TC4 titanium alloy thin-wall slender structure liquid cooling plate brazing method

Abstract

The invention provides a TC4 titanium alloy thin-wall slender structure liquid cooling plate brazing method, and belongs to the technical field of micro-channel heat exchange. The problems that according to an existing welding method for the TC4 titanium alloy thin-wall long and thin structure liquid cooling plate, the metal brazing connection performance is not stable, a connection interface has defects, and the flatness of the welded thin-wall liquid cooling plate is poor are solved. The thin-wall liquid cooling plate and the slender structural part are buckled and combined, metal foil type brazing filler metal is clamped between the thin-wall liquid cooling plate and the slender structural part to form a TC4 titanium alloy thin-wall liquid cooling plate and slender structural combined part, a graphite pressing block A and a graphite pressing block B are combined and pressed on the TC4 titanium alloy thin-wall liquid cooling plate and slender structural combined part, and after being assembled, the TC4 titanium alloy thin-wall liquid cooling plate and slender structural combined part are put into a vacuum furnace. According to the method, the one-time welding success rate is increased, meanwhile, the brazing seam quality is better, intermetallic compounds of the welding seam are uniform in welding seam microcosmic metallographic display, and the phenomena that the brazing seam is not resistant to pressure and prone to leakage are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of microchannel heat exchange, and in particular relates to a brazing method for a TC4 titanium alloy thin-walled slender structure liquid cooling plate. Background Art

[0002] Titanium alloys are widely used in the field of high-performance heat exchange technology because of their advantages such as high strength, low density, high temperature resistance, good thermal conductivity and fatigue resistance, especially good corrosion resistance. Microchannel heat exchange technology is an enhanced heat exchange technology that uses the heat transfer characteristics and structural characteristics of microchannels to improve the heat exchange capacity of working fluids. After years of development, microchannel heat exchange technology has been successfully promoted and applied in many industries such as aerospace, microelectronics, automotive industry, energy and chemical industry. Liquid cooling plates are a technical product in the field of microchannel heat exchange technology, and the demand in the above fields is also increasing. Therefore, in-depth research on key brazing process technologies in the field of TC4 titanium alloy thin-walled liquid cooling plate technology is of great significance to the development and application of microchannel heat exchange technology.

[0003] Although traditional brazing can produce TC4 titanium alloy thin-walled slender structure liquid cooling plates, micro cracks will be formed in the brazing forming area, and distortion will occur in the direction perpendicular to the pressure. The fatigue pressure resistance of the weld is poor. After heating, the titanium alloy thin-walled liquid cooling plate will deform, resulting in poor flatness and failure to meet the technical requirements. Summary of the invention

[0004] In view of this, in order to solve the problems of unstable metal brazing connection performance, defects in the connection interface, and poor flatness of the thin-walled liquid cooling plate after welding in the existing welding method of TC4 titanium alloy thin-walled and slender structure liquid cooling plate, the present invention proposes a TC4 titanium alloy thin-walled and slender structure liquid cooling plate brazing method.

[0005] To achieve the above object, the present invention adopts the following technical solution: a TC4 titanium alloy thin-walled slender structure liquid cooling plate brazing method, specifically comprising the following steps:

[0006] Step 1: Before brazing assembly, the TC4 titanium alloy thin-wall liquid cooling plate is first subjected to ultrasonic vibration degreasing cleaning, and then pickled;

[0007] Step 2: The thin-walled liquid-cooling plate and the slender structural part are buckled together, and a metal foil brazing filler metal is sandwiched therein to form a TC4 titanium alloy thin-walled liquid-cooling plate and a slender structural assembly, and the graphite pressing block A and the graphite pressing block B are pressed onto the TC4 titanium alloy thin-walled liquid-cooling plate and the slender structural assembly. After assembling them, they are placed in a vacuum brazing furnace, the furnace door is closed, and the vacuum is evacuated to the vacuum degree of the brazing process, and then the temperature is increased, and then the vacuum brazing furnace is opened to cool to room temperature and taken out;

[0008] Step 3: Install the test joint at the position of the reserved hole of the slender structural part, carry out water pressure test and air tightness test, and after passing the test, process it to the required shape contour to obtain the TC4 titanium alloy thin-walled slender structure liquid cooling plate.

[0009] Furthermore, in step 2, the parameters of heating and cooling are uniformly heating to 920-970°C for 2-5h, keeping warm for 0.5-2h, and cooling with the furnace to below 150°C after the holding time.

