A high-temperature resistant selective infrared emission stealth material and its preparation method

Abstract

A high-temperature resistant selective emission infrared stealth material, which has a layered structure and successively includes a base layer, a metal layer and a silicon nitride layer; the thickness of the metal layer is 50 nm - 1000 nm; the thickness of the silicon nitride layer is 1.2 μm - 1.8 μm. Preparation method of the infrared stealth material: (1) Clean and dry the base material; (2) Deposit the metal material on the base by magnetron sputtering, chemical vapor deposition or atomic layer deposition to form a metal layer; (3) Then deposit silicon nitride on the surface of the metal layer by magnetron sputtering or chemical vapor deposition to complete the preparation of the infrared stealth material. The selective emission infrared stealth material of the present invention, through the optimization of the thickness of the metal layer and the silicon nitride layer, takes into account the requirements of low emissivity and radiative heat dissipation, and has important significance for better realizing infrared stealth.

Description

Technical Field

[0001] The present invention belongs to the field of new materials, and particularly relates to a high-temperature resistant selective emission infrared stealth material and a preparation method thereof. Background Art

[0002] Stealth technology, as one of the cutting-edge military technologies, has received extensive attention from researchers. Infrared stealth occupies a very important position among various stealth technologies. Infrared stealth mainly refers to eliminating or reducing the difference in radiation characteristics between the target and the background in the mid- and far-infrared bands of the two atmospheric windows (3.0 μm - 5.0 μm, 8.0 μm - 14.0 μm). Materials with spectral selective emission characteristics can achieve infrared stealth of the target from two aspects: reducing the emissivity of the target and radiative cooling. Compared with traditional low-emissivity infrared stealth materials, selective emission materials can effectively avoid the risk of increased temperature caused by low radiation efficiency of traditional materials, thereby increasing the possibility of target exposure, and have more excellent infrared stealth effects. It should be noted that due to the ability of radiative cooling, selective emission materials are of more important significance for the infrared stealth of high-temperature targets.

[0003] Currently, the research on selective emission infrared stealth materials has become a hot topic in the stealth field. At present, researchers have designed and prepared infrared stealth materials with selective emission characteristics by using multi-layer film systems or metamaterial structures. However, most of the currently obtained selective emission materials have complex structures, which are not conducive to large-area preparation and application. At the same time, due to the complexity of the structure, the material is prone to be damaged in a high-temperature environment; some infrared stealth materials cannot exhibit the expected selective emission characteristics in a high-temperature environment, which all limit their use in a high-temperature environment. In addition, the application of selective emission materials in the field of infrared stealth technology is also immature, and relevant application reports are still relatively rare. Therefore, developing a selective emission infrared stealth material with a simple structure, spectral selective emission characteristics, and suitable for high-temperature environments has important value for the infrared stealth of high-temperature military targets. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies and defects in the background art, and provide a selective emission material with a simple structure, easy to prepare, and applicable to high-temperature infrared stealth, and a preparation method thereof.

[0005] To solve the above technical problem, the technical solution proposed by the present invention is as follows:

[0006] A high-temperature resistant selective emission infrared stealth material, the infrared stealth material is a layered structure, sequentially including a base layer, a metal layer, and a silicon nitride layer; the material of the metal layer is any one of aluminum, stainless steel, tungsten, and copper. In the present invention, preferably, the bonding force between the metal layer and the silicon nitride is good, the stress matching is strong, and it is not easy to fall off at high temperatures.

[0007] For the above infrared stealth material, preferably, the thickness of the metal layer is 50nm - 1000nm; the thickness of the silicon nitride layer is 1.2μm - 1.8μm. Changing the thickness of the metal layer and the silicon nitride layer in the present invention may cause the spectral characteristics of the material obtained in the present invention to deviate from the preset target of the present invention. Controlling the thickness of the metal layer and the silicon nitride layer within the above range can obtain a selective emission material with better effects.

[0008] For the above infrared stealth material, preferably, the material of the base layer is any one of silicon, glass, metal (such as aluminum, stainless steel, alloy, etc.).

