A method for preparing an amorphous alloy protective film on the surface of polyimide by using a magnetron co-sputtering process

Abstract

A method for depositing and preparing an amorphous alloy protective film on the surface of a polyimide by using a magnetron co-sputtering process, which relates to a method for preparing an amorphous alloy protective film. It aims to solve the problem that the existing polyimide film has poor tolerance to the space environment. Method: Treatment of the polyimide film substrate, ion pre-sputtering is carried out, and magnetron sputtering of the amorphous alloy protective film is carried out in a magnetron sputtering vacuum chamber to form an amorphous alloy protective film on the surface of the polyimide film substrate; the target materials used include an alloy target material and a single-element Ni target material. The present invention combines the magnetron sputtering deposition technology for the growth of the amorphous alloy film to prepare an aluminum-based amorphous alloy / polyimide-based hybrid film, which has excellent tolerance to the space environment and improves its resistance to atomic oxygen erosion.

Description

Technical Field

[0001] The present invention relates to a method for preparing an amorphous alloy protective film. Background Art

[0002] With the continuous development of space technology and the increasing number of space activities, the requirements for the service performance of materials in extreme space environments are becoming increasingly strict. There are various extreme environmental factors in space, including high vacuum, extreme temperature cycling, ultraviolet irradiation, atomic oxygen erosion, ion irradiation, and high-speed impacts of space debris, dust, and micrometeoroids. These conditions pose great challenges to the protective materials applied on the surface of on-orbit spacecraft.

[0003] Polyimide (Kapton), one of the most widely used organic polymers in current space activities, has excellent dielectric, mechanical, physical and chemical properties, as well as good high and low temperature stability. Compared with other polymer materials, it has better space stability and applicability. Polyimide is widely used as the main structure of thermal control coatings on the surface of spacecraft and the substrate of solar cells. However, under the combined challenges of multiple space environmental factors, there are still some problems. For example, the synergistic effect of atomic oxygen erosion and high-speed impacts of space debris will significantly accelerate the erosion of polyimide, and the synergistic effect of vacuum ultraviolet irradiation and high-energy electromagnetic irradiation will accelerate the embrittlement of flexible polyimide, seriously affecting the normal on-orbit operation state of spacecraft.

[0004] The space environmental tolerance of polyimide is poor. Currently, the commonly used polyimide protective coatings mainly include pure metals and oxides. However, due to the properties of the protective coating materials themselves and the preparation methods, there are risks such as low bonding strength between the coating and the polyimide substrate, which is prone to cracking and peeling, and local clusters appear in the coating during the preparation process, resulting in uneven performance distribution. These problems will seriously affect the overall protective effect of the coating. Therefore, it is urgent to improve the space environmental tolerance of space application organic polymers such as polyimide to extend the normal on-orbit operation life of spacecraft. Summary of the Invention

[0005] In order to solve the problem of poor space environmental tolerance of existing polyimide films, the present invention proposes a method for preparing an amorphous alloy protective film on the surface of polyimide by using a magnetron co-sputtering process.

[0006] The method for preparing an amorphous alloy protective film on the surface of polyimide by using a magnetron co-sputtering process according to the present invention is carried out according to the following steps:

[0007] I. Treatment of the polyimide film substrate: Use an ultrasonic cleaner to clean the polyimide film in acetone, methanol, and deionized water for 14 - 16 min respectively, and then dry it in a vacuum drying oven at 78 - 82 °C for 4 - 6 h to obtain the treated polyimide film substrate;

[0008] II. Place the treated polyimide film substrate in a magnetron sputtering vacuum chamber, evacuate to 10 -3 Pa, set the sputtering power to 29 - 31 W, and perform ion pre-sputtering for 9 - 11 min; Ion pre-sputtering can effectively remove the organic substances and other contaminants attached to the surface of the polyimide film substrate, thereby improving the purity and quality of the film; In addition, high-energy ion pre-sputtering can effectively change the substrate structure and micro-topography of the substrate surface, provide a surface more suitable for the growth of amorphous films, and can greatly improve the interfacial bonding between the amorphous alloy and the polyimide film;