[0010] Furthermore, the shape of the slender structural member corresponds to the many microchannel openings on the TC4 titanium alloy thin-walled liquid cooling plate. Through the slender structural member, the inlets and outlets of the microchannels inside the liquid cooling plate are gathered on the structural member, and finally two reserved holes for entry and exit are formed.

[0011] Furthermore, threads are later processed through two reserved holes to form a quick-connect connector, which facilitates quick connection and assembly.

[0012] Furthermore, the protrusion on the side of the graphite pressing block A cooperates with the groove on the side of the graphite pressing block B.

[0013] Furthermore, after the graphite pressed block A and the graphite pressed block B are effectively pressed, weight may be applied to the graphite pressed block A and the graphite pressed block B again.

[0014] Furthermore, the metal foil solder uses a high-temperature Ag-Cu based solder, and the solder thickness is 0.05 mm.

[0015] Furthermore, the TC4 titanium alloy thin-wall liquid cooling plate has a thickness of 1.2 mm.

[0016] Compared with the prior art, the TC4 titanium alloy thin-walled slender structure liquid cooling plate brazing method described in the present invention has the following beneficial effects:

[0017] 1. The present invention provides a TC4 titanium alloy thin-walled slender structure liquid cooling plate brazing method, so as to improve the problem that the TC4 titanium alloy thin-walled liquid cooling plate and the slender structure are prone to poor brazing weld filling and low one-time welding success rate during the brazing process, and improve the one-time welding success rate while making the brazing weld quality better. In the weld microscopic metallographic display, the weld metal intermetallic compounds are uniform, which greatly reduces the phenomenon of poor pressure resistance and easy leakage at the brazing weld.

[0018] 2. Compared with traditional welding and brazing processes, the TC4 titanium alloy thin-walled and slender structure liquid cooling plate brazing method described in the present invention can achieve high bonding strength of the TC4 titanium alloy thin-walled and slender structure and maintain the integrity of the microstructure, avoid the generation of microcracks during welding, and effectively improve its production efficiency and product quality.

[0019] 3. The present invention can realize controllable adjustment of the positioning of the TC4 titanium alloy thin-walled slender structure during the brazing assembly process, ensuring that the thin-walled brazing surface is uniform after assembly; during the brazing process, the deformation of the TC4 titanium alloy thin-walled liquid cooling plate is effectively limited, so that the deformation of the TC4 titanium alloy thin-walled slender structure liquid cooling plate after welding is relatively uniform, meeting the flatness requirements of the thin-walled liquid cooling plate.

[0020] 4. The TC4 titanium alloy thin-walled and slender structure liquid cooling plate brazing method described in the present invention has stable and reliable performance, a dense welding area, and no fine cracks, which can effectively improve its production efficiency and product quality and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a schematic diagram of the TC4 titanium alloy thin-wall liquid cooling plate of the present invention;

[0023] Figure 2 It is a front view schematic diagram of the slender structural member of the present invention;

[0024] Figure 3 It is a schematic diagram of the reverse side of the slender structural member of the present invention;

[0025] Figure 4 It is a schematic diagram of the metal foil solder of the present invention;

[0026] Figure 5 It is a schematic diagram of the combination of the TC4 titanium alloy thin-wall liquid cooling plate and the slender structural member of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the graphite block A of the present invention;

[0028] Figure 7 This is a schematic diagram of the structure of the graphite block B of the present invention;

[0029] Figure 8 This is a schematic diagram of the graphite pressing block tooling assembly of the present invention after it is completed and ready for vacuum brazing. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0031] See also Figure 1-8 This embodiment describes a TC4 titanium alloy thin-walled elongated structure liquid cooling plate brazing method, which specifically includes the following steps:

[0032] Step 1: Before brazing assembly, the TC4 titanium alloy thin-wall liquid cold plate is first subjected to ultrasonic vibration degreasing cleaning, and then pickled. The pickling liquid ratio is HNO3:HF=5:1, and water is appropriate. The pickling time is 2-8min to achieve the purpose of removing the oxide layer. After pickling, the surface should be smooth, with a metallic luster and silvery white or grayish white. It is considered qualified without pits, spots, fingerprints and other traces.

