Multilayer composite film and preparation method thereof

Abstract

The multi-layer composite film comprises a transition layer which is deposited and fixed on a substrate, and an aluminum oxide film and a nickel-based film which are alternately deposited based on the transition layer, the adjacent aluminum oxide film and the nickel-based film form a processing cycle; the single-layer thickness of the aluminum oxide film is 0.2 to 0.8 [mu] m; the thickness of a single layer of the nickel-based thin film is 1.2 to 2.0 microns; and the thickness ratio of the aluminum oxide film to the nickel-based film is 1: 2-1: 10. The pure aluminum film and the nickel-based film are alternately deposited on the transition layer to form a functional multilayer structure, so that the problem of low sputtering rate of the aluminum oxide film is solved, columnar growth of the nickel-based film is effectively inhibited, defects and cracks are reduced, and the density and uniformity of the film are improved.

Description

Technical Field

[0001] The invention relates to the field of films, and in particular to a multi-layer composite film and a preparation method thereof. Background Art

[0002] Nickel-based film is a thin film material with excellent physical and chemical properties. It has good electrical conductivity, magnetism, high hardness, excellent wear resistance, and excellent anti-oxidation and corrosion resistance, which enables it to maintain stable working performance in harsh environments such as high temperature and high pressure. The tribological properties of nickel-based film are related to the surface chemistry and physical state of the friction contact point. Under appropriate process conditions, nickel-based film can show a very low friction coefficient in the atmosphere, oil lubrication and high temperature environment. It is a nickel-based film with great potential for service in more harsh environments. At present, the research on nickel-based film is still at the stage of exploring the preparation process and related properties of nickel-based film. There are few reports on the research on structural design, which greatly limits the further development and application of nickel-based film. The traditional nickel-based / aluminum oxide multilayer film structure generally adopts an iso-periodic stacking method. Due to the low sputtering rate of pure aluminum target material, if the multilayer film is directly deposited, the overall deposition rate of the film will be slow, affecting the production efficiency. During the magnetron sputtering process, nickel-based films tend to grow in a columnar manner, which easily causes film defects and cracks. Although the multi-layer design can slow down the columnar growth to a certain extent, the improvement effect is not significant due to the thickness limitation of the aluminum oxide film.

[0003] Therefore, how to increase the deposition rate of nickel-based / aluminum oxide films, inhibit the columnar growth of nickel-based films, and optimize the friction properties of nickel-based multilayer films are urgent issues to be solved in the field of nickel-based films. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the prior art such as slow deposition speed of nickel-based / aluminum oxide film and columnar growth of nickel-based film.

[0005] The purpose of the present invention is to adopt the following technical solutions to achieve:

[0006] Provided is a multilayer composite film, comprising: a transition layer deposited and fixed on a substrate, and an aluminum oxide film and a nickel-based film alternately deposited based on the transition layer;

[0007] The adjacent aluminum oxide film and the nickel-based film are processed in one cycle;

[0008] The single layer thickness of the aluminum oxide film is 0.2 to 0.8 μm;

[0009] The single layer thickness of the nickel-based film is 1.2 to 2.0 μm;

[0010] The thickness ratio of the aluminum oxide film to the nickel-based film is 1:2 to 1:10.

[0011] Furthermore, the substrate is selected from at least one of aluminum alloy, nickel-based alloy, stainless steel and silicon wafer.

[0012] Furthermore, the thickness of the film is 4-8 μm.

[0013] The method for preparing the multilayer composite film as described in any one of the above items comprises the following steps:

[0014] The substrate is cleaned with a cleaning agent, dried and placed in a coating chamber;

[0015] The coating chamber is evacuated and then introduced with argon gas;

[0016] In the coating chamber, pre-sputtering is performed on an aluminum target and a nickel-based target in sequence;

[0017] sputtering the nickel-based target again to obtain a thicker nickel-based film, namely, the transition layer;

[0018] Introducing oxygen into the coating chamber and controlling its flow rate to sputter the aluminum target, and controlling the sputtering time according to the desired thickness of the aluminum oxide film;

[0019] The nickel-based target is sputtered, and the sputtering time is controlled according to the required thickness of the nickel-based film.

[0020] The composite film is obtained by sputtering deposition according to a preset period and a thickness ratio of the aluminum oxide film to the nickel-based film.

[0021] Furthermore, the pressure of the coating chamber after evacuation is 2×10 -4 ~4×10 -4 Pa.

[0022] Furthermore, the washing agent is selected from at least one of acetone, ethanol and water.

[0023] Furthermore, the washing time is 20 to 30 minutes.

[0024] Furthermore, the drying time is 1 to 1.5 hours.

[0025] Furthermore, the drying temperature is 40-60°C.

[0026] Furthermore, the target-substrate distance of the aluminum target during sputtering is 95 to 200 mm.

[0027] Furthermore, the power of sputtering the aluminum target is 100-300W.