[0009] III. Place the polyimide film substrate after ion pre-sputtering in a magnetron sputtering vacuum chamber, evacuate to 10 - 3 Pa, and perform magnetron sputtering of the amorphous alloy protective film to form an amorphous alloy protective film on the surface of the polyimide film substrate;

[0010] The process of magnetron sputtering of the amorphous alloy protective film is as follows:

[0011] ①. Adjust the target-substrate distance to 9.5 - 10.5 cm, adjust the DC power supply bias voltage to 69 - 71 V, adjust the magnetron sputtering power to 49 - 51 W, and adjust the argon gas flow rate. After the target material starts to glow stably, adjust the system pressure to 0.79 - 0.81 Pa;

[0012] ②. Set a baffle between the target material and the polyimide film substrate, then perform pre-sputtering for 14 - 16 min, then remove the baffle, control the polyimide film substrate to rotate uniformly, and control the temperature of the polyimide film substrate not to exceed 60 °C, and perform magnetron sputtering of the amorphous alloy protective film; Pre-sputtering on the baffle first can reduce the influence of impurities on the surface of the target material on the film quality;

[0013] The target material includes an alloy target material and a single-element Ni target material.

[0014] The principle and beneficial effects of the present invention are:

[0015] Amorphous alloys are a type of metastable alloys prepared through a non-equilibrium solidification process. The internal atomic arrangement shows a long-range disorder and short-range order structure, and there are no crystal defects inside. This special structure endows them with extraordinary excellent mechanical, physical, and chemical properties. By using advanced magnetron sputtering technology to prepare high-quality amorphous alloy thin films, the size constraint of amorphous alloys can be overcome to a great extent, and large-area amorphous alloy thin films can be obtained. The present invention combines the process advantages of magnetron sputtering deposition technology for the growth of amorphous alloy thin films, deposits and prepares aluminum-based amorphous alloy / polyimide-based hybrid thin films, and enhances the interfacial bonding strength by adjusting the deposition parameters, enabling them to have excellent space environment tolerance capabilities. Under the same atomic oxygen exposure conditions, the atomic oxygen erosion rate of the polyimide thin film with an amorphous alloy protective thin film prepared by the method of the present invention has decreased by two orders of magnitude compared with the original polyimide thin film, and there is no obvious surface morphology change.

[0016] The method of the present invention can form a uniform and dense aluminum-based amorphous alloy thin film on the surface of the polyimide thin film. It can be obtained through X-ray diffraction that the surface alloy thin film presents a completely amorphous structure; it is observed through a microscope that the surface roughness of the deposited aluminum-based amorphous alloy thin film is small; by observing the cross-section of the aluminum-based amorphous alloy / polyimide hybrid thin film through a scanning electron microscope, it can be seen that the aluminum-based amorphous alloy and the polyimide thin film substrate are tightly connected together.

[0017] The present invention solves the application defects of the existing polyimide surface protective thin film preparation process, such as complex process, uneven coating preparation, low interfacial bonding strength, and easy cracking and peeling, and can be used for space protection.

[0018] In order to deposit and prepare aluminum-based amorphous alloy thin film materials on the polyimide thin film substrate, the present invention adopts an ultrasonic cleaning, ion sputtering pretreatment-assisted magnetron sputtering process, which is an advanced deposition process for preparing alloy thin films. At present, there is no relevant report on depositing and preparing amorphous alloy thin films on a polyimide thin film substrate for space protection. Description of the Drawings

[0019] Figure 1 XED diagram of the polyimide thin film with an amorphous alloy protective thin film obtained in Example 1;

[0020] Figure 2 Surface atomic force microscope morphology diagram of the polyimide thin film with an amorphous alloy protective thin film obtained in Example 1;

[0021] Figure 3 Cross-section SEM diagram of the polyimide thin film with an amorphous alloy protective thin film obtained in Example 1. Detailed Embodiments

[0022] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination between the specific embodiments.