[0033] TC4 titanium alloy thin-walled liquid cooling plates and slender structural parts need to be degreased and pickled to ensure that the surfaces of the liquid cooling plates and slender structural parts are clean, which is conducive to the flow of the brazing material to a molten state during the subsequent vacuum brazing process, and to obtain a better brazing material wetting effect, thereby ensuring the quality of the vacuum brazing weld. The liquid cooling plate, metal foil brazing material and structural parts can be fixed and assembled through positioning pins.

[0034] Step 2: Combine the thin-walled liquid-cooling plate and the slender structure, insert the metal foil brazing material into the TC4 titanium alloy thin-walled liquid-cooling plate and the slender structure assembly, press the graphite blocks A and B onto the TC4 titanium alloy thin-walled liquid-cooling plate and the slender structure assembly, put them into the vacuum brazing furnace after assembly, close the furnace door, and evacuate to the vacuum degree of the brazing process. The process parameters are: uniformly increase the temperature to 920-970℃ in 2-5h, and keep it warm for 0.5-2h. After the insulation time is over, cool it to below 150℃ with the furnace, open the vacuum brazing furnace, cool it to about room temperature and take it out.

[0035] After multiple rounds of experiments on various brazing materials and brazing process, high-temperature Ag-Cu-based silver-copper-titanium brazing materials can form good brazing seams at 920-970°C and have better brazing effects than other brazing materials under pressure resistance and fatigue tests. At this temperature, the graphite block can effectively release the stress of TC4 materials, and can achieve the purpose of stress relief and correction of TC4 during brazing, avoiding deformation of TC4 thin-walled liquid cooling plates due to excessive stress, and meeting their flatness requirements.

[0036] Figure 1 This is a schematic diagram of the TC4 titanium alloy thin-wall liquid cooling plate. Figure 2 is a schematic diagram of a slender structural member. Figure 3 Schematic diagram of metal foil solder.

[0037] The metal foil brazing material is high-temperature Ag-Cu based brazing material with a thickness of 0.05mm. The thickness of the TC4 titanium alloy thin-wall liquid cooling plate is 1.2mm.

[0038] The shape of the slender structural part corresponds to the many microchannel openings on the TC4 titanium alloy thin-wall liquid cooling plate. Through the slender structural part, the inlet and outlet of each microchannel inside the liquid cooling plate are gathered on the structural part, and finally two reserved holes for entry and exit are formed. This structure is designed based on the application space of the titanium alloy thin-walled slender structure liquid cooling plate. Through the two reserved holes, threads can be processed later to form a quick plug connector, which is convenient for quick connection and assembly.

[0039] The thin-walled liquid cooling plate and the slender structural member are buckled together, and a metal foil brazing material is sandwiched between them to form a Figure 4 The schematic diagram of the combination of TC4 titanium alloy thin-wall liquid cooling plate and slender structural parts is shown. The positioning pin gap can be adjusted according to different positioning requirements.

[0040] Metal foil brazing filler metal is relatively thin and prone to deformation and warping, which affects the quality of vacuum brazing. Therefore, vacuum brazing is performed by adding graphite blocks for counterweighting.

[0041] Figure 5 It is the structural schematic diagram of graphite block A. Figure 5 The shape of graphite block A follows the shape of the slender structural part. Figure 6 Schematic diagram of the structure of graphite block B. Figure 6 The shape of the groove of the graphite block B follows the shape of the slender structural part, and the straight edge should be slightly larger than the outer size of the thin-walled liquid cooling plate, so that it can fully exert pressure on the entire surface of the thin-walled liquid cooling plate, thereby limiting the deformation of the plate surface and releasing stress to produce a thermal correction effect.

[0042] Figure 5 Graphite block A is convex, and Figure 6 The groove of graphite pressing block B can be perfectly matched.

[0043] Press it to Figure 4 The TC4 titanium alloy thin-wall liquid cooling plate and the slender structural parts shown in the figure are combined. Figure 7 shown.

[0044] Specifically, the TC4 titanium alloy thin-wall liquid cooling plate, metal foil brazing material and slender structural parts are fixed and assembled with positioning pins, such as Figure 4 As shown, the graphite blocks A and B are pressed onto the TC4 titanium alloy thin-walled elongated structure liquid cooling plate. Figure 7 As shown, it can be loaded into a vacuum brazing furnace.

