Novel aluminum alloy water-cooled plate CAB furnace brazing stop-off agent and application of novel aluminum alloy water-cooled plate CAB furnace brazing stop-off agent

Abstract

The invention discloses a novel aluminum alloy water-cooling plate CAB in-furnace brazing stop-off agent and application, and relates to the technical field of brazing stop-off agent preparation. The inorganic binder, titanium oxide, aluminum oxide, magnesium oxide, an aluminum dihydrogen phosphate inorganic binder, polyethylene glycol and other organic additives in the composite solid powder form a synergistic system; according to the invention, neodymium oxide can be subjected to a solid-phase interface reaction with oxidation films on the surfaces of 3003 and 6063 dissimilar aluminum alloys at a high brazing temperature to generate rare earth aluminate, so that firm chemical bonding is established between a coating and a matrix, and the problems that a traditional flow stopping agent is insufficient in adhesive force on the 6063 aluminum alloy and is easy to peel off under thermal stress and brazing filler metal scouring to cause flow stopping failure are solved. The stop-off agent is prepared into a slurry form, and the homogeneity and stability of the stop-off agent are ensured through a specific high-speed dispersion process.

Description

Technical Field

[0001] This invention belongs to the field of brazing choke agent preparation technology, and in particular relates to a novel aluminum alloy water-cooled plate CAB furnace brazing choke agent and its application. Background Technology

[0002] In the manufacturing process of aluminum alloy water-cooled plates, it is often necessary to perform in-furnace brazing of dissimilar materials, such as 3003 aluminum alloy and 6063 aluminum alloy. However, the adhesion of traditional flow-retardant is severely uneven on the two base materials with different compositions, which leads to its premature failure on the critical 6063 aluminum alloy side.

[0003] The root of this problem lies in the high magnesium content in 6063 aluminum alloy, which causes the formation of a more stable and unique oxide film on its surface (mainly containing magnesium). (and MgO). The composition system of traditional flow-blocking agents is difficult to form an effective chemical bond with this type of oxide film, resulting in inherently weak interfacial bonding between it and the 6063 aluminum alloy substrate.

[0004] Therefore, under the thermal stress and physical erosion of molten solder during CAB brazing, the flow-retardant coating preferentially cracks and peels off from the side with weaker adhesion, the 6063 aluminum alloy. Once the coating loses its integrity, the flow-retardant effect immediately fails, and the solder spreads undesirably, directly leading to product scrap. This uneven adhesion problem caused by dissimilar materials has become a major obstacle restricting the yield and reliability of water-cooled plate products. Therefore, the following solutions are proposed to address the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a novel CAB in-furnace brazing choke agent for aluminum alloy water-cooled plates and its application. By introducing high-purity neodymium oxide as a key interfacial active component into the high-performance choke agent formulation, it can undergo a unique solid-phase interfacial reaction with the oxide film on the surface of dissimilar aluminum alloys, forming a strong chemical bond bridge. This solves the problem of severely uneven adhesion of existing choke agents on the combination of 3003 and 6063 dissimilar aluminum alloys, especially on the 6063 side, where insufficient interfacial bonding leads to early peeling of the coating under brazing thermal stress and brazing filler metal erosion.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a novel CAB furnace brazing resistant agent for aluminum alloy water-cooled plates. The resistant agent is in slurry form, and its raw materials include the following components by weight percentage: The composition of the composite solid powder is as follows: 50% aluminum dihydrogen phosphate aqueous solution: 20%; composite solid powder: 38%; sodium carboxymethyl cellulose: 1.0%; polyethylene glycol: 22.5%; propylene glycol: 2.0%; fumed silica: 1.5%; ammonium polyacrylate dispersant: 0.5%; modified bentonite suspending agent: 0.8%; benzisothiazolinone preservative: 0.1%; deionized water: balance; wherein the composite solid powder is composed of the following components: titanium dioxide 58%, aluminum oxide 22%, magnesium oxide 10%, and neodymium oxide 10%.

[0007] Furthermore, the average particle size D50 of the composite solid powder is not greater than 5 μm.

[0008] Furthermore, the purity of the neodymium oxide is greater than 99.5%.

