MAB phase reinforced Cu-Sn-Ti active brazing filler metal and preparation method thereof

Abstract

The invention relates to the technical field of metal material connection and surface engineering, in particular to MAB phase reinforced Cu-Sn-Ti active brazing filler metal and a preparation method thereof. According to the MAB phase enhanced Cu-Sn-Ti active brazing filler metal, an MAB phase serves as a strengthening phase and is layered ternary boride ceramic, M is Mo or Cr, A is Al, and the brazing filler metal comprises, by mass, 60%-65% of Cu powder, 15%-18% of Sn powder, 10%-12% of Ti powder and the balance MAB powder. The MAB phase ceramic with a unique layered structure and chemical activity is introduced, the interface reaction of a diamond / steel substrate can be actively regulated and controlled while dispersion strengthening of the brazing filler metal substrate is achieved, a tough and tough combined gradient interface is formed, and therefore the diamond composite wear-resistant coating with excellent comprehensive performance is obtained.

Description

Technical Field

[0001] This invention relates to the field of metal material joining and surface engineering technology, specifically to a MAB phase reinforced Cu-Sn-Ti active solder and its preparation method. Background Technology

[0002] High-nitrogen steel, tool steel, and other high-performance steels are widely used in key components of heavy machinery, mining tools, and molds due to their excellent strength, toughness, and wear resistance. To meet the wear resistance requirements under extreme working conditions, diamond composite coatings are often prepared on their surfaces. Among them, active brazing has attracted much attention because it can achieve metallurgical bonding between diamond, steel substrate, and brazing filler metal. Commonly used Cu-Sn-Ti active brazing filler metal can react on the diamond surface to generate TiC, achieving high-strength bonding.

[0003] However, the existing technology has the following bottlenecks: (1) contradiction between strength and toughness: the pure Cu-Sn-Ti brazing matrix is ​​soft, and the overall wear resistance of the coating depends on the diamond particles. When the particles wear or fall off, the wear will be aggravated. If traditional hard ceramic phases, such as WC and Al2O3, are added to strengthen the matrix, the plasticity and wetting and spreading ability of the brazing filler will be severely deteriorated, resulting in increased brittleness of the coating. Under impact load, the coating is prone to peeling off as a whole; (2) insufficient interface control: there are huge physical and chemical differences between diamond and steel matrix, resulting in high residual stress at the interface. Traditional methods are difficult to actively control the thickness and morphology of the interface reaction layer. The interface is often a brittle single TiC layer, which is easy to become a crack source; (3) poor high temperature stability: at the brazing temperature, the traditional reinforcing phase may have a harmful interface reaction with the active element Ti, or cause the brazing filler alloy elements to burn off, affecting the performance.

[0004] Therefore, developing a novel composite brazing filler metal that can enhance the brazing filler metal matrix and possess both high strength, toughness, and high wear resistance is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a MAB-phase reinforced Cu-Sn-Ti active solder and its preparation method. This solder introduces MAB-phase ceramics with a unique layered structure and chemical activity, achieving dispersion reinforcement of the solder matrix while actively regulating the interfacial reaction of the diamond / steel matrix to form a strong and tough gradient interface, thereby obtaining a diamond composite wear-resistant coating with excellent comprehensive performance.

[0006] To achieve the above objectives, this application provides a MAB-phase reinforced Cu-Sn-Ti active solder. In this MAB-phase reinforced Cu-Sn-Ti active solder, the MAB phase serves as the reinforcing phase and is a layered ternary boride ceramic, wherein M is Mo or Cr and A is Al. The solder comprises, by mass percentage, 60-65% Cu powder, 15-18% Sn powder, 10-12% Ti powder, and the remainder being MAB powder.

[0007] A method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder includes the following steps: S1. Weigh M, A and B according to the atomic ratio, mix and ball-mill, heat-treat, and obtain MAB powder; S2. Weigh out Cu powder, Sn powder, Ti powder and MAB powder according to the formula and mix them to obtain composite solder powder; S3. Mix the composite solder powder from step S2 with polyacrylate, roll, degrease, and sinter to obtain a MAB phase reinforced Cu-Sn-Ti active solder foil, or melt and atomize the composite solder powder from step S2 to obtain a MAB phase reinforced Cu-Sn-Ti active solder powder.

[0008] Furthermore, the Cu powder has a purity of ≥99.5% and an average particle size of 10-45 μm; the Sn powder has a purity of ≥99.5% and an average particle size of 10-45 μm; and the Ti powder has a purity of ≥99.5% and an average particle size of 10-45 μm.

[0009] Furthermore, the MAB powder is Cr2AlB2 or MoAlB.

[0010] Furthermore, in step S1, the ball milling medium is cemented carbide balls, the ball-to-material ratio is 10-20:1, the rotation speed is 300-500 rpm, and the time is 20-50 h.

