Ti3alC2 / w-cu composite coating and preparation method thereof

Abstract

This invention describes a Ti3AlC2 / W-Cu composite coating and its preparation method. The specific steps are as follows: First, pure W powder, pure Cu powder, and Ti3AlC2 powder are mixed evenly. Then, the mixed powder is spread onto the surface of a substrate to obtain the Ti3AlC2 / W-Cu composite coating. This invention introduces Ti3AlC2 into the W-Cu coating, promoting element diffusion and interfacial reaction at the W / Cu interface during sintering, thereby improving the bonding state of the W / Cu interface, increasing the coating's cohesive strength and wear resistance, while its electrical conductivity does not show a significant decrease.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite materials and surface engineering technology, specifically relating to a Ti3AlC2 / W-Cu composite coating and its preparation method. Background Technology

[0002] Copper and copper alloys possess excellent electrical and thermal conductivity, making them widely used in electrical contacts, electromagnetic railguns, and high heat flux density components. However, copper and copper alloys have relatively low surface hardness, making them prone to wear and spalling under high-speed sliding, high load, and high-temperature environments, thus making it difficult to simultaneously meet the service requirements of high conductivity, high strength, and high wear resistance.

[0003] W-Cu composites are metal matrix composites with W as the reinforcing phase and Cu as the matrix. They exhibit not only the high melting point, high density, corrosion resistance, low coefficient of thermal expansion, and good arc resistance of W, but also the high electrical and thermal conductivity, plasticity, and ease of processing of Cu, making them ideal materials for surface modification of copper and copper alloys. However, the inherent immiscibility and poor wettability of the W-Cu system result in weak W / Cu interfacial bonding and low coating cohesive strength. The weak W / Cu interface makes W particles prone to interfacial debonding and pull-out during sliding friction. The voids formed after particle pull-out cause localized stress concentration, promoting crack initiation and propagation, thereby exacerbating coating peeling and wear. Therefore, improving the W / Cu interfacial bonding is crucial for enhancing the coating's cohesive strength and wear resistance. Summary of the Invention

[0004] This invention proposes a Ti3AlC2 / W-Cu composite coating and its preparation method. By introducing Ti3AlC2 into the W-Cu coating, element diffusion and interfacial reaction at the W / Cu interface are promoted during sintering, thereby improving the bonding state of the W / Cu interface, increasing the cohesive strength and wear resistance of the coating, while its electrical conductivity does not show a significant decrease.

[0005] The technical solution for realizing the present invention is as follows:

[0006] A method for preparing a Ti3AlC2 / W-Cu composite coating includes the following steps:

[0007] (1) Mix pure W powder, pure Cu powder and Ti3AlC2 powder evenly;

[0008] (2) The dried mixed powder is spread on the substrate surface to obtain a Ti3AlC2 / W-Cu composite coating.

[0009] Furthermore, in step (1), the pure W powder is an irregular powder with a particle size of 1~10 μm.

[0010] Furthermore, in step (1), the pure Cu powder is a spherical powder with a particle size of 1~10 μm.

[0011] Furthermore, in step (1), the Ti3AlC2 powder has a lamellar structure and a particle size of 5~15 μm.

[0012] Furthermore, in step (1), the mass ratio of pure W powder, pure Cu powder and Ti3AlC2 powder is 30~38 : 50~60 : 2~10.

[0013] Furthermore, in step (1), pure W powder, pure Cu powder and Ti3AlC2 powder are mixed evenly by wet ball milling. The specific process is as follows: agate balls with a diameter of 6 mm are used for ball milling, the ball-to-material ratio is 8:1~10:1, alcohol is used as the wet ball milling medium, and pure W powder and pure Cu powder are first loaded into cans and mixed under an argon atmosphere. The ball mill speed is 180~300 r / min and the ball milling time is 4~6 hours. Then Ti3AlC2 powder is added under an argon atmosphere and mixed again. The ball mill speed is 150~200 r / min and the ball milling time is 30~50 min.

[0014] Furthermore, in step (2), the base material is copper or a copper alloy.

[0015] Furthermore, in step (2), the Ti3AlC2 / W-Cu composite coating is obtained by spark plasma sintering. The specific process is as follows: First, the powder is pre-pressed to ensure good contact between the powder layer and the substrate, and at the same time, it is beneficial for the residual gas between the particles to be gradually removed during the heating process. The pre-pressing time is 1~4 min, the pre-pressing pressure is 10~20 MPa, and then sintering is carried out. The sintering temperature is 650℃~950℃, the sintering pressure is 15~45 MPa, the holding time is 5~15 min, and the heating rate is 80~100℃ / min.

