Preparation and application of composite solder based on cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase

Abstract

This invention discloses the preparation and application of a composite brazing filler metal with uniform TiC reinforcing phase distribution based on the cold spray impact embedding effect, relating to the field of welding materials technology. The method involves cold spraying component powders for preparing the composite brazing filler metal onto the surface of the workpiece to be welded, thereby preparing a composite brazing filler metal layer. The composite brazing filler metal layer of this invention has advantages such as high deposition efficiency, low porosity, and uniform distribution, which can significantly improve the strength and welding efficiency of the welded joint. This invention solves the problems of easy oxidation of active elements, easy agglomeration of reinforcing phases, and poor bonding with the matrix in traditional composite brazing filler metals. It helps to alleviate residual stress in dissimilar joints, improve joint strength and stability, and allows for flexible control of multiple physical properties of the intermediate layer of the composite brazing filler metal, increasing the freedom of preparation and design, and achieving high-quality and reliable bonding between composite materials and metals.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, specifically to the preparation and application of a composite brazing filler metal based on the cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase. Background Technology

[0002] Composite materials are widely used in the aerospace field due to their lightweight, high strength and thermal stability. To solve the problems of high brittleness and difficult machining of composite materials, it is necessary to prepare ceramic-metal composite components.

[0003] Active brazing is currently the most common method for joining composite materials and metals. It utilizes the reaction between active elements in the brazing filler metal and the composite material to promote the wetting of the liquid brazing filler metal. The active brazing of composite materials and metals needs to solve the following problems: (1) Select a suitable intermediate layer of brazing filler metal and reinforcing phase to achieve the wetting of the composite material by the brazing filler metal and to achieve a gradient transition of the thermal expansion coefficient of the brazed joint, thereby controlling the residual stress of the joint. (2) Improve the distribution of the reinforcing phase in the joint, avoid a large amount of agglomeration of the reinforcing phase in the joint, reduce the brittleness of the joint structure, and improve the load-bearing capacity of the joint.

[0004] Compared to metal-based composite brazing intermediate layers prepared by traditional methods, the cold spraying technique not only significantly improves the aforementioned problems but also offers the following unique advantages: The low-temperature processing characteristic of cold spraying avoids the oxidation and pre-reaction of active elements such as Ti in the brazing filler metal at high temperatures, resulting in a dense coating structure with high bonding strength. The impact embedding effect of cold spraying allows for uniform distribution of the reinforcing phase. Hard reinforcing phase particles (such as SiC, TiC, and Si3N4) impact the plastic brazing filler metal matrix with high kinetic energy; some particles directly embed into the plastic deformation zone of the matrix, while others are encapsulated by subsequently deposited brazing filler metal particles, forming a "mechanical interlocking" structure and achieving a uniformly dispersed distribution.

[0005] In summary, the preparation and application of composite brazing filler metals with uniform TiC reinforcing phase distribution based on the cold spraying impact embedding effect is a novel process with unique advantages and has great application potential in the field of composite materials or ceramic-metal bonding. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technology, this invention provides a composite brazing filler metal preparation and application based on the cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase. It aims to solve the problems of easy oxidation of active elements in the intermediate layer, easy agglomeration of reinforcing phase, and poor bonding with the matrix prepared by traditional methods, thereby improving the reliability of composite materials or ceramic-metal brazing joints.

[0007] The first objective of this invention is to provide a method for preparing composite solders that achieves uniform distribution of TiC reinforcing phase based on the cold spraying impact embedding effect, comprising the following steps: The reinforcing phase powder and the brazing filler matrix powder were mixed using a ball milling process to obtain a uniformly mixed powder. By cold spraying the uniformly mixed powder onto a metal substrate to form a composite solder coating of a certain thickness, a composite solder intermediate layer with uniformly distributed reinforcing phase can be obtained. The composite brazing filler metal intermediate layer is polished to 200~400μm with SiC sandpaper, cleaned with anhydrous ethanol, and then the composite material base material to be welded is placed on the composite brazing filler metal intermediate layer to obtain the part to be welded. The workpiece to be welded is placed in a vacuum brazing furnace with a vacuum level of 10. -2 ~10 -3 Pa, heat to the brazing temperature of 1120~1180℃ at a certain heating rate, hold for 10~30min, then cool to 300~500℃ at a certain cooling rate, and then cool with the furnace to below 100℃. Open the furnace and take out the part, thus completing the brazing of the composite material and the metal substrate. The reinforcing phase powder is one or more of TiC, WC, Si3N4, SiC, and Al2O3; The solder matrix powder is one or more of copper powder, silver powder, titanium powder, and nickel powder.

