Heat transfer surfaces and their preparation methods, phase change heat transfer devices and welds, bending methods

Abstract

This invention relates to a heat transfer surface and its preparation method, a phase change heat transfer device, and a welding and bending method. The preparation method includes the following steps: S11, preparing a copper substrate and adding a copper oxide layer of a certain thickness to one side of the copper substrate; S12, laying a copper wire array composed of multiple copper wires spaced at a certain interval and along the same direction on the top surface of the copper oxide layer to obtain a precursor; S13, placing the precursor in a protective atmosphere at a certain temperature and performing a heat treatment for a preset time to obtain the heat transfer surface. By implementing embodiments of this invention, a multi-scale capillary structure heat transfer surface can be obtained, and this heat transfer surface can be used to prepare a phase change heat transfer device to improve the heat dissipation efficiency of electronic devices, etc.

Description

Technical Field

[0001] This invention relates to the field of capillary material and equipment manufacturing, and particularly to a heat transfer surface and its preparation method, a phase change heat transfer device and welding seam, and a bending method. Background Technology

[0002] Currently, grooved wick structures for ultrathin heat pipes are primarily fabricated using specialized processes such as laser etching and chemical etching. While these processes can produce thinner heat pipes with certain heat transfer properties, they suffer from high costs, inconsistent quality, and complex, time-consuming procedures, limiting their application to small-batch production and specialized fields like aerospace. Furthermore, the grooves are difficult to efficiently construct in irregular shapes, such as narrower tops and wider bottoms, and the top spacing cannot be made to be smaller and more closely spaced. For traditional metal-cased heat pipes, the grooved wick structure is currently manufactured primarily using drawing processes, but this requires a certain wall thickness, hindering the development of ultrathin heat pipes. Therefore, exploring novel grooved capillary structures is crucial for promoting the development of phase change heat transfer devices such as ultrathin heat pipes. Summary of the Invention

[0003] In view of the above problems, the main objective of the present invention is to provide a heat transfer surface and its preparation method, a phase change heat transfer device and a welding seam and bending method, so as to overcome the shortcomings of the relevant prior art.

[0004] To achieve the objectives of this invention, the following technical solution is adopted:

[0005] In a first aspect, the present invention provides a method for preparing a heat transfer surface, characterized in that the preparation method includes the following steps:

[0006] S11. Prepare a copper substrate and add a copper oxide layer of a certain thickness to one side of the copper substrate; the corresponding implementation methods include reacting one side of the copper substrate with oxygen, or, laying a layer of copper oxide powder, or, laying a layer of copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer of a preset thickness.

[0007] S12. An array of copper wires arranged at a certain spacing and along the same direction is laid on the top surface of the copper oxide layer to obtain a precursor; the certain spacing includes adjacent and / or 0.1-2mm; the shape of the direction includes straight line or sine wave; the cross-sectional shape of the copper wire includes circle, square or rectangle.

[0008] S13. The precursor is placed in a protective atmosphere at a certain temperature and heated for a preset time to obtain the heat transfer surface; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

[0009] In a second aspect, the present invention provides a heat transfer surface, characterized in that it is constructed as a top layer, a bottom layer, and an intermediate layer bonded to the bottom layer and the top layer respectively on both sides; the structure type corresponding to the bottom layer includes a copper substrate, the structure type corresponding to the intermediate layer includes a porous copper single component, and the structure type corresponding to the top layer includes a micro-gap structure.

[0010] The porous copper single component is obtained by heating a copper oxide layer of a certain thickness in a protective atmosphere at a certain temperature for a preset time; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO; the copper oxide layer is disposed on one side of the copper substrate and / or the surface of the micro-pore structure; the one side includes part or all of it; the surface includes part or all of it.

[0011] The microgap structure includes a copper wire array consisting of multiple copper wires spaced at a certain interval and along the same direction; the certain interval includes adjacent and / or 0.1-2 mm; the shape of the direction includes a straight line or a sine wave; the cross-sectional shape of the copper wire includes a circle, a square or a rectangle.

[0012] The copper wire array can be replaced by a fourth laying layer;

[0013] The fourth laying layer has the following corresponding structural types: rectangular copper sheet array, copper wire mesh, copper powder, or copper wire column array; wherein...

[0014] The rectangular copper sheet array has the following structural types: multiple rectangular copper sheets are arranged in parallel at a certain interval and along the same direction; the bottom sides of the rectangular copper sheets with the same orientation are located on the same plane and are used to couple to one side of the intermediate layer; wherein the certain interval includes adjacent and / or 0.1-2mm; the direction of the rectangular copper sheets along the length direction includes a straight line or a sine wave.

[0015] The copper wire mesh has the following structural types: woven wire mesh or erected wire mesh; and the corresponding shape types include sheet or tubular; wherein the erected wire mesh includes a single-layer structure or a multi-layer structure.

[0016] The single-layer structure includes the following structural types: an array of copper wires arranged at a certain spacing and along the same direction; and a connector is provided between adjacent copper wires, wherein the connector is obtained by spot welding; wherein the certain spacing includes being adjacent and / or 0.1-2mm.

[0017] The multilayer structure includes the following structural types: a first copper wire array consisting of multiple first copper wires arranged at a first spacing and along a first direction, and a second copper wire array consisting of multiple second copper wires arranged at a second spacing and along a second direction; wherein the first spacing does not exceed the second spacing, and the first spacing includes adjacent and / or 0.1-2mm; the second copper wire array is mounted on the first copper wire array, and the corresponding contact points of the mounting are bonded; one side of the first copper wire array is coupled to the intermediate layer;

[0018] The copper wire pillar array has the following structural types: multiple copper wire pillars are arranged at a certain interval and along the same direction; wherein the certain interval includes adjacent and / or 1-10μm; one end of each copper wire pillar is set as a fixed end for coupling to the intermediate layer, and the other end is set as a free end.

[0019] Thirdly, the present invention provides a phase change heat transfer device, the corresponding product types including heat pipes, heat spreaders or loops, characterized in that the phase change heat transfer device includes a heat transfer surface as described in any one of the first to second aspects above; wherein the heat transfer surface is coupled to the inner circumference formed by the outer shell of the phase change heat transfer device.

[0020] Fourthly, the present invention provides a welding method for sealing a butt joint of a heat transfer surface as described in any one of the first to third aspects above, wherein the butt joint is obtained by fitting two cover plates constructed by cutting the heat transfer surface into a preset shape, or by rolling a cover plate into a tubular shape, characterized in that the welding method includes the following steps:

[0021] S301. Clamp the two cover plates to maintain the mating posture, and make the mating seam face upward;

[0022] S302. Apply a certain amount of powder to the joint seam, and use a friction stirring head with a diameter larger than the width of the seam to rub and stir the joint seam and the powder, so that the joint seam is sealed together.

[0023] The width of the powder application is not less than the width of the edge; the powder includes copper powder, alloy powder or brazing filler powder.