[0045] During the brazing process, the TC4 thin-walled liquid cooling plate and slender structural parts will release stress and deform, forming bends or corrugations, resulting in poor flatness of the brazing surface between the liquid cooling plate and the structural parts, uneven flow of the brazing material after melting, and extremely poor wettability of the brazing material, resulting in poor brazing results and leakage points that are very likely to occur at the brazing points.

[0046] After the graphite blocks A and B are combined, the graphite block A can effectively press the slender structural part as a whole, and then compress the foil brazing material, so that it can melt and flow evenly during brazing. Under pressure, the brazing point between the liquid cooling plate and the structural part can achieve good wettability, effectively improving the brazing effect. The graphite block B can effectively press the plate surface of the liquid cooling plate except the brazing position to limit the deformation of the plate surface.

[0047] After both of them apply pressure effectively, weight can be applied to the graphite blocks A and B again, such as placing graphite counterweights and metal counterweights on the graphite blocks A and B, so that the pressure can satisfy the flatness of the brazing surfaces of the liquid cooling plate and the structural parts, and satisfy the purpose of stress relief and correction of TC4 by applying effective pressure to limit deformation.

[0048] During mass production, Figure 5 Graphite pressing block A can press two slender structural parts on the left and right sides at the same time (making the structural parts, metal foil brazing filler metal and thin-walled liquid cooling plate in close contact with each other), so that one graphite pressing block A presses two slender structural parts, cooperates with two metal foil brazing filler metals and two thin-walled liquid cooling plates, and presses one graphite pressing block B on each of the two liquid cooling plates, which saves costs and improves production efficiency.

[0049] Step 3: Install the test joint at the reserved hole of the slender structure, and conduct water pressure test and air tightness test. After passing the test, it is processed to the required shape contour, and the solid part outside the thin-walled liquid cooling plate flow channel is moderately milled to achieve the purpose of weight reduction, and the TC4 titanium alloy thin-walled slender structure liquid cooling plate is obtained.

[0050] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A brazing method for a TC4 titanium alloy thin-walled, elongated structure liquid cooling plate, characterized in that: The specific steps include: Step 1: Before brazing assembly, the TC4 titanium alloy thin-wall liquid cooling plate is first subjected to ultrasonic vibration degreasing cleaning, and then pickled; Step 2: The thin-walled liquid-cooling plate and the slender structure are buckled together, and a metal foil brazing filler metal is sandwiched therein to form a TC4 titanium alloy thin-walled liquid-cooling plate and a slender structure assembly, and the graphite pressing block A and the graphite pressing block B are pressed onto the TC4 titanium alloy thin-walled liquid-cooling plate and the slender structure assembly. After assembling them, they are placed in a vacuum brazing furnace, the furnace door is closed, and the vacuum is evacuated to the vacuum degree of the brazing process, and then the temperature is increased, and then the vacuum brazing furnace is opened to cool to room temperature and taken out; Step 3: Install the test joint at the position of the reserved hole of the slender structural part, carry out water pressure test and air tightness test, and after passing the test, process it to the required shape contour to obtain the TC4 titanium alloy thin-walled slender structure liquid cooling plate.

2. The brazing method of the TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: In step 2, the parameters of heating and cooling are to uniformly heat to 920-970°C for 2-5h, keep warm for 0.5-2h, and cool to below 150°C with the furnace after the holding time.

3. The brazing method of the TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: The shape of the slender structural member corresponds to the many microchannel openings on the TC4 titanium alloy thin-walled liquid cooling plate. The inlets and outlets of the various microchannels inside the liquid cooling plate are gathered on the structural member through the slender structural member, and finally two reserved holes for entry and exit are formed.

4. The brazing method of the TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 3 is characterized in that: The threads are processed later through the two reserved holes to form a quick-connect connector, which is convenient for quick connection and assembly.

5. The brazing method of TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: The protrusion on the side of the graphite pressing block A is matched with the groove on the side of the graphite pressing block B.

6. The brazing method of TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: After the graphite pressed block A and the graphite pressed block B are effectively pressed, weight may be applied to the graphite pressed block A and the graphite pressed block B again.

7. The brazing method of TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: The metal foil solder uses high-temperature Ag-Cu based solder, and the solder thickness is 0.05mm.

8. The brazing method of TC4 titanium alloy thin-walled elongated structure liquid cooling plate according to claim 1, characterized in that: The TC4 titanium alloy thin-wall liquid cooling plate has a thickness of 1.2 mm.

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