Multi-scale composite surface structure based on liquid absorption and air exhaust coordination for spray cooling

Abstract

The application discloses a spray cooling multi-scale composite surface structure based on liquid absorption and air exhaust cooperation and relates to the field of electronic equipment thermal control technology.The spray cooling multi-scale composite surface structure comprises a metal substrate, a micrometer-scale stepped metal microcolumn array and a nanometer metal oxide layer, the micrometer-scale stepped metal microcolumn array is arranged on the top of the metal substrate, and a plurality of the micrometer-scale stepped metal microcolumns in the transverse row are gradually reduced in width from both ends to the middle and are arranged at equal intervals in the same transverse row and at gradient intervals in the vertical column.In the application, the nanometer-scale oxide structure is used to promote liquid-phase capillary spreading, the microcolumn interchannel is used to promote gas overflow, and the anisotropic microcolumn interval design is used to promote directional liquid discharge.The multi-scale micro-nano structure promotes gas-liquid ordered countercurrent through the liquid absorption and air exhaust functions, effectively inhibits heat transfer deterioration caused by bubble accumulation and maintains high-efficiency nucleate boiling, and simultaneously improves the spray cooling heat transfer coefficient and the critical heat flux density.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic equipment thermal control, and particularly relates to a spray cooling multi-scale composite surface structure based on liquid absorption and air exhaust cooperation. BACKGROUND

[0002] With the increasing complexity of spacecraft technology tasks, space electronic equipment faces more complex working environments, and the requirements of space electronic equipment for integration, miniaturization and high-speed computing are becoming higher and higher, resulting in a sharp increase in heat dissipation density. Electronic equipment high-temperature failure not only seriously threatens the normal operation and service life of the spacecraft, but also can cause equipment burning, space fire and other incalculable losses. Therefore, in order to ensure the reliable operation of the 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 medium, fast thermal control response, etc., and has important application prospects in the field of space thermal control. The spray cooling heat transfer principle lies in the forced convection generated by the high-frequency impact of micro-droplets, as well as the disturbance field and velocity field caused by droplet impact. These are closely related to the wall film flow state and convective heat transfer. In addition, droplet impact can also promote bubble breaking on the wall surface and enhance boiling heat transfer. Therefore, the flow and heat transfer characteristics of the droplet impact process on the solid surface are the fundamental reason affecting the spray cooling heat transfer performance, and it is urgent to develop engineering technology for strengthening and regulating the flow and heat transfer characteristics of the droplet impact process.

[0004] Surface structure characteristics are an important factor affecting the heat transfer performance of spray cooling. The strengthened surface mainly optimizes the heat transfer effect by improving wettability, expanding contact area, prolonging three-phase contact line length, and increasing boiling nucleation points. Specific methods include adjusting surface roughness, constructing porous coating, and changing surface geometry. Surface roughness directly affects the liquid film thickness, bubble size and residual vapor state, and changes the dominant heat transfer mechanism. Super-smooth surfaces suppress nucleate boiling due to the lack of nucleation sites, and mainly rely on liquid film evaporation for heat transfer; while rough surfaces can significantly promote nucleate boiling and become the main heat transfer method. Porous coatings can change the three-phase contact characteristics and heat transfer performance of the surface. By spraying nano-scale silica, copper particles and other high-porosity structures, the three-phase contact line can be prolonged, thereby strengthening the heat transfer effect of spray cooling. Although these coatings and porous structures increase the surface thermal resistance, their heat transfer strengthening effect is sufficient to offset this negative impact, improving the overall heat transfer performance.

[0005] With the development of micro-electro-mechanical system (MEMS) technology, micro / nano structured surface becomes an important method to improve the performance of spray cooling. Micro-rib, nano-wire and micro-porous structure can greatly improve the spray cooling heat transfer coefficient and critical heat flux. However, in high heat flux spray cooling, the aggregation and detachment of wall boiling bubbles hinder the droplet spreading and block the contact heat exchange between the liquid and the wall, and even cause the wall to dry, which seriously limits the further improvement of the heat flux. In addition, the macro surface structure or micro / nano structure of a single scale has limitations in improving the performance of spray droplet impact flow heat transfer, because they often cannot meet the needs of rapid spreading of droplets and effective reverse overflow of steam at the same time.