[0011] Furthermore, the heat treatment involves heating to 800-1100°C at a heating rate of 5-20°C / min, holding at that temperature for 0.5-2 hours, and purging with inert gas for protection during the heat treatment.

[0012] Furthermore, the degreasing process is carried out at a temperature of 250-350℃ for 2-3 hours.

[0013] Furthermore, the sintering is carried out at a temperature of 450-550℃ for 1-2 hours, during which argon gas is introduced.

[0014] Furthermore, the melting temperature is 1100-1300℃.

[0015] Furthermore, in the atomization powder production process, the atomizing gas is nitrogen or argon with a purity ≥99% and an atomization pressure of 3-6 MPa.

[0016] Furthermore, the active solder powder is a spherical powder with a particle size of 15-53 μm.

[0017] In summary, this application has the following beneficial effects: This invention is the first to introduce a type of layered ternary boride ceramic known as the "MAB phase," such as Cr2AlB2 and MoAlB, as a reinforcing phase into the Cu-Sn-Ti active solder system. Compared with traditional reinforcing phases, the MAB phase brings multiple synergistic enhancement effects: 1. Structural innovation and performance synergy: The MAB phase has a layered structure similar to graphite, with strong covalent / metallic bonds between its MB layers and weaker metallic bonds between the MB and Al layers. This structure gives it the high hardness and high modulus of ceramics, as well as good damage tolerance and thermal conductivity similar to metals. Introducing it into solder can significantly improve the hardness and resistance to abrasive wear, and its quasi-plastic deformation ability will not cause severe brittleness, thus achieving a synergistic effect of strong toughness between soft matrix and hard reinforcing phase.

[0018] 2. Interface Activity Regulation Mechanism: At the high temperature of brazing, the Al and B elements in the MAB phase possess certain activity and can undergo a controllable interfacial reaction with the Ti element in the brazing filler metal. This process: (1) Regulation of Ti activity and diffusion: The release of some B can react with Ti to generate fine TiB2 in situ around the MAB phase. These TiB2 can further pin the interface and strengthen the bonding. At the same time, this reaction finely regulates the concentration of Ti atoms reaching the diamond surface, which helps to form a TiC reaction layer with moderate thickness and good bonding with diamond.

[0019] (2) Formation of gradient transition interface: In the end, a multi-scale, gradient composite interface structure of diamond / TiC / (Sn-rich phase and TiB2) / MAB phase / solder matrix may be formed in the interface region. This structure can effectively relax stress, hinder crack propagation, and greatly improve the bonding strength and reliability of the coating.

[0020] 3. Innovation and feasibility of the preparation process: This invention designs a complete preparation process that can be industrially promoted. High-purity, fine-grained MAB phase powder can be prepared on a large scale through high-energy mechanical alloying and controllable heat treatment, solving the processability problem. The subsequent use of low-energy mixing or gas atomization process effectively avoids the structural damage and component segregation of the MAB phase, ensuring the uniform distribution and structural integrity of the reinforcing phase in the solder. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0022] In the specific embodiments of this application, the Cu powder has a purity of 99.9% and an average particle size of 20 μm; the Sn powder has a purity of 99.9% and an average particle size of 20 μm; the Ti powder has a purity of 99.9% and an average particle size of 20 μm; the Cr powder has a purity of 99.9% and an average particle size of 20 μm; the Al powder has a purity of 99.9% and an average particle size of 20 μm; the B powder has a purity of 99.9% and an average particle size of 20 μm; and the polyacrylate is selected from Jiangsu Runfeng Synthetic Technology Co., Ltd., No.: RFHC073.

[0023] Example 1 A method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder includes the following steps: S1. Weigh Cr powder, Al powder and B powder in an atomic ratio of 2:1:2 and mix them in a ball mill (the ball milling media is cemented carbide balls, the ball-to-material ratio is 15:1, the rotation speed is 400 rpm, and the time is 30 h). Heat treatment (heat to 900℃ at a heating rate of 10℃ / min, hold for 1 h, and pass inert gas for protection during the heat treatment) to obtain Cr2AlB2 powder. S2. Weigh 65% Cu powder, 15% Sn powder, 10% Ti powder and 10% Cr2AlB2 powder by mass percentage and mix them in a three-dimensional powder mixer (60 rpm, 6 h) to obtain composite solder powder. S3. The composite brazing filler powder and polyacrylate are mixed at a mass ratio of 100:8 (rotation speed 60, time 2h), rolled into a strip with a thickness of 100μm by a rolling mill, and then degreased in a vacuum degreasing furnace (degreasing temperature 300℃, time 2h), and sintered in argon at 500℃ for 2h to obtain a MAB phase reinforced Cu-Sn-Ti active brazing filler foil.

