Coating-free lightweight metal radiation heat dissipation plate for spacecraft, thermal management system

Abstract

This invention discloses a coating-free, lightweight metallic radiative heat sink and thermal management system for spacecraft, relating to the field of engineering thermophysics. It solves the technical problems of heavy weight and poor space environment stability associated with existing spacecraft radiative heat dissipation coating technologies. The key technical solution is the design of a coating-free, pure metallic radiative heat sink with a micro-nano-scale superstructure constructed on its radiating surface. This superstructure, through photonics design, can simultaneously achieve efficient broadband, multi-angle infrared photon capture, thereby obtaining an infrared emissivity far exceeding the intrinsic value of metals. On the one hand, this significantly reduces the weight of the heat dissipation system, saving launch costs; on the other hand, the pure metallic monolithic structure has stronger resistance to space irradiation, atomic oxygen corrosion, and thermal cycling fatigue compared to coating materials, ensuring long-term, stable, and reliable heat dissipation for spacecraft in orbit.

Description

Technical Field

[0001] This application relates to the field of engineering thermophysics technology, and in particular to a coating-free lightweight metal radiant heat sink and thermal management system for spacecraft. Background Technology

[0002] In the near-Earth orbit and deep space environment, the waste heat generated by the electronic equipment and propulsion system inside the spacecraft cannot be dissipated through convection and conduction. The only way to dissipate heat is through thermal radiation into the deep space, where the temperature is approximately 3 Kelvin (3 K). Therefore, radiant heat sinks are the core component of the spacecraft's thermal management system.

[0003] Currently, the mainstream technical solution for spacecraft radiant heat sinks is to spray or adhere a high infrared emissivity coating (such as white paint or ceramic coating) onto the surface of a metal substrate (such as aluminum or titanium alloy). This solution has the following inherent drawbacks: (1) Large launch load: To achieve effective radiative heat dissipation, a coating tens to hundreds of micrometers thick needs to be sprayed, which significantly increases the launch mass of the spacecraft. It is estimated that the coating part can account for more than 20% of the total weight of the heat sink, which is costly for space missions that urgently need to reduce weight.

[0004] (2) Poor stability of space environment: Severe factors such as atomic oxygen, ultraviolet radiation, high-energy particles, and extreme temperature cycling in the space environment can lead to degradation of organic binders and powdering, peeling or deterioration of coatings, which seriously threaten the reliability of long-term on-orbit operation of spacecraft.

[0005] To overcome the shortcomings of coating technology, the industry has undertaken some explorations, mainly including: (1) Surface microstructure modification: Attempts were made to prepare structures such as black silicon and carbon composite materials on metal surfaces to improve emissivity. However, these structures often have weak mechanical strength and are difficult to withstand the mechanical loads during the launch phase. Moreover, their preparation process is complex and they have poor compatibility with aerospace-grade metal substrates.

[0006] (2) Develop new stable coatings: such as using all-inorganic coatings, but the weight problem still exists, and inorganic coatings usually have poor toughness and are prone to cracking or even falling off under thermal shock and thermal cycling conditions.

[0007] Therefore, the aerospace field urgently needs a new type of radiative heat dissipation solution that is high-radiation, coating-free, lightweight, and has excellent environmental stability. Summary of the Invention

[0008] This application provides a coating-free lightweight metal radiative heat sink and thermal management system for spacecraft. The technical objective is to provide a metal radiative heat sink without an external coating, which reduces the weight of the heat sink while increasing its infrared emissivity.

