A method for low temperature fabrication of a fluidic element

Abstract

The application provides a low-temperature manufacturing method of a fluidic element. The method comprises the following steps: S1, processing, surface pretreatment and soldering pad polishing of a cover plate, a bottom plate and a substrate of the fluidic element; S2, cleaning of a surface to be connected of the cover plate, the bottom plate and the substrate and a soldering pad; S3, coating of a soldering part with flux; S4, heating, heat preservation and cooling; S5, glue injection to a bonding part; S6, pressure standing; and S7, heating, heat preservation and cooling, specifically comprising the following steps: placing the bonded whole into a muffle furnace for slow heating and heat preservation, and taking out after natural cooling to room temperature in the furnace. The application can avoid thermal damage, reduce welding stress and reduce cost, and the manufactured fluidic element has no damage to the base material, small internal residual stress and good joint impact resistance, so that the working life is greatly prolonged.

Description

Technical Field

[0001] This application relates to the field of jet element manufacturing technology for core components of hydraulic down-the-hole hammers, and in particular to a cryogenic manufacturing method for jet elements. Background Technology

[0002] High-energy hydraulic down-the-hole hammers are key equipment for deep resource exploration and development, and their core functional component is the jet element. The jet element typically consists of three layers of hard alloy components: an upper cover plate, a lower base plate, and a middle base plate. The base plate is machined with precise jet channels, while the cover plate and base plate mainly serve as seals and structural supports. The three components are assembled into a whole through pre-machined positioning structures, forming a complex flow channel inside for high-pressure fluid switching and jetting.

[0003] During operation, this component is subjected to severe erosion from high-speed liquid flow internally and vibration and impact from other components externally, making its working conditions extremely harsh. Traditionally, the three-layer structure of jet components is generally connected using high-temperature silver brazing (welding temperature above 577℃). This process has significant drawbacks: First, the high temperature softens and leaches the cobalt binder phase of the cemented carbide and oxidizes the tungsten carbide framework phase, leading to thermal damage and reduced strength. Second, due to the difference in the coefficients of linear expansion between the cover plate, base plate (usually YG8 alloy), and substrate (usually YG25C alloy), the high-temperature welding process generates enormous thermal stress, easily inducing microcracks near the welding area. These thermal damages and microcracks will propagate and extend under alternating impact loads, ultimately leading to failure at the component connection points and leakage in the flow channel, significantly shortening the service life of the jet component.

[0004] Furthermore, silver-based solders are expensive, and high-temperature brazing typically requires a vacuum or protective atmosphere, making the process complex and demanding on equipment, resulting in high overall manufacturing costs. Therefore, there is an urgent need in the field for a new method for manufacturing jet components that can avoid thermal damage, reduce welding stress, and simultaneously lower costs. Summary of the Invention

[0005] In view of this, the present application provides a low-temperature manufacturing method for jet elements to solve the problems of easy thermal damage, welding stress, and high manufacturing cost of jet elements in the prior art.

[0006] A first aspect of this application provides a method for low-temperature fabrication of a jet element, comprising the following steps:

[0007] S1: Processing, surface pretreatment, and solder pad polishing of the cover plate, base plate, and substrate of the jet element; specifically including: the outer edge of the contact surface of the cover plate, base plate, and substrate is the welding part, the inner edge is the bonding part, the adhesive groove for adhesive is milled in the bonding part of the cover plate and base plate, the overall pre-connected surface is roughened by sandblasting, the outer edge welding part is copper plated or cold sprayed with a layer of purple copper, and the surface of the SnPb material solder pad is polished with a metallographic grinding and polishing machine; the material of the cover plate and base plate is YG8, and the material of the substrate is YG25C;

[0008] S2: Clean the surfaces of the cover plate, base plate, and substrate to be joined, as well as the solder pads; specifically, this includes ultrasonic cleaning of the cover plate, base plate, substrate, and solder pads in anhydrous ethanol, and further cleaning the edges to be joined with a desmearing agent.

