Spray cooling multi-scale composite surface structure based on cooperation of liquid suction and exhaust

Abstract

The invention discloses a spray cooling multi-scale composite surface structure based on liquid absorption and exhaust synergy, and relates to the technical field of electronic equipment thermal control, the spray cooling multi-scale composite surface structure comprises a metal substrate, a micron-scale stepped metal microcolumn array and a nano metal oxide layer, the micron-scale stepped metal microcolumn array is arranged on the top of the metal substrate, and the nano metal oxide layer is arranged on the top of the metal substrate. And the plurality of longitudinally and transversely arranged micron-scale stepped metal microcolumns are arranged in a manner that the widths of column bodies are gradually reduced from the two ends to the middle, and the column bodies are arranged in the same transverse row at equal intervals and in the same longitudinal row at gradient intervals, so that liquid-phase capillary spreading can be promoted by utilizing a nano-scale oxide structure, and gas overflow is promoted by utilizing channels among the micron-scale stepped metal microcolumns; the anisotropic micro-column spacing design is utilized to promote directional liquid discharge, the multi-scale micro-nano structure promotes ordered countercurrent of gas and liquid through liquid absorption and exhaust functions, heat transfer deterioration caused by bubble accumulation is effectively inhibited, efficient nucleate boiling is kept, and meanwhile, the spray cooling heat transfer coefficient and the critical heat flux density are improved.

Description

Technical Field

[0001] The present invention relates to the field of electronic equipment thermal control technology, and in particular to a spray cooling multi-scale composite surface structure based on coordinated liquid suction and exhaust. Background Art

[0002] As spacecraft technical missions become increasingly complex, aerospace electronic equipment faces a more complex working environment, and aerospace electronic equipment has higher and higher requirements for integration, miniaturization, and high-speed computing, resulting in a sharp increase in its heat density. High-temperature failure of electronic equipment not only seriously threatens the normal operation and service life of spacecraft, but may even cause immeasurable losses such as equipment burnout and space fires. Therefore, in order to ensure the reliable operation of spacecraft and space safety, the development of high heat flux density heat dissipation technology is crucial.

[0003] Spray cooling has the advantages of high heat dissipation density, low heat transfer temperature difference, less required working fluid, and fast thermal control response. It has important application prospects in the field of aerospace thermal control. The heat transfer principle of spray cooling lies in the forced convection generated by the high-frequency impact of microscopic droplets, as well as the disturbance field and velocity field caused by the droplet impact, which are closely related to the wall liquid film flow state and convective heat transfer. In addition, droplet impact can also promote the wall bubble breakage and enhance boiling heat transfer. Therefore, the flow heat transfer characteristics of the droplet impact process on the solid surface are the fundamental reason that affects the heat transfer performance of spray cooling, and it is urgent to develop engineering technologies to enhance and regulate the flow heat transfer characteristics of the droplet impact process.

[0004] Surface structural characteristics are important factors affecting the heat transfer performance of spray cooling. Strengthening the surface mainly optimizes the heat transfer effect by improving wettability, expanding contact area, extending the length of the three-phase contact line, and increasing boiling nucleation points. Specific methods include adjusting surface roughness, constructing porous coatings, and changing surface geometry. Surface roughness directly affects the thickness of the liquid film, bubble size, and residual vapor state, and changes the dominant heat transfer mechanism. Ultra-smooth surfaces inhibit nucleate boiling due to the lack of nucleation points, and mainly rely on liquid film evaporation for heat transfer; while rough surfaces can significantly promote nucleate boiling, which becomes the main heat transfer method. Porous coatings can change the three-phase contact characteristics and heat transfer performance of the surface. By spraying high-porosity structures such as nanoscale silica and copper particles, the three-phase contact line can be extended, thereby enhancing the heat transfer effect of spray cooling. Although these coatings and porous structures increase the surface thermal resistance, their enhanced effect on heat transfer is sufficient to offset this negative impact and improve the overall heat transfer performance.