[0009] The above-mentioned technical objective of this application is achieved through the following technical solution: A coating-free, lightweight metal radiant heat sink for spacecraft, comprising: The main body of the heat sink, and At least one metal-based radiative heat dissipation layer with surface microstructure is provided on the main body of the heat sink; The heat sink body is a metal substrate, and the surface microstructure is a micro-nano composite structure layer. The micro-nano composite structure layer includes an angle extension structure and an absorption enhancement structure. The incident infrared radiation first passes through the angle extension structure and is then absorbed by the absorption enhancement structure. The angle extension structure is composed of any one or any combination of a cone array, pyramid array, frustum array, truncated cone array, hollow inverted truncated cone array, and hollow inverted truncated cone array, forming a periodic or non-periodic structure. The outer wall surfaces of each cone in the conical array and each frustum in the frustum array, the side wall surfaces of each pyramid in the pyramidal array and each frustum in the frustum array, and the inner wall surfaces of each hollow inverted frustum in the hollow inverted frustum array and each hollow inverted frustum in the hollow inverted frustum array are inclined at an angle of 30° to 60° to the normal direction of the metal-based radiative heat dissipation layer. The absorption-enhancing structure is composed of any one or a combination of periodically or non-periodically arranged grooves and holes.

[0010] Preferably, when the angle extension structure is a cone array, a pyramid array, a frustum array, or a frustum array, the base feature size of the cone, the frustum, the pyramid, or the frustum is in the range of [5μm, 50μm], and the height is in the range of [3μm, 50μm]; wherein, the base feature size represents the maximum lateral span of the base.

[0011] Preferably, each cone in the cone array and each frustum in the frustum array are disposed on a cylinder, and the space enclosed by adjacent cylinders and the groove formed by the surface of the cylinder constitute the absorption and strengthening structure; wherein, the base area of ​​the cone is the same as the cross-sectional area of ​​the cylinder, and the base area of ​​the frustum is the same as the cross-sectional area of ​​the cylinder. Each pyramid in the pyramid array and each frustum in the frustum array are mounted on a prism. The space enclosed by adjacent prisms and the groove formed by the surface of the prism constitute the absorption and reinforcement structure. The base area and shape of the pyramid are the same as the cross-sectional area and shape of the prism, and the base area and shape of the frustum are the same as the cross-sectional area and shape of the prism.

[0012] Preferably, each hollow inverted frustum in the hollow frustum array is disposed on a hollow prism, the inner wall of the hollow prism and its internal holes constitute the absorption enhancement structure, and the hollow inverted frustum and the hollow prism constitute a grating; wherein, the bottom surface area and shape of the hollow inverted frustum are the same as the cross-sectional area and shape of the hollow prism. Each hollow frustum in the hollow frustum array is mounted on a hollow cylinder. The inner wall and internal holes of the hollow cylinder constitute the absorption enhancement structure. The hollow frustum and the hollow cylinder together form a grating. The bottom area and shape of the hollow frustum are the same as the cross-sectional area and shape of the hollow cylinder.

[0013] Preferably, the ratio of the groove depth or hole height to the opening width in the absorption-enhancing structure is in the range of [1.5, 5].

[0014] Preferably, the characteristic dimension of the absorption enhancement structure is not less than the target infrared radiation wavelength at its location, and the characteristic dimension is the groove width or the hole diameter.

[0015] Preferably, the metal substrate is provided with a heat-spreading component and a mechanical support structure. The heat-spreading component is in contact with the radiative heat dissipation surface and is in thermal contact with the micro-nano composite structure layer. The mechanical support structure is connected to the heat-spreading component. The heat-spreading component is provided with a heat pipe mounting groove or a heat-spreading plate cavity.

[0016] Preferably, the mechanical support structure adopts a topology-optimized configuration, and its structural form is any one of an internally hollowed-out mesh structure, a reinforcing rib structure, and a lattice structure; the material of the mechanical support structure is a high-strength lightweight metal or a composite material.

[0017] Preferably, the metal substrate is made of any one of aluminum, aluminum alloy, titanium, and titanium alloy, and the micro-nano composite structure layer is prepared on the formed metal substrate by femtosecond laser processing or electrochemical etching process.

[0018] A spacecraft thermal management system includes the aforementioned coating-free lightweight metal radiative heat sink, the main body of which is connected to an internal heat source of the spacecraft via the heat dissipation component, and dissipates heat towards space via the radiative heat dissipation surface.