[0023] Specific Embodiment 1: The method for preparing an amorphous alloy protective film on the surface of a polyimide by using a magnetron sputtering process is carried out according to the following steps:

[0024] I. Treatment of the polyimide film substrate: The polyimide film is cleaned in acetone, methanol, and deionized water for 14 - 16 min respectively by using an ultrasonic cleaner, and then dried in a vacuum drying oven at 78 - 82 °C for 4 - 6 h to obtain the treated polyimide film substrate;

[0025] II. Place the treated polyimide film substrate into the magnetron sputtering vacuum chamber, evacuate to 10 -3 Pa, set the sputtering power to 29 - 31 W, and perform ion pre - sputtering for 9 - 11 min;

[0026] III. Place the polyimide film substrate after ion pre - sputtering into the magnetron sputtering vacuum chamber, evacuate to 10 - 3 Pa, and perform magnetron sputtering of the amorphous alloy protective film to form an amorphous alloy protective film on the surface of the polyimide film substrate;

[0027] The process of magnetron sputtering of the amorphous alloy protective film is as follows:

[0028] ①. Adjust the target - substrate distance to 9.5 - 10.5 cm, adjust the DC power supply bias voltage to 69 - 71 V, adjust the magnetron sputtering power to 49 - 51 W, and adjust the argon gas flow rate. After the target material starts to glow stably, adjust the system pressure to 0.79 - 0.81 Pa;

[0029] ②. Set baffles between the target material and the polyimide film substrate, then perform pre - sputtering for 14 - 16 min, then remove the baffles, control the polyimide film substrate to rotate uniformly, and control the temperature of the polyimide film substrate not to exceed 60 °C, and perform magnetron sputtering of the amorphous alloy protective film;

[0030] The target materials in step III② include an alloy target material and a single - element Ni target material.

[0031] Amorphous alloys are a type of metastable alloys prepared through non-equilibrium solidification processes. The internal atomic arrangement exhibits a long-range disorder and short-range order structure, and there are no crystal defects inside. This special structure endows them with extraordinary excellent mechanical, physical, and chemical properties. By using advanced magnetron sputtering technology to prepare high-quality amorphous alloy thin films, the size constraint of amorphous alloys can be overcome to a great extent, and large-area amorphous alloy thin films can be obtained. This embodiment combines the process advantages of magnetron sputtering deposition technology for the growth of amorphous alloy thin films, deposits and prepares aluminum-based amorphous alloy / polyimide-based hybrid thin films, and enhances the interfacial bonding strength by adjusting the deposition parameters, enabling them to have excellent space environment tolerance capabilities. Under the same atomic oxygen exposure conditions, the atomic oxygen erosion rate of the polyimide thin film with an amorphous alloy protective thin film prepared by the method of this embodiment is reduced by two orders of magnitude compared with the original polyimide thin film, and there is no obvious morphological change on the surface.

[0032] The method of this embodiment can form a uniform and dense aluminum-based amorphous alloy thin film on the surface of the polyimide thin film. It can be obtained through X-ray diffraction that the surface alloy thin film presents a completely amorphous structure; it is observed through a microscope that the surface roughness of the deposited aluminum-based amorphous alloy thin film is small; by observing the cross-section of the aluminum-based amorphous alloy / polyimide hybrid thin film through a scanning electron microscope, it can be seen that the aluminum-based amorphous alloy and the polyimide thin film substrate are tightly connected together.

[0033] This embodiment solves the application defects of the existing polyimide surface protective thin film preparation process, such as complex process, uneven coating preparation, low interfacial bonding strength, and easy cracking and erosion, and can be used for space protection.

[0034] In order to deposit and prepare aluminum-based amorphous alloy thin film materials on the polyimide thin film substrate in this embodiment, an ultrasonic cleaning, ion sputtering pretreatment-assisted magnetron sputtering process is adopted, which is an advanced deposition process for preparing alloy thin films. At present, there are no relevant reports on using this technology to deposit and prepare amorphous alloy thin films with polyimide thin films as the substrate for space protection.

