A method and product for enhancing the bonding strength between cold spray coating and substrate.

Abstract

This invention provides a method and product for enhancing the bonding strength between a cold-sprayed coating and a substrate, belonging to the field of materials engineering technology. The method involves first subjecting the cold-sprayed workpiece to ultrasonic curing, using ultrasonic energy to break down the oxide film between particles in the cold-sprayed coating, improving the interparticle interface. Then, annealing is performed to further enhance the bonding strength between the cold-sprayed coating and the substrate. The ultrasonic curing frequency is 15kHz to 40kHz, and the peak power is 500W to 2000W. Annealing further eliminates microscopic defects in the cold-sprayed coating, promotes metallurgical bonding between cold-sprayed particles and between particles and the substrate, thereby improving the bonding strength between the coating and the substrate. This invention also provides a workpiece with a firmly bonded cold-sprayed coating to the substrate obtained by the above method. The method of this invention is simple in process, convenient to operate, has a significant improvement effect, and is widely applicable.

Description

Technical Field

[0001] This invention belongs to the field of materials engineering technology, specifically relating to a method and product for ultrasonically assisted enhancement of the bonding strength between a cold spray coating and a substrate. Background Technology

[0002] Cold spraying is a solid-state deposition technique that uses compressed gas to accelerate powder particles to above a critical velocity, causing them to deposit into a coating through solid-state plastic deformation. Throughout the process, the powder particles are not melted. Therefore, cold spraying offers advantages such as low powder heating temperature, low coating porosity, and dense structure, making it highly favored by researchers. Cold spraying can be used not only for coating preparation and part repair but also for the preparation of certain bulk materials, demonstrating significant application potential.

[0003] Because powder particles are deposited through intense plastic deformation, the bonding between particles is primarily mechanical and physical. Therefore, the internal particle bonding within the coating is not strong, resulting in numerous defects and low adhesion between the coating and the substrate. Appropriate post-processing techniques can improve the adhesion between cold-sprayed coatings and the substrate. These techniques include heat treatment, laser remelting, friction stir processing, and hot isostatic pressing, which can significantly enhance the adhesion. However, these post-processing techniques have limited effectiveness in improving adhesion and are constrained by their respective processing characteristics. For example, the temperature of heat treatment is limited by both the coating and substrate materials, laser remelting can easily cause significant residual stress, and hot isostatic pressing has a limited processing area.

[0004] Therefore, there is an urgent need to explore a cold spraying post-treatment process that is simple to process and has good applicability. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method and product for enhancing the bonding strength between cold spray coating and substrate. It combines ultrasonic curing and annealing to improve the bonding strength between cold spray coating and substrate, aiming to solve the deficiencies of cold spray post-treatment processes in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for enhancing the bonding strength between a cold-sprayed coating and a substrate is provided. The cold-sprayed workpiece is first subjected to ultrasonic curing treatment, which uses ultrasonic energy to destroy the oxide film between particles in the cold-sprayed coating and improve the interparticle interface state. Then, an annealing treatment is performed to enhance the bonding strength between the cold-sprayed coating and the substrate.

[0007] Furthermore, it includes the following steps:

[0008] S1: Grinding and smoothing the surface of the coating after cold spraying.

[0009] S2: Perform ultrasonic curing treatment on the surface of the cold-sprayed coating after grinding and leveling. The ultrasonic frequency of the ultrasonic curing treatment is 15KHZ~40KHZ, and the peak power of the ultrasonic curing treatment is 500W~2000W.

[0010] S3: Anneal the sample after ultrasonic curing.

[0011] Furthermore, in step S1, the thickness of the cold spray coating is 0.4 mm to 2 mm.

[0012] Furthermore, the materials of the cold spray coating and the substrate are one or more of pure metals, alloys, and metal-based composite materials.

[0013] Furthermore, the thickness of the cold spray coating is 0.8mm to 1.2mm, the ultrasonic frequency of the ultrasonic curing treatment is 20KHZ to 30KHZ, and the peak power of the ultrasonic curing treatment is 800W to 1500W.

[0014] Furthermore, in step S3, the annealing process is one of vacuum annealing, induction annealing, protective atmosphere annealing, and unprotected atmosphere annealing.