[0008] Preferably, when using ball milling for mixing, the mixture is uniformly mixed at a transmission ratio of 1 to 2.25 and a ball milling rate of 100 to 500 r / min.

[0009] Preferably, during the cold spraying process, a gas temperature of 200℃~600℃, a main gas pressure of 2~6MPa, a spraying distance of 10~40mm, and a spraying speed of 20~80mm / s are used for cold spraying.

[0010] Preferably, the thickness of the composite solder coating is 0.5-2 mm.

[0011] Preferably, the metal substrate comprises a high-temperature alloy, a high-entropy alloy, or a refractory metal substrate.

[0012] Preferably, the base material of the composite material to be welded is Si3N4, SiC / SiC, or C / C composite material.

[0013] Preferably, the heating rate is 10~20℃ / min; the cooling rate is 4~10℃ / min.

[0014] Preferably, the volume fraction ratio of the reinforcing phase powder to the solder matrix powder is 1:1~2.

[0015] A second objective of this invention is to provide an application of the above-described method in the bonding of composite materials or ceramics with metal substrates.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a composite brazing filler metal preparation and application based on the impact embedding effect of cold spraying to achieve uniform distribution of TiC reinforcing phase. The low-temperature solid deposition characteristics of the cold spraying technology involved in this invention effectively avoid the oxidation and pre-reaction of active elements such as Ti in the brazing filler metal at high temperatures, and can form a dense and high-bonding-strength coating structure. In the brazed joint, it promotes the diffusion of elements such as Ni, Ti, and Cr, thereby improving the distribution state of brittle compounds in the joint.

[0017] This invention utilizes the process of breaking down and uniformly spreading TiC through layer-by-layer impacts, embedding it into the deformation pits of a ductile solder matrix. Subsequent continuous particle impacts generate a micro-forging embedding effect, ensuring uniform dispersion of TiC within the composite solder and suppressing agglomeration. This entirely solid-state process, without liquid phase flow or gravity-driven TiC agglomeration, solves the agglomeration problem inherent in traditional melting, casting, and sintering methods.

[0018] This invention utilizes cold spraying technology to flexibly adjust various physical properties of the metal composite solder interlayer, including the reinforcing phase content, elastic modulus, and coefficient of thermal expansion. It also enables the fabrication of high-quality composite solder interlayers on various complex metal structures, offering high design freedom and fabrication efficiency. This provides significant advantages in certain specialized applications. Attached Figure Description

[0019] Figure 1 SiC prepared for Comparative Example 1 f Microstructure of brazed joints of SiC composite materials; Figure 2 The microstructure of the composite solder interlayer with uniformly distributed TiC reinforcing phase prepared in Example 1; Figure 3 The X-ray diffraction results are for the composite solder interlayer with uniformly distributed TiC reinforcing phase prepared in Example 1. Figure 4 The SiC prepared in Example 1 f Microstructure of brazed joints of SiC composite materials. Detailed Implementation

[0020] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0021] The purpose of this invention is to provide a composite brazing filler metal preparation and application based on the impact embedding effect of cold spraying to achieve uniform distribution of TiC reinforcing phase. It aims to solve the technical problems of welding defects caused by reinforcing phase agglomeration and reduced joint performance in metal composite brazing filler metals, as well as the easy oxidation of active elements and poor bonding between the reinforcing phase and the matrix in traditional composite brazing filler metals. This invention prepares a composite brazing filler metal layer by cold spraying the component powders used to prepare the composite brazing filler metal onto the surface of the workpiece to be welded. Benefiting from the impact embedding effect of cold spraying technology, the composite brazing filler metal layer of this invention has advantages such as high deposition efficiency, low porosity, and uniform distribution, which can significantly improve the strength and welding efficiency of the welded joint. This invention solves the problems of easy oxidation of active elements, easy agglomeration of reinforcing phase, and poor bonding with the matrix in traditional composite brazing filler metals. It helps to alleviate residual stress in dissimilar joints, improve joint strength and stability, and allows for flexible control of multiple physical properties of the intermediate layer of the composite brazing filler metal, increasing the freedom of preparation and design, and achieving high-quality and reliable connection between composite materials and metals. It can be widely used in the design and manufacturing of high-performance components in aerospace, energy, and advanced manufacturing fields such as aircraft brake discs, solid rocket throat liner diffusion sections, and materials for the International Thermonuclear Experimental Reactor (ITER).