[0028] Furthermore, the gas pressure for sputtering the aluminum target is 0.5-2Pa.

[0029] Furthermore, the target-substrate distance of the nickel-based target during sputtering is 95 to 200 mm.

[0030] Furthermore, the power of sputtering the nickel-based target is 100-400W.

[0031] Furthermore, the gas pressure for sputtering the nickel-based target is 0.5-2Pa.

[0032] Furthermore, the deposition temperature is 200-400°C.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a multilayer composite film, which comprises: a transition layer deposited and fixed on a substrate, and an aluminum oxide film and a nickel-based film alternately deposited based on the transition layer; the thickness of a single layer of the aluminum oxide is selected from 0.2 to 0.8 μm; the thickness of a single layer of the nickel-based film is selected from 1.2 to 2.0 μm; and the thickness ratio of the aluminum oxide film to the nickel-based film is 1:2 to 1:10, respectively.

[0035] The present invention adopts a transition layer, on which an aluminum oxide film and a nickel-based film are alternately deposited to form a functional multilayer structure. In the preparation of the multilayer composite film, a thicker nickel-based film is first deposited on the surface of a substrate (such as an aluminum alloy, a nickel-based alloy, etc.) as a transition layer. Columnar growth is formed due to the rapid growth of grains in the vertical direction in the early growth stage of the film. This structure easily leads to more defects and cracks inside the film. The thicker nickel-based transition layer deposited in advance can promote the good combination between the subsequently deposited aluminum oxide film and the nickel-based film, while improving the compactness and uniformity of the entire multilayer structure, reducing defects, and thus improving the overall performance of the film. In addition, the transition layer can also improve the compatibility between the substrate and the functional layer, further improve the comprehensive performance of the composite film, not only solve the problem of low sputtering rate of the aluminum oxide film, but also effectively inhibit the columnar growth of the nickel-based film, reduce the occurrence of defects and cracks, and improve the density and uniformity of the film.

[0036] After solving the columnar growth problem of nickel-based films, the friction coefficient of the multilayer composite film is reduced, which is mainly attributed to the following aspects:

[0037] 1. Improved surface smoothness: Columnar growth will cause the film surface to be rough and increase friction. By depositing a thicker nickel-based film and reducing the formation of columnar structures, the film surface can be made smoother, thereby reducing the friction coefficient.

[0038] 2. Improved density and uniformity: Inhibiting the columnar growth of nickel-based films helps improve the density and uniformity of the film and reduce defects on the surface and interface. Inhibiting columnar growth is one of the reasons for increased friction because it increases the contact area and friction resistance. A denser and more uniform film surface can better resist external mechanical stress, reduce wear, and thus reduce the friction coefficient.

[0039] 3. Enhanced interface bonding strength: The improved film has a stronger bonding strength between the structural layers and between the film and the substrate. Stronger interface bonding can prevent relative sliding between the layers during friction and reduce additional friction losses.

[0040] In summary, by solving the problem of columnar growth of nickel-based films, the surface quality and mechanical properties of multilayer composite films can be significantly improved, thereby effectively reducing their friction coefficient and improving wear resistance and service life.

[0041] Through structural design optimization, the multilayer composite film has excellent mechanical properties such as high hardness, low stress and strong toughness. This enables it to maintain stable working performance in harsh environments such as high temperature and high pressure, and has good wear and impact resistance.

[0042] The multilayer composite film has excellent tribological properties and can exhibit a very low friction coefficient in atmospheric, oil-lubricated and high-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the structure of the multi-layer composite film of the present invention;

[0044] Figure 2 This is a schematic diagram of the SEM microstructure of the multilayer composite film of the present invention;

[0045] Figure 3 It is a logical framework diagram of the method for preparing a multilayer composite film of the present invention;

[0046] Figure 4 This is a comparison chart of deposition time and film thickness between Comparative Example 1 and Example 1 of the present invention;

[0047] Figure 5 This is a schematic diagram of the SEM microstructure of the multilayer composite film of Comparative Example 2 of the present invention;

[0048] Among them, 1-substrate; 2-transition layer; 3-aluminum oxide film; 4-nickel-based film. DETAILED DESCRIPTION

[0049] The technical solution provided by the present invention is described in detail below by way of specific embodiments:

[0050] like Figure 1-2As shown, a multi-layer composite film comprises:

[0051] Depositing a transition layer 2 fixed to a substrate 1, and an aluminum oxide film 3 and a nickel-based film 4 alternately deposited on the transition layer 2;

[0052] The adjacent aluminum oxide film 3 and nickel-based film 4 are one processing cycle;

[0053] The single layer thickness of the aluminum oxide film 3 is 0.2 to 0.8 μm;

[0054] The single layer thickness of the nickel-based film 4 is 1.2 to 2.0 μm;

[0055] The thickness ratio of the aluminum oxide film 3 to the nickel-based film 4 is 1:2 to 1:10.

