Dewar nickel-based thin-wall cold shield for refrigeration type infrared detector with heat conduction enhanced by multilayer composite coating material on surface and preparation method of Dewar nickel-based thin-wall cold shield

Abstract

The invention relates to a Dewar nickel-based thin-wall cold shield for a refrigeration type infrared detector with heat conduction enhanced by a multilayer composite coating material on the surface and a preparation method of the Dewar nickel-based thin-wall cold shield, and belongs to the technical field of refrigeration type infrared detectors. The method comprises the following steps: loading a nickel-based thin-wall cold shield of which the inner surface is blackened into an electron beam evaporation coating clamp; carrying out high vacuum pumping on the electron beam evaporation coating equipment; when the vacuum degree of the electron beam evaporation coating equipment is greater than 1 * 10 <-3 > Pa, baking the surface of the thin-wall cold shield to be coated at 200 DEG C; when the vacuum degree of the electron beam evaporation coating equipment is greater than 5 * 10 <-4 > Pa, carrying out argon plasma cleaning treatment on the cold shield; a nickel adhesion layer, a copper heat conduction layer and a silver heat conduction layer are sequentially plated on the surface of the cold shield; on the basis of keeping the mechanical property and thermodynamic property of the nickel-based thin-wall cold shield unchanged, the thermal mass of the Dewar cold head is not obviously increased, the heat conduction property of the cold shield can be obviously enhanced, the heat transfer is accelerated, and the quick start of the refrigeration type infrared detector is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of refrigerated infrared detectors, and specifically relates to a Dewar nickel-based thin-walled cold shield for refrigerated infrared detectors with a multi-layer composite coating material on the surface to enhance thermal conductivity, and a preparation method thereof. Background Art

[0002] The Dewar product of the refrigerated infrared focal plane detector is a vacuum insulation device used for vacuum packaging of infrared detector chips. It is coupled with a refrigerator to form an infrared focal plane detector assembly. It not only provides a suitable low-temperature working environment for the detector chip, but also provides optical, mechanical and electrical interfaces for the detector. It is one of the core components of the infrared focal plane detector assembly. The Dewar cold head structure is a key part of the Dewar product. It provides low-stress mechanical support for thermal expansion matching for the chip. It is also a heat coupling channel between the detector chip and the cold finger of the refrigerator. The Dewar cold head usually includes a ceramic substrate, a detector chip, a metal thin-wall cold screen and a filter. In the fast-cooling infrared focal plane detector assembly, the Dewar cold head structure and the properties of the materials used directly determine the cooling time.

[0003] For a given Dewar cold head structure, with a certain thermal mass, the amount of heat to be extracted when the room temperature t0 (~300K) is reduced to the operating temperature t1 (~77K) can be expressed as:

[0004]

[0005] Where Q is the heat; m n is the quality of the material; c n is the specific heat capacity of the material; Δt=t0-t1 is the operating temperature difference of the detector; n is a positive integer, indicating the type of material contained in the cold head structure.

[0006] Generally, for a given Dewar cold head structure and material, the cold shield is the main source of heat during the cooling process. The material used to make the cold shield is usually nickel-based alloy. Nickel and its alloys are widely used in Dewar cold shields due to their good mechanical properties and molding process. However, the thermal conductivity of nickel is about ~70W / (m·K). Due to the low thermal conductivity, the cooling rate of the cold shield is slow during the cooling process of the detector, which in turn affects the cooling time of the detector product.

[0007] In summary, the thermal conductivity of the cooling process of the cold screen made of nickel and its alloys of the rapid cooling infrared focal plane detector is affected by the low thermal conductivity of the material, and it is difficult to improve the thermal conductivity of the cold screen by relying solely on structural design. That is, the disadvantage of the traditional single-layer thin-walled cold screen made of nickel and its alloys is that the detector assembly cools down slowly due to the low thermal conductivity of the material, which seriously affects the rapid cooling start of the cooling infrared focal plane detector.

[0008] Therefore, how to overcome the shortcomings of the existing technology is an urgent problem to be solved in the field of refrigerated infrared detector technology. Summary of the invention

[0009] The purpose of the present invention is to solve the problems of low thermal conductivity of the single-layer structural material of the Dewar nickel-based thin-walled cold shield of a refrigerated infrared focal plane detector and slow cooling speed during the refrigeration startup process, and to provide a Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multi-layer composite coating material to enhance thermal conductivity and a preparation method thereof, so as to improve the thermal conductivity of the Dewar nickel-based thin-walled cold shield, ensure rapid cooling of the cold head, and improve the rapid startup performance of the refrigerated infrared focal plane detector product.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing a Dewar nickel-based thin-wall cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity comprises the following steps:

[0012] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0013] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0014] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0015] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0016] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0017] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm to 1 μm;

[0018] The copper heat conducting layer is made of metal copper with a thickness of 5 μm to 50 μm;

[0019] The silver heat conductive layer is made of metallic silver and has a thickness of 5 μm to 50 μm.