[0022] To achieve the above objectives, the first aspect of the present invention provides a method for preparing composite solder based on the cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase, comprising the following steps: The reinforcing phase powder and the brazing filler matrix powder were mixed using a ball milling process to obtain a uniformly mixed powder. By cold spraying the uniformly mixed powder onto a metal substrate to form a composite solder coating of a certain thickness, a composite solder intermediate layer with uniformly distributed reinforcing phase can be obtained. The composite brazing filler metal intermediate layer is polished to 200~400μm with SiC sandpaper, cleaned with anhydrous ethanol, and then the composite material base material to be welded is placed on the composite brazing filler metal intermediate layer to obtain the part to be welded. The workpiece to be welded is placed in a vacuum brazing furnace with a vacuum level of 10. -2 ~10 -3 Pa, heat to the brazing temperature of 1120~1180℃ at a certain heating rate, hold for 10~30min, then cool to 300~500℃ at a certain cooling rate, and then cool with the furnace to below 100℃. Open the furnace and take out the part, thus completing the brazing of the composite material and the metal substrate. The reinforcing phase powder is one or more of TiC, WC, Si3N4, SiC, and Al2O3; The solder matrix powder is one or more of copper powder, silver powder, titanium powder, and nickel powder.

[0023] The volume fraction ratio of the reinforcing phase powder to the solder matrix powder is 1:1~2, preferably 1:1.5.

[0024] This invention utilizes the process of breaking down and uniformly spreading TiC through layer-by-layer impacts, embedding it into the deformation pits of a ductile solder matrix. Subsequent continuous particle impacts generate a micro-forging embedding effect, ensuring uniform dispersion of TiC within the composite solder and suppressing agglomeration. This entirely solid-state process, without liquid phase flow or gravity-driven TiC agglomeration, solves the agglomeration problem inherent in traditional melting, casting, and sintering methods.

[0025] When using ball milling for mixing, the mixture is uniformly mixed at a transmission ratio of 1 to 2.25 and a ball milling rate of 100 to 500 r / min.

[0026] During the cold spraying process, a gas temperature of 200℃~600℃, a main gas pressure of 2~6MPa, a spraying distance of 10~40mm, and a spraying speed of 20~80mm / s are used for cold spraying.

[0027] The thickness of the composite solder coating is 0.5-2mm.

[0028] The metal substrate includes high-temperature alloys, high-entropy alloys, or refractory metal substrates.

[0029] The base material of the composite material to be welded is Si3N4, SiC / SiC, or C / C composite material.

[0030] The heating rate is 10~20℃ / min; the cooling rate is 4~10℃ / min.

[0031] A second aspect of the present invention provides an application of the above-described method in the joining of composite materials or ceramics with metal substrates.

[0032] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0033] The SiC used below f The SiC composite material was independently developed and prepared by Northwestern Polytechnical University using the Chemical Vapor Infiltration (CVI) method, as described in references [1] and [2]. The CVI method is currently the most advanced method for preparing SiC composite materials. fThe preferred process for SiC composite materials involves using high-purity hydrogen as a carrier gas on a pre-woven SiC fiber preform to introduce organosilicon precursors such as methyl trichlorosilane (MTS) or tetramethyl silane (TMS) into a reaction chamber. The SiC matrix is ​​then deposited via pyrolysis at a constant temperature of approximately 1000°C. This technology offers significant advantages: First, its relatively low processing temperature (far below the melting point of the SiC matrix material) effectively reduces the risk of fiber damage, ensuring the integrity of the matrix structure. Second, the CVI process enables near-net-shape forming of complex components, significantly reducing subsequent processing costs. Furthermore, by precisely controlling process parameters such as deposition temperature, pressure, and gas flow rate, functionally graded materials with compositional and performance gradients can be prepared to meet the specific needs of different applications.