[0009] As a general inventive concept, the present invention also provides a preparation method of the above infrared stealth material, including the following steps:

[0010] (1) Clean and dry the substrate material;

[0011] (2) Deposit the metal material on the substrate by magnetron sputtering, chemical vapor deposition or atomic layer deposition to form a metal layer;

[0012] (3) Then deposit silicon nitride on the surface of the metal layer by magnetron sputtering or chemical vapor deposition to complete the preparation of the infrared stealth material.

[0013] For the above preparation method, preferably, in step (1), the cleaning means first cleaning with deionized water and then ultrasonically cleaning by soaking in absolute ethanol.

[0014] In the structure of the high-temperature resistant selective emission infrared stealth material of the present invention, the metal layer is an infrared reflection layer, making the entire structure impermeable to infrared electromagnetic waves; by virtue of the intrinsic infrared optical properties (reflectivity and emissivity) of the silicon nitride layer and the physical optical principle of the thin film, it can be ensured that the infrared stealth material of the present invention realizes a low emissivity in the range of 3 - 5μm and a high emissivity in the range of 5 - 20μm. In the infrared stealth material of the present invention, there are strict requirements for the thickness range of the silicon nitride layer. Only the silicon nitride layer with a thickness in the range of 1.2μm - 1.8μm can achieve the expected spectral selectivity (spectral selectivity means: low emissivity in the range of 3 - 5μm, high emissivity in the range of 5 - 20μm), otherwise the high emissivity and low emissivity bands may deviate from the expected design.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] (1) The selective emission infrared stealth material of the present invention can ensure that the infrared stealth material has a low emissivity in the infrared window band of 3.0 μm to 5.0 μm and an emissivity below 0.20 in the range from room temperature to 1000 °C through optimizing the thickness of the metal layer and the silicon nitride layer. In the non-window band of 5.0 μm to 20.0 μm, a high emissivity can be achieved, and the emissivity can reach above 0.70. This infrared stealth material realizes infrared selective emission, taking into account the requirements of low emissivity and radiation heat dissipation, which is of great significance for better realizing infrared stealth.

[0017] (2) The structure of the high-temperature resistant selective emission infrared stealth material of the present invention is simple, which is convenient for large-area preparation and application.

[0018] (3) The preparation process of the high-temperature resistant selective emission infrared stealth material of the present invention is simple and feasible, has good repeatability, and has low equipment requirements. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the selective emission infrared stealth material in Embodiment 1 of the present invention.

[0020] Figure 2 It is a theoretical emissivity spectrum diagram of the selective emission infrared stealth material in Embodiment 1 of the present invention in the band of 3.0 μm to 20.0 μm.

[0021] Figure 3 It is a photo of the selective emission infrared stealth material in Embodiment 2 of the present invention before heat treatment.

[0022] Figure 4 It is a photo of the selective emission infrared stealth material in Embodiment 2 of the present invention before heat treatment.

[0023] Legend Explanation:

[0024] 1. Substrate; 2. Aluminum layer; 3. Silicon nitride layer. Detailed Embodiments

[0025] To facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings of the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0027] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or can be prepared by existing methods.

[0028] Example 1:

[0029] A high-temperature resistant selective emission infrared stealth material, as Figure 1 shown, the selective emission material is a material that can regulate the emission characteristics of the infrared spectrum. The material uses stainless steel as the substrate 1, and an aluminum layer 2 and a silicon nitride layer 3 are sequentially coated on the surface of the substrate 1; the thickness of the aluminum layer 2 is 200 nm, and the thickness of the silicon nitride layer 3 is 1.5 μm.

[0030] The preparation method of the high-temperature resistant selective emission infrared stealth material in this example includes the following steps:

[0031] (1) First, clean the stainless steel material with deionized water, then soak it in absolute ethanol and ultrasonically clean it, and dry it to be used as the substrate;

[0032] (2) Use magnetron sputtering (DC sputtering; power 200 W, deposition temperature: room temperature, deposition pressure: 0.5 Pa) to deposit aluminum on the substrate to form an aluminum layer with a thickness of 200 nm;

[0033] (3) Then use chemical vapor deposition to deposit silicon nitride on the surface of the aluminum layer. The thickness of the silicon nitride layer is 1.5 μm, and the preparation of the infrared stealth material is completed.