[0006] In summary, the current enhanced surface is difficult to promote liquid immersion and steam overflow at the same time, and difficult to effectively suppress heat transfer deterioration and maintain high-efficiency nucleate boiling. Therefore, how to construct a multi-scale composite surface structure, promote the ultra-fast spreading, directional flow and rapid evaporation of spray droplets on the hot wall, is the core challenge faced by the efficient application of micro / nano structured surface in spray cooling technology. SUMMARY

[0007] The purpose of the present application is to provide a spray cooling multi-scale composite surface structure based on liquid absorption and gas exhaust cooperation to solve at least any of the problems raised in the background art.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a spray cooling multi-scale composite surface structure based on liquid absorption and gas exhaust cooperation, comprising a metal substrate, a micro-scale stepped metal micro-column array and a nano metal oxide layer.

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

[0010] Preferably, the micro-scale stepped metal micro-column with the maximum width in the same horizontal row is 3-4 times the width of the micro-scale stepped metal micro-column with the minimum width, and the spacing between the two end micro-scale stepped metal micro-columns in the adjacent horizontal row is the width of a maximum micro-scale stepped metal micro-column.

[0011] Preferably, the micro-scale stepped metal micro-column is combined with the metal substrate by double anode electroplating method.

[0012] Preferably, the microscale stepped metal microcolumn and the metal substrate material are both copper, and the nanometer metal oxide layer is a nanometer copper oxide layer.

[0013] Preferably, the gaps between the microscale stepped metal microcolumns in the same horizontal row are the same.

[0014] Based on the liquid absorption and air exhaust synergy, the microscale stepped metal microcolumn array is processed by the following steps:

[0015] S1: spin coating a layer of photoresist on the surface of the cleaned copper-based metal substrate and drying;

[0016] S2: according to the required microscale stepped metal microcolumn array scheme, a two-dimensional drawing of the microscale stepped metal microcolumn array is drawn, and a photo mask of the microscale stepped metal microcolumn array is made, the photo mask with the microscale stepped metal microcolumn array pattern is covered on the surface of the photoresist, a specific wavelength of ultraviolet light is used to irradiate the surface of the photoresist through the mask to expose, and then the sample is placed in an alkaline solution for cleaning and development, the photoresist covered by the mask forms a microcolumn array structure opposite to the mask pattern;

[0017] S3: the metal substrate with a patterned surface is placed in an electrolytic cell for double anode electroplating to form copper-plated microscale stepped metal microcolumns;

[0018] S4: the sample is placed in acetone to remove the remaining photoresist and dried to form microscale stepped metal microcolumns with stepped structures;

[0019] S5: the sample is placed in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nanoscale nanometer metal oxide layer surface structure, and the fabrication of the multiscale composite surface structure is completed.

[0020] Preferably, when the two-dimensional drawing of the microscale stepped metal microcolumn array is drawn according to the required microscale stepped metal microcolumn array scheme, the maximum width microscale stepped metal microcolumn in the same horizontal row of microscale stepped metal microcolumns is 3-4 times the width of the minimum width microscale stepped metal microcolumn, and the spacing between the two end microscale stepped metal microcolumns in the adjacent horizontal row of microscale stepped metal microcolumns is the width of a maximum microscale stepped metal microcolumn.

[0021] Preferably, the metal substrate with a patterned surface is placed in an electrolytic cell for double anode electroplating to form copper-plated microscale stepped metal microcolumns, and then the sample is placed in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nanoscale nanometer metal oxide layer surface structure, and the fabrication of the multiscale composite surface structure is completed.