[0005] With the development of micro-electromechanical system (MEMS) technology, micro-nanostructured surfaces have become an important method to improve the performance of spray cooling. Strengthened surfaces such as micro-fins, nanowires and microporous structures can greatly improve the heat transfer coefficient and critical heat flux density of spray cooling. However, in high heat flux density spray cooling, the aggregation and detachment of wall boiling bubbles hinder the spreading of droplets and block the contact heat exchange between liquid infiltration and the wall surface, and even cause the wall surface to dry up, which seriously limits the further improvement of its heat flux density. In addition, single-scale macroscopic surface structures or micro / nanostructures have limitations in improving the heat transfer performance of spray droplet impact flow, because they often cannot simultaneously meet the requirements of rapid droplet spreading and effective reverse overflow of steam.

[0006] In summary, it is difficult to simultaneously promote liquid wetting and vapor overflow on the enhanced surface, and it is difficult to effectively inhibit heat transfer deterioration and maintain efficient nucleate boiling. Therefore, how to construct a multi-scale composite surface structure and promote ultrafast spreading, directional flow and rapid evaporation of spray droplets on the hot wall is the core challenge faced by the efficient application of micro-nanostructured surfaces in spray cooling technology. Summary of the invention

[0007] The object of the present invention is to provide a multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust to solve at least any one of the problems raised in the above-mentioned background technology.

[0008] To achieve the above-mentioned object, the present invention provides the following technical solutions: a multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust, comprising a metal substrate, a micrometer-scale stepped metal micro-pillar array and a nano-metal oxide layer;

[0009] The micrometer-scale stepped metal micro-column array comprises a plurality of horizontally arranged micrometer-scale stepped metal micro-columns and a nano-metal oxide layer. The micrometer-scale stepped metal micro-column array is arranged on the top of the metal substrate. The micrometer-scale stepped metal micro-columns are rectangular columns. The width of the plurality of vertically and horizontally arranged micrometer-scale stepped metal micro-columns gradually decreases from both ends to the middle column and the same horizontal row is arranged with equal spacing and vertical column gradient spacing. The nano-metal oxide layer is a nano-metal oxide layer formed on the surface of the micrometer-scale stepped metal micro-columns by chemical oxidation.

[0010] Preferably, the maximum width of the micrometer-scale stepped metal microcolumn in the same horizontal row of micrometer-scale stepped metal microcolumns is 3-4 times the width of the minimum width of the micrometer-scale stepped metal microcolumn, and the distance between the micrometer-scale stepped metal microcolumns at the two ends of adjacent horizontal rows of micrometer-scale stepped metal microcolumns is the width of the largest micrometer-scale stepped metal microcolumn.

[0011] Preferably, the micrometer-scale stepped metal micro-columns are bonded to the metal substrate by double anode electroplating.

[0012] Preferably, the micrometer-scale stepped metal micro-columns and the metal substrate are both made of copper, and the nano-metal oxide layer is a nano-metal copper oxide layer.

[0013] Preferably, the gaps between micrometer-scale stepped metal micro-pillars in the same horizontal row are the same.

[0014] The multi-scale composite surface structure is processed based on the spray cooling with coordinated liquid suction and exhaust. The specific process steps are as follows:

[0015] S1: Spin-coat a layer of photoresist on the cleaned copper-based metal substrate and dry it;

[0016] S2: Draw a two-dimensional drawing of the micron-scale stepped metal micro-pillar array according to the required micron-scale stepped metal micro-pillar array scheme, and make a photomask of the micron-scale stepped metal micro-pillar array, cover the photomask with the micron-scale stepped metal micro-pillar array pattern on the photoresist surface, use ultraviolet light of a specific wavelength to irradiate the photoresist surface through the mask for exposure, and then place the sample in an alkaline solution for cleaning and development, so that the part of the photoresist covered by the mask forms a micro-pillar array structure opposite to the mask pattern;

[0017] S3: placing the metal substrate with the patterned surface into an electrolytic bath for double-anodic electroplating to form copper-plated micrometer-scale stepped metal micro-pillars;

[0018] S4: placing the sample in acetone to remove the remaining photoresist and drying it to form micrometer-scale stepped metal micro-pillars with a stepped structure;

[0019] S5: Place the sample in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nanoscale nano-metal oxide layer surface structure, completing the production of a multi-scale composite surface structure.