[0016] In a second aspect, the present invention provides a Ti3AlC2 / W-Cu composite coating prepared by the method described in the first aspect.

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

[0018] This invention improves the cohesive strength and wear resistance of a W-Cu coating by introducing an appropriate amount of Ti3AlC2 into the coating, thereby promoting the diffusion of interfacial elements during sintering. Compared with the original W-Cu coating, the W-Cu coating with 2 wt% Ti3AlC2 maintains the original relative density, and its electrical conductivity decreases only slightly from 62% IACS to 59% IACS, while the cohesive strength and wear resistance of the coating are significantly improved, with its shear strength increasing to 230 MPa and its room temperature wear rate decreasing to 3 × 10⁻⁶.-6 mm 3 / (N·m), the high-temperature (600 ℃) wear rate decreased to 2 ×10 -4 mm 3 / (N·m). Attached Figure Description

[0019] Figure 1 SEM images of the undercoat surface with different contents of Ti3AlC2 were added, where (a) 0 wt% Ti3AlC2, (b) 2 wt% Ti3AlC2, (c) 6 wt% Ti3AlC2, and (d) 10 wt% Ti3AlC2.

[0020] Figure 2 Shear test results for different contents of Ti3AlC2 added to the lower coating, where (a) shear stress-displacement curve, (b) shear strength;

[0021] Figure 3 The electrical conductivity of the lower coating with different contents of Ti3AlC2 was determined.

[0022] Figure 4 Hardness of the undercoat with different contents of Ti3AlC2 added;

[0023] Figure 5 Room temperature wear rate of the undercoat with different contents of Ti3AlC2;

[0024] Figure 6 The wear rate of the coatings with 2 wt% Ti3AlC2 added in Comparative Example 1 (without Ti3AlC2) and in Example 1 (with Ti3AlC2) at 600°C is given. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solutions of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. All other embodiments obtained by those skilled in the art based on the given embodiments without innovative effort are within the scope of protection of this application.

[0026] It should be noted that, unless otherwise specified in the examples, the conditions should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0027] The reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0028] The technical term "and / or" in this application is only a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0029] In addition, the character " / " in this application generally indicates that the objects before and after it are in an "or" relationship.

[0030] The principle of this invention is as follows: Ti3AlC2 is a typical MAX phase layered conductive ceramic with certain conductivity and high hardness. During spark plasma sintering, some Al is deintercalated from the Ti3AlC2 layered structure and diffuses into the Cu phase, forming a Cu(Al) solid solution. The resulting interfacial element diffusion and Cu migration from Ti3AlC2 to the W particle surface are beneficial to improving the local W / Cu interfacial bonding, thereby enhancing the cohesive strength and wear resistance of the coating.

[0031] Comparative Example 1

[0032] The coating prepared in this comparative example is a W-60 wt% Cu coating.

[0033] The specific steps are as follows:

[0034] Step 1: Cleaning the substrate. Before coating preparation, the surface of the CuCrZr substrate is sanded with sandpaper to remove the oxide layer and dirt. The substrate is then ultrasonically cleaned in deionized water for 5 minutes and dried for later use.

[0035] Step 2: Preparation of the mixed powder. Weighed pure W powder and pure Cu powder were placed in a container under argon atmosphere and added to 6 mm diameter agate balls at a ball-to-powder ratio of 10:1. Alcohol was used as the wet ball milling medium. The ball mill speed was set to 300 r / min, and the milling time was 6 hours. To avoid overheating, the milling was stopped for 30 minutes after every 3 hours of milling. After the ball milling and mixing were completed, the mixed powder was placed in a vacuum drying oven at 60℃ to dry.

[0036] Step 3: Preparation of the W-Cu coating. The dried mixed powder was uniformly pre-placed on the CuCrZr surface and placed into a graphite mold. Sintering was performed using a spark plasma sintering (SPCS) apparatus. First, a pre-pressure of 15 MPa was applied over 1 minute, then the temperature was increased to 950℃ at a rate of 100℃ / min. After reaching 950℃, the sintering pressure was increased to 45 MPa over 1 minute, and the temperature was maintained at 950℃ and 45 MPa for 10 minutes. After sintering and cooling, the sample was removed, revealing a W-Cu coating approximately 1 mm thick on the CuCrZr surface.

