3 is 10 minutes to 30 minutes. The other steps are the same as those in specific embodiments 1 to 7.

[0040] Specific Embodiment 9: This embodiment differs from Specific Embodiments 1 to 8 in that, in step 3, the aluminum-based composite material with the porous alumina ceramic coating is placed in a high-temperature furnace, heated to 600°C to 650°C, and then maintained at 600°C to 650°C for a period of time. The remaining steps are the same as Specific Embodiments 1 to 8.

[0041] Specific embodiment 10: The difference between this embodiment and specific embodiments 1 to 9 is that the aluminum-based composite material with a porous Al2O3 / Al ceramic coating on the surface described in step 3 has excellent mechanical properties and high thermal conductivity, excellent mechanical properties, a friction coefficient of less than 0.5, and the composite material remains intact after 500 thermal shocks at 400°C. The thermal expansion coefficient is 5 to 15×10 -6 / ℃, room temperature compression and bending strength>1GPa, fracture toughness about 16~20MPa·m 1 / 2 , thermal conductivity ≥ 100 W / mK. Other steps are the same as those in specific embodiments 1 to 9.

[0042] The following examples are used to verify the beneficial effects of the present invention:

[0043] Example 1: A method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material, specifically completed by the following steps:

[0044] 1. Pretreatment of the surface of aluminum-based composite materials:

[0045] Removing impurities and oil stains on the surface of the aluminum-based composite material to obtain a pretreated substrate;

[0046] In step 1, the surface of the aluminum-based composite material was polished using 800#, 1000#, and 1200# sandpaper in sequence to remove impurities and an oxide layer on the surface, and then ultrasonically cleaned using anhydrous ethanol and deionized water for 15 minutes respectively to obtain a pretreated substrate;

[0047] The aluminum-based composite material described in step 1 is SiC-reinforced 2024 aluminum alloy, wherein the mass fraction of SiC is 45%;

[0048] 2. Preparation of porous micro-arc oxidation coating:

[0049] ① Dissolve sodium silicate, sodium aluminate, sodium phosphate and sodium hydroxide in deionized water to obtain an electrolyte;

[0050] The electrolyte in step 2 (1) has a sodium silicate concentration of 15 g / L, a sodium aluminate concentration of 10 g / L, a sodium phosphate concentration of 20 g / L, and a sodium hydroxide concentration of 5 g / L;

[0051] ② Immerse the pretreated substrate in a stainless steel electrolytic cell filled with electrolyte, connect the pretreated substrate to the positive electrode of a power supply, and connect the stainless steel electrolytic cell to the negative electrode of the power supply. Micro-arc oxidation is performed for 50 minutes at an electrolyte temperature of 40°C, an applied voltage of 500V, a frequency of 600Hz, and a duty cycle of 10% to obtain an aluminum-based composite material with a porous alumina ceramic coating;

[0052] In step 2②, the thickness of the porous alumina ceramic coating is 100 μm and the porosity is 30%;

[0053] 3. Preparation of Al2O3 / Al ceramic coating with complete structure:

[0054] The aluminum matrix composite material with porous alumina ceramic coating was placed in a high temperature furnace, heated from room temperature to 600°C at a heating rate of 5°C / min, and kept at 600°C for 20 minutes. Figure 1 As shown, an aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating on the surface can be obtained. It has a dual composite material structure, in which the substrate is an aluminum-based composite material and the surface is completely wrapped by the Al2O3 / Al composite material. This special structure has excellent mechanical and thermal properties.

[0055] Figure 2 This is a macroscopic image of the aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0056] Figure 2 The results show that aluminum particles with uniform distribution and metallic luster appear on the coating surface ( Figure 2 The white bright point in the middle proves that the aluminum in the aluminum-based composite material fills the pores in the porous ceramic layer through high-temperature diffusion and diffuses into the coating surface.