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

[0023] 1. In the present application, based on the principle of scale coordination and anisotropic structure, a multi-scale anisotropic composite surface is proposed to promote the directional flow of liquid and the reverse overflow of vapor, realizing the ultra-fast 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 application, the nano-scale structure is used to promote the capillary spreading of liquid phase, the micro-scale structure is used to promote the overflow of gas phase, and the anisotropic surface structure is used to promote the directional flow of fluid, so as to provide a controllable preparation method of multi-scale anisotropic micro-nano composite surface structure, which can realize the directional regulation and control of spray cooling flow and heat transfer performance by optimizing the surface structure, and provide technical support for the application of spray cooling technology in complex thermal control scenes.

[0025] 3. In the present application, compared with the traditional heat transfer enhancement means, such as using a large amount of cooling liquid or a complex fluid pipeline system, the spray cooling multi-scale composite surface structure with liquid absorption and gas exhaust cooperation can reduce unnecessary energy loss, improve energy utilization efficiency, has lower energy consumption and cost, and at the same time, the manufacturing technology of micro-nano multi-scale composite structure is constantly improving, and in the future, it is expected to realize large-scale and low-cost production, further reducing the application cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic side view of the multi-scale composite surface structure of the present application.

[0027] Figure 2 It is a schematic top view of the multi-scale composite surface structure of the present application.

[0028] Figure 3 It is a schematic diagram of the preparation process of the multi-scale composite surface structure of the present application.

[0029] Figure 4 It is a schematic diagram of the multi-scale micro-nano structure promoting liquid absorption and gas exhaust together.

[0030] Figure 5 It is a schematic diagram of the anisotropic micro-column spacing design promoting directional liquid discharge.

[0031] In the figure: 1, metal substrate; 2, micron-scale stepped metal micro-column array; 21, micron-scale stepped metal micro-column; 3, nano metal oxide layer; 4, photoresist; 41, photoresist covered part; 5, capillary liquid absorption; 6, buoyancy gas exhaust; 7, gradient direction; 8, small channel; 9, large channel; 10, liquid directional flow direction. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

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

[0034] The micron-scale stepped metal micropillar array 2 includes multiple horizontal rows of micron-scale stepped metal micropillars 21 and a nano-metal oxide layer 3. The micron-scale stepped metal micropillar array 2 is arranged on the top of the metal substrate 1. The micron-scale stepped metal micropillars 21 are rectangular pillars. The width of the multiple horizontal rows of micron-scale stepped metal micropillars 21 gradually decreases from the two ends to the middle pillar, 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 micron-scale stepped metal micropillars 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 heating 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-pillar array 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-pillars 21. Out, forming buoyancy exhaust 6. At the same time, the liquid flows downward along the micron-scale stepped metal micropillars 21 under the action of 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 micron-scale stepped metal micropillar arrays 2 and the nano-metal oxide layer 3 on the surface of the micron-scale stepped metal micropillar array 2 jointly promote capillary absorption 5 and buoyancy exhaust 6, forming an orderly countercurrent of gas and liquid, which strengthens the nucleate boiling heat transfer while suppressing the occurrence of surface drying phenomenon, and can simultaneously enhance the heat transfer coefficient and increase the critical heat flux density.

[0036] The maximum width of the microscale stepped metal micro-pillar 21 in the same horizontal row is 3-4 times the width of the minimum width microscale stepped metal micro-pillar 21, and the spacing between the two end microscale stepped metal micro-pillars 21 in adjacent horizontal rows is the width of a maximum microscale stepped metal micro-pillar 21, and the spacing between the same horizontal row microscale stepped metal micro-pillars 21 is the same.

[0037] The arrangement of the microscale stepped metal micro-pillars 21 adopts an anisotropic spacing design, with equal spacing in the horizontal direction and gradient spacing in the vertical direction (as shown by the gradient direction 7). Figure 5 The small-size large-channel 9 is formed in the middle of the vertical microscale stepped metal micro-pillar 21, and the large-size small-channel 8 is formed at the edge. Since the small-channel 8 can generate greater capillary force, the corresponding capillary force of the large-channel 9 is small, and the liquid flows from the center large-channel 9 to the edge small-channel 8 under the driving of the capillary pressure difference, promoting the liquid to flow horizontally and directionally out of the surface (as shown by the liquid directional flow direction 10). Figure 5

[0038] The microscale stepped metal micro-pillar 21 is combined with the metal substrate 1 by a double anode electroplating method, the microscale stepped metal micro-pillar 21 and the metal substrate 1 are both made of copper, and the nanometer metal oxide layer 3 is a nanometer copper oxide layer.