[0009] The preparation method of the novel aluminum alloy water-cooled plate CAB furnace brazing resistant agent of the present invention includes the following steps: Add the prescribed amounts of deionized water, propylene glycol, ammonium polyacrylate dispersant, and sodium carboxymethyl cellulose to a disperser and stir until completely dissolved; Add the amount of modified bentonite suspending agent specified in the formula and disperse at high speed for 10 minutes; Slowly add all of the composite solid powder, then stir at high speed for more than 40 minutes to form a homogeneous slurry; Add the prescribed amounts of polyethylene glycol and benzisothiazolinone preservative, and stir at medium speed for 15 minutes; Add 50% of the formula amount of aluminum dihydrogen phosphate aqueous solution and stir at medium speed for 20 minutes; Finally, add the prescribed amount of fumed silica to adjust the slurry viscosity, stir for another 15 minutes, and then discharge to obtain the flow barrier agent.

[0010] The application method of the novel aluminum alloy water-cooled plate CAB furnace brazing resistant agent of the present invention includes the following steps: The flow-blocking agent slurry is applied to the non-brazing spread area of ​​the aluminum alloy water-cooled plate through a coating process to form a wet film. The wet film is dried to form a flow-blocking agent coating with a dry film thickness of 30 μm to 70 μm; The aluminum alloy water-cooled plate coated with a flow-blocking agent was placed in a CAB brazing furnace for brazing, with a peak brazing temperature of 605℃±5℃. After brazing, an aluminum alloy water-cooled plate product with clear flow-blocking boundaries and no brazing filler metal penetration is obtained.

[0011] An aluminum alloy water-cooled plate coated with a flow-blocking agent, wherein the flow-blocking agent is a dry film coating formed by any of the flow-blocking agents described above.

[0012] Furthermore, the dry film thickness of the flow barrier coating is 30 μm to 70 μm.

[0013] Furthermore, the dry film thickness of the flow barrier coating is 30 μm to 50 μm.

[0014] Furthermore, the base material of the aluminum alloy water-cooled plate includes 3003+4343 composite plate and 6063 aluminum alloy.

[0015] The present invention has the following beneficial effects: The novel CAB furnace brazing flow retardant for aluminum alloy water-cooled plates provided by this invention introduces high-purity neodymium oxide, which can undergo a unique solid-phase interface reaction with the oxide film on the surface of 3003 and 6063 aluminum alloys at high brazing temperatures to generate rare earth aluminates, thereby establishing a strong chemical bond between the coating and the dissimilar substrate. This achieves ultra-high and uniform adhesion on dissimilar aluminum alloys, especially the difficult-to-process 6063 alloy, solving the problem of coating peeling caused by insufficient adhesion. The interfacial bonding force enables it to effectively resist thermal stress caused by the difference in thermal expansion coefficients of dissimilar materials, exhibiting resistance to thermal shock cracking. At the same time, the coating is dense and stable, effectively resisting flux erosion and brazing filler metal scouring, ensuring clear and sharp flow retardant boundaries without penetration.

[0016] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the process for a novel aluminum alloy water-cooled plate CAB furnace brazing resistant agent and its application according to the present invention. Figure 2 This is a schematic diagram of the state of the novel flux throttling agent of the present invention after air drying. Figure 3 This is a schematic diagram showing the state of the novel flow-blocking agent after brazing according to the present invention; Figure 4 This is a schematic diagram of the state of the conventional flux throttling agent of the present invention after air drying; Figure 5 This is a schematic diagram of the state of the conventional flow-blocking agent after brazing according to the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention relates to a novel CAB furnace brazing resistant agent for aluminum alloy water-cooled plates. The resistant agent is in slurry form, and its raw materials include the following components by weight percentage: The composition of the composite solid powder is as follows: 50% aluminum dihydrogen phosphate aqueous solution: 20%; composite solid powder: 38%; sodium carboxymethyl cellulose: 1.0%; polyethylene glycol: 22.5%; propylene glycol: 2.0%; fumed silica: 1.5%; ammonium polyacrylate dispersant: 0.5%; modified bentonite suspending agent: 0.8%; benzisothiazolinone preservative: 0.1%; deionized water: balance; wherein the composite solid powder is composed of the following components: titanium dioxide 58%, aluminum oxide 22%, magnesium oxide 10%, and neodymium oxide 10%.