[0019] The above technical solution can achieve at least some of the following technical effects: (1) By changing the physical structure of the heat sink surface instead of spraying a coating, the additional weight and failure risks such as coating degradation and peeling caused by the use of coatings are fundamentally eliminated. The heat sink body is made of pure metal material. Since the high radiation characteristics come from the permanent structure of the metal substrate surface rather than the attached foreign material, the heat sink body has the same space environment resistance (radiation resistance, antigen oxygen resistance, high and low temperature cycle resistance) as the metal substrate, and the reliability is extremely high.

[0020] (2) Spectral targeted design: Construct a micro-nano scale superstructure (micro-nano composite structure layer) on the radiative heat dissipation surface. This superstructure can achieve efficient wide-spectrum, multi-angle infrared photon capture through photonic design (such as forming an optical resonant cavity), thereby obtaining an infrared emissivity that is much higher than the intrinsic value of metal (according to Kirchhoff's law, the absorptivity under thermal equilibrium is the emissivity).

[0021] The spectral characteristics of the micro / nano composite structure layer are directly determined by its geometric parameters, such as period, depth, and duty cycle. By adjusting these parameters, high emissivity bands can be precisely designed. For example, for the heat dissipation surface of a high-temperature thruster (approximately 400 Kelvin, with a peak radiation of about 7 to 8 micrometers), the structure can be designed to have higher emissivity in that band; for the heat dissipation surface of a low-temperature electronic device (approximately 300 Kelvin, with a peak radiation of about 10 micrometers), the structure can be adjusted to optimize performance in that band. This ability to design on demand maximizes heat dissipation efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the coating-free lightweight metal radiant heat sink in the embodiments of this application; Figure 2 This is a schematic diagram illustrating the principle of the angular extension structure and the absorption reinforcement structure working together as described in this application; Figure 3 This is a schematic diagram of the angle extension structure and the absorption strengthening structure in the embodiments of this application; Figure 4 This is a cross-sectional view of an exemplary embodiment 1 of this application; Figure 5 The spectrum of Exemplary Example 1; Figure 6 This is a cross-sectional view of an exemplary embodiment 2 of this application; Figure 7 The spectrum of Exemplary Example 2; In the figure, 1-micro-nano composite structure layer; 11-angle extension structure; 12-absorption enhancement structure; 2-heat dissipation component; 3-mechanical support structure. Detailed Implementation

[0023] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, the coating-free lightweight metal radiative heat sink for spacecraft described in this application includes a heat sink body, which is a metal substrate, and at least one metal substrate radiative heat sink layer with surface microstructure is provided on the metal substrate.

[0025] Preferably, the metal matrix is ​​made of any one of aluminum, aluminum alloy, titanium, and titanium alloy.

[0026] The surface microstructure is a micro-nano composite structure layer 1, which is integrally formed from pure metal material. This layer is fabricated on a pre-formed metal substrate using femtosecond laser processing or electrochemical etching. The micro-nano composite structure layer 1 consists of two functionally synergistic and geometrically integrated substructures: an angle-expanding structure 11 and an absorption-enhancing structure 12, with the absorption-enhancing structure 12 located below the angle-expanding structure 11. Incident infrared radiation first undergoes angle expansion through the angle-expanding structure before being absorbed by the absorption-enhancing structure.

[0027] The angle extension structure is composed of any one or a combination of several of the following: a conical array, a pyramidal array, a frustum array, a truncated cone array, a hollow inverted truncated cone array, and a hollow inverted truncated cone array, forming a periodic or non-periodic structure. For example... Figure 2 As shown, the outer wall surface of the cone or frustum, the side wall surface of the pyramid or frustum, and the inner wall surface of the hollow inverted frustum or hollow inverted truncated cone in the angle extension structure are inclined at an angle of 30° to 60° with the normal direction of the radiation heat dissipation surface. Its core function is to change the propagation direction of the incident infrared radiation, improve the radiation absorption characteristics for the difficult-to-capture angle range, and realize wide-angle light capture.

[0028] Preferably, when the angle extension structure is a cone array, a pyramid array, a frustum array, or a truncated cone array, the base feature size of the cone, the frustum, the pyramid, or the truncated cone ranges from [5μm to 50μm], and the height ranges from [3μm to 50μm]; wherein, the base feature size represents the maximum lateral span of the base.