[0024] Fifthly, the present invention provides a bending method for bending a specific portion of a phase change heat transfer device as described in the third aspect above, wherein the phase change heat transfer device corresponds to a shape including a flat tube, characterized in that the bending method includes:

[0025] S401. Bending the specific location at a certain speed;

[0026] S402. Simultaneously, the activated friction stirring head is applied with a certain pressure to the outer rounded corner formed by bending, so as to reduce the curvature of the outer rounded corner, and / or increase the thickness of the copper substrate at the outer rounded corner, and / or reduce the cross-sectional area of ​​the cavity of the phase change heat transfer device corresponding to the outer rounded corner.

[0027] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0028] Compared to existing technologies, the heat transfer surface provided by this invention has a multi-scale capillary structure, and by applying this heat transfer surface to phase change heat transfer devices, the heat dissipation efficiency of electronic devices can be improved. Implementing this invention enables, for example, the ultra-thinning of grooved heat pipes, offering advantages such as large-scale, low-cost, environmentally friendly, simple, and highly efficient fabrication, while also improving heat transfer performance and enhancing the user experience and lifespan of electronic devices. Further features and benefits of this invention will be described in detail in the following specific embodiments section. Detailed Implementation

[0029] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the described embodiments are merely some embodiments of this invention, not all embodiments. The specific embodiments described herein are only used to explain this invention and are not intended to limit it. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0030] First aspect, embodiment

[0031] A first aspect of the present invention provides a method for preparing a heat transfer surface, characterized in that the preparation method includes the following steps:

[0032] S11. Prepare a copper substrate and add a copper oxide layer of a certain thickness to one side of the copper substrate; the corresponding implementation methods include reacting one side of the copper substrate with oxygen, or, laying a layer of copper oxide powder, or, laying a layer of copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer of a preset thickness.

[0033] S12. An array of copper wires arranged at a certain spacing and along the same direction is laid on the top surface of the copper oxide layer to obtain a precursor; the certain spacing includes adjacent and / or 0.1-2mm; the shape of the direction includes straight line or sine wave; the cross-sectional shape of the copper wire includes circle, square or rectangle.

[0034] S13. The precursor is placed in a protective atmosphere at a certain temperature and heated for a preset time to obtain the heat transfer surface; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

[0035] Step S11 can be implemented, for example, by exposing one side of the copper substrate to an atmosphere containing oxygen at a preset temperature; or by applying a copper oxide powder of a certain thickness, or by applying a layer of copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer shell of a preset thickness; or by other methods. The copper oxide layer contains CuO and / or Cu2O. The temperature required for the reduction reaction of CuO and Cu2O differs from that required for H2, and when the oxygen supply is low or its concentration is low, the copper oxide side primarily produces Cu2O. Different proportions of CuO and Cu2O can be obtained by varying the oxygen supply, thereby achieving the adjustment of the specified temperature to prevent thermal bonding at the tangent point of the copper wires after step S13. The copper substrate can be flat, tubular, or irregularly shaped such as wavy.

[0036] The copper substrate can also be a pre-prepared stainless steel substrate, with copper plated on one side of the stainless steel substrate to obtain another type of copper substrate, thus achieving a high-strength structure. The stainless steel substrate can also be replaced with a copper alloy substrate or an aluminum substrate, etc.

[0037] For example, step S12 can be implemented by laying multiple copper wires at a certain interval and along the same direction on the top surface of the copper oxide layer, with the bottom side of each copper wire tangent to the copper oxide layer, thereby forming the copper wire array on the copper substrate. The copper wires are, for example, 1m long, with both ends fixed to the sides of the copper substrate.

[0038] The shape of the copper wire along its direction includes a straight line or a sinusoidal wave. The sinusoidal wave shape allows the copper wire to adaptively adapt to thermal expansion caused by temperature increases before and during heat treatment, as well as contraction during and after heat treatment. This better ensures the structural toughness and resistance to damage at the resulting joint. Furthermore, when using this heat transfer surface to fabricate devices such as phase change heat transfer devices (e.g., heat pipes, vapor chambers), better capillary toughness will be obtained when the device is flattened and / or bent, thereby improving the capillary structure's resistance to peeling or fracture. The sinusoidal wave shape can be obtained, for example, by extrusion.

[0039] The specified thickness includes 1-10μm, 10-50μm, or 50-100μm. The specific setting depends on the requirements of the actual application.

[0040] The specified spacing includes adjacent and / or 0.1-2 mm. The specific setting depends on the requirements of the actual application. In one embodiment, the adjacent spacing is located at a portion of the heat transfer surface that is pre-planned as a flat plate; and the 0.1-2 mm spacing is located at a portion of the heat transfer surface that is pre-planned as a bend or curl, and after the bend or curl, the copper wire is located on the inner perimeter, thereby reducing the specified spacing to adjacent. The greater the pre-planned degree of the bend or curl, the larger the specified spacing. Preferably, after the bend or curl, the specified spacing becomes adjacent.

[0041] The specified spacing can also include 0.05-0.1 mm. A smaller spacing results in greater capillary force and stronger anti-gravity performance, but requires higher control precision compared to being adjacent and / or 0.1-2 mm, although the adjacent spacing is relatively easy to achieve. The 0.05-0.1 mm spacing provides greater capillary force than the 0.1-2 mm spacing, but reduces permeability. The specific spacing should be set according to actual needs.

[0042] In step S13, the specified temperature includes 300-500℃ and / or 500-850℃, which is used to reduce the copper oxide to copper and to make the reduction product of the copper oxide layer form a porous copper single component. The top and bottom surfaces of the copper single component are respectively bonded to the copper wire array and the copper substrate; but not so that if the specified spacing is close together, the tangential points of adjacent copper wires on the heat transfer surface are bonded. The preset time includes 10-30 min and / or 30-90 min. The specified temperature can be gradually changed with the preset time. Optionally, the specified temperature may also include 850-950℃ to shorten the preset time. It can be raised to 850-950℃ and maintained for a short period of time, but it is necessary to ensure, for example, that the tangential points of the copper wires are not thermally bonded, or that more than half of them are thermally bonded. If a small area of ​​the copper wires becomes thermally bonded at the point of contact, a cutting blade must be used to cut the thermally bonded area; or, the cutting can be omitted, and the small area of ​​thermal bond can be maintained. However, if the small area of ​​thermal bond is located in a first region, which is configured as, for example, the evaporation end of a heat pipe, the cutting must be performed to ensure unobstructed passage for the rising and bursting of boiling bubbles.

[0043] The specific values ​​for the predetermined temperature and the predetermined time are determined according to the needs of actual applications, but the benchmark is to ensure that the copper oxide layer is reduced to copper, and that the reduced copper forms a single component with a porous layered structure. The top and bottom surfaces of this single component are respectively bonded to the copper wire array and the copper substrate, and the tangential points of the copper wires when they are close together do not stick together. The reduction is an exothermic reaction, and the copper oxide layer has high porosity and high specific surface area. The heating reduction product is a porous layered structure, whose constituent units are at the micron and / or nanometer scale and are bonded to each other. Therefore, it is less sensitive to heating and its time, and has low strength requirements. In one embodiment, the higher the predetermined temperature, the shorter the predetermined time.