[0034] References: [1]WJ Kim, SM Kang, JY Park, et al. Effect of a SiC whiskerformation on the densification of Tyranno SiC / SiC composites fabricated by the CVI process [J]. Fusion Engineering and Design, 2006, 81:931. [2]W. Yang, H. Araki, A. Kohyama, et al. The effect of SiC nanowireson the flexural properties of CVI-SiC / SiC composited [J]. J NuclearMaterials, 2007, 367-370:708. Example 1 This embodiment 1 provides a method for preparing composite solder based on the cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase, which is implemented according to the following steps: 1. Put TiC powder, copper powder and titanium powder into a ball mill in a volume fraction ratio of 4:3:3, and mix them evenly using ball milling process at a transmission ratio (r) of 1.5 and a ball milling rate of 400 r / min. 2. The uniformly mixed powder is cold-sprayed at a gas temperature of 500℃, a main gas pressure of 5MPa, a spraying distance of 20mm, and a spraying speed of 40mm / s. The mixed powder is sprayed onto the metal substrate to form a composite solder coating with a thickness of 0.5mm, thus obtaining a composite solder intermediate layer with a uniformly distributed TiC reinforcing phase. 3. After polishing the intermediate layer of the composite solder obtained in step 2 to 300μm with SiC sandpaper and cleaning it with anhydrous ethanol, the SiC layer to be soldered is then... f The SiC composite material matrix is ​​placed on the GH3536 metal substrate to be welded, which has a composite material intermediate layer, to obtain the workpiece to be welded.

[0035] 4. Place the workpiece obtained in step 3 into a vacuum brazing furnace, heat it to 1160°C at a heating rate of 10°C / min, hold it at that temperature for 20 minutes, then cool it to 400°C at a cooling rate of 5°C / min, and then cool it down to below 100°C with the furnace. Open the furnace and remove the workpiece to complete the brazing of the composite material and the high-temperature alloy.

[0036] This embodiment utilizes the impact embedding effect of cold spraying to prepare a composite brazing filler metal with a uniformly distributed TiC reinforcing phase, significantly improving brazing connections. The low-temperature processing characteristic of cold spraying avoids the oxidation and pre-reaction of active elements such as Ti at high temperatures, resulting in a dense coating structure with high bonding strength. Simultaneously, the TiC is broken down during the layer-by-layer impact of cold spraying and benefits from the micro-forging embedding effect generated by continuous impact, ensuring uniform dispersion of TiC in the composite brazing filler metal and inhibiting agglomeration. The uniform distribution of the reinforcing phase in the composite brazing filler metal prepared by this method is beneficial for improving joint strength and stability, achieving a high-quality and reliable connection between the composite material and the metal.

[0037] Example 2 This embodiment is the same as Embodiment 1, except that the reinforcing phase described in step one is WC particles with a volume fraction of 40%.

[0038] Example 3 This embodiment is the same as Embodiment 1, except that the brazing filler metal matrix described in step one is a mixture of titanium powder and nickel powder in a volume ratio of 1:1.

[0039] Example 4 This embodiment is the same as Embodiment 1, except that the thickness of the sprayed coating in step two is 0.6 mm.

[0040] Example 5 This embodiment is the same as Embodiment 1, except that the type of metal substrate mentioned in step two is the refractory metal Nb.

[0041] Example 6 This embodiment is the same as Embodiment 1, except that the base material in step three is C.f / C composite material.

[0042] Example 7 This embodiment is the same as Embodiment 1, except that the heating rate in step four is 10℃ / min and the brazing temperature is 1120℃.

[0043] Example 8 This embodiment is the same as Embodiment 1, except that in step four, the temperature is cooled to 400°C at a rate of 10°C / min, and then cooled to below 100°C in the furnace.

[0044] Comparative Example 1 Direct welding of SiC using traditional brazing filler metal intermediate layer f The / SiC composite material is produced by the following steps: I. This experiment uses the casting method to obtain the intermediate layer of traditional brazing filler metal; 2. Place the solder interlayer obtained in step one on two SiC blocks. f The SiC composite material is fixed in the middle to obtain the part to be welded; 3. Place the workpiece to be welded obtained in step 2 into a vacuum brazing furnace, heat it to 1160°C at a heating rate of 15°C / min, hold it at that temperature for 20 minutes, and then cool it to 400°C at a cooling rate of 5°C / min. After that, cool it down to below 100°C with the furnace, open the furnace and take out the workpiece. This completes the brazing of the composite material and the high-temperature alloy. Comparative Example 1 was tested and found that SiC f The shear strength of the brazed joint of the SiC composite material is 28.3 MPa.