[0057] Figure 3 This is a SEM image of the aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0058] pass Figure 3It was found that the porous ceramic coating had been filled with molten aluminum (see the marked position) to form a ceramic-metal composite coating, which once again proved that we used a simple one-step method to prepare a ceramic-metal composite coating on the surface of an aluminum-based composite material.

[0059] Figure 4 XRD pattern of the aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in Example 1;

[0060] Figure 4 After the surface of the coating was scraped, XRD characterization was performed and it was found that in addition to the diffraction peak of Al2O3, there were also a large number of Al diffraction peaks in the coating, proving that this technology can be used to prepare ceramic-metal composite coatings.

[0061] Figure 5 Thermal conductivity data of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments.

[0062] from Figure 5 It can be seen that the aluminum-based composite material with porous Al2O3 / Al ceramic metal coating exhibits a high thermal conductivity of more than 100W / mK.

[0063] Example 2: The difference between this example and Example 1 is that the concentration of sodium silicate in the electrolyte described in step 2 ① is 10 g / L, the concentration of sodium aluminate is 10 g / L, the concentration of sodium phosphate is 10 g / L, and the concentration of sodium hydroxide is 5 g / L; in step 2 ②, the pretreated substrate is immersed in a stainless steel electrolytic cell filled with electrolyte, the pretreated substrate is connected to the positive electrode of the power supply, and the stainless steel electrolytic cell is connected to the negative electrode of the power supply, and the electrolyte temperature is 45°C, the applied voltage is 600 V, the frequency is 600 Hz, and the ratio is 0. Micro-arc oxidation was performed for 60 minutes at a void ratio of 6% to obtain an aluminum-based composite material having a porous alumina ceramic coating. In step 2 (2), the porous alumina ceramic coating had a thickness of 120 μm and a porosity of 39%. In step 3, the aluminum-based composite material having a porous alumina ceramic coating was placed in a high-temperature furnace and heated from room temperature to 650°C at a heating rate of 5°C / min, and then maintained at 650°C for 30 minutes to obtain an aluminum-based composite material having a porous Al2O3 / Al ceramic metal coating. Other steps and parameters were the same as in Example 1.

[0064] Example 3: The difference between this example and Example 1 is that the concentration of sodium silicate in the electrolyte described in step 2 ① is 20 g / L, the concentration of sodium aluminate is 5 g / L, the concentration of sodium phosphate is 30 g / L, and the concentration of sodium hydroxide is 10 g / L; in step 2 ②, the pretreated substrate is immersed in a stainless steel electrolytic cell filled with electrolyte, the pretreated substrate is connected to the positive electrode of the power supply, and the stainless steel electrolytic cell is connected to the negative electrode of the power supply, and the electrolyte temperature is 45°C, the applied voltage is 600 V, the frequency is 600 Hz, and the ratio is 0. Micro-arc oxidation was performed for 80 minutes at a void ratio of 20% to obtain an aluminum-based composite material having a porous alumina ceramic coating. In step 2 (2), the porous alumina ceramic coating had a thickness of 160 μm and a porosity of 42%. In step 3, the aluminum-based composite material having a porous alumina ceramic coating was placed in a high-temperature furnace and heated from room temperature to 630°C at a heating rate of 5°C / min. The temperature was then maintained at 630°C for 30 minutes to obtain an aluminum-based composite material having a porous Al2O3 / Al ceramic metal coating. Other steps and parameters were the same as in Example 1.

[0065] Figure 6 Friction coefficient of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments.

[0066] Figure 7 Thermal expansion coefficient of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments.

[0067] Figure 8 Room temperature compressive strength of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments.

[0068] Figure 9 The fracture toughness of aluminum-based composite materials with porous Al2O3 / Al ceramic metal coatings prepared in different embodiments;

[0069] from Figures 6 to 9 It can be seen that:

[0070] The aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in Example 1 exhibits a low friction coefficient of 0.35 and a thermal expansion coefficient of about 9.5×10 -6 / ℃, compressive strength 1.21GPa, fracture toughness ~16.2MPa·m 1 / 2 .