[0044] The diameter of the copper wire is at least 0.05-1 mm and / or 1-2 mm. The cross-sectional shape of the copper wire includes circular, triangular, square, rectangular, elliptical, or other arbitrary shapes. The triangle includes an equilateral triangle, and if it is an equilateral triangle, the first side of one adjacent copper wire is coupled to the top surface of the copper oxide layer, and one side of the other copper wire is coupled to the first side. The finer the diameter of the copper wire, the smaller the capillary scale of the constructed copper wire array structure, and the thinner the obtained heat transfer surface thickness.

[0045] The rectangle or square shape can be formed during the copper wire forming process; alternatively, after the copper wire is formed, it can be circular, with multiple copper wires arranged closely together along the same direction to form a copper wire array, and laid on a stainless steel plate. The multiple copper wire arrays form a layered structure with baffles around its perimeter for lateral confinement. Another stainless steel plate is applied perpendicularly to the first stainless steel plate to cause the copper wire array to extend and deform. The baffles limit the extension beyond the baffles, thereby forcing the copper wires to deform into the rectangle or square shape, with the four corners of the rectangle or square being rounded. Alternatively, it can be formed by applying pressure along the normal direction of the copper substrate with copper wires of circular cross-section after the laying process in step S12. The pressure can be applied by a rigid member or by a rigid member that conducts ultrasonic waves. The rectangle or square shape allows the contact area of ​​the copper wires to obtain a flat plate-shaped gap with better directionality and a larger capillary driving area, which is beneficial for applications such as liquid working fluid reflux and boiling bubbles or gaseous working fluid rising at the evaporation end when used in phase change heat transfer devices.

[0046] In some embodiments, the copper wire is selected from monocrystalline copper. Monocrystalline copper has high ductility and thermal conductivity. For example, when used in heat pipes, the copper wire exhibits good resistance to peeling or breakage when the heat pipe is bent.

[0047] In one embodiment, the precursor includes the copper substrate, the copper oxide layer, and the copper wire array. In another embodiment, the precursor includes the copper substrate and the core-shell structured copper wire array described in step S22 below.

[0048] The aforementioned preparation method offers advantages such as large-scale, environmentally friendly, low-cost, simple, high-yield, and highly repeatable preparation of the heat transfer surface. The obtained heat transfer surface can be used to fabricate phase change heat transfer devices (e.g., heat pipes, vapor chambers). Specifically, the copper substrate serves as the shell of the closed cavity of the phase change heat transfer device, the copper wire array serves as grooves on the inner wall surface of the device, and the reduction product of the copper oxide layer can be a micron and / or nanoscale structure, serving as another scale of capillary structure on the inner wall surface of the phase change heat transfer device. This other dimension is smaller than the capillary structure dimension of the copper wire array construction. The capillary structure dimension of the copper wire array construction includes the contact hole angle formed when the copper wires are close together and a hollow cavity parallel to the direction of the copper wires, formed by the inner periphery of the copper oxide layer after reduction (the top of the hollow cavity is a gap along the axial direction of the copper wires formed by the contact hole angle). This is beneficial for enhancing radial capillary force, obtaining greater radial suction, promoting the penetration of condensate droplets into the reflux capillary channel, enhancing reflux liquid supply, reducing the space occupation of the condensate phase in the gas channel, and reducing radial thermal resistance. This trench is used for condensate phase reflux. When the size of the trench is small enough, it enables gravity water reflux and / or capillary reflux. Compared to traditional grooved wicks, the multi-scale capillary structure obtained by the heat transfer surface, including the micron and / or nanoscale structure, can be used to absorb more liquid working fluid. When the heat transfer surface is used to prepare, for example, a gas-liquid two-phase phase change heat transfer device, it can achieve the benefit of increasing the optimal total amount of working fluid.

[0049] It should be noted that the copper substrate can be a flat plate; one side of the copper substrate can also be the inner wall surface of a circular shell, in which case the copper wire array can be formed into a circular tube, thereby coupling the copper wire array to the inner wall surface of the shell. The circular shell can be further constructed as, for example, the shell of a heat pipe.

[0050] Furthermore, if the copper wire array is replaced with, for example, a single-layer (or sheet-like) structure array composed of multiple copper wires with a predetermined thickness of copper oxide layer obtained through surface oxidation treatment and arranged at a predetermined spacing and along the same direction, then after step S13, the product of the reduction of the shell in each of the single-layer (or sheet-like) structure copper wires can be a porous copper single component at the micron and / or nanometer scale. This copper single component allows adjacent, closely spaced shell-core structure copper wires to be connected (or bonded) at their tangential points. However, this copper single component has high porosity, thus ensuring that the portion of the shell-core structure copper wire corresponding to the core does not bond together. This ensures that after step S13, the tangential point of the shell-core structure copper wires retains high capillary force, rather than being bonded and thus closed or extensively closed. The capillary scale corresponding to the product after reduction of the tangential point is consistent with the capillary scale corresponding to the product after reduction of a copper oxide layer of a certain thickness added to one side of the copper substrate.

[0051] In another embodiment, step S11 is to prepare a copper substrate, wherein no copper oxide layer is added to any side of the copper substrate; step S12 is to prepare a single-layer structure array composed of a plurality of copper wires that have undergone surface oxidation treatment to obtain a copper oxide layer of a predetermined thickness and are arranged at a predetermined spacing and along the same direction, wherein the predetermined spacing includes adjacent and / or 0.1-2 mm, the shape of the direction includes a straight line or a sine wave, and the cross-sectional shape of the copper wire includes a circle, a square or a rectangle; step S13 is to place the preform in a protective atmosphere at a certain temperature and heat it for a predetermined time to obtain the heat transfer surface, wherein the certain temperature includes 300-500℃ and / or 500-850℃, and the protective atmosphere includes H2 or CO. Its advantage lies in the fact that the thickness of the prepared copper substrate needs to ensure a certain strength and anti-leakage performance (for example, when applied to ultra-thin heat spreaders), and step S11 does not require strict control of the modification of the copper substrate again, such as reacting the copper substrate with oxygen to obtain the copper oxide layer. If the degree of oxidation is too large, the thickness of the copper substrate will become thinner, the anti-leakage performance will become worse, and the strength will become weaker. Adding the copper oxide layer to the layup layer (such as the single-layer structure array composed of the core-shell structure copper wires) has better flexibility.

[0052] The heat spreader can be obtained by welding the butt joints of upper and lower cover plates that match the shape. The upper and lower cover plates can be obtained by cutting the heat transfer surface according to a preset shape, in which case the certain spacing can be that they are adjacent. The heat pipe can be obtained by cutting the heat transfer surface according to the preset shape, then rolling it into a tube body, and then welding the butt joints and flattening it. The certain spacing of the copper wires at the flattened part includes 0.1-2mm, so as to avoid the copper wires from being squeezed together and having spatial position conflicts due to the reduced spacing between the copper wires at the flattened part after flattening.