[0035] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the thickness of the polyimide thin film in Step 1 is 22.5 - 27.5 μm, and the monomer molecular formula is C 22 H 10 O5N2.

[0036] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that: in Step 2, the treated polyimide thin film substrate is placed in the magnetron sputtering vacuum chamber, evacuated to 10 -3 Pa, the sputtering power is set to 30 W, and ion pre-sputtering is carried out for 10 min.

[0037] Specific Embodiment 4: The difference between this embodiment and one of Embodiments 1 to 3 is that: the alloy target in step ③② is composed of 89-91% Al and 9-11% Ce by atomic percentage.

[0038] Specific Embodiment 5: The difference between this embodiment and one of Embodiments 1 to 4 is that: the alloy target in step ③② is composed of 90% Al and 10% Ce by atomic percentage.

[0039] Specific Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that: the alloy target in step ③② is cylindrical, with a diameter of 59.99-60.01 mm and a height of 2.99-3.01 mm.

[0040] Specific Embodiment 7: The difference between this embodiment and one of Embodiments 1 to 6 is that: the purity of the elemental Ni target in step ③② is 99.9%, with a diameter of 59.99-60.01 mm and a height of 1.99-2.01 mm.

[0041] Specific Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is that: the amorphous alloy protective film in step ③② is composed of 84-86% Al, 7.9-8.1% Ni and the balance Ce by atomic percentage.

[0042] Specific Embodiment 9: The difference between this embodiment and one of Embodiments 1 to 8 is that: the amorphous alloy protective film in step ③② is composed of 85% Al, 8% Ni and the balance Ce by atomic percentage.

[0043] Specific Embodiment 10: The difference between this embodiment and one of Embodiments 1 to 9 is that: the thickness of the amorphous alloy protective film in step ③② is 300-500 nm.

[0044] Example 1:

[0045] The method for preparing an amorphous alloy protective film on the surface of polyimide by using the magnetron co-sputtering process of the present invention is carried out according to the following steps:

[0046] I. Treatment of the polyimide film substrate: The polyimide film is cleaned in acetone, methanol and deionized water for 15 min respectively by using an ultrasonic cleaner, and then dried in a vacuum drying oven at 80 °C for 5 h to obtain the treated polyimide film substrate;

[0047] The thickness of the polyimide film is 25 μm, and the monomer molecular formula is C 22 H 10 O5N2;

[0048] II. Place the processed polyimide film substrate in the magnetron sputtering vacuum chamber, evacuate to 10 -3 Pa, set the sputtering power to 30 W, and perform ion pre-sputtering for 10 min;

[0049] III. Place the polyimide film substrate after ion pre-sputtering in the magnetron sputtering vacuum chamber, evacuate to 10 - 3 Pa, and perform magnetron sputtering of the amorphous alloy protective film to form an amorphous alloy protective film on the surface of the polyimide film substrate;

[0050] The process of magnetron sputtering of the amorphous alloy protective film is as follows:

[0051] ①. Adjust the target-substrate distance to 10 cm, adjust the DC power supply bias voltage to 70 V, adjust the magnetron sputtering power to 50 W, and adjust the argon gas flow rate. After the target material starts to glow stably, adjust the system pressure to 0.8 Pa;

[0052] ②. Set a baffle between the target material and the polyimide film substrate, then perform pre-sputtering for 14 - 16 min, then remove the baffle, control the polyimide film substrate to rotate at a constant speed, and control the temperature of the polyimide film substrate not to exceed 60 °C, and perform magnetron sputtering deposition of the amorphous alloy protective film; Pre-sputtering on the baffle first can reduce the influence of impurities on the surface of the target material on the film quality;

[0053] The target material includes an alloy target material and a single-element Ni target material;

[0054] The alloy target material is composed of 90% Al and 10% Ce by atomic percentage;

[0055] The alloy target material is cylindrical, with a diameter of 60 mm and a height of 3 mm;

[0056] The purity of the single-element Ni target material is 99.9%, with a diameter of 60 mm and a height of 2 mm;

[0057] The amorphous alloy protective film is composed of 85% Al, 8% Ni, and the balance Ce by atomic percentage;

[0058] The thickness of the amorphous alloy protective film is 400 nm.