[0020] Preferably, when drawing a two-dimensional drawing of a micron-scale stepped metal microcolumn array according to the required micron-scale stepped metal microcolumn array scheme, the micron-scale stepped metal microcolumn with the largest width in the same horizontal row of micron-scale stepped metal microcolumns is 3-4 times the width of the micron-scale stepped metal microcolumn with the smallest width, and the spacing between the micron-scale stepped metal microcolumns at the two ends of adjacent horizontal rows of micron-scale stepped metal microcolumns is the width of a largest micron-scale stepped metal microcolumn.

[0021] Preferably, a metal substrate with a patterned surface is placed in an electrolytic cell for double-anodizing to form copper-plated micrometer-scale stepped metal micro-columns, and then the sample is placed in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nanoscale nano-metal oxide layer surface structure, thereby completing the production of a multi-scale composite surface structure.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. In the present invention, based on the scale synergy principle and anisotropic structure, a multi-scale anisotropic composite surface is proposed to promote the directional flow of liquid and the reverse overflow of steam, so as to realize the ultrafast wetting, directional flow and rapid evaporation of spray droplets on the hot surface. This efficient gas-liquid reverse flow behavior can greatly increase the heat transfer efficiency, shorten the evaporation time, and delay the occurrence of film boiling, thereby significantly improving the spray cooling heat transfer coefficient and critical heat flux density.

[0024] 2. In the present invention, nanoscale structures are used to promote the capillary spreading of the liquid phase, micron-scale structures are used to promote the overflow of the gas phase, and the anisotropic surface structure is combined to promote the directional flow of the fluid. A controllable preparation method of a multi-scale anisotropic micro-nano composite surface structure is proposed. The directional regulation of the spray cooling flow heat transfer performance can be achieved by optimizing the surface structure, providing technical support for the application of spray cooling technology in complex thermal control scenarios.

[0025] 3. In the present invention, compared with traditional means of enhancing heat transfer, such as using a large amount of coolant or a complex fluid piping system, the liquid suction and exhaust coordinated spray cooling multi-scale composite surface structure can reduce unnecessary energy loss and improve energy utilization efficiency by optimizing the interaction between the gas-liquid two phases and the composite surface structure, and has lower energy consumption and cost. At the same time, the manufacturing technology of micro-nano multi-scale composite structures is constantly improving, and it is expected to achieve large-scale, low-cost production in the future, further reducing application costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic side view of the multi-scale composite surface structure of the present invention;

[0027] Figure 2 A schematic top view of the multi-scale composite surface structure of the present invention;

[0028] Figure 3 This is a schematic diagram of the preparation process of the multi-scale composite surface structure of the present invention;

[0029] Figure 4 This is a schematic diagram of the multi-scale micro-nanostructures of the present invention jointly promoting liquid absorption and exhaust;

[0030] Figure 5 Schematic diagram of the anisotropic micro-pillar spacing design of the present invention to promote directional drainage.

[0031] In the figure: 1. Metal substrate; 2. Micrometer-scale stepped metal microcolumn array; 21. Micrometer-scale stepped metal microcolumns; 3. Nanometal oxide layer; 4. Photoresist; 41. The part of the photoresist covered by the mask; 5. Capillary absorption; 6. Buoyancy exhaust; 7. Gradient direction; 8. Small channel; 9. Large channel; 10. Directional flow direction of liquid. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides Figure 1-5 The multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust shown includes a metal substrate 1, a micrometer-scale stepped metal micro-pillar array 2 and a nano-metal oxide layer 3;