[0009] S3: Apply flux to the welding part; specifically, this includes: applying flux to the edge of the contact surface and placing solder pads on it, stacking them in a sandwich structure of cover plate-solder pad-substrate-solder pad-bottom plate, and adding weights to apply a certain pressure;

[0010] S4: Heating, holding, and cooling; specifically, this includes: placing the component after pressure is applied in S3 into a tube furnace, introducing argon as a protective gas, heating and holding it at that temperature for a period of time, and then removing it after it has cooled naturally to room temperature in the furnace.

[0011] S5: Inject adhesive into the bonding area: Inject adhesive into the adhesive groove through the adhesive injection holes on the cover plate and the base plate;

[0012] S6: Pressurized Settling: After the glue is filled, pressurize and block the glue injection hole and vent hole, and let it stand for a period of time;

[0013] S7: Heating, heat preservation, and cooling; specifically including: placing the bonded whole into a muffle furnace for slow heating and heat preservation, and then removing it after it has cooled naturally to room temperature in the furnace.

[0014] Preferably, in step S1, the width of the welded portion is 4-10 mm.

[0015] Preferably, in step S1, the depth of the adhesive groove is 0.1-0.5 mm.

[0016] Preferably, in step S1, the thickness of the copper plating is 30-100 μm, and the thickness of the copper plating is greater than or equal to 100 μm.

[0017] Preferably, in step S1, the thickness of the solder sheet is 30-100 μm.

[0018] Preferably, in step S3, the outline of the welding sheet is adapted to the shape of the welding surface, and the width of the welding sheet is configured to completely cover and fill the welding area after melting.

[0019] Preferably, in step S4, the heating rate is 2-4℃ / min, the holding temperature is 200-230℃, and the holding time is 3-5min.

[0020] Preferably, in step S5, the diameter of the injection hole is 1-3 mm, and all injection holes are injected with glue simultaneously.

[0021] Preferably, in step S6, the adhesive is left to stand at room temperature for 12-24 hours to allow it to initially cure.

[0022] Preferably, in step S7, the heating and holding process is carried out using stepped heating, heating to 80-90℃ at a rate of 1-2℃ / min and holding for 2 hours, and then raising the temperature to 120-180℃ at a rate of 1-2℃ / min and holding for 2 hours.

[0023] The beneficial effects of this application embodiment compared with the prior art are as follows: This application embodiment adopts a low-temperature process, eliminating thermal damage: The core of this invention lies in "low temperature." The welding temperature (200-230℃) is far lower than that of traditional silver brazing, completely avoiding the deterioration of the microstructure and properties of hard alloys due to high temperatures (thermal damage). Simultaneously, it significantly reduces welding stress caused by the difference in the linear expansion coefficients of dissimilar materials, fundamentally improving the component's strength and fatigue resistance. An innovative composite connection scheme of "low-temperature brazing + adhesive bonding" is adopted. Brazing is used on the outer edge to ensure the strength and high-temperature resistance of the connection joint; adhesive bonding is used on the inner edge, utilizing the excellent damping, vibration reduction, uniform stress distribution, and sealing properties of the adhesive to effectively resist vibration and impact during operation. The combination of these two methods achieves a balance between strength and toughness. Cost is significantly reduced: The cost of the SnPb solder and adhesive used is far lower than that of silver-based solder. At the same time, the low-temperature process has lower equipment requirements and lower energy consumption, significantly reducing production costs. The jet element manufactured in this application has a significantly extended service life due to the absence of damage to the matrix material, low internal residual stress, and good impact resistance of the joint. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a structural flowchart of a low-temperature fabrication method for a jet element provided in an embodiment of this application;

[0026] Figure 2 This is a front view of the jet element provided in the embodiments of this application;

[0027] Figure 3 This is a left view of the jet element provided in the embodiment of this application;

[0028] Figure 4 This is a cross-sectional view of the jet element AA provided in the embodiment of this application;

[0029] Figure 5 This is a cross-sectional view of the jet element BB provided in the embodiment of this application;

[0030] In the diagram: 10-cover plate, 20-base plate, 30-substrate plate, 40-vent hole, 50-injection hole, 60-glue groove, 70-welding surface, 80-pin hole. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] The following will describe in detail, with reference to the accompanying drawings, a method for low-temperature fabrication of a jet element according to an embodiment of this application. Example