[0039] The double anode electroplating method can accurately control the growth process of the nanometer 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 nanometer metal oxide layer 3 can be accurately controlled. This precise control can ensure that the nanometer metal oxide layer 3 can play the best performance in promoting liquid capillary spreading and providing nucleation sites. Precise height control enables the nanometer metal oxide layer 3 to generate sufficient capillary force to promote droplet spreading, and also prevents the nanometer metal oxide layer 3 from being too high to affect the gas-liquid flow between the microscale stepped metal micro-pillars 21. The appropriate density and morphology can ensure that sufficient nucleation sites are provided when the wall temperature rises, thereby strengthening the boiling heat transfer. Since the wettability of the copper oxide layer is higher than that of the copper surface of the microscale stepped metal micro-pillar array 2, the nanometer metal oxide layer 3 formed on the surface of the microscale stepped metal micro-pillar 21 is small in size and does not affect the void of the micro-pillar array, so the influence on the permeability can be ignored, thereby facilitating the capillary diffusion of the liquid working medium on the composite structure surface, accelerating the droplet spreading speed, shortening the liquid film formation time, laying a good foundation for the subsequent heat transfer process, and effectively improving the contact efficiency of the liquid and the hot surface in the spray cooling process, thereby strengthening 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 following specific process steps:

[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 surface of the photoresist 4 with the photomask having the pattern of the micron-scale stepped metal micro-pillar array 2, use ultraviolet light of a specific wavelength to pass through the mask and irradiate the surface of the photoresist 4 for exposure, then place the sample in an alkaline solution for cleaning and development, and the portion 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 bath for double-anodic electroplating to form copper-plated micrometer-scale stepped metal micropillars 21;

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

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

[0046] More specifically, first, a cleaning device is used to clean the copper-based metal substrate 1 to remove impurities, oil stains, etc. on the surface to ensure good adhesion of subsequent coatings and provide a clean base surface for the entire preparation process. Then, a photoresist 4 is spin-coated on the surface of the metal substrate 1 through a processing device. The spin coating process can evenly cover the photoresist 4 on 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 and better fixing it to the metal substrate 1.

[0047] Then, a two-dimensional blueprint is drawn based on the pre-designed micrometer-scale stepped metal micropillar array 2 scheme (the blueprint accurately plans the position, size, spacing and other parameters of the micropillars). The largest micrometer-scale stepped metal micropillar 21 in the same horizontal row is 3-4 times the width of the smallest micrometer-scale stepped metal micropillar 21. The spacing between the micrometer-scale stepped metal micropillars 21 at the two ends of adjacent horizontal rows is the width of the largest micrometer-scale stepped metal micropillar 21. Then, a micrometer-scale stepped metal micropillar array is made based on this blueprint. 2. A photomask with a structure (the photomask is like a template, the pattern on it corresponds to the pattern of micrometer-scale stepped metal micropillars 21 to be ultimately formed on the metal substrate 1, except that its light-transmitting and light-blocking areas are opposite) is placed on the metal substrate 1 coated with photoresist 4. Ultraviolet light of a specific wavelength is then passed through the mask by a processing device to illuminate the surface of the photoresist 4. During the exposure process, the ultraviolet light causes a photochemical reaction in the photoresist 4, changing the chemical properties of the portion of the photoresist 4 exposed to the light, while the portion of the photoresist 4 covered by the mask retains its original properties.

[0048] After exposure, the sample is placed in an alkaline solution for cleaning and development. The alkaline solution dissolves the photoresist 4 that has undergone a photochemical reaction. However, the portion of the photoresist covered by the mask 41 is not exposed to ultraviolet light and is not dissolved during the development process. Ultimately, it remains. These retained portions of the photoresist 4 form a micropillar array structure that is the opposite of the mask pattern. For example, if the micropillar array pattern on the photomask is a solid micropillar shape, then the photoresist 4 that remains after development forms micropillar-shaped grooves (i.e., the opposite of the mask pattern). Subsequent electroplating and other steps can form micron-scale stepped metal micropillars 21 at these groove locations.