[0053] Optionally, after the laying in step S12, the preparation method includes the following steps:

[0054] A certain pressure is applied to the copper wire in a direction perpendicular to one side of the copper substrate so that the copper wire is embedded into the copper oxide layer to a certain depth.

[0055] The specified depth includes half or more than half of the specified thickness as described above. For example, if the specified thickness is 50 μm, then the specified depth is 25 μm. In practical applications, the specified pressure can be released after application, maintained after application, or continuously increased. The greater the specified pressure, the deeper the specified depth, thereby allowing the copper wire and the copper oxide layer to obtain a larger contact area, resulting in a tighter bond and stronger adhesion after the copper oxide layer is reduced, and achieving lower radial thermal resistance. Furthermore, for example, if the copper wire has a circular cross-section, the copper oxide layer is similarly embedded in the gap cavity between adjacent copper wires, forming a corresponding embedding. After the copper oxide layer is reduced, a porous copper structure is generated, which can be at the micrometer and / or nanometer scale, thereby enhancing the capillary force of the inner cavity or hollow channel formed between the copper wires.

[0056] Furthermore, when adjacent copper wires are close together, a gap is formed at the tangent point, and the adjacent copper wires and the insert constitute an inner hollow cavity, the top of which has the gap. Further, the hollow cavity can be filled with copper powder, the particle size of which is smaller than the gap width. This filling with copper powder can be achieved by laying a certain thickness of copper powder on the top surface of the copper oxide layer before laying, and then containing it in the inner hollow cavity between the adjacent copper wires and the copper oxide layer after laying; or it can be injected through one end opening of the hollow cavity after step S13, and the copper powder is confined within the hollow cavity after sealing both ends of the hollow cavity. This has the advantage of obtaining greater capillary forces along the axial and radial directions of the hollow cavity, resulting in a multi-scale capillary structure.

[0057] In one embodiment, after the laying, the copper wire is embedded into the copper oxide layer to a certain depth, and then step S13 is performed. In another embodiment, the laying, in addition to applying a certain pressure to the copper wire, also includes tautly pulling the copper wire and rubbing it back and forth along the axis of the copper wire on the copper oxide layer, so that the copper wire is embedded into the copper oxide layer to a certain depth and the contact at the contact point is better.

[0058] Optionally, after step S13, the preparation method includes the following steps:

[0059] The copper wires provided on the heat transfer surface are cut into multiple segments with a length of 1-20mm, and the corresponding slit widths obtained include no more than 0.1mm; the shape of the slits includes a plane or an arc surface; the inclination angle of the slits includes orthogonal or oblique to the copper substrate.

[0060] For example, the cutting can be performed using a cutting blade of a certain shape. After the copper wire is heated to a preset temperature, it is cut into multiple segments according to a preset length unit. This "certain shape" can be a flat plate, a curved plate, or a folded plate formed by combining the ends of two flat plates. The resulting cut will have a shape corresponding to at least a flat or curved surface. The curved surface, relative to the flat surface, provides the heat transfer surface with better capillary force or greater liquid-phase working fluid reflux intensity, as well as greater gas-phase working fluid eddy current intensity, thereby enhancing the heat transfer performance of the gas-liquid two-phase phase change heat transfer device. The preset temperature improves the ductility and ease of cutting of the copper wire, and the preset length unit includes 1-20 mm or 0.5-1 mm. The cutting can also employ a composite ultrasonic cutting blade (to enhance the cutting effect), laser, or other methods, which can be selected according to actual needs. The multi-segment cutting also serves to break or prevent the gas and liquid columns generated in existing channel-type liquid suction cores from being spaced apart, thus forming a liquid plug. The gas column impedes the backflow of the liquid column and causes it to pulsate back and forth in the channel. The slit is used to allow the liquid column to flow across and converge in adjacent channels, disrupting the equilibrium state between the gas and liquid columns, thereby improving the replenishment efficiency to the evaporation end.

[0061] Furthermore, after the cutting, if the size of the slit does not reach the preset size, i.e., does not reach the preset capillary force, the cut heat transfer surface is placed in a protective atmosphere at a second preset temperature, and pressure is applied to the cut copper wire along the normal direction of the copper substrate to reduce the width of the slit. This is particularly advantageous when the inclination angle of the slit is oblique to the copper substrate. The second preset temperature is set to ensure that the copper wire and the porous copper layer of the copper oxide layer reduction product have better ductility than at outdoor temperatures, but without causing thermal contact at the contact points of the copper wire, including 300-500°C.

[0062] Furthermore, after the cutting, if the size of the slit does not reach the preset size, i.e., does not reach the preset capillary force, the obtained heat transfer surface undergoes a secondary oxidation treatment to obtain a copper oxide layer of a certain thickness at least at the slit corresponding to the copper wire. Then, it is placed in a reducing atmosphere for heating treatment (e.g., 300-500°C) to reduce the copper oxide layer into nanostructured porous copper. This nanostructured porous copper is used to reduce the size of the slit. This heating treatment prevents the contact area of ​​the copper wire from becoming thermally bonded.

[0063] Optionally, after step S13, if the certain spacing is adjacent and the local part of the tangent of the copper wires is thermally bonded, the preparation method further includes the following step: using a cutting blade to cut or slit the thermally bonded area.

[0064] Furthermore, the preparation method described in the embodiments of the first aspect of the present invention further includes:

[0065] The copper wire array can be replaced by a second laying layer;

[0066] The second laying layer, corresponding to the following structural types, includes: a second copper wire array consisting of multiple copper wires with a certain thickness of copper oxide layer obtained through surface oxidation treatment and spaced at a certain interval along the same direction; a rectangular copper sheet array; or a rectangular copper sheet array with a certain thickness of copper oxide layer obtained through surface oxidation treatment; or a copper wire mesh; or a copper wire mesh with a certain thickness of copper oxide layer obtained through surface oxidation treatment; or second copper powder with a certain thickness of copper oxide layer obtained through surface oxidation treatment; or a mixed powder consisting of copper powder and second copper powder mixed in a certain proportion; or a copper wire column array; or a copper wire column array with a certain thickness of copper oxide layer obtained through surface oxidation treatment.

[0067] The rectangular copper sheet array has the following structural types: multiple rectangular copper sheets are arranged in parallel at a certain interval and along the same direction; the bottom sides of the rectangular copper sheets with the same orientation are located on the same plane for coupling to the copper oxide layer; wherein the certain interval includes adjacent and / or 0.1-2mm; the direction of the rectangular copper sheets along the length direction includes a straight line or a sine wave.

[0068] The copper wire mesh has the following structural types: woven wire mesh or erected wire mesh; and the corresponding shape types include sheet or tubular; wherein the erected wire mesh includes a single-layer structure or a multi-layer structure.

[0069] The single-layer structure includes the following structural types: an array of copper wires arranged at a certain spacing and along the same direction; and a connector is provided between adjacent copper wires, wherein the connector is obtained by spot welding; wherein the certain spacing includes being adjacent and / or 0.1-2mm.