[0020] Furthermore, preferably, in step 1, the thickness of the nickel-based thin-walled cold shield is 0.08 mm to 0.30 mm.

[0021] Furthermore, preferably, in step three, the baking time is 10 minutes.

[0022] Furthermore, preferably, in step 4, when argon plasma cleaning is adopted, the cleaning time is 300 s.

[0023] Furthermore, preferably, in step five, a 0.5 μm thick nickel adhesion layer, a 5 μm thick copper thermal conductive layer and a 5 μm thick silver thermal conductive layer are plated on the surface of the cold shield in sequence.

[0024] Furthermore, preferably, in step five, the total thickness of the copper heat conductive layer and the silver heat conductive layer is 9.5% to 10.5% of the thickness of the nickel-based thin-wall cold shield.

[0025] The present invention provides a Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multilayer composite coating material having enhanced thermal conductivity, which is prepared by a method for preparing the Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multilayer composite coating material having enhanced thermal conductivity.

[0026] The present invention enables the thin-walled cold shield to be free from the limitation of the low thermal conductivity of the nickel-based material, and functionally has high thermal conductivity, so as to achieve the purpose of improving the refrigeration and temperature reduction rate of the Dewar cold head.

[0027] The surface multilayer composite coating material structure of the present invention has a material system of nickel copper silver (Ni / Cu / Ag). In addition to the nickel layer, silver (~430W / (m·K)) and copper (~400W / (m·K)) both have better thermal conductivity than nickel (~70W / (m·K)). The multilayer composite coating material includes an adhesion layer and an enhanced thermal conductivity layer. Among them, the nickel layer is used as an adhesion layer to achieve reliable connection with the surface of the nickel-based thin-walled cold shield, and the enhanced thermal conductivity layer includes silver and copper high thermal conductivity metal layers. A copper thermal conductive layer is required to transition between the nickel adhesion layer and the silver thermal conductive layer to avoid loose adhesion between the nickel element and the silver element due to low mutual solubility. The surface emissivity of silver is lower than that of nickel. At this time, the emissivity of the outer surface of the cold shield can be reduced, and the radiation heat leakage of the cold shield can be further reduced.

[0028] The Dewar nickel-based thin-walled cold shield for refrigerated infrared detectors with a multi-layer composite coating material on the surface to enhance thermal conductivity can significantly enhance the thermal conductivity of the cold shield without significantly increasing the thermal mass of the Dewar cold head while maintaining the high-reliability mechanical properties of traditional nickel-based thin-walled cold shields.

[0029] According to the detector's requirements for cooling and cooling rate, the present invention can flexibly adjust the thickness ratio between the nickel-based thin-wall cold screen and the surface multi-layer composite coating material, so as to obtain the cooling rate requirements for different application scenarios. Among them, the preferred parameter is that the total thickness of the copper thermal conductive layer and the silver thermal conductive layer is 10% of the thickness of the nickel-based thin-wall cold screen. At this time, the thermal conductivity of the nickel-based thin-wall cold screen after enhanced thermal conductivity can be significantly increased, and its thermal mass has no significant change.

[0030] In the present invention, the outermost metal of the surface multi-layer composite coating material is silver, which has lower loss than nickel in the infrared band, thereby obtaining a higher reflectivity, thereby reducing the radiation heat leakage of the Dewar.

[0031] The preparation method of the present invention can select physical vapor deposition process technology such as electron beam evaporation coating equipment, has high feasibility, and is suitable for mass production.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention avoids the limitation of using a single material in the traditional nickel-based thin-walled cold screen design, which makes it difficult to take both mechanical properties and thermal transfer properties into consideration. A multi-layer composite surface coating material is used to enhance the thermal conductivity of the nickel-based thin-walled cold screen, so that the cold screen has both highly reliable mechanical properties and excellent thermal conductivity. Since the silver and copper in the enhanced thermal conductive layer have thermal conductivity coefficients several times higher than that of nickel, a few microns thick enhanced thermal conductive layers can significantly improve the thermal conductivity of the cold screen, while the overall thermal mass of the cold screen is not significantly increased. The nickel-based thin-walled cold screen with a multi-layer composite surface coating material can easily meet the requirements of highly reliable mechanical support and rapid cooling in refrigerated infrared detectors.

[0034] The present invention can significantly enhance the thermal conductivity of the cold shield, accelerate heat transfer, and realize rapid startup of the refrigerated infrared detector without significantly increasing the thermal mass of the Dewar cold head while maintaining the mechanical and thermodynamic properties of the nickel-based thin-wall cold shield.