[0037] The obtained coating was analyzed. Figure 1 The image shows the SEM image of the coating. Without the addition of Ti3AlC2 (0 wt% Ti3AlC2), W particles are dispersed in the Cu matrix, and no obvious pores are observed. Figure 2 The shear test results of the coating with different contents of Ti3AlC2 are shown. When Ti3AlC2 is not added, the shear strength of the coating is 197 MPa. Figure 3 The conductivity of the coating was measured by adding different amounts of Ti3AlC2. Without Ti3AlC2, the conductivity of the coating was 62% IACS. Figure 4 The hardness of the coating was adjusted by adding different amounts of Ti3AlC2. Without Ti3AlC2, the microhardness of the coating was 155 HV. 0.5 . Figure 5 The room temperature wear rate of the coating with different amounts of Ti3AlC2 was measured. Without Ti3AlC2, the wear rate of the coating was 4 × 10⁻⁶. -6 mm 3 / (N·m). Figure 6 The wear rate of the coating at 600℃ is shown for coatings without and with 2 wt% Ti3AlC2. Without Ti3AlC2, the high-temperature wear rate of the coating is 3 × 10⁻⁶. -4 mm 3 / (N·m).

[0038] Example 1

[0039] The coating prepared in this embodiment is a Ti3AlC2 / W-60 wt%Cu composite coating.

[0040] The only difference compared to the preparation steps in Comparative Example 1 is that in step two, after ball milling and mixing W and Cu powders for 6 hours, 2 wt% of Ti3AlC2 powder was added under an argon protective atmosphere, the ball mill speed was reduced to 150 r / min, and mixing continued for 45 min. After the powder mixing was completed, the mixed powder was placed in a vacuum drying oven at 60℃ to dry.

[0041] The obtained coating was analyzed. Figure 1The image shows a SEM image of the coating. W and Ti3AlC2 particles are dispersed in the Cu matrix. After adding 2 wt% Ti3AlC2, the coating surface becomes relatively dense. Figure 2 The shear test results of the coating with different contents of Ti3AlC2 were presented. After adding 2 wt% Ti3AlC2, the shear strength of the coating increased to 230 MPa, indicating that the cohesive strength of the coating was significantly improved. Figure 3 The conductivity of the coating was improved by adding different amounts of Ti3AlC2. After adding 2 wt% Ti3AlC2, the conductivity of the coating was 59% IACS, which was 3% IACS lower than that without Ti3AlC2, but did not show a significant decreasing trend. Figure 4 The hardness of the coating was adjusted by adding different amounts of Ti3AlC2. After adding 2 wt% Ti3AlC2, the microhardness of the coating was 164 HV. 0.5 Compared to when Ti3AlC2 was not added, it increased by 9 HV. 0.5 . Figure 5 The room temperature wear rate of the coating with different contents of Ti3AlC2 was measured. After adding 2 wt% Ti3AlC2, the wear rate of the coating increased from 4 × 10⁻⁶. -6 mm 3 / (N·m) decreased to 3 × 10 -6 mm 3 / (N·m) was reduced by 32%, and the wear resistance of the coating was improved. Figure 6 The wear rate of the coating at 600℃ was compared with that without Ti3AlC2 and with 2 wt% Ti3AlC2. After adding 2 wt% Ti3AlC2, the high-temperature wear rate of the coating decreased to 2 × 10⁻⁶. -4 mm 3 / (N·m). After adding 2 wt% Ti3AlC2, the electrical conductivity of the coating showed a slight decreasing trend, but its cohesive strength, hardness, room temperature and high temperature tribological properties were all improved.

[0042] Example 2

[0043] The coating prepared in this embodiment is a Ti3AlC2 / W-60 wt%Cu composite coating.

[0044] The only difference compared to the preparation steps in Comparative Example 1 is that in step two, after ball milling and mixing W and Cu powders for 6 hours, 6 wt% of Ti3AlC2 powder was added under an argon protective atmosphere, the ball mill speed was reduced to 150 r / min, and mixing continued for 45 min. After the powder mixing was completed, the mixed powder was placed in a vacuum drying oven at 60℃ to dry.