[0034] The micrometer-scale stepped metal microcolumn array 2 includes a plurality of horizontally arranged micrometer-scale stepped metal microcolumns 21 and a nano-metal oxide layer 3. The micrometer-scale stepped metal microcolumn array 2 is arranged on the top of the metal substrate 1. The micrometer-scale stepped metal microcolumns 21 are rectangular columns. The width of the plurality of vertically and horizontally arranged micrometer-scale stepped metal microcolumns 21 gradually decreases from the two ends to the middle column, and the same horizontal row is arranged with equal spacing and vertical column gradient spacing. The nano-metal oxide layer 3 is a nano-metal oxide layer 3 formed on the surface of the micrometer-scale stepped metal microcolumns 21 by chemical oxidation method.

[0035] During the spray cooling process, when the liquid working medium is atomized into high-speed droplets through the nozzle and hits the surface of the composite structure, the droplets quickly spread along the nano-metal oxide layer 3 due to the strong capillary force generated by the nano-metal oxide layer 3. A large number of droplets merge with each other during the spreading process to form a liquid film and wet the entire heated surface. When the wall temperature rises and the liquid temperature exceeds the boiling point, the nano-metal oxide layer 3 provides enough nucleation points to generate a large number of boiling bubbles between the micron-scale stepped metal micro-column arrays 2. The bubbles grow upward under the action of buoyancy and merge into large bubbles, which are discharged upward along the channels between the micron-scale stepped metal micro-columns 21. At the same time, the liquid flows downward along the micrometer-scale stepped metal microcolumns 21 under the strong capillary force of the nano-metal oxide layer 3, and replenishes the vacancies generated after vaporization near the three-phase contact line (a line at the intersection of the solid-liquid-gas three-phases), forming capillary absorption 5. The channels between the micrometer-scale stepped metal microcolumn arrays 2 and the nano-metal oxide layer 3 on the surface of the micrometer-scale stepped metal microcolumn arrays 2 jointly promote the capillary absorption 5 and the buoyancy exhaust 6, forming an orderly gas-liquid countercurrent, which strengthens the nucleate boiling heat transfer while suppressing the occurrence of surface drying, and can simultaneously strengthen the heat transfer coefficient and increase the critical heat flux density.

[0036] The maximum width of the micrometer-scale stepped metal microcolumns 21 in the same horizontal row is 3-4 times the width of the micrometer-scale stepped metal microcolumns 21 with the smallest width. The spacing between the micrometer-scale stepped metal microcolumns 21 at the two ends of adjacent horizontal rows of micrometer-scale stepped metal microcolumns 21 is the width of the maximum micrometer-scale stepped metal microcolumn 21, and the spacing between the micrometer-scale stepped metal microcolumns 21 in the same horizontal row is the same.

[0037] The arrangement of the micrometer-scale stepped metal micro-pillars 21 adopts anisotropic spacing design, with equal spacing in the horizontal direction and gradient spacing in the vertical direction (e.g. Figure 5 The gradient direction 7 is shown in the figure). A small-sized large channel 9 is formed in the middle of the longitudinal micrometer-scale stepped metal micro-pillar 21, and a large-sized small channel 8 is formed at the edge. Since the small channel 8 can generate a larger capillary force and the capillary force corresponding to the large channel 9 is smaller, the liquid flows horizontally from the central large channel 9 to the edge small channel 8 under the drive of the capillary pressure difference, promoting the liquid to be discharged horizontally from the surface (such as Figure 5 The directional flow direction of the liquid shown in FIG10 avoids the accumulation of liquid in the center, which leads to a thick liquid film and increases the thermal resistance of the liquid film, which is beneficial to the renewal of the liquid film and strengthens the convective heat transfer. In addition, the directional discharge of the liquid can also take away the bubbles overflowing upward from the micro-columns, further promoting boiling heat transfer.

[0038] The micrometer-scale stepped metal micro-pillars 21 are combined with the metal substrate 1 by double anode electroplating. The micrometer-scale stepped metal micro-pillars 21 and the metal substrate 1 are both made of copper, and the nano-metal oxide layer 3 is a nano-metal copper oxide layer.

