Radiation refrigeration / heat dissipation surface device based on ultrafast laser direct writing and preparation method thereof

Abstract

The invention belongs to the technical field of radiation thermal control equipment, and particularly relates to a radiation refrigeration / heat dissipation surface device based on ultrafast laser direct writing and a preparation method of the radiation refrigeration / heat dissipation surface device. The laser direct writing technology is adopted, the characteristic attributes of the raw materials are guaranteed, and meanwhile the micro-nano structure surface with the radiation refrigeration or radiation heat dissipation function is rapidly formed on the raw materials; the method specifically comprises the steps that ultrafast laser is used for scanning metal to be machined on the surface of metal or alloy, and then a surface micro-nano structure with the radiation refrigeration / heat dissipation characteristic is formed; the laser power is regulated and controlled to be 2-5 W, and the metal radiation refrigeration device is prepared and called as a white body; the laser power is regulated and controlled to be 6-20 W, and a metal radiation heat dissipation device is prepared and called a black body. The surface of the black body shows excellent heat dissipation performance; compared with a black body sample and an original sample, the white body sample has higher reflectivity in a visible light wave band and has higher emissivity in an infrared medium and long wave band, partitioned spectrum cutting is realized, and the obvious passive cooling characteristic under illumination is shown.

Description

Technical Field

[0001] The invention belongs to the field of radiation heat control equipment, and in particular relates to a radiation cooling / heat dissipation surface device and a preparation method thereof. Background Art

[0002] With the intensifying global energy crisis and the demand for applications in more extreme scenarios (such as the vacuum of space), efficient thermal management technologies have become a core requirement in aerospace, electronics, building energy conservation, and other fields. In particular, in aerospace, spacecraft face extreme temperature swings (-170°C to +120°C), vacuum radiation environments, and lightweight requirements during on-orbit operation. There is an urgent need to develop thermal control solutions that combine high heat dissipation efficiency, low energy consumption, and strong environmental adaptability. Traditional active thermal control systems rely on fluid circulation or electric drives, which pose challenges such as heavy weight, low reliability, and high energy consumption. Passive radiative cooling technology, through material and structural design, directly dissipates heat into the cold space (~3K) as infrared radiation, offering a revolutionary approach to thermal management in aerospace. However, low-power density radiative cooling / heat dissipation devices, such as satellite radiative cooling skins or shells (primarily made of aluminum and titanium alloys), and high-power density radiative cooling / heat dissipation passive thermal management components (primarily made of high-temperature alloys such as niobium-tungsten alloys), inherently conflict with the low infrared emission characteristics (ε < 0.1) of passive thermal management components for satellite radiative cooling / heat dissipation. Conventional radiative cooling / heat dissipation solutions, such as coatings / platings and multilayer thin-film structures, suffer from acute drawbacks such as low environmental adaptability in the vacuum of space and limited stable lifespan. Directly forming photoregulated micro-nanostructures on the surface of a parent material can effectively avoid these problems. Therefore, how to design and fabricate micro-nanostructures that overcome the intrinsic optical limitations of metals and even other materials (such as oxide dielectrics and polymers) to meet the requirements of radiative cooling / heat dissipation has become a current research focus. However, surface treatment methods such as nanoimprinting, chemical etching, and physical vapor deposition are constrained by their inherent mechanisms. Within the micro-nanoscale, both the rapid fabrication of high-precision micro-nanostructures and the customized integration of multi-dimensional functions face a series of thorny challenges, including resolution bottlenecks, process complexity, and material compatibility. Furthermore, conventional micro-nanostructured surfaces struggle to achieve the spectral properties of high visible light reflectance and high infrared light emission required for radiative cooling. Therefore, the development of a novel, efficient, stable, and universal process for fabricating radiative cooling / heat dissipation surface devices applicable to the aerospace industry is urgent.

[0003] Laser processing technology, with its non-contact, high-precision, and customizable advantages, provides an efficient approach for fabricating functionalized micro-nanostructures on metal surfaces. By directly writing periodic micro-nanostructures with specific geometric dimensions and spatial organization through femtosecond lasers, surfaces responsive to different light wavelengths can be obtained, enabling the manipulation of the infrared emissivity and visible light reflectivity of materials such as metals. Specifically, laser direct writing of micron-scale periodic structures, similar in size to infrared wavelengths, can enhance the infrared emissivity of target materials, ultimately enabling the fabrication of radiative cooling / heat dissipation devices. Furthermore, laser direct writing can be combined with polymer materials (e.g., polyimide films, Pi films) and phase change materials (e.g., VO2) to create a synergistic "laser processing-micro-nanostructure-dynamic coating" strategy. Leveraging the metal-insulator phase transition effect of phase change materials, dynamic spectral manipulation can be achieved to meet the requirements of spacecraft adaptability to day-night temperature fluctuations. This technology has potential applications in applications such as satellite cooling panels and spacecraft skins, achieving cooling and weight reduction for aerospace components through passive thermal management mechanisms. Furthermore, it provides scalable solutions for 5G chip cooling and building energy efficiency, promoting the industrialization and upgrading of green management technologies. Summary of the Invention

[0004] The object of the present invention is to provide a radiation cooling / heat dissipation surface device based on ultrafast laser direct writing and a preparation method thereof.