[0029] The absorption-enhancing structure is composed of any one or a combination of periodically or non-periodically arranged grooves and holes.

[0030] Preferably, each cone in the conical array and each frustum in the frustum array are mounted on a cylinder, and the space enclosed by adjacent cylinders and the groove formed by the surface of the cylinder constitute the absorption-enhancing structure, such as... Figure 3As shown in (a) and (b) in the figure. In this figure, the base area of ​​the cone is the same as the cross-sectional area of ​​the cylinder, and the base area of ​​the frustum is the same as the cross-sectional area of ​​the cylinder.

[0031] Preferably, each pyramid in the pyramid array and each frustum in the frustum array are disposed on a prism, and the space enclosed by adjacent prisms and the surface of the prisms constitute the absorption and strengthening structure; wherein, the base area and shape of the pyramid are the same as the cross-sectional area and shape of the prism, and the base area and shape of the frustum are the same as the cross-sectional area and shape of the prism.

[0032] Preferably, each hollow frustum in the hollow frustum array is disposed on a hollow cylinder, the inner wall of the hollow cylinder and its internal holes constitute the absorption enhancement structure, and the hollow frustum and the hollow cylinder form a grating; wherein, the base area and shape of the hollow frustum are the same as the cross-sectional area and shape of the hollow cylinder, such as... Figure 3 As shown in (c) in the figure.

[0033] Preferably, each hollow chamfered frustum in the hollow frustum array is disposed on a hollow prism, and the inner wall and internal holes of the hollow prism constitute the absorption enhancement structure. The hollow chamfered frustum and the hollow prism form a grating; wherein, the base area and shape of the hollow chamfered frustum are the same as the cross-sectional area and shape of the hollow prism, such as... Figure 3 As shown in (d) in the figure.

[0034] The absorption-enhancing structure is located in an internal region (such as a groove or hole and its corresponding metal wall) guided and converged by adjacent angular expansion structures. It consists of periodically or non-periodically arranged grooves, holes, or combinations thereof, and their corresponding metal walls. Its key geometric feature is that the ratio of the groove depth or hole height to its opening width is greater than 1:1, preferably between 1.5:1 and 5:1, and its characteristic dimension is equal to or greater than the target infrared radiation wavelength at its location. This subwavelength structure with a depth-to-width ratio greater than 1 forms "optical traps" or resonant cavities, causing the infrared radiation guided there to undergo multiple reflections and strong local electromagnetic field resonance. The energy is efficiently absorbed by the metal material and converted into heat energy, thereby overcoming the radiation escape problem caused by the high intrinsic reflectivity of the metal surface and achieving efficient absorption and radiation.

[0035] In this embodiment, the feature dimension is the groove width or the hole diameter.

[0036] The angle-expansion structure and the absorption-enhancing structure are physically integrated and work together to increase the hemispherical average emissivity of a pure metal surface with low emissivity (typically <0.05) to above 0.5 in the infrared band. The angle-expansion structure designed in this application, by changing the propagation direction of incident infrared radiation, can achieve preliminary absorption of infrared radiation to a certain extent. Then, the enhanced absorption structure further enhances the absorption of infrared radiation, thus forming a double-layer absorption of infrared radiation and significantly increasing the absorption rate.

[0037] Preferably, to ensure the efficient operation of the micro-nano composite structure layer, the metal substrate is provided with a heat dissipation component and a mechanical support structure.

[0038] The heat spreader is equipped with heat pipe mounting slots or heat spreader cavities for connection to the spacecraft's heat source. The heat spreader has excellent thermal contact with the micro / nano composite structure layers to achieve efficient heat conduction from the heat source to the radiative heat dissipation surface, thereby improving heat dissipation performance. Furthermore, the heat spreader can uniformly diffuse waste heat generated inside the spacecraft to the radiative heat dissipation surface, improving heat dissipation performance while preventing the formation of localized hot spots.

[0039] The heat dissipation structure and the radiative heat dissipation surface are supported by a mechanical support structure. This mechanical support structure is made of high-strength lightweight metals (such as titanium alloys or aluminum alloys) or composite materials, and undergoes topology optimization or hollow design to achieve extreme lightweighting of the overall structure while meeting the mechanical load requirements of the launch segment. This mechanical support structure is connected to the spacecraft body.