[0034] The theoretical emissivity spectrum diagram of the selective emission infrared stealth material in this example in the 3.0 μm - 20.0 μm band is shown in Figure 2 shown. From Figure 2 it can be seen that for the high-temperature resistant selective emission material in this example, the emissivity in the 3.0 μm - 5.0 μm infrared window band is 0.08, while the emissivity in the non-window band of 5.0 μm - 20.0 μm is about 0.70.

[0035] Test the emissivity curve of the selective emission infrared stealth material in this example in the range of room temperature to 1000 °C. The curves at different temperatures basically coincide with the emissivity curve at room temperature, that is, the low emissivity in the 3.0 μm - 5.0 μm infrared window band, with an emissivity below 0.20, and a high emissivity is achieved in the 5.0 μm - 20.0 μm non-window band, with an emissivity reaching above 0.70.

[0036] Example 2:

[0037] A high-temperature resistant selective emission infrared stealth material, the selective emission material is a material that can regulate the emission characteristics of the infrared spectrum. The material uses a silicon wafer as the substrate, and a tungsten layer and a silicon nitride layer are sequentially coated on the surface of the substrate; the thickness of the tungsten layer is 500 nm, and the thickness of the silicon nitride layer is 1.7 μm.

[0038] The preparation method of the high-temperature resistant selective emission infrared stealth material in this embodiment includes the following steps:

[0039] (1) Clean the silicon wafer with deionized water first, then soak it in absolute ethanol for ultrasonic cleaning, and dry it to serve as the substrate;

[0040] (2) Deposit tungsten on the substrate by magnetron sputtering (DC sputtering; power 200W, deposition temperature: room temperature; deposition pressure: 0.3Pa) to form a tungsten layer with a thickness of 500nm;

[0041] (3) Then deposit silicon nitride on the surface of the tungsten layer by magnetron sputtering (RF sputtering; power 200W, deposition temperature: room temperature; deposition pressure: 0.6Pa). The thickness of the silicon nitride layer is 1.7μm, and the preparation of the infrared stealth material is completed.

[0042] The final high-temperature resistant selective emission material in this embodiment has an emissivity of 0.16 in the 3.0μm - 5.0μm infrared window band, while the emissivity in the non-window band of 5.0μm - 20.0μm is approximately 0.73.

[0043] Heat-treat the finally prepared high-temperature resistant selective emission material in this embodiment in an air environment at 1000°C for 4 hours. The photos before and after the treatment are shown in Figure 3 and Figure 4 respectively. It can be seen from the figure that the high-temperature resistant selective emission material of the present invention has a well-preserved structure in a high-temperature environment and is not easily damaged.

Claims

1. A high-temperature resistant selective infrared stealth material, characterized in that, the infrared stealth material has a layered structure, successively including a base layer, a metal layer and a silicon nitride layer; the thickness of the metal layer is 50 nm - 1000 nm; the thickness of the silicon nitride layer is 1.2 μm - 1.8 μm; the material of the metal layer is any one of aluminum, stainless steel, tungsten and copper; in the range from room temperature to 1000 °C, the infrared stealth material has a low emissivity in the infrared window band of 3.0 μm - 5.0 μm, and its emissivity is below 0.20, and a high emissivity in the non-window band of 5.0 μm - 20.0 μm, and the emissivity reaches above 0.

70.

2. The infrared stealth material according to claim 1, characterized in that, the material of the base layer is any one of silicon, glass and metal.

3. A preparation method of the infrared stealth material according to any one of claims 1 to 2, characterized in that, it includes the following steps: (1) Clean and dry the substrate material; (2) Deposit the metal material on the substrate by magnetron sputtering, chemical vapor deposition or atomic layer deposition to form a metal layer; (3) Then deposit silicon nitride on the surface of the metal layer by magnetron sputtering or chemical vapor deposition to complete the preparation of the infrared stealth material.

4. The preparation method according to claim 3, characterized in that, in the step (1), the cleaning means first cleaning with deionized water and then ultrasonic cleaning in absolute ethanol.

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