[0033] Figure 1 This is a flowchart illustrating a method for cryogenic fabrication of a jet element according to an embodiment of this application. It includes the following steps:

[0034] S1: Processing, surface pretreatment, and solder pad grinding of the cover plate 10, base plate 20, and substrate 30 of the jet element;

[0035] Specifically, the outer edge of the contact surface between the cover plate 10, the base plate 20 of YG8, and the substrate 30 of YG25C is used as the welding point (e.g. Figure 4 , Figure 5The weld surface 70 shown has a weld width of 4mm, with the inner edge serving as the bonding area. This design utilizes the high strength and high-temperature resistance of the weld to bear the main structural load and provide edge sealing; while the inner edge bonding leverages the adhesive's excellent damping and stress distribution capabilities to absorb vibrations and shocks during operation, and reduce overall stress caused by differences in linear expansion coefficients. Adhesive groove 60 machining: A 0.1mm deep adhesive groove 60 is milled at the bonding area between the cover plate 10 and the base plate 20. The purpose of the adhesive groove 60 is to: provide space for the adhesive, ensuring a controllable and uniform adhesive layer; increase the bonding area and improve connection strength; and enhance the peel and shear resistance between the cover plate 10, base plate 20, and base plate 30 through mechanical interlocking effects. Surface roughening and plating: The entire pre-connected surface is sandblasted to roughen it, increasing the surface area and improving mechanical bonding. A 30μm thick layer of copper is electroplated onto the outer edge weld area. This step is crucial because cemented carbide (YG8, YG25C) has poor wettability with SnPb solder, making direct soldering difficult. The copper plating layer, acting as an intermediate transition layer, significantly improves solder wetting and spreading on the cemented carbide surface, ensuring a dense, defect-free weld. Solder sheet treatment: The 30μm thick SnPb solder sheet surface is ground using a metallographic grinding and polishing machine to remove the oxide film, ensuring clean and effective melting and bonding of the solder during soldering.

[0036] S2: The surfaces to be connected, including the cover plate 10, the base plate 20, and the substrate 30, as well as the solder pads, are cleaned.

[0037] Specifically, the three alloy plates (cover plate 10, base plate 20, and substrate 30) and the solder pads are ultrasonically cleaned in anhydrous ethanol to remove oil and particulate matter. Subsequently, the edges to be soldered (solder surface 70) are cleaned again with a descaling agent. This step aims to thoroughly remove any trace organic matter or oxides that may affect the soldering quality, ensuring that the flux and solder can function effectively.

[0038] S3: Apply flux to the welded parts;

[0039] Flux is applied along the welding surface on the contact surfaces of the cover plate 10 and the base plate 20, and SnPb solder pads are placed on top. The contour of the solder pads conforms to the shape of the welding surface, and the width of the solder pads is configured to completely cover and fill the welding area after melting. The role of the flux is to further remove oxides from the surface to be welded and reduce the surface tension of the molten solder, promoting its flow and filling. The components are stacked in a sandwich structure of cover plate 10-solder pad-base plate 30-solder pad-base plate 20. This structure ensures uniform transmission of welding pressure and accurate positioning between components. A weight is added to apply pressure. The purpose of applying pressure is to: ensure close contact between the components, maintain the solder pads in the preset position; and, when the solder melts, help to expel gas and slag from the weld, forming a dense weld zone.

[0040] S4: Heating, heat preservation, and cooling;

[0041] The entire assembly of the components was placed in a tube furnace, and argon gas was introduced as a protective gas. The core purpose of introducing the protective gas was to displace the air in the furnace chamber, preventing the workpiece and solder from being oxidized during heating, which is crucial for ensuring welding quality. The components were heated to 200°C at a relatively slow rate of 3°C / min, and then held for 3 minutes. Slow heating helps the components to be heated evenly, reducing thermal stress. The holding temperature was set in the low-temperature range above the solidus line and near the liquidus line of the SnPb solder (far lower than the 577°C or higher required for traditional silver brazing). The fundamental purpose was to achieve melting and bonding of the solder while completely avoiding thermal damage to the cemented carbide caused by high temperatures (cobalt phase softening, WC oxidation). Holding for a period of time allowed the liquid solder to fully wet the copper plating layer and fill the weld. Finally, the components were removed after natural cooling to room temperature in the furnace. Cooling in the furnace further reduces internal stress caused by uneven cooling.