[0070] The multilayer structure includes the following structural types: a first copper wire array consisting of multiple first copper wires arranged at a first spacing and along a first direction, and a second copper wire array consisting of multiple second copper wires arranged at a second spacing and along a second direction; wherein the first spacing does not exceed the second spacing, and the first spacing includes adjacent and / or 0.1-2mm; the second copper wire array is mounted on the first copper wire array, and the corresponding contact points of the mounting are bonded; the bottom surface of the first copper wire array is used for coupling to the top surface of the copper oxide layer;

[0071] The copper wire pillar array has the following corresponding structural types: multiple copper wire pillars are arranged at a certain interval and along the same direction; wherein the certain interval includes adjacent and / or 1-10μm; one end of each copper wire pillar is set as a fixed end and used to couple to the copper oxide layer, and the other end is set as a free end or used to couple to the copper oxide layer.

[0072] The specified proportion includes a weight ratio of the copper powder and the second copper powder of 1:1 to 1:10.

[0073] Specifically, the aforementioned array of copper wires, each having undergone surface oxidation to obtain a copper oxide layer of a certain thickness, is arranged at a certain spacing and along the same direction to form a second copper wire array. The second copper wires are prepared from copper wires with a circular cross-section and obtained through the surface oxidation treatment. The certain spacing includes being adjacent to each other. The second copper wires form a core-shell structure, and the outer copper oxide layer, due to its high specific surface area and high porosity, ensures that when adjacent second copper wires are placed adjacent to each other, the contact area at the tangent point still retains high porosity. After step S13, the copper oxide layer generates a micron- and / or nano-scale porous layered structure, which resides between the unoxidized copper wires inside adjacent second copper wires. The presence of the copper oxide layer reduces the difficulty of placement, requiring only pushing them closer together, while simultaneously ensuring that the tangent point between adjacent second copper wires is a highly porosity gap.

[0074] In the single-layer structure, the spot welding, exemplarily, can obtain a connector whose height does not exceed half the diameter of the copper wire, and whose top is lower than the top side of the copper wire.

[0075] The width of the rectangular copper sheet is at least 0.05-1 mm and / or 1-2 mm. The thickness of the rectangular copper sheet is at least 0.05-1 mm and / or 1-2 mm. The smaller the width of the rectangular copper sheet, the smaller the height (or thickness) of the constructed rectangular copper sheet array, and the thinner the obtained heat transfer surface thickness. The thinner the rectangular copper sheet and the smaller the spacing, the smaller the capillary scale of the constructed rectangular copper sheet array, and the greater the capillary force. The orientation of the rectangular copper sheet along its length includes a straight line or a sinusoidal waveform.

[0076] The aforementioned second copper powder, after surface oxidation treatment to obtain a copper oxide layer of a certain thickness, wherein the surface includes part or all of the outer wall surface of each particle in the second copper powder, and the particle is a core-shell structure powder. Compared with copper oxide powder, the second copper powder, after step S13, obtains a porous structure with multi-scale pores, which can combine high capillary force and high permeability, and is more pressure resistant. In contrast, the copper oxide powder, after step S13, obtains a porous structure with a single-scale pore structure and high capillary force, but low permeability.

[0077] The weight ratio of the copper powder and the second copper powder described above is 1:1 to 1:10, where the weight ratio can also correspond to the particle number ratio. For example, when the particle sizes of the copper powder and the second copper powder are consistent or similar, and the weight ratio is 1:10, the second copper powders have a higher probability of contacting each other. After step S13, the second copper powders thermally bond the contact areas together at a lower temperature. The thermal bonding between the copper powder and the second copper powder is slower or insufficient compared to the thermal bonding between the two copper powders themselves, thus forming a porous single-component structure where the copper powder is "enclosed" by the reduction product of the second copper powder, exhibiting high porosity, capillary force, and permeability. The weight ratio is preferably such that the minimum number of second copper powder particles achieves the "enclosure" of a single copper powder particle. The copper powder has a regulating effect, including permeability.

[0078] In one embodiment, the copper wire mesh, after surface oxidation treatment to obtain a copper oxide layer of a certain thickness, has a core-shell structure. After step S13, the shell product is a first copper single component with a nanoscale porous structure. Then, combined with the second copper single component with a nanoscale porous structure formed after step S13 on the copper oxide layer of the copper substrate, the first and second copper single components are bonded together, forming a thicker and more resilient porous buffer layer. This is beneficial for processing the heat transfer surface, such as bending it after fabrication into a phase change heat transfer device, ensuring a more stable structure and impact resistance.

[0079] Optionally, the preparation method described in the embodiments of the first aspect of the present invention further includes:

[0080] The fabrication method for the copper wire pillar array includes the following sub-steps S101-S105:

[0081] S101. Prepare multiple copper wires and perform an oxidation treatment on the surface of the copper wires; wherein the product obtained by the oxidation treatment includes a copper oxide layer of a certain thickness; the surface includes part or all of the outer wall surface of the copper wires;

[0082] S102. The copper wires are straightened and run in the same direction to form a copper wire bundle;

[0083] S103. Cut the copper wire bundle along the two cross-sections to obtain an intermediate body formed by the copper wire bundle between the two cross-sections;

[0084] S104. The intermediate is placed in a protective atmosphere at a certain temperature and heated for a preset time to obtain a second intermediate; wherein the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

[0085] S105. Cutting and / or grinding is performed on one of the cross sections corresponding to the second intermediate to reduce the height of the second intermediate, thereby obtaining the third intermediate; wherein the copper wire pillar array corresponds to the structure type of the intermediate, the second intermediate, or the third intermediate;

[0086] If the wire mesh being laid is a copper wire mesh that has undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness, then the corresponding preparation method includes the following sub-steps S201-S202 or S211-S212:

[0087] S201. Prepare the single-layer structure; wherein the shape of the copper wire includes a straight line or a sinusoidal wave, and the certain spacing is close together;

[0088] S202. The single-layer structure is placed in a protective atmosphere at a certain temperature and heated for a preset time, thereby reducing the copper oxide to porous copper and bonding the adjacent copper wires together; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

[0089] or,

[0090] S211. Prepare the multilayer structure; wherein the shape of the first copper wire includes a straight line or a sine wave, the shape of the second copper wire includes a straight line, and the first spacing is adjacent;

[0091] S212. The multilayer structure is placed in a protective atmosphere at a certain temperature and heated for a preset time, thereby reducing the copper oxide to porous copper. The porous copper bonds adjacent first copper wires together, and the corresponding contact points of the frame are bonded. The certain temperature includes 300-500℃ and / or 500-850℃. The protective atmosphere includes H2 or CO.

[0092] Specifically, in a first aspect embodiment of the present invention, a copper wire pillar array comprises multiple copper wire pillars spaced at a certain interval and along the same direction; wherein the certain interval means adjacent to each other; one end of each copper wire pillar is a fixed end for coupling to the copper oxide layer, and the other end is a free end or for coupling to the copper oxide layer. The periphery of the copper wire pillar array can be maintained, moved, and used, for example, by bundling.