[0040] The spacecraft thermal management system described in this application includes the coating-free lightweight metal radiative heat sink, the main body of which is connected to the heat source inside the spacecraft through the heat dissipation component and dissipates heat towards space through the radiative heat dissipation surface.

[0041] Figure 4 This is a cross-sectional view of an exemplary embodiment 1 of this application. In this embodiment, the entire body of the heat sink is made of 1060 aluminum. The angle trapping layer is conical with a height of 15 micrometers and a bottom diameter of 10 micrometers. The enhanced absorption layer is composed of a space enclosed by adjacent cylindrical structures and the surface of the cylinders, with a height of 200 micrometers and a diameter of 10 micrometers. The distance between the central axes of the adjacent cylinders is 20 micrometers. The dashed lines show periodic units arranged in a two-dimensional periodic pattern within the heat dissipation surface of the radiant heat sink.

[0042] Figure 5The surface emissivity spectrum of this exemplary embodiment 1 is shown. This embodiment exhibits good high-bandwidth radiation (>70%) at different angles. Especially near the 20-micron wavelength range, the spectral emissivity of this embodiment is relatively high, corresponding to the region with a high thermal radiation weight at 200 K. Therefore, it has higher average emissivity and radiative heat dissipation performance at lower operating temperatures (as shown in Table 1).

[0043] Figure 6 This is a cross-sectional view of another exemplary embodiment 2 of this application. In this embodiment, the entire body of the heat sink is made of 1060 aluminum. The angle trapping layer is a square pyramid with a height of 10 micrometers and a regular quadrilateral base with a side length of 5 micrometers. The enhanced absorption layer is composed of a space enclosed by adjacent square prism structures and the surface of the prisms. The prisms are 200 micrometers high, have a regular quadrilateral cross-section, and a side length of 5 micrometers. The groove width is 10 micrometers. The dashed lines show periodic units arranged in a two-dimensional periodic pattern within the heat dissipation surface of the radiant heat sink.

[0044] Figure 7 The surface emissivity spectrum of this exemplary embodiment 2 is shown. This embodiment exhibits good high-bandwidth radiation (>70%) at different angles. Especially in the wavelength range of 8 to 10 micrometers, the spectral emissivity of this embodiment is relatively high, corresponding to the regions with higher thermal radiation weights at 300 K and 400 K. Therefore, it has higher average emissivity and radiative heat dissipation performance at higher operating temperatures (as shown in Table 1).

[0045] The radiative heat dissipation performance of the two examples is shown in Table 1: at operating temperatures of 200 K and 300 K, Example 1 exhibits better radiative performance; while at an operating temperature of 400 K, Example 2 demonstrates stronger radiative heat dissipation capability. The above comparison reflects the design capabilities of this application for different operating scenarios.

[0046] Table 1

[0047] The two examples above are expected to reduce coating weight by 0.5 kg per square meter and reduce metal sheet weight by 0.03 kg per square meter through subtractive manufacturing. Based on the average launch cost of existing spacecraft (approximately 100,000 yuan per kg), the total cost savings would be approximately 53,000 yuan per square meter.

[0048] The above are exemplary embodiments of this application, and the scope of protection of this application is defined by the claims and their equivalents.

Claims

1. A coating-free lightweight metal radiative heat sink for spacecraft, characterized in that, include: The main body of the heat sink, and At least one metal-based radiative heat dissipation layer with surface microstructure is provided on the main body of the heat sink; The heat sink body is a metal substrate, and the surface microstructure is a micro-nano composite structure layer. The micro-nano composite structure layer includes an angle extension structure and an absorption enhancement structure. The incident infrared radiation first passes through the angle extension structure and is then absorbed by the absorption enhancement structure. The angle extension structure is composed of any one or any combination of a cone array, pyramid array, frustum array, truncated cone array, hollow inverted truncated cone array, and hollow inverted truncated cone array, forming a periodic or non-periodic structure. The outer wall surfaces of each cone in the conical array and each frustum in the frustum array, the side wall surfaces of each pyramid in the pyramidal array and each frustum in the frustum array, and the inner wall surfaces of each hollow inverted frustum in the hollow inverted frustum array and each hollow inverted frustum in the hollow inverted frustum array are inclined at an angle of 30° to 60° to the normal direction of the metal-based radiative heat dissipation layer. The absorption-enhancing structure is composed of any one or a combination of periodically or non-periodically arranged grooves and holes.