[0042] S5: Apply adhesive to the bonding area;

[0043] Adhesive is injected into the adhesive groove 60 through the injection holes 50 on the cover plate 10 and the base plate 20. The diameter of each injection hole 50 is 1mm, and all injection holes 50 inject adhesive simultaneously. The purpose of providing multiple injection holes 50 is to achieve rapid and uniform filling, avoiding cavitation or incomplete filling caused by single-point injection.

[0044] S6: Pressurize and allow to stand;

[0045] After the adhesive is fully injected (indicated by the continuous and stable outflow of adhesive from the vent hole 40 while pressure is applied to the injection hole 50, with the outflow volume being roughly equivalent to the injected volume), immediately pressurize and plug the injection hole 50 and the vent hole 40. The purpose of plugging the injection hole 50 and the vent hole 40, besides preventing adhesive backflow, is more importantly to establish and maintain a certain pressure within the adhesive, thereby increasing the contact pressure between the adhesive and the alloy surface, expelling residual air bubbles, and promoting the penetration of the adhesive into microscopically rough surfaces, ultimately achieving a higher-strength bond. Allow the adhesive to stand at room temperature for 24 hours to complete its initial curing (surface dry or reaching a certain operational strength).

[0046] S7: Heating, heat preservation, and cooling;

[0047] The bonded assembly is placed in a muffle furnace for stepped heating and curing. First, it is heated to 80°C at a rate of 2°C / min and held for 2 hours. This low-temperature step is designed to allow the adhesive to complete the primary curing reaction smoothly, avoiding violent solvent evaporation or bubble formation due to rapid heating. Then, it is heated to 120°C at a slower rate of 1°C / min and held for 2 hours. This high-temperature step is designed to achieve complete curing of the adhesive, enabling it to reach the final designed strength, heat resistance, and media resistance. The entire curing process uses a slow, stepped heating method, the core purpose of which is to control the curing rate of the adhesive, minimize curing stress caused by the difference in thermal expansion coefficients between the adhesive and the metal, and ensure complete and uniform curing of the adhesive layer. Finally, it is allowed to cool naturally to room temperature in the furnace before being removed to obtain the finished product. Example

[0048] like Figure 5 As shown, this embodiment, based on Embodiment 1, introduces a mechanical interlocking structure to further enhance the shear resistance and connection reliability of the bonded area. Specifically, it includes:

[0049] S1: Processing, surface pretreatment, and solder pad grinding of the cover plate 10, base plate 20, and substrate 30 of the jet element;

[0050] Specifically, the outer edge of the contact surface between the cover plate 10, the base plate 20 of YG8, and the substrate 30 of YG25C is used as the welding point (e.g. Figure 4 , Figure 5The weld surface 70 shown has a weld width of 7mm, with the inner edge serving as the bonding area. The purpose of this design is to utilize the high strength and high-temperature resistance of the weld to bear the main structural load and provide edge sealing; while the bonding on the inner edge utilizes the excellent damping and stress distribution capabilities of the adhesive to absorb vibration and impact during operation and reduce overall stress caused by differences in linear expansion coefficients. Adhesive groove 60 machining: A 0.3mm deep adhesive groove 60 is milled at the bonding area between the cover plate 10 and the base plate 20. The purpose of the adhesive groove 60 is to: provide space for the adhesive, ensuring a controllable and uniform adhesive layer; increase the bonding area and improve connection strength; and enhance the peel and shear resistance between the cover plate 10, base plate 20, and base plate 30 through mechanical interlocking effects. Surface roughening and plating: The entire pre-connected surface is sandblasted to roughen it, increasing the surface area and improving mechanical bonding. A 100μm thick layer of copper is electroplated onto the outer edge weld area. This step is crucial because cemented carbide (YG8, YG25C) has poor wettability with SnPb solder, making direct soldering difficult. The copper plating layer, acting as an intermediate transition layer, significantly improves the wetting and spreading of the solder on the cemented carbide surface, ensuring a dense, defect-free weld. Solder sheet treatment: The 50μm thick SnPb solder sheet surface is ground using a metallographic polishing machine to remove the oxide film, ensuring clean and effective melting and bonding of the solder during soldering. Pin holes 80 are drilled in the cover plate 10, base plate 20, and substrate 30 corresponding to the adhesive layer. The purpose of adding pin holes 80 is to form a mechanical interlocking structure by adding pins during the adhesive bonding process, which greatly improves the anti-peeling and anti-shear performance of the jet element under vibration and impact loads.