[0035] The preparation process of the present invention is simple, and physical vapor deposition such as conventional electron beam evaporation coating equipment can be used to complete the preparation of the multi-layer composite coating material. The process is mature and highly operable.

[0036] The outermost layer material of the multi-layer composite coating material of the present invention is silver, which can improve the reflection characteristics of the outer surface of the cold shield, reduce the radiation heat transfer between the cold shield and the dewar shell, reduce the heat leakage of the dewar cold head, and reduce the power required by the refrigerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a diagram of the structure of a conventional refrigeration type Dewar nickel-based thin-walled cold shield;

[0038] Figure 2 A schematic diagram of the structure of a Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity of the present invention

[0039] Figure 3 Schematic diagram of the layered structure of the Dewar nickel-based thin-walled cold shield for a refrigeration-type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity of the present invention;

[0040] Figure 4The cooling simulation curve of the Dewar nickel-based thin-walled cold shield for the refrigeration type infrared detector with the surface multi-layer composite coating material enhanced thermal conductivity of the present invention;

[0041] In the figure, 1-nickel-based thin-walled cold shield, 2-cold shield black coating, 3-surface multi-layer composite plating material, 4-nickel adhesion layer, 5-copper thermal conductive layer, 6-silver thermal conductive layer. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with embodiments.

[0043] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0044] Example 1

[0045] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0046] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0047] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0048] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0049] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0050] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0051] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.8 μm;

[0052] The copper heat-conducting layer is made of metallic copper with a thickness of 20 μm;

[0053] The silver heat conductive layer is made of metallic silver and has a thickness of 10 μm.

[0054] Example 2

[0055] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0056] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0057] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0058] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0059] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0060] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0061] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm;

[0062] The copper heat-conducting layer is made of metallic copper with a thickness of 5 μm;

[0063] The silver heat conductive layer is made of metallic silver and has a thickness of 5 μm.

[0064] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.08 mm.

[0065] In step 3, the baking time is 10 minutes.

[0066] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0067] Example 3

[0068] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0069] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0070] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0071] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0072] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0073] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0074] The nickel adhesion layer is made of metallic nickel and has a thickness of 1 μm;

[0075] The copper heat-conducting layer is made of metallic copper with a thickness of 50 μm;

[0076] The silver heat conductive layer is made of metallic silver and has a thickness of 50 μm.

[0077] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.30 mm.

[0078] In step 3, the baking time is 10 minutes.

[0079] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0080] Example 4

[0081] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0082] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0083] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0084] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0085] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0086] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0087] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0088] The copper heat-conducting layer is made of metallic copper with a thickness of 25 μm;

[0089] The silver thermal conductive layer is made of metallic silver and has a thickness of 25 μm.

[0090] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.25 mm.

[0091] In step 3, the baking time is 10 minutes.

[0092] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0093] Example 5

[0094] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0095] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0096] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0097] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0098] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0099] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0100] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0101] The copper heat-conducting layer is made of metallic copper with a thickness of 5 μm;

[0102] The silver heat conductive layer is made of metallic silver and has a thickness of 5 μm.

[0103] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.2 mm.

[0104] In step 3, the baking time is 10 minutes.

[0105] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0106] Example 6

[0107] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0108] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0109] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0110] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0111] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0112] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0113] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm;

[0114] The copper heat-conducting layer is made of metallic copper with a thickness of 5 μm;

[0115] The silver heat conductive layer is made of metallic silver and has a thickness of 5 μm.

[0116] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.095 mm.

[0117] In step 3, the baking time is 10 minutes.

[0118] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0119] The total thickness of the copper heat conductive layer and the silver heat conductive layer is 9.5% of the thickness of the nickel-based thin-wall cold shield.

[0120] Example 7

[0121] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0122] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0123] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0124] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0125] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0126] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0127] The nickel adhesion layer is made of metallic nickel and has a thickness of 1 μm;

[0128] The copper heat-conducting layer is made of metallic copper with a thickness of 10 μm;

[0129] The silver heat conductive layer is made of metallic silver and has a thickness of 10 μm.

[0130] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.21 mm.

[0131] In step 3, the baking time is 10 minutes.

[0132] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0133] The total thickness of the copper thermal conductive layer and the silver thermal conductive layer is 10.5% of the thickness of the nickel-based thin-walled cold shield.

[0134] Example 8

[0135] A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that it comprises the following steps:

[0136] Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture;

[0137] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0138] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C;

[0139] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0140] Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence;

[0141] The nickel adhesion layer is made of metallic nickel and has a thickness of 0.5 μm;

[0142] The copper heat-conducting layer is made of metallic copper with a thickness of 5 μm;

[0143] The silver heat conductive layer is made of metallic silver and has a thickness of 5 μm.

[0144] In step 1, the thickness of the nickel-based thin-walled cold shield is 0.10 mm.