[0005] The present invention first provides a method for rapidly fabricating radiative cooling / heat dissipation surface devices directly on metal. Using ultrafast laser direct writing technology, while maintaining the characteristic properties of the raw materials, a micro-nanostructured surface with radiative cooling or radiative heat dissipation functions is rapidly formed. The two functional surfaces can be freely switched and customized through the process. The specific steps are:

[0006] (1) Cut the metal to be processed by wire cutting to obtain a metal sample, place the metal sample in a sealed beaker with acetone solution, perform ultrasonic cleaning, take it out and rinse it with anhydrous ethanol and deionized water in sequence, and then place it in a low-temperature oven for drying; then place the metal sample in a sample box for use;

[0007] (2) An ultrafast laser with an average power of 2 to 20 W is then used to scan back and forth on the surface of the metal sample, thereby forming a surface micro-nanostructure with radiative cooling / heat dissipation properties.

[0008] The radiation cooling / heat dissipation surface device may have a plate / foil structure.

[0009] Further:

[0010] In step (1), the size of the metal sample after wire cutting is 1.5 cm-10 cm, and the thickness is 0.5 mm-10 mm; the ultrasonic time is 0.1 h-0.5 h; and the temperature of the low-temperature oven is set to 50° C.-75° C.

[0011] In step (2):

[0012] The ultrafast laser has an available wavelength of 515nm-1030nm, a pulse width of 300fs-100ps, an average power of 2-20W, and a scanning speed of 200-400mm / s.

[0013] Customization of metal samples from white body to black body is achieved by adjusting the average laser power; specifically:

[0014] By controlling the average laser power to 2-5W, a metal radiation cooling device, called a white body, was prepared.

[0015] By controlling the average laser power to 6 to 20W, a metal radiation heat dissipation device is prepared, which is called a black body.

[0016] Further:

[0017] The metal radiation cooling device (white body) has a surface micro-nano structure that is a micropore array with a diameter of 5 to 100 μm and a depth of 0.5 to 50 μm, and a micropore spacing of 0 to 50 μm (preferably a micropore spacing of 5 to 20 μm);

[0018] The metal radiation heat dissipation device (black body) has a surface micro-nano structure of a micropore array with a diameter of 50 to 150 μm and a depth of 50 to 300 μm, and a micropore spacing of 0 to 50 μm (preferably a micropore spacing of 0 to 5 μm);

[0019] The metal is aluminum or its alloy, titanium or its alloy, stainless steel, tungsten or its alloy.

[0020] The present invention also includes a radiation cooling / heat dissipation surface device prepared by the above method.

[0021] In the present invention, ultraviolet-visible spectrophotometer and Fourier transform infrared spectrometer were used to measure and compare the visible light reflectance and infrared emissivity of the radiative cooling white body, radiative heat dissipation black body and the original sample, and the results were as follows:

[0022] For metal radiation cooling white body devices (aluminum alloy as an example), in the visible light band (400-780), the visible light reflectivity is increased from ~65% to ~82%. In the infrared atmospheric window band (8-13μm), the infrared emissivity is increased from ~2% to ~95%. Figure 2 shown.

[0023] For metal radiation heat dissipation blackbody devices (aluminum alloy as an example), in the visible light band (400-780), the visible light reflectivity is reduced from ~65% to ~1.5%. In the infrared atmospheric window band (8-13μm), the infrared emissivity is increased from ~2% to ~98%. Figure 3 shown.

[0024] In this invention, a thermocouple contact temperature measuring instrument is used to measure the temperature change of the sample, and an infrared thermal imaging camera (Hikmicro) is used to capture the infrared thermal image of the sample. The simulated sunlight irradiation temperature rise test and infrared thermal imaging are performed on the radiation cooling white body sample, the radiation heat dissipation black body sample, and the original sample (aluminum alloy as an example), showing:

[0025] Compared with the blackbody sample and the original sample, the whitebody sample showed significant passive cooling characteristics. After 1 hour of simulated sunlight irradiation, the temperature of the whitebody radiation cooling sample dropped by ~10°C compared with the original sample. Compared with the blackbody sample, the temperature of the whitebody radiation cooling sample dropped by ~15°C. Figure 3 shown.