[0093] Sub-steps S101-S105 are used to prepare another type of copper wire pillar array. In sub-step S101, the surface of the copper wire is oxidized to obtain a core-shell structure copper wire. After sub-step S104, the copper oxide layer of this core-shell structure copper wire is reduced to a porous copper single component with a micron and / or nanometer scale. The height (or thickness) of this copper single component includes 1-10 μm and / or 0.01-1 μm. It can be seen that after sub-step S104, the diameter of the copper wire pillars in the copper wire pillar array is smaller than that of the copper wires in step S101 without the oxidation treatment. This copper single component is bonded between adjacent copper wire pillars, making the copper wire pillars form a single component (i.e., the copper wire pillar array), which is convenient for movement, storage, and use. This copper single component also avoids thermal bonding at the tangential points of the copper wires, which would lead to a decrease or significant decrease in the permeability at those points. This copper single component, like the corresponding connector obtained by spot welding mentioned above, serves the same purpose: to couple multiple copper wires together, thereby forming a copper single component with a multi-scale porous structure. However, this copper single component has greater capillary force, while its directionality and permeability are inferior to the micro-channel structure formed by the inner cavity of the copper wires.

[0094] In step S101, the copper wire surface is oxidized. The location of the added copper oxide layer can be random and uncontrolled; alternatively, an anti-oxidation layer can be applied locally to the copper wire surface before the oxidation process, and then the anti-oxidation layer is removed. The thickness of the copper oxide layer is coupled to the intensity and duration of the oxidation process.

[0095] The methodological ideas of the above sub-steps S101-S105 can also be applied to the setting up of the wire mesh to prepare another type of wire mesh, achieving similar ease of transfer, storage, and use as woven wire mesh.

[0096] In another possible implementation of the preparation method described in the first aspect of the present invention, the steps include:

[0097] S21, Prepare the copper substrate;

[0098] S22. Prepare a sheet-like core-shell structure copper wire array consisting of multiple copper wires that have undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness, arranged at a certain spacing and along the same direction, and lay them on one side of the copper substrate to obtain a second preform; wherein the certain spacing includes adjacent and / or 0.1-2mm; the shape of the direction includes straight line or sine wave; the cross-sectional shape of the copper wire includes circular, square or rectangular.

[0099] S23. The second precursor is placed in a protective atmosphere at a certain temperature and heated for a preset time to obtain the heat transfer surface; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

[0100] The core-shell structure copper wire array can be replaced by a third laying layer;

[0101] The third laying layer has the following corresponding structural types: a rectangular copper sheet array that has undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness; a copper wire mesh that has undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness; a second copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness; a mixed powder composed of copper powder and the second copper powder in a certain proportion; or a copper wire column array that has undergone surface oxidation treatment to obtain a copper oxide layer of a certain thickness.

[0102] The rectangular copper sheet array has the following structural types: multiple rectangular copper sheets are arranged in parallel at a certain interval and along the same direction; the bottom sides of the rectangular copper sheets facing the same direction are located on the same plane and are used to couple to one side of the copper substrate; wherein the certain interval includes adjacent and / or 0.1-2mm; the direction of the rectangular copper sheets along the length direction includes a straight line or a sine wave.

[0103] The copper wire mesh has the following structural types: woven wire mesh or erected wire mesh; and the corresponding shape types include sheet or tubular; wherein the erected wire mesh includes a single-layer structure or a multi-layer structure.

[0104] The single-layer structure includes the following structural types: an array of copper wires arranged at a certain spacing and along the same direction; wherein the certain spacing includes adjacent and / or 0.1-2mm.

[0105] The multilayer structure includes the following structural types: a first copper wire array consisting of a plurality of first copper wires arranged at a first spacing and along a first direction, and a second copper wire array consisting of a plurality of second copper wires arranged at a second spacing and along a second direction; wherein the first spacing does not exceed the second spacing, and the first spacing includes adjacent and / or 0.1-2mm; the second copper wire array is mounted on the first copper wire array, and the corresponding contact points of the mounting are bonded; the first copper wire array is coupled to one side of the copper substrate;

[0106] The copper wire pillar array has the following corresponding structural types: multiple copper wire pillars are arranged at a certain interval and along the same direction; wherein the certain interval includes adjacent and / or 1-10μm; one end of each copper wire pillar is set as a fixed end for coupling to one side of the copper substrate, and the other end is set as a free end;

[0107] The specified proportion includes a weight ratio of the copper powder and the second copper powder of 1:1 to 1:10.

[0108] In step S22 above, the copper wire undergoes surface oxidation treatment to obtain a copper oxide layer of a certain thickness. This copper wire can also obtain a copper oxide layer of a certain thickness through coating or other methods. Preferably, obtaining a copper oxide layer of a certain thickness through surface oxidation treatment is advantageous due to its high efficiency, convenience, environmental friendliness, low cost, uniform and stable structure, and the absence of impurities such as binders.

[0109] Optionally, after the laying described in step S22, the following steps are included:

[0110] A certain pressure is applied to the core-shell structure copper wire array in a direction perpendicular to one side of the copper substrate, so that the copper oxide layer can obtain a larger contact area with the copper substrate.

[0111] Optionally, after the laying described in step S22, a second layer of the core-shell structure copper wire array is laid on the top surface of the core-shell structure copper wire array, thereby forming a third preform corresponding to the copper substrate and the two layers of the core-shell structure copper wire array; wherein, the core-shell structure copper wire array in the upper layer and the core-shell structure copper wire array in the lower layer have the same or different orientations; the spacing between the core-shell structure copper wires in the two layers can be the same or different; the diameter of the core-shell structure copper wires in the two layers can be the same or different; the cross-sectional shape of the core-shell structure copper wires in the two layers can be the same or different; and the thickness of the copper oxide layer of the core-shell structure copper wire in the former layer is not greater than the thickness of the copper oxide layer of the core-shell structure copper wire in the latter layer, so as to obtain a scale gradient of the capillary structure along the thickness direction after step S23, thereby enhancing, for example, the capillary suction force along the thickness direction.

[0112] Optionally, after step S23, the following steps are included:

[0113] The core-shell copper wire, after being reduced to its original product, is cut into multiple segments along the axial direction of the core-shell copper wire, with a length unit of 1-20 mm. The width of the corresponding cut is no more than 0.1 mm. The shape of the cut includes a plane or an arc. The inclination angle of the cut includes orthogonal or oblique to the copper substrate.

[0114] Second aspect of the embodiment

[0115] A second aspect of the present invention provides a heat transfer surface, characterized in that it is constructed as a top layer, a bottom layer, and an intermediate layer bonded to the bottom layer and the top layer on both sides respectively; the structure type corresponding to the bottom layer includes a copper substrate, the structure type corresponding to the intermediate layer includes a porous copper single component, and the structure type corresponding to the top layer includes a micro-gap structure.

[0116] The porous copper single component is obtained by heating a copper oxide layer of a certain thickness in a protective atmosphere at a certain temperature for a preset time; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO; the copper oxide layer is disposed on one side of the copper substrate and / or the surface of the micro-pore structure; the one side includes part or all of it; the surface includes part or all of it.