[0045] To illustrate the preparation of a composite solder based on the cold spraying impact embedding effect to achieve uniform distribution of TiC reinforcing phase, the accompanying drawings are provided.

[0046] Figure 1 SiC obtained for Comparative Example 1 f Microstructure of SiC composite brazed joints. From Figure 1 It can be observed that the dark gray TiC on the composite material side agglomerates, and the microstructure at the interface is uneven, resulting in stress concentration at the joint.

[0047] The difference between Example 1 and Comparative Example 1 is that step one uses cold spraying to prepare the active metal composite solder interlayer. Example 1 was tested and found that SiC... f The shear strength of the SiC composite brazed joint is 81.3 MPa. This is attributed to the uniform distribution of the TiC reinforcing phase in the composite brazing filler metal prepared by cold spraying. The joint obtained in Example 1 avoids the aggregation of brittle phases, thereby hindering crack initiation and propagation. The joint strength in Example 1 is approximately 187% higher than that in Comparative Example 1.

[0048] Figure 2 The microstructure of the composite solder interlayer with uniformly distributed TiC reinforcing phase prepared in Example 1; from Figure 2 It can be observed that the dark gray TiC reinforcing phase is relatively uniformly distributed in the solder matrix and is tightly bonded to the solder matrix without obvious pores.

[0049] Figure 3 The X-ray diffraction results are for the composite solder interlayer with uniformly distributed TiC reinforcing phase prepared in Example 1; from Figure 3 Diffraction peaks of Ti, Cu and TiC can be observed, confirming that no metallurgical reaction occurred between the TiC reinforcing phase, Ti powder and Cu powder during the cold spraying process, thus achieving effective solid-state low-temperature deposition.

[0050] Figure 4 The SiC prepared in Example 1 f Microstructure of SiC composite brazed joints. From Figure 4 It can be observed that the microstructure in the brazing seam is uniformly distributed, which is significantly different from the microstructure of the joint in Comparative Example 1. In this joint, TiC did not agglomerate, and the joint bonding is good.

[0051] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing composite solder based on the impact embedding effect of cold spraying to achieve uniform distribution of TiC reinforcing phase, characterized in that, Includes the following steps: The reinforcing phase powder and the brazing filler matrix powder were mixed using a ball milling process to obtain a uniformly mixed powder. By cold spraying the uniformly mixed powder onto a metal substrate to form a composite solder coating of a certain thickness, a composite solder intermediate layer with uniformly distributed reinforcing phase can be obtained. The composite brazing filler metal intermediate layer is polished to 200~400μm with SiC sandpaper, cleaned with anhydrous ethanol, and then the composite material base material to be welded is placed on the composite brazing filler metal intermediate layer to obtain the part to be welded. The workpiece to be welded is placed in a vacuum brazing furnace with a vacuum level of 10. -2 ~10 -3 Pa, heat to the brazing temperature of 1120~1180℃ at a certain heating rate, hold for 10~30min, then cool to 300~500℃ at a certain cooling rate, and then cool with the furnace to below 100℃. Open the furnace and take out the part, thus completing the brazing of the composite material and the metal substrate. The reinforcing phase powder is one or more of TiC, WC, Si3N4, SiC, and Al2O3; The solder matrix powder is one or more of copper powder, silver powder, titanium powder, and nickel powder.

2. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, When using ball milling for mixing, uniform mixing is achieved at a transmission ratio of 1 to 2.25 and a ball milling rate of 100 to 500 r / min.

3. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, During the cold spraying process, a gas temperature of 200℃~600℃, a main gas pressure of 2~6MPa, a spraying distance of 10~40mm, and a spraying speed of 20~80mm / s are used for cold spraying.

4. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, The thickness of the composite solder coating is 0.5-2mm.

5. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, The metal substrate includes high-temperature alloys, high-entropy alloys, or refractory metal substrates.

6. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, The base material of the composite material to be welded is Si3N4, SiC / SiC, or C / C composite material.

7. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, The heating rate is 10~20℃ / min; the cooling rate is 4~10℃ / min.

8. The method for preparing composite solder with uniform distribution of TiC reinforcing phase based on cold spraying impact embedding effect according to claim 1, characterized in that, The volume fraction ratio of the reinforcing phase powder to the solder matrix powder is 1:1~2.

9. The application of the method according to any one of claims 1 to 8 in the bonding between composite materials or ceramics and metal substrates.

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