[0015] Furthermore, in step S3, the annealing treatment is used to further eliminate micro-defects in the cold spray coating, promote metallurgical bonding between cold spray particles and between particles and the substrate, thereby improving the bonding strength between the coating and the substrate.

[0016] Furthermore, the thickness of the cold spray coating, the frequency of the ultrasonic curing process, the peak power of the ultrasonic curing process, and the duration of the ultrasonic curing process are coordinated and adjusted to achieve a dense structure between the cold spray particles and between the cold spray particles and the substrate. For example, the ultrasonic curing process can be divided into multiple segments, each with different amplitudes, frequencies, and peak powers. In practical engineering, different combinations of ultrasonic curing processes are selected based on the different cold spray powder materials, substrate materials, powder particle sizes, properties, etc.

[0017] According to a second aspect of the invention, a processed part in which a cold spray coating obtained by the method described above is firmly bonded to a substrate is also provided.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention have the following advantages:

[0019] Beneficial effects:

[0020] (1) This invention combines ultrasonic curing and annealing. First, ultrasonic energy is used to destroy the oxide film between particles in the cold spray coating and improve the interfacial state between particles. Then, annealing is used to eliminate micro-defects in the coating and promote metallurgical bonding, thereby improving the bonding strength between the coating and the substrate. In this invention, the process sequence of ultrasonic curing and annealing must be ultrasonic curing first and then annealing. If the process sequence is reversed, there will be more defects between the cold spray coating and the substrate, and the bonding strength will be lower than that of the process of ultrasonic curing first and then annealing.

[0021] (2) The method of the present invention has a simple process, is easy to operate, has a significant improvement effect, and is widely applicable. Attached Figure Description

[0022] Figure 1 This is a flowchart of the steps of the method for enhancing the bonding strength between an ultrasonically assisted cold spray coating and a substrate provided in an embodiment of the present invention;

[0023] Figure 2 This is a cross-sectional microstructure diagram of the initial state cold spray coating provided in the embodiments of the present invention;

[0024] Figure 3 This is a microstructure diagram of the cross-section of the workpiece after ultrasonic curing and annealing in Embodiment 2 of the present invention;

[0025] Figure 4 The image shows the cross-sectional microstructure of the cold-sprayed coating after annealing in Comparative Example 1.

[0026] Figure 5 This is a comparison of the shear strength between the composite coating and the substrate under different treatment conditions. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] This application proposes a method for ultrasonically assisted enhancement of the bonding strength between a cold-sprayed coating and a substrate. The inventive concept involves: smoothing the surface of the cold-sprayed sample, performing ultrasonic curing, using ultrasonic energy to break down the oxide film between particles in the cold-sprayed coating, improving the interparticle interface state, and then annealing to eliminate microscopic defects in the coating, promoting metallurgical bonding, and thus improving the bonding strength between the coating and the substrate. In this invention, the process sequence of ultrasonic curing and annealing must be ultrasonic curing first, followed by annealing. The ultrasonic curing time, ultrasonic frequency, and peak power need to be matched and suitable; excessively strong ultrasonic curing has limited improvement on the sample and is detrimental to ultrasonic treatment.

[0029] Figure 1 This is a flowchart illustrating the steps of the method for enhancing the bonding strength between an ultrasonically assisted cold-spray coating and a substrate, as provided in this embodiment of the invention. Figure 1 As shown, it includes the following steps:

[0030] (1) Grind the surface of the cold spray coating sample until it is smooth;

[0031] (2) Perform ultrasonic curing treatment on the sample surface;

[0032] (3) Anneal the ultrasonically cured sample.

[0033] The following will describe, with reference to several specific embodiments, a method for enhancing the bonding strength between an ultrasonically assisted cold spray coating and a substrate as described in this application.

[0034] Example 1

[0035] Step 1: Using CuCrZr powder and pure W powder as raw materials, the CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3. The CuCrZr powder was spherical with a particle size distribution of 15μm–53μm, and the pure W powder was spherical with a particle size distribution of 5μm–25μm. Then, low-energy ball milling was performed to prepare the composite powder, with a ball-to-powder ratio of 1:1, a rotation speed of 250 r / min, and a time of 4 h. Using Cu-Al2O3 (C17560) as the substrate, a CuCrZr-W composite coating was prepared on the surface of the Cu-Al2O3 substrate by cold spraying. The cold spraying parameters were: gun chamber temperature: 800℃, gun chamber pressure: 5MPa, scanning interval: 1 pith / min, powder feed rotation speed: 10 r / min, and gun travel speed: 300 mm / s. The sample surface was then polished until smooth, and the coating thickness after polishing was 800 μm.