[0021] Furthermore, the average particle size D50 of the composite solid powder is not greater than 5 μm.

[0022] Furthermore, the purity of the neodymium oxide is greater than 99.5%.

[0023] Please see Figure 1 As shown, the preparation method of the novel aluminum alloy water-cooled plate CAB furnace brazing resistant agent according to any of the above-described methods is characterized by comprising the following steps: Add the prescribed amounts of deionized water, propylene glycol, ammonium polyacrylate dispersant, and sodium carboxymethyl cellulose to a disperser and stir until completely dissolved; Add the amount of modified bentonite suspending agent specified in the formula and disperse at high speed for 10 minutes; Slowly add all of the composite solid powder, then stir at high speed for more than 40 minutes to form a homogeneous slurry; Add the prescribed amounts of polyethylene glycol and benzisothiazolinone preservative, and stir at medium speed for 15 minutes; Add 50% of the formula amount of aluminum dihydrogen phosphate aqueous solution and stir at medium speed for 20 minutes; Finally, add the prescribed amount of fumed silica to adjust the slurry viscosity, stir for another 15 minutes, and then discharge to obtain the flow barrier agent.

[0024] A method for applying a novel CAB in-furnace brazing resistant agent for aluminum alloy water-cooled plates, characterized by comprising the following steps: The flow-blocking agent slurry is applied to the non-brazing spread area of ​​the aluminum alloy water-cooled plate through a coating process to form a wet film. The wet film is dried to form a flow-blocking agent coating with a dry film thickness of 30 μm to 70 μm; The aluminum alloy water-cooled plate coated with a flow-blocking agent was placed in a CAB brazing furnace for brazing, with a peak brazing temperature of 605℃±5℃. After brazing, an aluminum alloy water-cooled plate product with clear flow-blocking boundaries and no brazing filler metal penetration is obtained.

[0025] Working principle: Interfacial chemical bonding of neodymium oxide: At the high temperatures of CAB brazing, neodymium oxide can bond with the surface of 3003 aluminum alloy. and the surface of 6063 aluminum alloy It undergoes a unique solid-phase interfacial reaction with MgO to generate substances such as Rare earth aluminates. This reaction establishes a strong chemical bridge between the flow-retardant coating and the two different substrates, transforming mechanical adhesion into strong chemical bonding, fundamentally solving the bottleneck problem of insufficient adhesion on 6063 aluminum alloy.

[0026] This strong interfacial bonding allows the coating to better withstand the stress caused by the difference in thermal expansion between dissimilar materials, significantly reducing the tendency of the coating to crack at the interface.

[0027] Multi-component synergistic system: Titanium oxide: As the main framework, it provides the main physical barrier properties and excellent chemical inertness to flux.

[0028] Synergistic effect of magnesium oxide and neodymium oxide: Magnesium oxide regulates the network structure of the aluminum phosphate glass phase to prevent excessive flow; together with neodymium oxide, it optimizes the sintering behavior of the coating, enabling it to achieve a balance between high strength and moderate porosity at the brazing temperature, ensuring both adhesion and post-weld cleanability.

[0029] Aluminum dihydrogen phosphate: As an inorganic binder matrix, it forms a high-temperature resistant composite bonding network together with magnesium oxide and neodymium oxide.

[0030] Polyethylene glycol and propylene glycol: provide flexibility during the drying and preheating stages, compensate for stress, and improve the slurry's coverage on difficult-to-wet 6063 aluminum alloy surfaces.

[0031] Additive system: Ensures the storage stability of the slurry and excellent construction operation.

[0032] Preferably, the neodymium oxide has a purity greater than 99.5% and an average particle size D50 of no more than 3 μm. High purity and ultrafine particle size ensure its high surface activity and efficiency and uniformity in interfacial reactions.

[0033] An aluminum alloy water-cooled plate coated with the high-adhesion flow-blocking agent, the base material of which includes 3003+4343 composite plate and 6063 aluminum alloy.