[0039] The double anode electroplating method can accurately control the growth process of the nano-metal oxide layer 3. By adjusting the electroplating parameters, such as current density, electroplating time, electrolyte composition, etc., the height, density, and morphology of the nano-metal oxide layer 3 can be precisely controlled. This precise control can ensure that the nano-metal oxide layer 3 performs optimally in promoting the capillary spreading of the liquid phase and providing nucleation points. Accurate height control enables the nano-metal oxide layer 3 to generate a sufficiently strong capillary force to promote the spreading of droplets, while not affecting the gas-liquid flow between the micrometer-scale stepped metal microcolumns 21 due to being too high; the appropriate density and morphology can ensure that sufficient nucleation points are provided when the wall temperature rises, thereby enhancing boiling heat transfer. Since the wettability of the copper oxide layer is higher than that of the copper surface of the micron-scale stepped metal microcolumn array 2, the nano-metal oxide layer 3 produced on the surface of the micron-scale stepped metal microcolumn 21 is smaller in scale and does not affect the gaps in the microcolumn array, and its effect on the permeability can be ignored, which is beneficial to the capillary diffusion of the liquid phase working fluid on the surface of the composite structure, accelerates the droplet spreading speed, shortens the liquid film formation time, lays a good foundation for the subsequent heat transfer process, effectively improves the contact efficiency between the liquid and the hot surface during the spray cooling process, and enhances the heat transfer effect.

[0040] The production process of multi-scale composite surface structure based on spray cooling with coordinated liquid suction and exhaust is characterized by: the specific process steps are:

[0041] S1: Spin-coat a layer of photoresist 4 on the surface of the cleaned copper-based metal substrate 1 and dry it;

[0042] S2: Draw a two-dimensional drawing of the micron-scale stepped metal micro-pillar array 2 according to the required scheme of the micron-scale stepped metal micro-pillar array 2, and make a photomask of the micron-scale stepped metal micro-pillar array 2, cover the photomask with the pattern of the micron-scale stepped metal micro-pillar array 2 on the surface of the photoresist 4, use ultraviolet light of a specific wavelength to pass through the mask to irradiate the surface of the photoresist 4 for exposure, and then place the sample in an alkaline solution for cleaning and development, and the part 41 of the photoresist covered by the mask forms a micro-pillar array structure opposite to the mask pattern;

[0043] S3: placing the metal substrate 1 having the patterned surface into an electrolytic cell for double-anodal electroplating to form copper-plated micrometer-scale stepped metal micro-pillars 21;

[0044] S4: placing the sample in acetone to remove the remaining photoresist 4 and drying the sample to form a micrometer-scale stepped metal micro-column 21 having a stepped structure;

[0045] S5: placing the sample in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nano-scale nano-metal oxide layer 3 surface structure, thus completing the production of a multi-scale composite surface structure.

[0046] More specifically, firstly, the copper-based metal substrate 1 is cleaned by a cleaning device to remove impurities, oil stains, etc. on the surface to ensure that the subsequent coating can adhere well and provide a clean basic surface for the entire preparation process. Then, the photoresist 4 is spin-coated on the surface of the metal substrate 1 by a processing device. The spin-coating process can make the photoresist 4 evenly cover the metal substrate 1. After the spin coating is completed, the photoresist 4 is dried by a drying device to remove the solvent in the photoresist 4, thereby enhancing the adhesion between the photoresist 4 and the metal substrate 1, so that the photoresist 4 is better fixed on the metal substrate 1.