[0036] Figure 2 This is a cross-sectional microstructure diagram of the initial state cold-sprayed coating provided in the embodiments of the present invention, such as... Figure 2 As shown, the cross-sectional microstructure of the CuCrZr-W composite coating after spraying was observed. Due to the predominantly mechanical bonding of powder particles during cold spraying, numerous micro-defects appeared within the coating, and the interparticle bonding was weak, with W particles easily detaching and leaving pits. A thin metal plate double shear strength test was performed on the sample, and the shear strength between the composite coating and the substrate was 169±11 MPa.

[0037] Step 2: Perform ultrasonic curing treatment on the surface of the cold-sprayed sample. The parameters are as follows: frequency is 20KHZ, peak power is 500W, time is 2s, and the ultrasonic curing treatment frequency band is divided into two segments: segment A has an amplitude of 90% and segment B has an amplitude of 50%.

[0038] Step 3: The ultrasonically cured samples were annealed at 500℃ for 20 hours without atmosphere protection. The samples treated with ultrasonic curing and annealing were then subjected to a thin metal sheet double shear strength test. The shear strength between the composite coating and the substrate was 213±7 MPa. This represents a significant improvement compared to the original shear strength of 169±11 MPa.

[0039] Example 2

[0040] Step 1: Using CuCrZr powder and pure W powder as raw materials, the CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3. The CuCrZr powder was spherical with a particle size distribution of 15-53 μm, and the pure W powder was spherical with a particle size distribution of 5-25 μm. Then, low-energy ball milling was performed to prepare composite powder, with a ball-to-powder ratio of 1:1, a rotation speed of 250 r / min, and a time of 4 h. Using Cu-Al2O3 (C17560) as the substrate, a CuCrZr-W composite coating was prepared on the surface of the Cu-Al2O3 substrate by cold spraying. The cold spraying parameters were: gun chamber temperature: 800℃, gun chamber pressure: 5 MPa, scanning interval: 1 pith / min, powder feed rotation speed: 10 r / min, and gun travel speed: 300 mm / s. The sample surface was then polished until smooth, and the coating thickness after polishing was 800 μm.

[0041] like Figure 2 As shown, the cross-sectional microstructure of the CuCrZr-W composite coating after spraying was observed. Due to the predominantly mechanical bonding of powder particles during cold spraying, numerous micro-defects appeared within the coating, and the interparticle bonding was weak, with W particles easily detaching and leaving pits. A thin metal plate double shear strength test was performed on the sample, and the shear strength between the composite coating and the substrate was 169±11 MPa.

[0042] Step 2: Perform ultrasonic curing treatment on the surface of the cold-sprayed sample. The parameters are as follows: frequency is 20KHZ, peak power is 1000W, time is 1s, and the ultrasonic curing treatment frequency band is divided into two segments: segment A has an amplitude of 90% and segment B has an amplitude of 50%.

[0043] Step 3: Anneal the ultrasonically cured sample. The annealing parameters are 500℃ for 20 hours without atmosphere protection. Figure 3 This is a microstructure image of the cross-section of the workpiece after ultrasonic curing and annealing in Embodiment 2 of the present invention. Figure 3 It can be seen that after ultrasonic curing and annealing, the coating has a dense internal structure with no obvious defects. The thin metal plate double shear strength test was performed on the sample after ultrasonic curing and annealing. The shear strength between the composite coating and the substrate was 246±17 MPa. The shear strength is significantly improved compared to the original state.

[0044] Example 3

[0045] Step 1: Using CuCrZr powder and pure W powder as raw materials, the CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3. The CuCrZr powder was spherical with a particle size distribution of 15-53 μm, and the pure W powder was spherical with a particle size distribution of 5-25 μm. Then, low-energy ball milling was performed to prepare composite powder, with a ball-to-powder ratio of 1:1, a rotation speed of 250 r / min, and a time of 4 h. Using Cu-Al2O3 (C17560) as the substrate, a CuCrZr-W composite coating was prepared on the surface of the Cu-Al2O3 substrate by cold spraying. The cold spraying parameters were: gun chamber temperature: 800℃, gun chamber pressure: 5 MPa, scanning interval: 1 pith / min, powder feed rotation speed: 10 r / min, and gun travel speed: 300 mm / s. The sample surface was then polished until smooth, and the coating thickness after polishing was 800 μm.