[0051] S2: The surfaces to be connected, including the cover plate 10, the base plate 20, and the substrate 30, as well as the solder pads, are cleaned.

[0052] Specifically, the three alloy plates (cover plate 10, base plate 20, and substrate 30) and the solder pads are ultrasonically cleaned in anhydrous ethanol to remove oil and particulate matter. Subsequently, the edges to be soldered (solder surface 70) are cleaned again with a descaling agent. This step aims to thoroughly remove any trace organic matter or oxides that may affect the soldering quality, ensuring that the flux and solder can function effectively.

[0053] S3: Apply flux to the welded parts;

[0054] Flux is applied along the welding surface of the contact surface of the cover plate 10 and the base plate 20, and SnPb solder pads are placed on top. The outline of the solder pads conforms to the shape of the welding surface, and the width of the solder pads is configured to completely cover and fill the welding area after melting. The role of the flux is to further remove oxides from the surface to be welded and reduce the surface tension of the molten solder, promoting its flow and filling. A 5mm long and 6mm diameter pin is inserted into the pin hole 80, and then the cover plate 10-solder pad (pin)-base plate 30-solder pad (pin)-base plate 20 are stacked and pressed. The pins here not only serve a positioning function, but also form a strong mechanical anchor point in the adhesive layer, complementing the chemical bonding effect of the adhesive to achieve a composite reinforcement effect of "chemical bonding + mechanical locking". A certain pressure is applied by adding a weight. The purpose of pressurization is to ensure close contact between components and keep the solder pads in the preset position; and to help remove gas and slag from the weld when the solder melts, forming a dense weld zone.

[0055] S4: Heating, heat preservation, and cooling;

[0056] The entire assembly of the components was placed in a tube furnace, and argon gas was introduced as a protective gas. The core purpose of introducing the protective gas was to displace the air in the furnace chamber, preventing the workpiece and solder from being oxidized during heating, which is crucial for ensuring welding quality. The components were heated to 215°C at a relatively slow rate of 2°C / min, and then held for 5 minutes. Slow heating helps the components to be heated evenly and reduces thermal stress. The holding temperature was set in the low-temperature range above the solidus line and near the liquidus line of the SnPb solder (far lower than the 577°C or higher required for traditional silver brazing). The fundamental purpose was to achieve melting and bonding of the solder while completely avoiding thermal damage to the cemented carbide caused by high temperatures (cobalt phase softening, WC oxidation). Holding for a period of time allowed the liquid solder to fully wet the copper plating layer and fill the weld. Finally, the components were removed after natural cooling to room temperature in the furnace. Cooling in the furnace further reduces internal stress caused by uneven cooling.

[0057] S5: Apply adhesive to the bonding area;

[0058] Adhesive is injected into the adhesive groove 60 through the injection holes 50 on the cover plate 10 and the base plate 20. The diameter of each injection hole 50 is 2mm, and all injection holes 50 inject adhesive simultaneously. The purpose of providing multiple injection holes 50 is to achieve rapid and uniform filling, avoiding air pockets or incomplete filling caused by single-point injection.