[0047] Then, a two-dimensional drawing is drawn according to the pre-designed micrometer-scale stepped metal microcolumn array 2 scheme (the drawing accurately plans the position, size, spacing and other parameters of the microcolumns), the micrometer-scale stepped metal microcolumn 21 with the largest width in the same horizontal row of micrometer-scale stepped metal microcolumns 21 is 3-4 times the width of the micrometer-scale stepped metal microcolumn 21 with the smallest width, and the spacing between the micrometer-scale stepped metal microcolumns 21 at the two ends of adjacent horizontal rows of micrometer-scale stepped metal microcolumns 21 is the width of a largest micrometer-scale stepped metal microcolumn 21, and then a micrometer-scale stepped metal microcolumn array is made according to this drawing. 2 structure photomask (the photomask is like a template, the pattern on it corresponds to the pattern of micrometer-scale stepped metal micro-pillars 21 to be finally formed on the metal substrate 1, except that the light-transmitting and light-shielding areas are opposite), the prepared photomask is covered on the metal substrate 1 coated with photoresist 4, and ultraviolet light of a specific wavelength is used through the mask to irradiate the surface of the photoresist 4 through the processing equipment (during the exposure process, the ultraviolet light will cause the photoresist 4 to undergo a photochemical reaction, and the chemical properties of the part of the photoresist 4 irradiated by the light will change, while the part of the photoresist 4 covered by the mask will maintain the original properties);

[0048] After the exposure is completed, the sample is placed in an alkaline solution for cleaning and development. The alkaline solution will dissolve the photoresist 4 that undergoes a photochemical reaction, while the photoresist portion 41 covered by the mask will not be dissolved during the development process because it is not exposed to ultraviolet light, and will eventually remain. These retained photoresist 4 portions form a micro-pillar array structure opposite to the mask pattern. For example, if the micro-pillar array pattern on the photomask is a solid micro-pillar shape, then the photoresist 4 retained after development forms a micro-pillar-shaped groove (i.e., opposite to the mask pattern), and micron-scale stepped metal micro-pillars 21 can be formed at these groove positions through subsequent steps such as electroplating;

[0049] Then, the metal substrate 1 with the patterned photoresist 4 (i.e., the groove pattern of the micro-pillar array structure) is placed in an electrolytic cell for double-anodal electroplating. During the electroplating process, copper ions are deposited in the grooves of the photoresist 4 under the action of the electric field to gradually form a copper plating layer 6. By controlling the electroplating time, current and other parameters, the thickness of the micrometer-scale stepped metal micro-pillars 21 (i.e., the height of the micrometer-scale stepped metal micro-pillar array 2) can be accurately controlled.

[0050] After the electroplating is completed, the sample is placed in acetone, which can dissolve and remove the remaining photoresist 4. After removing the photoresist 4, the sample is dried, and at this time, a stepped metal micro-column 21 with a stepped structure and a micrometer scale is obtained;

[0051] Then, the copper surface structure sample with the stepped micrometer-scale stepped metal micro-pillar array 2 is placed in the hydrogen peroxide solution of the device for chemical oxidation corrosion and modification. Under the action of the solution, the micrometer-scale stepped metal micro-pillar array 2 reacts chemically with the surface of the metal substrate 1 to form a nanometer-scale copper oxide structure 3, and the preparation is completed. The processing equipment used in the preparation is all existing technology.

[0052] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust, characterized by: It comprises a metal substrate (1), a micrometer-scale stepped metal micro-column array (2) and a nano-metal oxide layer (3); The micrometer-scale stepped metal micro-pillar array (2) comprises a plurality of horizontally arranged micrometer-scale stepped metal micro-pillars (21) and a nanometer metal oxide layer (3); the micrometer-scale stepped metal micro-pillar array (2) is arranged on the top of the metal substrate (1); the micrometer-scale stepped metal micro-pillars (21) are rectangular pillars; the plurality of vertically and horizontally arranged micrometer-scale stepped metal micro-pillars (21) are arranged with a gradually decreasing pillar width from both ends to the middle and with equal spacing in the same horizontal row and gradient spacing in the vertical column; and the nanometer metal oxide layer (3) is a layer of nanometer metal oxide layer (3) formed on the surface of the micrometer-scale stepped metal micro-pillars (21) by chemical oxidation.