[0046] The sample was subjected to a thin metal plate double shear strength test, and the shear strength between the composite coating and the substrate was 169±11 MPa.

[0047] Step 2: Perform ultrasonic curing treatment on the surface of the cold-sprayed sample. The parameters are as follows: frequency is 20KHZ, peak power is 1150W, time is 1.3s, and the ultrasonic curing treatment frequency band is divided into two segments: segment A has an amplitude of 90% and segment B has an amplitude of 50%.

[0048] Step 3: The ultrasonically cured samples were annealed at 500℃ for 20 hours without atmosphere protection. The samples treated with ultrasonic curing and annealing were then subjected to a thin metal sheet double shear strength test. The shear strength between the composite coating and the substrate was 221±32 MPa. The shear strength was significantly improved compared to the original state.

[0049] Example 4

[0050] Step 1: Using CuCrZr powder and pure W powder as raw materials, the CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3. The CuCrZr powder was spherical with a particle size distribution of 15-53 μm, and the pure W powder was spherical with a particle size distribution of <30 μm. Then, low-energy ball milling was performed to prepare composite powder, with a ball-to-powder ratio of 1:1, a rotation speed of 250 r / min, and a time of 4 h. Using Cu-Al2O3 (C17560) as the substrate, a CuCrZr-W composite coating was prepared on the surface of the Cu-Al2O3 substrate by cold spraying. The cold spraying parameters were: gun chamber temperature: 800℃, gun chamber pressure: 5 MPa, scanning interval: 1 pith / min, powder feed speed: 10 r / min, and gun travel speed: 300 mm / s. The sample surface was then polished until smooth, and the coating thickness after polishing was 800 μm.

[0051] The sample was subjected to a thin metal plate double shear strength test, and the shear strength between the composite coating and the substrate was 147±35MPa.

[0052] Step 2: Perform ultrasonic curing treatment on the surface of the cold-sprayed sample. The parameters are as follows: frequency is 20KHZ, peak power is 1000W, time is 0.3s, and the ultrasonic curing treatment frequency band is divided into two segments: segment A has an amplitude of 80% and segment B has an amplitude of 50%.

[0053] Step 3: The ultrasonically cured samples were annealed at 500℃ for 20 hours without atmosphere protection. The ultrasonically cured and annealed samples were then subjected to a thin metal sheet double shear strength test. The shear strength between the composite coating and the substrate was 197±15 MPa. The shear strength was significantly improved compared to the original state.

[0054] Comparative Example 1

[0055] Using CuCrZr powder and pure W powder as raw materials, the CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3. The CuCrZr powder was spherical with a particle size distribution of 15-53 μm, and the pure W powder was spherical with a particle size distribution of 5-25 μm. The mixture was then ball-milled at a low-energy ball-to-powder ratio of 1:1 at a speed of 250 r / min for 4 h. Using Cu-Al2O3 (C17560) as the substrate, a CuCrZr-W composite coating was prepared on the surface of the Cu-Al2O3 substrate by cold spraying. The cold spraying parameters were: gun chamber temperature: 800℃, gun chamber pressure: 5 MPa, scanning interval: 1 pith / min, powder feed speed: 10 r / min, and gun travel speed: 300 mm / s. The sample surface was then polished until smooth, and the coating thickness after polishing was 800 μm.

[0056] The cross-sectional microstructure of the CuCrZr-W composite coating after spraying was observed. Due to the predominantly mechanical bonding of powder particles during cold spraying, numerous micro-defects appeared within the coating, and the interparticle bonding was weak, with W particles easily detaching and leaving pits. A thin metal plate double shear strength test was performed on the sample, and the shear strength between the composite coating and the substrate was 169±11 MPa. The original sample was then annealed at 500℃ for 20 hours without atmosphere protection.