[0059] S6: Pressurize and allow to stand;

[0060] After the adhesive is fully injected (indicated by the continuous and stable outflow of adhesive from the vent hole 40 while pressure is applied to the injection hole 50, with the outflow volume being roughly equivalent to the injected volume), immediately pressurize and plug the injection hole 50 and the vent hole 40. The purpose of plugging the injection hole 50 and the vent hole 40, besides preventing adhesive backflow, is more importantly to establish and maintain a certain pressure within the adhesive, thereby increasing the contact pressure between the adhesive and the alloy surface, expelling residual air bubbles, and promoting the penetration of the adhesive into microscopically rough surfaces, ultimately achieving a higher-strength bond. Allow the adhesive to stand at room temperature for 24 hours to complete its initial curing (surface dry or reaching a certain operational strength).

[0061] S7: Heating, heat preservation, and cooling;

[0062] The bonded assembly is placed in a muffle furnace for stepped heating and curing. First, it is heated to 90°C at a rate of 1.5°C / min and held for 2 hours. This low-temperature step is designed to allow the adhesive to complete the primary curing reaction smoothly, avoiding violent solvent evaporation or bubble formation due to rapid heating. Then, it is heated to 150°C at a slower rate of 1°C / min and held for 2 hours. This high-temperature step is designed to achieve complete curing of the adhesive, enabling it to reach the final designed strength, heat resistance, and media resistance. The entire curing process uses a slow, stepped heating method, the core purpose of which is to control the curing rate of the adhesive, minimize curing stress caused by the difference in thermal expansion coefficients between the adhesive and the metal, and ensure complete and uniform curing of the adhesive layer. Finally, it is allowed to cool naturally to room temperature in the furnace before being removed to obtain the finished product. Example

[0063] like Figure 2 As shown, this embodiment, based on embodiment 1, incorporates an innovative design for the contact surface shape to further increase the bonding area and improve connection reliability and sealing. Specifically, it includes:

[0064] S1: Processing, surface pretreatment, and solder pad grinding of the cover plate 10, base plate 20, and substrate 30 of the jet element;

[0065] Specifically, the outer edge of the contact surface between the cover plate 10, the base plate 20 of YG8, and the substrate 30 of YG25C is used as the welding point (e.g. Figure 4 , Figure 5The weld surface 70 shown has a weld width of 10mm, with the inner edge serving as the bonding area. The connection surfaces of the YG8 cover plate 10, base plate 20, and YG25C substrate 30 are made into a wavy shape with a amplitude of 2mm. The purpose of changing the planar connection to a wavy connection surface is to significantly increase the effective bonding area (usually by more than 30%) without increasing the external dimensions of the parts, thereby proportionally improving the bonding strength. At the same time, the wavy interface can more effectively prevent crack propagation and provide a more tortuous sealing path, greatly enhancing the sealing reliability of the jet element. A 100μm thick layer of copper is cold-sprayed onto the weld surface 70 (cold spraying is an efficient and strong coating preparation method when the workpiece size is large or not suitable for electroplating). The purpose of this design is to utilize the high strength and high temperature resistance of the welded area to bear the main structural load and edge sealing; while the bonding of the inner edge utilizes the excellent damping and stress distribution capabilities of the adhesive to absorb the vibration impact during operation and reduce the overall stress caused by the difference in the coefficient of linear expansion. Adhesive Groove 60 Machining: A 0.5mm deep adhesive groove 60 is milled at the bonding area between the cover plate 10 and the base plate 20. The purpose of setting the adhesive groove 60 is to: provide space for the adhesive to ensure the formation of a controllable and uniform adhesive layer; increase the bonding area and improve the connection strength; and enhance the peel and shear resistance between the cover plate 10, the base plate 20, and the substrate 30 through the mechanical interlocking effect. Surface Roughening and Coating: The entire pre-connected surface is roughened by sandblasting to increase the surface area and improve the mechanical bonding force. Solder Sheet Treatment: The surface of the 100μm thick SnPb solder sheet is polished using a metallographic grinding and polishing machine to remove the oxide film and ensure that the solder can melt and bond cleanly and effectively during welding.

[0066] S2: The surfaces to be connected, including the cover plate 10, the base plate 20, and the substrate 30, as well as the solder pads, are cleaned.