2. The multi-scale composite surface structure of spray cooling based on liquid suction and exhaust coordination according to claim 1 is characterized in that: The micrometer-scale stepped metal microcolumns (21) with the largest width in the same horizontal row are 3-4 times the width of the micrometer-scale stepped metal microcolumns (21) with the smallest width, and the distance between the micrometer-scale stepped metal microcolumns (21) at the two ends of adjacent horizontal rows of the micrometer-scale stepped metal microcolumns (21) is the width of the largest micrometer-scale stepped metal microcolumn (21).

3. The multi-scale composite surface structure of spray cooling based on liquid suction and exhaust coordination according to claim 1 is characterized in that: The micrometer-scale stepped metal micro-columns (21) are combined with the metal substrate (1) by using a double anode electroplating method.

4. The multi-scale composite surface structure of spray cooling based on liquid suction and exhaust coordination according to claim 1 is characterized in that: The micrometer-scale stepped metal micro-columns (21) and the metal substrate (1) are both made of copper, and the nano-metal oxide layer (3) is a nano-metal copper oxide layer.

5. The multi-scale composite surface structure of spray cooling based on liquid suction and exhaust coordination according to claim 1 is characterized in that: The gaps between the micrometer-scale stepped metal micro-pillars (21) in the same horizontal row are the same.

6. A production process for a multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust, which is used to produce the multi-scale composite surface structure of spray cooling based on the coordination of liquid suction and exhaust as described in claims 1-5, characterized in that: The specific process steps are: S1: Spin-coating a layer of photoresist (4) on the surface of a cleaned copper-based metal substrate (1) and drying the same; S2: drawing a two-dimensional drawing of the micrometer-scale stepped metal micro-pillar array (2) according to the required scheme of the micrometer-scale stepped metal micro-pillar array (2), and making a photomask of the micrometer-scale stepped metal micro-pillar array (2), covering the surface of the photoresist (4) with the photomask having the pattern of the micrometer-scale stepped metal micro-pillar array (2), using ultraviolet light of a specific wavelength to pass through the mask to irradiate the surface of the photoresist (4) for exposure, and then placing the sample in an alkaline solution for cleaning and development, so that the part of the photoresist covered by the mask (41) forms a micro-pillar array structure opposite to the mask pattern; S3: placing the metal substrate (1) having a patterned surface into an electrolytic cell for double-anodal electroplating to form copper-plated micrometer-scale stepped metal micro-pillars (21); S4: placing the sample in acetone to remove the remaining photoresist (4) and drying the sample to form micrometer-scale stepped metal micro-pillars (21) with a stepped structure; S5: placing the sample in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nano-scale nano-metal oxide layer (3) surface structure, thereby completing the production of a multi-scale composite surface structure.

7. The production process of multi-scale composite surface structure based on spray cooling with coordinated liquid suction and exhaust according to claim 6 is characterized in that: When a two-dimensional drawing of the micrometer-scale stepped metal microcolumn array (2) is drawn according to the required scheme of the micrometer-scale stepped metal microcolumn array (2), the micrometer-scale stepped metal microcolumn (21) with the largest width in the same horizontal row of the micrometer-scale stepped metal microcolumns (21) is 3-4 times the width of the micrometer-scale stepped metal microcolumn (21) with the smallest width, and the distance between the micrometer-scale stepped metal microcolumns (21) at the two ends of adjacent horizontal rows of the micrometer-scale stepped metal microcolumns (21) is the width of a largest micrometer-scale stepped metal microcolumn (21).

8. The production process of multi-scale composite surface structure based on spray cooling with coordinated liquid suction and exhaust according to claim 6 is characterized in that: The metal substrate (1) with a patterned surface is placed in an electrolytic cell for double-anodizing to form copper-plated micrometer-scale stepped metal micro-pillars (21), and then the sample is placed in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nanometer-scale surface structure of the nano-metal oxide layer (3), thereby completing the production of a multi-scale composite surface structure.

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