[0026] In the present invention, the infrared emissivity of the radiation heat dissipation blackbody device can be directly customized by laser direct writing, such as Figure 5 By simply adjusting the scanning distance and thus the spacing of the microhole array, different infrared emissivity can be customized. Taking tungsten metal as an example, when the hole spacing is 1-3μm, the infrared emissivity is 95%; when the hole spacing is 3-6μm, the infrared emissivity is 80%; when the hole spacing is 6-9μm, the infrared emissivity is 65%; when the hole spacing is 9-12μm, the infrared emissivity is 50%.

[0027] In the present invention, the radiation heat dissipation blackbody surface exhibits excellent heat dissipation performance. Its high infrared emissivity in the range of 8 to 13 μm enables the heat of the blackbody device to quickly pass through the atmosphere and be transferred to the vacuum of the universe. Figure 6 As shown in the figure, when heated to 1000°C, the temperature of the radiative heat dissipation blackbody surface dropped by about 40°C compared to the original surface after cooling for 60 seconds. When heated to 1000°C, the temperature of the radiative heat dissipation blackbody surface dropped by about 100°C after cooling for 3 hours. In addition, the higher the infrared emissivity of the radiative heat dissipation device, the better its heat dissipation and cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The invention discloses a radiation cooling white-body device and a radiation heat dissipation black-body device which are rapidly prepared by laser scanning.

[0029] Figure 2 The visible light reflection spectrum and infrared emission spectrum of the radiative cooling white body device measured by the present invention are compared with those of the original sample aluminum alloy.

[0030] Figure 3 The present invention compares the visible light reflection spectrum and infrared emission spectrum of the radiative heat dissipation blackbody device and the original sample aluminum alloy.

[0031] Figure 4 It is a schematic diagram of the test device for testing the temperature changes of the radiative cooling white-body device, the radiative heat dissipation black-body device and the original sample aluminum alloy under simulated sunlight for one hour in the present invention.

[0032] Figure 5 The temperature rise curves of the radiation cooling white-body device, the radiation heat dissipation black-body device and the original sample aluminum alloy measured by the present invention under simulated sunlight exposure for one hour.

[0033] Figure 6 This is a graph showing how the present invention customizes different infrared emissivities on the surface of an aluminum alloy by regulating laser parameters.

[0034] Figure 7 The present invention calculates and obtains the cooling curves of metal tungsten having radiation heat dissipation surfaces with different infrared emissivities after being heated to 1000° C. in 1 minute and 3 hours. DETAILED DESCRIPTION

[0035] The present invention is further described below through embodiments with reference to the accompanying drawings.

[0036] In Example 1, aluminum alloy is used to manufacture radiation cooling white body and radiation heat dissipation black body devices using ultrafast laser. Figure 1 The actual device is shown in the figure. The ultrafast laser has a pulse width of 300 fs, a power of 2 to 15 W, a scanning speed of 300 mm / s, a repetition rate of 10 kHz, and a laser wavelength of 1030 nm. Using a laser power of 2 to 5 W can produce a white-body surface for radiative cooling, while using a laser power of 6 to 15 W can produce a black-body surface for radiative heat dissipation.

[0037] For radiative cooling white-body devices, the reflectivity in the visible light band increased from an initial 65% to 82%, and in the infrared band, the emissivity increased from an initial 2% to 95%. For radiative cooling black-body devices, the visible light reflectivity decreased from ~65% to ~1.5% in the visible light band (400-780). In the infrared atmospheric window band (8-13μm), the infrared emissivity increased from ~2% to ~98%.

[0038] A thermocouple contact temperature measuring instrument was used to measure the temperature change of the sample, and an infrared thermal imaging camera (Hikmicro) was used to capture the infrared thermal image of the sample. The radiation cooling white body sample, radiation heat dissipation black body sample and the original sample were subjected to simulated sunlight irradiation temperature rise test and infrared thermal imaging. Compared with the black body sample and the original sample, the white body sample showed significant passive cooling characteristics. After 1 hour of simulated sunlight irradiation, the temperature of the white body radiation cooling sample dropped by ~10°C compared with the original sample. Compared with the black body sample, the temperature of the white body radiation cooling sample dropped by ~15°C. Figure 3 shown.

[0039] In Example 2, titanium alloy is used to manufacture radiation cooling white body and radiation heat dissipation black body devices using ultrafast laser. Figure 1 The actual device is shown in the figure. The ultrafast laser has a pulse width of 300 fs, a power of 4 to 20 W, a scanning speed of 400 mm / s, a repetition rate of 10 kHz, and a laser wavelength of 1030 nm. Using a laser power of 4 to 5 W can produce a white-body surface for radiative cooling, while using a laser power of 8 to 20 W can produce a black-body surface for radiative heat dissipation.

[0040] For white-body devices with radiative cooling, their reflectivity in the visible light band is increased from the initial 55% to 80%, and their emissivity in the infrared band is increased from the initial 10% to 95%.