[0071] The aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in Example 2 has a friction coefficient of <0.37, a thermal shock of 350°C for 500 times without damage, and a thermal expansion coefficient of 11.2×10-6 / ℃, room temperature compressive strength ~1.1GPa, fracture toughness ~16.8MPa·m 1 / 2 , thermal conductivity ≥100W / mK.

[0072] The aluminum-based composite material with porous Al2O3 / Al ceramic metal coating prepared in Example 3 has a friction coefficient of 0.42, a thermal shock of 400°C for 500 times without damage, and a thermal expansion coefficient of 12.3×10 -6 / ℃, room temperature compressive strength>1.02GPa, fracture toughness~17.1MPa·m 1 / 2 , thermal conductivity ≥100W / mK.

Claims

1. A method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material, characterized in that The preparation method is specifically completed according to the following steps:

1. Pretreatment of the surface of aluminum-based composite materials: Removing impurities and oil stains on the surface of the aluminum-based composite material to obtain a pretreated substrate; 2. Preparation of porous micro-arc oxidation coating: ① Dissolve sodium silicate, sodium aluminate, sodium phosphate and sodium hydroxide in deionized water to obtain an electrolyte; ②, immersing the pretreated substrate in a stainless steel electrolytic cell filled with an electrolyte, connecting the pretreated substrate to the positive electrode of a power supply, connecting the stainless steel electrolytic cell to the negative electrode of the power supply, and micro-arc oxidation for a period of time under the conditions of an electrolyte temperature of 30°C to 50°C, an applied voltage of 400V to 600V, a frequency of 200Hz to 1000Hz, and a duty cycle of 4% to 30%, to obtain an aluminum-based composite material with an alumina ceramic coating having a porous structure; 3. Preparation of Al2O3 / Al ceramic coating with complete structure: The aluminum-based composite material with a porous alumina ceramic coating is placed in a high-temperature furnace, heated to 550°C to 650°C, and kept at 550°C to 650°C for a period of time to obtain an aluminum-based composite material with a porous Al2O3 / Al ceramic metal coating on the surface.

2. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The aluminum-based composite material described in step 1 is a SiC-reinforced aluminum alloy, wherein the mass fraction of SiC is 10% to 50%.

3. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 2, characterized in that The aluminum alloy described in step 1 is 2024 aluminum alloy, 6061 aluminum alloy, or 1050 aluminum alloy.

4. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The concentration of sodium silicate in the electrolyte described in step 2① is 1g / L~20g / L, the concentration of sodium aluminate is 1g / L~20g / L, the concentration of sodium phosphate is 1g / L~40g / L, and the concentration of sodium hydroxide is 1g / L~20g / L.

5. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The time of the micro-arc oxidation described in step 2② is 10 minutes to 80 minutes.

6. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that In step 2②, the thickness of the porous alumina ceramic coating is 10 μm to 100 μm, and the porosity is 10% to 40%.

7. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The heating rate in step 3 is 5°C / min to 8°C / min.

8. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The insulation time described in step 3 is 10 minutes to 30 minutes.

9. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that In step three, the aluminum-based composite material with the alumina ceramic coating having a porous structure is placed in a high-temperature furnace, heated to 600° C. to 650° C., and kept at 600° C. to 650° C. for a period of time.

10. The method for preparing a porous Al2O3 / Al ceramic metal coating on the surface of an aluminum-based composite material according to claim 1, characterized in that The aluminum-based composite material with a porous Al2O3 / Al ceramic coating as described in step 3 has excellent mechanical properties and high thermal conductivity. The mechanical properties are excellent, the friction coefficient is less than 0.5, the composite material remains intact after 500 thermal shocks at 400°C, and the thermal expansion coefficient is 5-15×10 -6 / ℃, room temperature compression and bending strength>1GPa, fracture toughness about 16~20MPa·m 1 / 2 , thermal conductivity ≥100W / mK.

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