[0059] Figure 1 is the XED diagram of the polyimide film with an amorphous alloy protective film obtained in Example 1; Figure 2 is the surface atomic force microscope morphology diagram of the polyimide film with an amorphous alloy protective film obtained in Example 1; Figure 3 is the cross-sectional SEM diagram of the polyimide film with an amorphous alloy protective film obtained in Example 1. From Figures 1 to 3It can be seen that the alloy thin film deposited on the polyimide surface in Example 1 has a completely amorphous structure, and the surface of the aluminum-based amorphous alloy thin film is smooth, dense and has a low surface roughness. The aluminum-based amorphous alloy thin film forms a good interfacial bond with the polyimide film substrate without obvious pores. The atomic oxygen exposure conditions in this example are as follows: Atomic oxygen is generated by exciting oxygen molecules with a high-frequency laser source, with its own energy of 4 - 5 eV and a beam current density of 5×10 14～16 atoms / cm 2 ·s. The amorphous alloy / polyimide thin film is fixed in the atomic oxygen exposure environment, and the atomic oxygen fluences are 1×10 20 , 5×10 20 , 1×10 21 , 5×10 21 , 1×10 22 , 5×10 22 atoms / cm 2 ; The atomic oxygen erosion rate (expressed by the mass loss per unit area) of the polyimide film with the amorphous alloy protective film in this example is: 0.01 - 0.03 mg / cm 2 ; while the atomic oxygen erosion rate (expressed by the mass loss per unit area) of the original polyimide film is: 1.5 - 2 mg / cm 2 .

Claims

1. A method for preparing an amorphous alloy protective film on the surface of polyimide by using a magnetron co-sputtering process, characterized in that: A method for preparing an amorphous alloy protective film on the surface of a polyimide by a magnetron co-sputtering process is carried out according to the following steps: I. Treatment of the polyimide film substrate: The polyimide film is cleaned in acetone, methanol and deionized water for 15 min respectively by an ultrasonic cleaner, and then dried in a vacuum drying oven at 80 °C for 5 h to obtain the treated polyimide film substrate; The thickness of the polyimide film is 25 μm, and the monomer molecular formula is C 22 H 10 O5N2; II. Place the processed polyimide film substrate in a magnetron sputtering vacuum chamber, evacuate the chamber to 10 -3 Pa, set the sputtering power to 30 W, and perform ion pre-sputtering for 10 min; III. Place the polyimide film substrate after ion pre-sputtering in a magnetron sputtering vacuum chamber, evacuate to 10 -3 Pa, perform magnetron sputtering of the amorphous alloy protective film, and form an amorphous alloy protective film on the surface of the polyimide film substrate for space protection; The magnetron sputtering process of the amorphous alloy protective film is as follows: ①. Adjust the target-substrate distance to 10 cm, adjust the DC power supply bias voltage to 70 V, adjust the magnetron sputtering power to 50 W, and adjust the argon gas flow rate. After the target material starts to glow stably, adjust the system pressure to 0.8 Pa; ②. Set a baffle between the target material and the polyimide film substrate, then perform pre-sputtering for 14-16 min, then remove the baffle, control the polyimide film substrate to rotate uniformly, and control the temperature of the polyimide film substrate not to exceed 60 °C, and carry out magnetron sputtering deposition of the amorphous alloy protective film; The target material includes an alloy target material and a single-element Ni target material; The alloy target material is composed of 90% Al and 10% Ce by atomic percentage; The alloy target material is cylindrical, with a diameter of 60 mm and a height of 3 mm; The purity of the single-element Ni target material is 99.9%, with a diameter of 60 mm and a height of 2 mm; The amorphous alloy protective film is composed of 85% Al, 8% Ni and the balance Ce by atomic percentage; The thickness of the amorphous alloy protective film is 400 nm.

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