[0034] Due to the substantial improvement in coating adhesion, the dry film thickness of the flow-blocking agent coating can be optimized to 30 μm to 70 μm. Thinner coatings help achieve more precise flow-blocking boundaries, save material, and reduce cleaning burden.

[0035] The specific application of this embodiment is as follows: Example 1. Preparation of flow-resistant agent slurry Weigh each raw material according to the following weight percentages: 50% aluminum dihydrogen phosphate aqueous solution: 20%; Composite solid powder (titanium oxide 58%, aluminum oxide 22%, magnesium oxide 10%, neodymium oxide 10%, average particle size D50=5μm): 38%; sodium carboxymethyl cellulose: 1.0%; polyethylene glycol (PEG-800): 22.5%; propylene glycol: 2.0%; fumed silica: 1.5%; ammonium polyacrylate dispersant: 0.5%; modified bentonite suspending agent: 0.8%; benzisothiazolinone preservative: 0.1%; deionized water: balance.

[0036] Preparation process: Add deionized water, propylene glycol, dispersant, and sodium carboxymethyl cellulose to a high-speed disperser and stir until completely dissolved.

[0037] Add modified bentonite suspending agent and disperse at high speed for 10 minutes.

[0038] Slowly add all the composite solid powder (to ensure uniform dispersion of ultrafine neodymium oxide), and stir at high speed for more than 40 minutes to form a homogeneous slurry.

[0039] Add polyethylene glycol and preservative, and stir at medium speed for 15 minutes.

[0040] Add aluminum dihydrogen phosphate aqueous solution and stir at medium speed for 20 minutes.

[0041] Finally, fumed silica is added and adjusted to a viscosity suitable for screen printing. After stirring for 15 minutes, the mixture is discharged and packaged to obtain the flow-blocking agent slurry of this invention.

[0042] 2. Application Specimen: A simulated aluminum alloy water-cooled plate made of 3003+4343 composite plate and 6063 aluminum alloy.

[0043] Coating: The flow-blocking agent slurry of the present invention is applied to the non-brazing spread area of ​​the 6063 aluminum alloy plate using a brush.

[0044] Drying: After air drying at room temperature, a barrier agent coating with a dry film thickness of approximately 40 μm is formed, such as... Figure 2 As shown, the flow retardant bonds firmly to the surface of the product to be brazed after air drying.

[0045] Post-welding inspection: such as Figure 3 As shown, Figure 3 The brazing state of the new type of flow barrier agent is such that the aluminum solder spreads only along the edge of the flow barrier agent, and the edge of the flow barrier agent is clear after brazing.

[0046] Comparative example: Traditional flow-retardant 1. Preparation of flow-resistant agent slurry To simulate traditional techniques, a slurry containing no neodymium oxide was prepared as a comparative example.

[0047] Weigh each raw material according to the following weight percentages: 50% aluminum dihydrogen phosphate aqueous solution: 20%; Composite solid powder (titanium oxide 64%, aluminum oxide 26%, magnesium oxide 10%, no neodymium oxide added, average particle size D50=5μm): 38%; Sodium carboxymethyl cellulose: 1.0%; Polyethylene glycol (PEG-800): 22.5%; Propylene glycol: 2.0%; Fumed silica: 1.5%; Ammonium polyacrylate dispersant: 0.5%; Modified bentonite suspending agent: 0.8%; Benzo[a](x)isothiazolinone preservative: 0.1%; Deionized water: balance.

[0048] As can be seen from the comparative formulation, its main difference from the embodiments of the present invention is that it replaces the core component neodymium oxide with equal amounts of titanium oxide and aluminum oxide, thereby disrupting the synergistic effect between neodymium oxide and magnesium oxide.

[0049] The preparation process is exactly the same as in the examples.

[0050] 2. Application Test specimen: A simulated specimen made of the same 3003+4343 composite plate and 6063 aluminum alloy as in the example.

[0051] Coating and drying: The comparative flow barrier was coated using the same method, and the dry film thickness was controlled to be approximately 40 μm.

[0052] Pre-welding tests: such as Figure 4 As shown, after drying and during product transportation, it was observed that the adhesion between the anti-flow agent coating and the 6063 aluminum alloy surface was not firm, with slight peeling and obvious insufficient adhesion.