[0041] For blackbody devices that dissipate heat by radiation, the visible light reflectivity is reduced from ~55% to ~1.5% in the visible light band (400-780), and the infrared emissivity is increased from ~10% to ~98% in the infrared atmospheric window band (8-13μm).

[0042] A thermocouple contact temperature measuring instrument was used to measure the temperature change of the sample, and an infrared thermal imaging camera (Hikmicro) was used to capture the infrared thermal image of the sample. The radiation cooling white body sample, radiation heat dissipation black body sample and the original sample were subjected to simulated sunlight irradiation temperature rise test and infrared thermal imaging. Compared with the black body sample and the original sample, the white body sample showed significant passive cooling characteristics. After 1 hour of simulated sunlight irradiation, the temperature of the white body radiation cooling sample dropped by ~10°C compared with the original sample. Compared with the black body sample, the temperature of the white body radiation cooling sample dropped by ~15°C. Figure 3 shown.

[0043] Example 3: Using pure tungsten high temperature metal and ultrafast laser to manufacture radiation heat dissipation blackbody device, such as Figure 2The actual object is shown in the figure. The ultrafast laser has a pulse width of 300fs, a power of 15-20W, a scanning speed of 350mm / s, a repetition frequency of 10kHz, and a laser wavelength of 1030nm, which can produce a blackbody surface that radiates heat.

[0044] For the radiative heat dissipation blackbody device, the visible light reflectivity is reduced from ~55% to ~1.5% in the visible light band (400-780), and the infrared emissivity is increased from ~10% to ~98% in the infrared atmospheric window band (8-13μm).

[0045] The temperature change of the sample was measured using a thermocouple contact temperature measuring instrument. After the temperature was raised to 1000°C, the blackbody samples with different infrared emissivity and the original sample were tested for cooling. When heated to 1000°C, after cooling for 60 seconds, the temperature of the radiation heat dissipation blackbody surface dropped by about 40°C compared to the original surface; when heated to 1000°C, after cooling for 3 hours, the temperature of the radiation heat dissipation blackbody surface dropped by about 100°C compared to the original surface. Figure 7 .

[0046] Furthermore, the higher the infrared emissivity of a radiative heat dissipation device, the better its heat dissipation and cooling effect. The infrared emissivity of a radiative heat dissipation blackbody device can be directly customized by laser direct writing. By simply adjusting the scanning pitch, and thus the spacing of the microhole array, different infrared emissivities can be customized. When the hole spacing is 0-5μm, the infrared emissivity is 95%; when the hole spacing is 5-15μm, the infrared emissivity is 80%; when the hole spacing is 15-30μm, the infrared emissivity is 65%; and when the hole spacing is 30-50μm, the infrared emissivity is 50%.

Claims

1. A method for manufacturing a radiation cooling / heat dissipation surface device by ultrafast laser direct writing, characterized in that: The specific steps are: (1) Cut the metal sample to be processed by wire cutting process, then place it in a sealed beaker with acetone solution, take it out after ultrasonic cleaning, rinse it with anhydrous ethanol and deionized water in sequence, and place it in an oven to dry; put the metal sample into a sample box for later use; (2) An ultrafast laser with an average power of 2 to 20 W is then used to scan back and forth on the metal surface, thereby forming a surface micro-nanostructure with radiative cooling / heat dissipation properties.

2. The method according to claim 1, characterized in that The size of the metal wire sample to be processed after cutting in step (1) is 1.5 cm-10 cm, and the thickness is 0.5 mm-10 mm; the ultrasonic time is 0.1 h-0.5 h; and the oven temperature is set to 50° C.-75° C.

3. The method according to claim 1, characterized in that In step (2), the metal sample is customized from white body to black body by adjusting the laser power; specifically: By controlling the laser power to 2-5W, a metal radiation cooling device, called a white body, was prepared. By controlling the laser power to 6~20W, a metal radiation heat dissipation device is prepared, which is called a black body.

4. The method according to claim 2, wherein: The metal radiation cooling device has a sample surface with a diameter of 5 to 100 μm, a surface micro-nanostructure that is a micropore array with a depth of 0.5 to 50 μm, and a micropore spacing of 0 to 50 μm; The metal radiation heat dissipation device has a sample surface with a diameter of 50-150 μm, a surface micro-nano structure of a densely packed micropore array with a depth of 50-300 μm, and a micropore spacing of 0-50 μm.

5. The method according to claim 1, wherein The ultrafast laser has an available wavelength of 515nm-1030nm, a pulse width of 300 fs-100ps, an average power of 2-20W, and a scanning speed of 200-400 mm / s.

6. The method according to claim 1, characterized in that The metal is aluminum or its alloy, stainless steel, titanium or its alloy, tungsten or its alloy.

7. A radiative cooling / heat dissipation surface device prepared by the method according to any one of claims 1 to 6.

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