[0117] The microgap structure includes a copper wire array consisting of multiple copper wires spaced at a certain interval and along the same direction; the certain interval includes adjacent and / or 0.1-2 mm; the shape of the direction includes a straight line or a sine wave; the cross-sectional shape of the copper wire includes a circle, a square or a rectangle.

[0118] The copper wire array can be replaced by a fourth laying layer;

[0119] The fourth laying layer has the following corresponding structural types: rectangular copper sheet array, copper wire mesh, copper powder, or copper wire column array; wherein...

[0120] The rectangular copper sheet array has the following structural types: multiple rectangular copper sheets are arranged in parallel at a certain interval and along the same direction; the bottom sides of the rectangular copper sheets with the same orientation are located on the same plane and are used to couple to one side of the intermediate layer; wherein the certain interval includes adjacent and / or 0.1-2mm; the direction of the rectangular copper sheets along the length direction includes a straight line or a sine wave.

[0121] The copper wire mesh has the following structural types: woven wire mesh or erected wire mesh; and the corresponding shape types include sheet or tubular; wherein the erected wire mesh includes a single-layer structure or a multi-layer structure.

[0122] The single-layer structure includes the following structural types: an array of copper wires arranged at a certain spacing and along the same direction; and a connector is provided between adjacent copper wires, wherein the connector is obtained by spot welding; wherein the certain spacing includes being adjacent and / or 0.1-2mm.

[0123] The multilayer structure includes the following structural types: a first copper wire array consisting of multiple first copper wires arranged at a first spacing and along a first direction, and a second copper wire array consisting of multiple second copper wires arranged at a second spacing and along a second direction; wherein the first spacing does not exceed the second spacing, and the first spacing includes adjacent and / or 0.1-2mm; the second copper wire array is mounted on the first copper wire array, and the corresponding contact points of the mounting are bonded; one side of the first copper wire array is coupled to the intermediate layer;

[0124] The copper wire pillar array has the following structural types: multiple copper wire pillars are arranged at a certain interval and along the same direction; wherein the certain interval includes adjacent and / or 1-10μm; one end of each copper wire pillar is set as a fixed end for coupling to the intermediate layer, and the other end is set as a free end.

[0125] The copper oxide layer described above is disposed on one side of the copper substrate and / or the surface of the microgap structure, wherein the microgap structure is coupled to one side of the copper substrate. One side of the copper substrate includes a portion or all of that side. The surface of the microgap structure can be understood as the surface of the microgap structure and / or the surface layer.

[0126] The copper oxide layer can be implemented by exposing one side of the copper substrate and / or the surface of the micro-gap structure to an atmosphere containing oxygen at a preset temperature; or by depositing (or coating) copper oxide powder of a certain thickness onto one side of the copper substrate and / or the surface of the micro-gap structure, or by depositing (or coating) a layer of copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer shell of a preset thickness; or by other methods of increasing the copper oxide layer. The copper oxide layer contains CuO and / or Cu2O. The copper substrate can be flat, tubular, or irregularly shaped such as wavy.

[0127] Furthermore, the copper oxide layer can be configured, for example, by exposing one side of the copper substrate and / or the surface of the micro-gap structure to an atmosphere containing oxygen at a preset temperature. The degree of exposure includes the preset temperature, oxygen concentration, reaction time, and the surface area ratio for achieving this configuration, which are set according to actual needs.

[0128] For example, for copper powder, after a certain reaction time, 2 / 3 of the total surface area of ​​each particle in the copper powder is obtained to form the copper oxide layer. However, if this meets the requirements of one embodiment, the process can be stopped. Since the certain temperature is 300-500°C and / or 500-850°C, if the surface where the copper oxide layer is not obtained is tangent, the tangent part of the surface will not become bonded after the reaction time, thereby obtaining a contact hole angle and improving, for example, the permeability of the powder wick. Alternatively, this process can be achieved by mixing a first copper powder (i.e., oxygen-free copper powder) that has not undergone this process with a second copper powder (i.e., copper powder with an oxygen-containing core-shell structure on the surface) or copper oxide powder or cuprous oxide powder in a certain proportion.

[0129] In the above embodiments of the present invention, when adjacent copper wires are close together, a gap is formed at the tangent point, and the adjacent copper wires and the intermediate layer constitute an inner hollow cavity, the top of which has the gap. Further, the hollow cavity can be filled with copper powder, the particle size of which is smaller than the gap width. This is advantageous because it results in greater capillary forces along the axial and radial directions of the hollow cavity, leading to a multi-scale capillary structure.

[0130] In one method for preparing the heat transfer surface, one side of the copper substrate is oxidized to obtain a copper oxide layer of a certain thickness. This copper oxide layer serves as a precursor for the intermediate layer. The intermediate layer is obtained after the precursor undergoes a reaction in a reducing atmosphere containing H2 or CO at a certain temperature. The intermediate layer is a copper single-component with a porous structure at the micron and / or nanometer scale. This copper single-component is layered, with its two sides bonded to the bottom layer and the top layer, respectively. The certain temperature includes 300-500℃ and / or 500-850℃. The intermediate layer can also be replaced with solder. The solder melting temperature includes 300-500℃ and / or 500-850℃. For example, welding is achieved at the tangential points where each copper wire in the copper wire array contacts the solder layer. When the spacing between adjacent copper wires is close together, the resulting tangential points form a gap. For phase change heat transfer devices, this gap can be filled with either a liquid working medium or a gaseous working medium.

[0131] In another method for preparing the heat transfer surface, the micro-gap structure surface is oxidized to obtain a copper oxide layer of a certain thickness. This copper oxide layer serves as a precursor for the intermediate layer. The intermediate layer is obtained by reacting the precursor with a reducing atmosphere containing H2 or CO at a certain temperature. The intermediate layer has a micron- and / or nanon-scale porous copper single-component structure. A portion of the outer wall of this copper single-component is bonded to the copper substrate. The certain temperature includes 300-500℃ and / or 500-850℃.

[0132] It should be noted that the heat transfer surface and its preparation method described in the embodiments of the present invention can be applied to heat transfer fields such as heat pipes, heat spreaders, heat exchangers, and cooling of electronic components, and can also be used in other fields such as catalyst supports, high-efficiency separation, microreactors, light treatment, and electrical treatment.

[0133] Third aspect embodiment

[0134] A third aspect of the present invention provides a phase change heat transfer device, the corresponding product types including heat pipes, heat spreaders or loops, characterized in that the phase change heat transfer device includes a heat transfer surface as described in any one of the first to second aspects above; wherein the heat transfer surface is coupled to the inner circumference formed by the housing of the phase change heat transfer device.

[0135] The aforementioned heat transfer surface coupled to the inner circumference formed by the shell of the phase change heat transfer device includes: one side of the heat transfer surface with the copper wire array coupled to the inner circumference formed by the shell of the phase change heat transfer device; or, one side of the heat transfer surface with the microgap structure coupled to the inner circumference formed by the shell of the phase change heat transfer device. The copper wire array, or the microgap structure, can be used for the reflux of condensing working fluids in the form of gravity water and / or capillary water, and in some embodiments, also plays a role in enhancing the generation of eddies during the flow of the gaseous working fluid. The heat transfer surface can be considered as a sheet-like or tubular structure, and the corresponding side of the sheet-like structure, or the corresponding inner wall surface of the tubular structure, is processed by the preparation method described in this invention to obtain a portion coupled to the inner circumference formed by the shell of the phase change heat transfer device.