[0024] Example 2 A method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder includes the following steps: S1. Weigh Mo powder, Al powder, and B powder in an atomic ratio of 1:1:1 and mix them in a ball mill (the ball milling media is cemented carbide balls, the ball-to-material ratio is 15:1, the rotation speed is 400 rpm, and the time is 30 h). Heat treatment (heat to 900 °C at a heating rate of 10 °C / min, hold for 1 h, and purge with inert gas during the heat treatment) to obtain MoAlB powder. S2. Weigh 60% Cu powder, 18% Sn powder, 12% Ti powder and 10% MoAlB powder by mass percentage and mix them in a three-dimensional powder mixer (60 rpm, 6 h) to obtain composite solder powder. S3. The composite solder powder is melted in a vacuum induction melting furnace (temperature 1250℃), and then atomized with 99% pure nitrogen (atomization pressure 4.5MPa) to obtain a MAB phase reinforced Cu-Sn-Ti active solder powder.

[0025] Compare with Example 1 The difference between this comparative example and Example 2 is that Cu powder is used instead of MoAlB powder.

[0026] Performance testing Functionality tests were performed on the MAB phase-reinforced Cu-Sn-Ti active solders prepared in Examples 1-2 and Control Example 1.

[0027] The brazing filler metals obtained in Examples 1 and 2 and Comparative Example 1 were mixed with diamond particles and a wear-resistant coating was prepared on a high-nitrogen steel plate by vacuum brazing (temperature 920℃, holding for 10 min). The macroscopic Vickers hardness and bonding strength were measured respectively. Macro Vickers hardness test: A diamond indenter is used to contact the coating surface at a rate of 0.2 mm / s, the ambient temperature is 25℃, a test force of 49.03 N is selected, and the test is held for 10-15 s. The hardness is then calculated. Bond strength test: The bond strength of the coating is tested by a vertical tensile test.

[0028] The test results are shown in Table 1: Table 1 Group Macro Vickers hardness Bond strength MPa Example 1 285 238 Example 2 298 236 Compare with Example 1 165 180 As shown in Table 1, the MAB phase-reinforced Cu-Sn-Ti active solder prepared in the embodiments of this application has excellent performance. Its hardness and bonding strength are higher than those of the control example. Compared with Example 2, the control example 1 uses Cu powder instead of MoAlB powder. The test results show that the hardness and bonding strength of the wear-resistant coating are lower than those of Example 2, indicating that the control example 1 is not as good as Example 2.

[0029] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A MAB phase-reinforced Cu-Sn-Ti active solder, characterized in that, This MAB phase-reinforced Cu-Sn-Ti active solder uses the MAB phase as the reinforcing phase, which is a layered ternary boride ceramic, where M is Mo or Cr and A is Al. The solder, by mass percentage, includes 60-65% Cu powder, 15-18% Sn powder, 10-12% Ti powder, and the remainder is MAB powder.

2. The MAB phase-reinforced Cu-Sn-Ti active solder according to claim 1, characterized in that, The Cu powder has a purity of ≥99.5% and an average particle size of 10-45 μm; the Sn powder has a purity of ≥99.5% and an average particle size of 10-45 μm; the Ti powder has a purity of ≥99.5% and an average particle size of 10-45 μm.

3. The MAB phase-reinforced Cu-Sn-Ti active solder according to claim 1, characterized in that, The MAB powder is Cr2AlB2 or MoAlB.

4. A method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Weigh M, A and B according to the atomic ratio, mix and ball-mill, heat-treat, and obtain MAB powder; S2. Weigh out Cu powder, Sn powder, Ti powder and MAB powder according to the formula and mix them to obtain composite solder powder; S3. Mix the composite solder powder from step S2 with polyacrylate, roll, degrease, and sinter to obtain a MAB phase reinforced Cu-Sn-Ti active solder foil, or melt and atomize the composite solder powder from step S2 to obtain a MAB phase reinforced Cu-Sn-Ti active solder powder.

5. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, In step S1, the ball milling medium is cemented carbide balls, the ball-to-material ratio is 10-20:1, the rotation speed is 300-500 rpm, and the time is 20-50 h.

6. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, The heat treatment involves heating to 800-1100℃ at a heating rate of 5-20℃ / min and holding at that temperature for 0.5-2 hours, with an inert gas purging during the heat treatment process.

7. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, The degreasing process is carried out at a temperature of 250-350℃ for 2-3 hours.

8. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, The sintering process is carried out at a temperature of 450-550℃ for 1-2 hours, during which argon gas is introduced.

9. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, The atomization powder production process uses nitrogen or argon as the atomizing gas, with a purity ≥99%, and an atomization pressure of 3-6 MPa.

10. The method for preparing a MAB phase-reinforced Cu-Sn-Ti active solder according to claim 4, characterized in that, The active solder powder is a spherical powder with a particle size of 15-53 μm.