[0067] Specifically, the three alloy plates (cover plate 10, base plate 20, and substrate 30) and the solder pads are ultrasonically cleaned in anhydrous ethanol to remove oil and particulate matter. Subsequently, the edges to be soldered (solder surface 70) are cleaned again with a descaling agent. This step aims to thoroughly remove any trace organic matter or oxides that may affect the soldering quality, ensuring that the flux and solder can function effectively.

[0068] S3: Apply flux to the welded parts;

[0069] Flux is applied along the welding surface on the contact surfaces of the cover plate 10 and the base plate 20, and SnPb solder pads are placed on top. The contour of the solder pads conforms to the shape of the welding surface, and the width of the solder pads is configured to completely cover and fill the welding area after melting. The role of the flux is to further remove oxides from the surface to be welded and reduce the surface tension of the molten solder, promoting its flow and filling. The components are stacked in a sandwich structure of cover plate 10-solder pad-base plate 30-solder pad-base plate 20. This structure ensures uniform transmission of welding pressure and accurate positioning between components. A weight is added to apply pressure. The purpose of applying pressure is to: ensure close contact between the components, maintain the solder pads in the preset position; and, when the solder melts, help to expel gas and slag from the weld, forming a dense weld zone.

[0070] S4: Heating, heat preservation, and cooling;

[0071] The entire assembly of the components was placed in a tube furnace, and argon gas was introduced as a protective gas. The core purpose of introducing the protective gas was to displace the air in the furnace chamber, preventing the workpiece and solder from being oxidized during heating, which is crucial for ensuring welding quality. The components were heated to 230°C at a rate of 4°C / min, and then held for 4 minutes. Slow heating helps the components to be heated evenly and reduces thermal stress. The holding temperature was set in the low-temperature range above the solidus line and near the liquidus line of the SnPb solder (far lower than the 577°C or higher required for traditional silver brazing). The fundamental purpose was to achieve melting and bonding of the solder while completely avoiding thermal damage to the cemented carbide caused by high temperatures (cobalt phase softening, WC oxidation). Holding for a period of time allowed the liquid solder to fully wet the copper plating layer and fill the weld. Finally, the components were allowed to cool naturally to room temperature in the furnace before being removed. Cooling in the furnace further reduces internal stress caused by uneven cooling.

[0072] S5: Apply adhesive to the bonding area;

[0073] Adhesive is injected into the adhesive groove 60 through the injection holes 50 on the cover plate 10 and the base plate 20. The diameter of each injection hole 50 is 3mm, and all injection holes 50 inject adhesive simultaneously. The purpose of providing multiple injection holes 50 is to achieve rapid and uniform filling, avoiding air pockets or incomplete filling caused by single-point injection.

[0074] S6: Pressurize and allow to stand;

[0075] After the adhesive is fully injected (indicated by the continuous and stable outflow of adhesive from the vent hole 40 while pressure is applied to the injection hole 50, with the outflow volume being roughly equivalent to the injected volume), immediately pressurize and plug the injection hole 50 and the vent hole 40. The purpose of plugging the injection hole 50 and the vent hole 40, besides preventing adhesive backflow, is more importantly to establish and maintain a certain pressure within the adhesive, thereby increasing the contact pressure between the adhesive and the alloy surface, expelling residual air bubbles, and promoting the penetration of the adhesive into microscopically rough surfaces, ultimately achieving a higher-strength bond. Allow the adhesive to stand at room temperature for 24 hours to complete its initial curing (surface dry or reaching a certain operational strength).

[0076] S7: Heating, heat preservation, and cooling;

[0077] The bonded assembly is placed in a muffle furnace for stepped heating and curing. First, it is heated to 85°C at a rate of 1°C / min and held for 2 hours. This low-temperature step is designed to allow the adhesive to complete the primary curing reaction smoothly, avoiding violent solvent evaporation or bubble formation due to rapid heating. Then, it is heated to 180°C at a slower rate of 1.5°C / min and held for 2 hours. This high-temperature step is designed to achieve complete curing of the adhesive, enabling it to reach the final designed strength, heat resistance, and media resistance. The entire curing process uses a slow, stepped heating method, the core purpose of which is to control the curing rate of the adhesive, minimize curing stress caused by the difference in thermal expansion coefficients between the adhesive and the metal, and ensure complete and uniform curing of the adhesive layer. Finally, it is allowed to cool naturally to room temperature in the furnace before being removed to obtain the finished product.