[0045] The obtained coating was analyzed. Figure 1The SEM image of the coating shows that after adding 6 wt% Ti3AlC2, pores were observed on the coating surface, and the coating density decreased. Figure 2 The shear test results of the coating with different contents of Ti3AlC2 were presented. After adding 6 wt% Ti3AlC2, the shear strength of the coating was 172 MPa, and the cohesive strength of the coating was reduced. Figure 3 The conductivity of the coating was improved by adding Ti3AlC2 with different contents. After adding 6 wt% Ti3AlC2, the conductivity of the coating decreased from 62% IACS to 21% IACS, which was a significant decrease. Figure 4 The hardness of the coating was adjusted by adding different amounts of Ti3AlC2. After adding 6 wt% Ti3AlC2, the microhardness of the coating was 189 HV. 0.5 Compared to the coating without Ti3AlC2, the coating hardness increased by 22%. Figure 5 The room temperature wear rate of the coating with different contents of Ti3AlC2 was measured. After adding 6 wt% Ti3AlC2, the wear rate of the coating was 9 × 10⁻⁶. -6 mm 3 / (N·m), the wear rate is higher compared to the coating without Ti3AlC2.

[0046] Example 3

[0047] The coating prepared in this embodiment is a Ti3AlC2 / W-60 wt%Cu composite coating.

[0048] The only difference compared to the preparation steps in Comparative Example 1 is that in step two, after ball milling and mixing W and Cu powders for 6 hours, 10 wt% of Ti3AlC2 powder was added under an argon protective atmosphere, the ball mill speed was reduced to 150 r / min, and mixing continued for 45 min. After the powder mixing was completed, the mixed powder was placed in a vacuum drying oven at 60℃ to dry.

[0049] The obtained coating was analyzed. Figure 1 The SEM image of the coating shows that the coating density further decreased after adding 10 wt% Ti3AlC2. Figure 2 The shear test results of the coating with different contents of Ti3AlC2 were presented. After adding 10 wt% Ti3AlC2, the shear strength of the coating was 107 MPa, and the cohesive strength of the coating was significantly reduced. Figure 3 The conductivity of the coating was improved by adding different amounts of Ti3AlC2. After adding 10 wt% Ti3AlC2, the conductivity of the coating decreased to 14% IACS. Figure 4 The hardness of the coating was adjusted by adding different amounts of Ti3AlC2. After adding 10 wt% Ti3AlC2, the microhardness of the coating was 181 HV.0.5 Compared to adding 6 wt% Ti3AlC2, the coating hardness showed a decreasing trend. Figure 5 The wear rate of coatings at room temperature was measured with different amounts of Ti3AlC2. Adding 10 wt% Ti3AlC2 significantly increased the wear rate. When the added Ti3AlC2 content was too high, the coating hardness increased, but its cohesive strength and wear resistance decreased.

[0050] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for preparing a Ti3AlC2 / W-Cu composite coating, characterized in that, Includes the following steps: (1) Mix pure W powder, pure Cu powder and Ti3AlC2 powder evenly; (2) The dried mixed powder is spread on the substrate surface to obtain a Ti3AlC2 / W-Cu composite coating.

2. The preparation method according to claim 1, characterized in that, Pure W powder is an irregular powder with a particle size of 1~10 μm.

3. The preparation method according to claim 1, characterized in that, Pure Cu powder is a spherical powder with a particle size of 1~10 μm.

4. The preparation method according to claim 1, characterized in that, Ti3AlC2 powder has a lamellar structure and a particle size of 5~15 μm.

5. The preparation method according to claim 1, characterized in that, The mass ratio of pure W powder, pure Cu powder, and Ti3AlC2 powder is 30~38 : 50~60 : 2~10.

6. The preparation method according to claim 1, characterized in that, Pure W powder, pure Cu powder, and Ti3AlC2 powder were uniformly mixed using a wet ball milling method. The specific process was as follows: agate balls with a diameter of 6 mm were used for ball milling, with a ball-to-material ratio of 8:1 to 10:

1. Alcohol was used as the wet ball milling medium. During ball milling, pure W powder and pure Cu powder were first loaded into containers and mixed under an argon atmosphere. The ball mill speed was 180 to 300 r / min, and the ball milling time was 4 to 6 hours. Then, Ti3AlC2 powder was added under an argon atmosphere and the mixture was continued. The ball mill speed was 150 to 200 r / min, and the ball milling time was 30 to 50 minutes.

7. The preparation method according to claim 1, characterized in that, The base material is copper or a copper alloy.

8. The preparation method according to claim 1, characterized in that, Ti3AlC2 / W-Cu composite coatings were obtained by spark plasma sintering. The specific process was as follows: First, the powder was pre-pressed for 1-4 min at a pressure of 10-20 MPa. Then, sintering was carried out at a temperature of 650℃-950℃, a pressure of 15-45 MPa, a holding time of 5-15 min, and a heating rate of 80-100℃ / min.

9. A Ti3AlC2 / W-Cu composite coating prepared by the method according to any one of claims 1-8.

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