[0057] Figure 4 The image shows a cross-sectional microstructure of the cold-sprayed coating after annealing in Comparative Example 1, as shown below. Figure 4 As shown, the micro-defects inside the coating of the annealed sample are greatly reduced, but a small number of pores remain that are difficult to heal. A double shear strength test was performed on the annealed sample on a thin metal plate, and the shear strength between the composite coating and the substrate was 192±11 MPa. The shear strength improvement compared to the original state was small.

[0058] Figure 5 The figure shows a comparison of the shear strength between the composite coating and the substrate under different treatment conditions. As can be seen from the figure, a statistical comparison of the shear strength between the composite coating and the substrate in the original state, the examples, and the comparative examples shows that the shear strength between the composite coating and the substrate is partially improved after annealing compared to the original state. The shear strength of the sample treated with ultrasonic curing and annealing is significantly higher than that of the comparative example. Among them, Example 2 has a significant effect on improving the shear strength, and its shear strength is about 3 times that of the comparative example.

[0059] In this invention, the ultrasonic curing frequency is 15kHz to 40kHz, the peak power is 500W to 2000W, and the cold spray coating thickness is 0.4mm to 2mm. Preferably, the cold spray coating thickness is 0.8mm to 1.2mm, the ultrasonic curing frequency is 20kHz to 30kHz, and the peak power is 800W to 1500W. The cold spray coating thickness, ultrasonic curing frequency, peak power, and curing time are coordinated and adjusted to achieve a dense structure between cold spray particles and between the cold spray particles and the substrate. For example, the ultrasonic curing process can be divided into multiple segments, each with different amplitudes, frequencies, and peak powers. In practical engineering, different ultrasonic curing processes are selected and combined according to the different cold spray powder materials, substrate materials, powder particle size, properties, etc. The ultrasonic curing time can be flexibly determined according to the different substrate materials and powder qualities, generally ranging from several seconds to tens of seconds.

[0060] In this invention, ultrasonic curing is applied to the cold-sprayed sample. The vibrational energy of the ultrasound causes deformation of the oxide film at the particle interface, leading to oxide film breakage and exposing more fresh metal interfaces on the bonding surface. This facilitates the healing of micropores and metallurgical bonding between particles, thereby improving the bonding strength. The cold-sprayed coating has a dense internal structure with discontinuous micropores at the nanometer scale. Therefore, even when annealed in an air atmosphere, oxidation occurs only on the surface and cannot penetrate into the coating interior. This makes it suitable for various annealing conditions and has wide applicability.

[0061] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for enhancing the bonding strength between a cold-sprayed coating and a substrate, characterized in that, CuCrZr powder and pure W powder were mixed at a mass ratio of 2:3 to form a CuCrZr-W composite coating on a Cu-Al2O3 substrate. After cold spraying, the processed parts are first subjected to ultrasonic curing. Ultrasonic energy is used to break down the oxide film between particles in the cold spray coating, causing deformation of the oxide film at the particle interface, resulting in oxide film breakage and exposing more fresh metal interfaces. This improves the interparticle interface state, which is beneficial for the subsequent healing of micropores and metallurgical bonding between particles. Then, annealing is performed to further eliminate micro-defects in the cold-sprayed coating, promote metallurgical bonding between cold-sprayed particles and between particles and the substrate, thereby enhancing the bonding strength between the cold-sprayed coating and the substrate. It includes the following steps: S1: Grinding and smoothing the surface of the coating after cold spraying. S2: Perform ultrasonic curing treatment on the surface of the cold-sprayed coating after grinding and leveling. The thickness of the cold-sprayed coating is 0.4mm ~ 1.2mm, the ultrasonic frequency of the ultrasonic curing treatment is 20KHZ ~ 30KHZ, and the peak power of the ultrasonic curing treatment is 800W ~ 1500W. S3: Anneal the sample after ultrasonic curing.

2. The method for enhancing the bonding strength between a cold-sprayed coating and a substrate as described in claim 1, characterized in that, In step S3, the annealing process is one of vacuum annealing, induction annealing, protective atmosphere annealing, and unprotected atmosphere annealing.

3. The method for enhancing the bonding strength between a cold-sprayed coating and a substrate as described in claim 2, characterized in that, The thickness of the cold spray coating, the frequency of ultrasonic curing, the peak power of ultrasonic curing, and the time of ultrasonic curing are coordinated and adjusted to achieve a dense structure between cold spray particles and between cold spray particles and the substrate.

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