[0145] In step 3, the baking time is 10 minutes.

[0146] In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

[0147] The total thickness of the copper heat conductive layer and the silver heat conductive layer is 10% of the thickness of the nickel-based thin-wall cold shield.

[0148] Application Examples

[0149] like Figure 2 and Figure 3 As shown, a Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multi-layer composite coating material for enhanced thermal conductivity comprises: a nickel-based thin-walled cold shield 1, a cold shield blackening coating 2, and a surface multi-layer composite coating material 3. The surface multi-layer composite coating material 3 comprises: a nickel adhesion layer 4, a copper thermal conductive layer (5), and a silver thermal conductive layer 6.

[0150] Preparation steps of surface multi-layer composite coating material 3:

[0151] Step 1: Place a nickel-based thin-wall cold shield with a thickness of 0.1 mm and a blackened inner surface into an electron beam evaporation coating fixture;

[0152] Step 2: Pumping high vacuum on the electron beam evaporation coating equipment;

[0153] Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200℃ for 10min;

[0154] Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s;

[0155] Step 5: A 0.5 μm thick nickel adhesion layer, a 5 μm thick copper thermal conductive layer and a 5 μm thick silver thermal conductive layer are plated on the surface of the cold shield in sequence.

[0156] The simulation analysis of the cooling process of the nickel-based thin-walled cold shield with multi-layer composite coating material on the surface to enhance thermal conductivity is shown in Figure 4As shown. For the cold shield structure with a length of l = 5mm, a boundary condition of -200℃ is applied to end A, end B is at room temperature of 22℃, and the cooling time is 1s. When the surface multilayer composite coating material is not used to enhance thermal conductivity, the cooling rate of the nickel-based thin-walled cold shield is 151℃ / s, while the cooling rate of the nickel-based thin-walled cold shield with surface multilayer composite coating material to enhance thermal conductivity is 213℃ / s. The total thickness of the copper thermal conductive layer and the silver thermal conductive layer is 10μm, which is only 10% of the thickness of the nickel-based thin-walled cold shield of 0.1mm, while the cooling rate is increased by 41%, indicating that the cooling rate of the nickel-based thin-walled cold shield is significantly improved after the surface multilayer composite coating material is used to enhance the thermal conductivity.

[0157] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a Dewar nickel-based thin-walled cold shield for a refrigeration-type infrared detector with a multi-layer composite coating material on the surface to enhance thermal conductivity, characterized in that: The steps include: Step 1: Place the nickel-based thin-walled cold shield with a blackened inner surface into the electron beam evaporation coating fixture; Step 2: Pumping high vacuum on the electron beam evaporation coating equipment; Step 3: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 1×10 -3 Pa, the surface of the thin-walled cold shield to be plated is baked at 200°C; Step 4: Wait until the vacuum degree of the electron beam evaporation coating equipment is greater than 5×10 -4 Pa, the cold screen was cleaned with argon plasma for 300 s; Step 5: Plating a nickel adhesion layer, a copper thermal conductive layer and a silver thermal conductive layer on the surface of the cold shield in sequence; The nickel adhesion layer is made of metallic nickel and has a thickness of 0.1 μm to 1 μm; The copper thermal conductive layer is made of metallic copper with a thickness of 5μm~50μm; The silver thermal conductive layer is made of metallic silver and has a thickness of 5μm~50μm.

2. The method for preparing the Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface and enhanced thermal conductivity according to claim 1, characterized in that: In step 1, the thickness of the nickel-based thin-walled cold shield is 0.08 mm to 0.30 mm.

3. The method for preparing the Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface and enhanced thermal conductivity according to claim 1, characterized in that: In step 3, the baking time is 10 minutes.

4. The method for preparing the Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with enhanced thermal conductivity of the surface multi-layer composite coating material according to claim 1, characterized in that: In step 4, when argon plasma cleaning is used, the cleaning time is 300s.

5. The method for preparing the Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface and enhanced thermal conductivity according to claim 1, characterized in that: In step five, a 0.5 μm thick nickel adhesion layer, a 5 μm thick copper thermal conductive layer, and a 5 μm thick silver thermal conductive layer are plated on the surface of the cold shield in sequence.

6. The method for preparing the Dewar nickel-based thin-walled cold shield for a refrigeration type infrared detector with a multi-layer composite coating material on the surface and enhanced thermal conductivity according to claim 1, characterized in that: In step five, the total thickness of the copper thermal conductive layer and the silver thermal conductive layer is 9.5% to 10.5% of the thickness of the nickel-based thin-walled cold shield.

7. A Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multilayer composite coating material having enhanced thermal conductivity, obtained by the method for preparing a Dewar nickel-based thin-walled cold shield for a refrigerated infrared detector with a surface multilayer composite coating material having enhanced thermal conductivity as described in any one of claims 1 to 6.

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