[0049] The metal substrate 1 with the patterned photoresist 4 (i.e., the groove pattern of the micropillar array structure) is then placed in an electrolytic bath for double-anodic electroplating. During the electroplating process, copper ions are deposited in the grooves of the photoresist 4 under the action of an electric field, gradually forming a copper plating layer 6. By controlling parameters such as the electroplating time and current, the thickness of the micrometer-scale stepped metal micropillars 21 (i.e., the height of the micrometer-scale stepped metal micropillar array 2) can be precisely 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 micrometer-scale stepped metal micro-pillar 21 with a stepped structure is obtained;

[0051] The copper surface structure sample with the microscale stepped metal microcolumn array 2 having a stepped structure is placed into a hydrogen peroxide solution of the device for chemical oxidation corrosion and modification. Under the action of the solution, the microscale stepped metal microcolumn array 2 and the surface of the metal substrate 1 chemically react to form a nanoscale copper oxide structure 3, and the preparation is completed. The processing devices used in the preparation are all prior art.

[0052] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the foregoing embodiments of the present application have been described in detail, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made should be included in the protection scope of the present application.

Claims

1. A multi-scale composite surface structure of spray cooling based on the synergy of liquid suction and exhaust, characterized by: It comprises a metal substrate (1), a micrometer-scale stepped metal microcolumn array (2), and a nano-metal oxide layer (3); The micrometer-scale stepped metal microcolumn array (2) comprises 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 horizontally arranged micrometer-scale stepped metal microcolumns (21) gradually decreases from both ends to the middle column, and the columns are arranged with equal spacing in the same horizontal row and gradient spacing in the vertical column. 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.

2. The multi-scale composite surface structure for spray cooling based on coordinated liquid suction and exhaust 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 the micrometer-scale stepped metal microcolumns (21) in adjacent horizontal rows is the width of the largest micrometer-scale stepped metal microcolumn (21).

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

4. The multi-scale composite surface structure for spray cooling based on coordinated liquid suction and exhaust according to claim 1 is characterized in that: The micrometer-scale stepped metal microcolumns (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 for spray cooling based on coordinated liquid suction and exhaust according to claim 1 is characterized in that: The gaps between the micrometer-scale stepped metal micropillars (21) in the same horizontal row are the same.

6. A process for producing a multi-scale composite surface structure by spray cooling with coordinated liquid suction and exhaust, for producing the multi-scale composite surface structure by spray cooling with coordinated 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 the cleaned copper-based metal substrate (1) and drying it; S2: Draw a two-dimensional drawing of the micron-scale stepped metal micro-pillar array (2) according to the required micron-scale stepped metal micro-pillar array (2) scheme, 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, so that the portion 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) with the patterned surface into an electrolytic bath for double-anodic electroplating to form copper-plated micrometer-scale stepped metal micropillars (21); S4: placing the sample in acetone to remove the remaining photoresist (4) and drying it to form micrometer-scale stepped metal micropillars (21) with a stepped structure; S5: The sample is placed in a hydrogen peroxide solution for chemical oxidation corrosion and modification to form a nano-scale nano-metal oxide layer (3) surface structure, 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 micron-scale stepped metal microcolumn array (2) is drawn according to the required scheme of the micron-scale stepped metal microcolumn array (2), the micron-scale stepped metal microcolumn (21) with the largest width in the same horizontal row of the micron-scale stepped metal microcolumns (21) is 3-4 times the width of the micron-scale stepped metal microcolumn (21) with the smallest width, and the distance between the micron-scale stepped metal microcolumns (21) at the two ends of adjacent horizontal rows of the micron-scale stepped metal microcolumns (21) is the width of one largest micron-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-anodic electroplating to form copper-plated micrometer-scale stepped metal micropillars (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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