[0053] Post-welding inspection: such as Figure 5 As shown, after welding, the aluminum solder spreads beyond the flow-blocking agent, resulting in flow-blocking failure. Under thermal stress and capillary action, the solder breaks through the flow-blocking agent barrier on the 6063 aluminum alloy side, exhibiting significant spreading and penetration, with the flow-blocking boundary becoming blurred.

[0054] Coating condition: After brazing, especially in the interface area between 3003 and 6063, micro-cracks can be seen in the anti-flow agent coating due to the stress caused by the mismatch of the thermal expansion coefficients of dissimilar materials, and local coating peeling occurred on the 6063 side.

[0055] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A novel CAB furnace-based brazing resistant agent for aluminum alloy water-cooled plates, characterized in that, The flow-blocking agent is in slurry form, and its raw materials include the following components by weight percentage: 50% aluminum dihydrogen phosphate aqueous solution: 20%; composite solid powder: 38%; Sodium carboxymethyl cellulose: 1.0%; Polyethylene glycol: 22.5%; Propylene glycol ：2.0%； Fumed silica: 1.5%; ammonium polyacrylate dispersant: 0.5%; modified bentonite suspending agent: 0.8%; benzisothiazolinone preservative: 0.1%; deionized water: balance; wherein the composite solid powder is composed of the following components: titanium dioxide 58%, aluminum oxide 22%, magnesium oxide 10%, neodymium oxide 10%.

2. The novel CAB furnace brazing resistant agent for aluminum alloy water-cooled plates according to claim 1, characterized in that, The average particle size D50 of the composite solid powder is not greater than 5 μm.

3. The novel CAB furnace brazing resistant agent for aluminum alloy water-cooled plates according to claim 2, characterized in that, The purity of the neodymium oxide is greater than 99.5%.

4. A method for preparing a novel CAB furnace brazing resistant agent for aluminum alloy water-cooled plates, characterized in that, The preparation method includes the following steps: Add the prescribed amounts of deionized water, propylene glycol, ammonium polyacrylate dispersant, and sodium carboxymethyl cellulose to a disperser and stir until completely dissolved; Add the amount of modified bentonite suspending agent specified in the formula and disperse for 10 minutes; Slowly add all of the composite solid powder, then stir for more than 40 minutes to form a homogeneous slurry; Add the prescribed amounts of polyethylene glycol and benzisothiazolinone preservative, and stir for 15 minutes; Add 50% of the formula amount of aluminum dihydrogen phosphate aqueous solution and stir for 20 minutes; Finally, add the prescribed amount of fumed silica to adjust the slurry viscosity, stir for another 15 minutes, and then discharge to obtain the flow barrier agent.

5. A method for applying a novel CAB furnace-based brazing resistant agent to aluminum alloy water-cooled plates, characterized in that... The application method includes the following steps: The flow-blocking agent slurry is applied to the non-brazing spread area of ​​the aluminum alloy water-cooled plate through a coating process to form a wet film. The wet film is dried to form a flow-blocking agent coating with a dry film thickness of 30 μm to 70 μm; The aluminum alloy water-cooled plate coated with a flow-blocking agent was placed in a CAB brazing furnace for brazing, with a peak brazing temperature of 605℃±5℃. After brazing, an aluminum alloy water-cooled plate product with clear flow-blocking boundaries and no brazing filler metal penetration is obtained.

6. An aluminum alloy water-cooled plate coated with a flow-retardant agent, characterized in that, The flow barrier is a dry film coating formed by the flow barrier formed by any one of claims 1-3.

7. The aluminum alloy water-cooled plate coated with a flow-retardant agent according to claim 6, characterized in that, The dry film thickness of the flow barrier coating is 30 μm to 70 μm.

8. The aluminum alloy water-cooled plate coated with a flow-retardant agent according to claim 7, characterized in that, The dry film thickness of the flow barrier coating is 30 μm to 50 μm.

9. The aluminum alloy water-cooled plate coated with a flow-retardant agent according to claim 8, characterized in that, The base material of the aluminum alloy water-cooled plate includes 3003+4343 composite plate and 6063 aluminum alloy.

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