[0136] Fourth aspect embodiment

[0137] A fourth aspect of the present invention provides a welding method for sealing a butt joint of a heat transfer surface as described in any one of the first to third aspects above, wherein the butt joint is obtained by fitting two cover plates constructed by cutting the heat transfer surface into a preset shape, or by rolling a cover plate into a tubular shape, characterized in that the welding method includes the following steps:

[0138] S301. Clamp the two cover plates to maintain the mating posture, and make the mating seam face upward;

[0139] S302. Apply a certain amount of powder to the joint seam, and use a friction stirring head with a diameter larger than the width of the seam to rub and stir the joint seam and the powder, so that the joint seam is sealed together.

[0140] The width of the powder application is not less than the width of the edge; the powder includes copper powder, alloy powder or brazing filler powder.

[0141] In one embodiment, the mating seam forms a flat plate-shaped gap surface, with a flat copper substrate coupled to each of its two sides. The flat plate-shaped gap surface extends 2 mm in width, and the outer surface of the flat copper substrate can be limited by a pressure fixture to maintain close contact. Alternatively, before the friction stirring, the flat copper substrate can be ultrasonically welded to pre-obtain a certain bonding strength; or, a low-current resistance weld can be applied to preheat the flat copper substrate, which helps to improve the efficiency of the friction stirring.

[0142] In another embodiment, the mating seam is obtained by bonding the side of the copper substrate, and the bonding area forms a flat gap surface, which corresponds to the side surface formed by the length and thickness directions of the copper substrate.

[0143] In another embodiment, after step S302, the weld joint is further cut and / or ground to obtain a more aesthetically pleasing and lightweight weld structure.

[0144] The presence of the intermediate layer in the heat transfer surface makes it more resilient. However, sintering or resistance welding of the seams, as used in the prior art, should be avoided to prevent, for example, thermal bonding at the tangential points of the copper wire array, and to prevent further high-temperature exposure of the intermediate layer, which could lead to structural damage. The intermediate layer's structural type includes the micron and / or nanoscale porous copper single-component structures described above, which are relatively sensitive to heat; high-temperature sintering can easily cause instability or damage to the nanostructure. The welding method of the present invention allows for rapid conduction of heat generated on the surface during friction stir welding, which helps to avoid excessively high temperatures. It is a method with controllable heat generation temperature and range, and also offers advantages such as excellent sealing performance, high structural strength, and aesthetic appeal.

[0145] The aforementioned welding method has the advantages of the following: since the maximum heat is received at the outer wall surface of the copper substrate near the weld, the reduction products of the copper oxide layer located on the inner wall surface are not subjected to heat and structural damage, thereby better protecting the reduction products of the copper oxide layer or the intermediate layer. Furthermore, the process is simple, low-cost, and achieves better bond strength and improved leakage resistance.

[0146] Fifth aspect embodiment

[0147] A fifth aspect of the present invention provides a bending method for bending a specific portion of a phase change heat transfer device as described in the third aspect above, wherein the phase change heat transfer device has a shape including a flat tubular shape, characterized in that the bending method includes:

[0148] S401. Bending the specific location at a certain speed;

[0149] S402. Simultaneously, the activated friction stirring head is applied with a certain pressure to the outer rounded corner formed by bending, so as to reduce the curvature of the outer rounded corner, and / or increase the thickness of the copper substrate at the outer rounded corner, and / or reduce the cross-sectional area of ​​the cavity of the phase change heat transfer device corresponding to the outer rounded corner.

[0150] Compared to using step S401 alone, using steps S401-S402 will reduce the curvature at the outer rounded corner, and / or increase the thickness of the copper substrate at the outer rounded corner, and / or reduce the cross-sectional area of ​​the cavity of the phase change heat transfer device corresponding to the outer rounded corner.

[0151] Furthermore, to prevent cracks from appearing on the copper substrate at the outer rounded corners due to bending, a certain amount of copper powder can be applied to the outer rounded corners, and a friction stirring head can be used to rub and stir the outer rounded corners and the copper powder to reinforce the cracks. This can be used to thicken the copper substrate corresponding to the outer rounded corners, thereby obtaining greater structural strength.

[0152] The present invention also provides an electronic device, characterized in that the electronic device includes a phase change heat transfer device as described in any one of the third to fifth aspects above.

[0153] It should be noted that the step numbers in the specification and claims of this invention are only for the convenience of explaining specific embodiments and are not intended to limit the order in which the steps are performed. The terms "first," "second," "third," "fourth," etc. (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those described herein. Furthermore, the term "above" expressing quantity means two or more. The terms "comprising," "having," and any variations thereof are intended to cover non-exclusive inclusion.

[0154] It should be understood that the orientation descriptions, such as up, down, front, back, left, right, middle, inside, outside, top, bottom, etc. (if present), are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0155] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Where there is no conflict, the embodiments and features of the present invention can be combined with each other. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing a heat transfer surface, characterized in that, The preparation method includes the following steps: S11. Prepare a copper substrate and add a copper oxide layer of a certain thickness to one side of the copper substrate; the corresponding implementation methods include reacting one side of the copper substrate with oxygen, or, laying a layer of copper oxide powder, or, laying a layer of copper powder that has undergone surface oxidation treatment to obtain a copper oxide layer of a preset thickness. S12. An array of copper wires arranged at a certain spacing and along the same direction is laid on the top surface of the copper oxide layer to obtain a precursor; the certain spacing includes adjacent and / or 0.1-2mm; the shape of the direction includes straight line or sine wave; the cross-sectional shape of the copper wire includes circle, square or rectangle. S13. The precursor is placed in a protective atmosphere at a certain temperature and heated for a preset time to obtain the heat transfer surface; the certain temperature includes 300-500℃ and / or 500-850℃; the protective atmosphere includes H2 or CO.

2. The preparation method according to claim 1, characterized in that, After the laying is completed, the following steps are included: A certain pressure is applied to the copper wire in a direction perpendicular to one side of the copper substrate so that the copper wire is embedded into the copper oxide layer to a certain depth.

3. The preparation method according to claim 1, characterized in that, Following step S13, the following steps are included: The copper wires provided on the heat transfer surface are cut into multiple segments with a length of 1-20mm, and the corresponding slit widths obtained include no more than 0.1mm; the shape of the slits includes a plane or an arc surface; the inclination angle of the slits includes orthogonal or oblique to the copper substrate.

4. A phase change heat transfer device, the corresponding product types including heat pipes, heat spreaders, or loops, characterized in that, The phase change heat transfer device includes a heat transfer surface as described in any one of claims 1-3; wherein the heat transfer surface is coupled to the inner perimeter formed by the housing of the phase change heat transfer device.