2. The coating-free lightweight metal radiant heat sink as described in claim 1, characterized in that, When the angle extension structure is a cone array, a pyramid array, a frustum array, or a frustum array, the base feature size of the cone, the frustum, the pyramid, or the frustum is in the range of [5μm, 50μm], and the height is in the range of [3μm, 50μm]; wherein, the base feature size represents the maximum lateral span of the base.

3. The coating-free lightweight metal radiant heat sink as described in claim 2, characterized in that, Each cone in the conical array and each frustum in the frustum array are mounted on a cylinder. The space enclosed by adjacent cylinders and the groove formed by the cylinder surface constitute the absorption and strengthening structure. The base area of ​​the cone is the same as the cross-sectional area of ​​the cylinder, and the base area of ​​the frustum is the same as the cross-sectional area of ​​the cylinder. Each pyramid in the pyramid array and each frustum in the frustum array are mounted on a prism. The space enclosed by adjacent prisms and the groove formed by the surface of the prism constitute the absorption and reinforcement structure. The base area and shape of the pyramid are the same as the cross-sectional area and shape of the prism, and the base area and shape of the frustum are the same as the cross-sectional area and shape of the prism.

4. The coating-free lightweight metal radiant heat sink as described in claim 3, characterized in that, Each hollow inverted frustum in the hollow frustum array is disposed on a hollow prism, and the inner wall of the hollow prism and its internal holes constitute the absorption and strengthening structure; wherein, the base area and shape of the hollow inverted frustum are the same as the cross-sectional area and shape of the hollow prism. Each hollow frustum in the hollow frustum array is mounted on a hollow cylinder, and the inner wall and internal holes of the hollow cylinder constitute the absorption and strengthening structure; wherein, the bottom area and shape of the hollow frustum are the same as the cross-sectional area and shape of the hollow cylinder.

5. The coating-free lightweight metal radiant heat sink as described in claim 1, characterized in that, The ratio of the groove depth or hole height to its opening width in the absorption-enhancing structure is in the range of [1.5, 5].

6. The coating-free lightweight metal radiant heat sink as described in claim 1, characterized in that, The characteristic dimension of the absorption enhancement structure is not less than the target infrared radiation wavelength at its location, and the characteristic dimension is the groove width or the hole diameter.

7. The coating-free lightweight metal radiant heat sink as described in claim 1, characterized in that, The metal substrate is provided with a heat-spreading component and a mechanical support structure. The heat-spreading component is in contact with the radiative heat dissipation surface and is in thermal contact with the micro-nano composite structure layer. The mechanical support structure is connected to the heat-spreading component. The heat-spreading component is provided with a heat pipe mounting groove or a heat-spreading plate cavity.

8. The coating-free lightweight metal radiant heat sink as described in claim 7, characterized in that, The mechanical support structure adopts a topology-optimized configuration, and its structural form is any one of the following: an internally hollowed-out mesh structure, a reinforcing rib structure, and a lattice structure; the material of the mechanical support structure is a high-strength lightweight metal or composite material.

9. The coating-free lightweight metal radiant heat sink as described in claim 1, characterized in that, The metal substrate is made of any one of aluminum, aluminum alloy, titanium, and titanium alloy, and the micro-nano composite structure layer is prepared on the formed metal substrate by femtosecond laser processing or electrochemical etching process.

10. A spacecraft thermal management system, characterized in that, The thermal management system includes a coating-free lightweight metal radiative heat sink as described in any one of claims 1-9. The heat sink body is connected to the heat source inside the spacecraft through the heat dissipation component and dissipates heat towards space through the radiative heat dissipation surface.

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