[0078] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method of cryogenic fabrication of a fluidic element, characterized by, The method comprises the following steps: S1: processing, surface pretreatment, and polishing of the cover plate, bottom plate, and substrate of the fluidic element; specifically, the outer edge of the contact surface of the cover plate, bottom plate, and substrate is the welding site, and the inner edge is the bonding site; a glue groove for bonding is milled on the bonding site of the cover plate and bottom plate; the surface of the whole pre-connected element is sandblasted and roughened; the outer edge welding site is plated with copper or cold sprayed with a layer of red copper; the surface of the SnPb material welding sheet is polished and treated by a metallographic polishing machine; the material of the cover plate and bottom plate is YG8, and the material of the substrate is YG25C; S2: cleaning the surfaces to be connected of the cover plate, bottom plate, and substrate and the welding sheet; specifically, the cover plate, bottom plate, substrate, and welding sheet are placed in anhydrous ethanol for ultrasonic cleaning, and the edges to be welded are cleaned again with a debonding agent; S3: applying flux to the welding part; specifically, flux is applied to the edge of the contact surface and a welding sheet is placed thereon, and the cover plate-welding sheet-substrate-welding sheet-bottom plate sandwich structure is stacked and a weight is added to apply a certain pressure; S4: heating, holding, and cooling; specifically, the element after the pressure is applied in S3 is placed in a tube furnace, argon protective gas is introduced, and the element is heated and held for a period of time; the heating speed is 2-4 ℃ / min, the holding temperature is 200-230 ℃, and the holding time is 3-5 min; the element is naturally cooled to room temperature in the furnace and then taken out; S5: injecting glue into the bonding site; glue is injected into the glue groove from the glue injection holes on the cover plate and bottom plate; S6: pressure standing; after the glue is injected, the glue injection holes and exhaust holes are blocked by pressure and left to stand for a period of time; S7: heating, holding, and cooling; specifically, the bonded whole is placed in a muffle furnace for slow heating and holding, and then taken out after naturally cooled to room temperature in the furnace.

2. The method of claim 1, wherein the jet element is formed at a temperature of less than 1000C. In step S1, the welding site has a width of 4-10 mm.

3. The method of claim 1, wherein the jet element is formed at a temperature of less than 1000C. In step S1, the glue groove has a depth of 0.1-0.5 mm.

4. The method of claim 1, wherein the jet element is formed at a temperature of less than 1000C. In step S1, the copper plating has a thickness of 30-100 μm, and the red copper has a thickness of greater than or equal to 100 μm.

5. The method of claim 1, wherein the jet element is formed at a temperature of less than 100°C. In step S1, the welding sheet has a thickness of 30-100 μm.

6. The method of claim 1, wherein the jet element is formed at a temperature of less than 1000C. In step S3, the profile of the welding sheet is adapted to the shape of the welding surface, and the width dimension of the welding sheet is configured to be able to completely cover and fill the welding site after melting.

7. The method of claim 1, wherein the jet element is formed at a temperature of less than about 100°C. In step S5, the diameter of the glue injection hole is 1-3 mm, and the glue injection holes are injected with glue at the same time.

8. The method of claim 1, wherein the jet element is formed at a temperature of less than about 1000C. In step S6, the adhesive is preliminarily cured by standing at room temperature for 12-24 h.

9. The method of claim 1, wherein the fluidic element is fabricated at a low temperature. In step S7, the heating and holding are performed in a stepwise manner, the temperature is increased to 80-90 ℃ at a speed of 1-2 ℃ / min and held for 2 h, and then increased to 120-180 ℃ at a speed of 1-2 ℃ / min and held for 2 h.

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