[0056] The substrate 1 is selected from at least one of aluminum alloy, nickel-based alloy, stainless steel and silicon wafer.

[0057] The thickness of the film is selected from 4 to 8 μm.

[0058] Preferably, a thicker nickel-based film is used as the transition layer 2, on which a pure aluminum film and a nickel-based film 4 are alternately deposited to form a functional multilayer structure, which helps to improve the overall stability of the material. The alternately deposited layered structure can improve the adhesion between the film and the substrate, reduce the shedding and cracking of the film, and thus improve the reliability and durability of the film.

[0059] The above structural design solves the problem of low sputtering rate of the aluminum oxide film 3 and also effectively suppresses the columnar growth of the nickel-based film 4, reduces the occurrence of defects and cracks, and improves the density and uniformity of the film.

[0060] Through structural design optimization, the multilayer composite film has excellent mechanical properties such as high hardness, low stress and strong toughness. This enables it to maintain stable working performance in harsh environments such as high temperature and high pressure, and has good wear and impact resistance.

[0061] The multilayer composite film has excellent tribological properties and can exhibit a very low friction coefficient in atmospheric, oil-lubricated and high-temperature environments.

[0062] like Figure 3 As shown, the present invention also provides a method for preparing a multilayer composite film, comprising the following steps:

[0063] The substrate 1 is cleaned with a cleaning agent, dried and mounted on a sample tray;

[0064] The coating chamber was evacuated and then introduced with argon gas;

[0065] In the coating chamber, the aluminum target and the nickel-based target are pre-sputtered in sequence;

[0066] The nickel-based target is sputtered again to obtain a thicker nickel-based film, i.e., a transition layer 2;

[0067] Introduce oxygen into the coating chamber and control its flow rate to sputter the aluminum target, and control the sputtering time according to the required thickness of the aluminum oxide film 3;

[0068] The nickel-based target is sputtered, and the sputtering time is controlled according to the required thickness of the nickel-based film 4 .

[0069] The composite film is obtained by sputtering deposition according to a preset period and a thickness ratio of the aluminum oxide film 3 and the nickel-based film 4 .

[0070] The pressure of the coating chamber after vacuuming is 2×10 -4 ~4×10 -4 Pa.

[0071] Furthermore, the washing agent is at least one of acetone, ethanol and water.

[0072] Furthermore, the washing time is 20 to 30 minutes, and more preferably 25 to 28 minutes.

[0073] Furthermore, the drying time is 60 to 90 minutes, and more preferably 70 to 80 minutes.

[0074] Furthermore, the drying temperature is 40-60°C, and more preferably 50-55°C.

[0075] Furthermore, the target-substrate distance of the sputtering aluminum target is 95 to 200 mm, and more preferably 130 mm.

[0076] Furthermore, the power of sputtering the aluminum target is 100-300W, and more preferably 200W.

[0077] Furthermore, the gas pressure of the sputtering aluminum target is 0.5-2Pa, and more preferably 1Pa.

[0078] Furthermore, the target-substrate distance of the sputtering nickel-based target is 95 to 200 mm, and more preferably 125 mm.

[0079] Furthermore, the sputtering power of the majority of nickel-based targets is 100-400W, and more preferably 250W.

[0080] Furthermore, the gas pressure of the sputtering nickel-based target is 0.5-2Pa, and more preferably 1Pa.

[0081] Furthermore, the deposition temperature is 200-400°C, and more preferably 300°C.

[0082] Example 1

[0083] A multi-layer composite film, comprising: a transition layer 2 deposited and fixed on a substrate 1, and an aluminum oxide film 3 and a nickel-based film 4 alternately deposited on the transition layer 2;

[0084] The adjacent aluminum oxide film 3 and nickel-based film 4 are one processing cycle;

[0085] The film was set for three cycles;

[0086] The single layer thickness of the aluminum oxide film 3 is 0.6; 0.3; 0.2;

[0087] The single layer thickness of the nickel-based film 4 is 1.2; 1.2; 1.6;

[0088] The thickness ratios of the aluminum oxide film 3 and the nickel-based film 4 are 1:2; 1:4; 1:8.

[0089] The method for preparing the multilayer composite film comprises the following steps:

[0090] First, an aluminum alloy is selected as the substrate 1 and cleaned to remove surface dirt and impurities to ensure the adhesion and quality of the film. Next, the cleaned substrate 1 material is mounted on a sample tray of a magnetron sputtering device to prepare for subsequent sputtering deposition.

[0091] The washing reagent is preferably acetone, ethanol and water; the specific steps of washing are: washing the substrate 1 with acetone, ethanol and water in sequence; each washing time is 25 minutes; the drying temperature is 50° C.; the drying time is 75 minutes.

[0092] In the magnetron sputtering equipment, the sputtering target A is set to be a pure aluminum target, and the sputtering target B is set to be a nickel-based target. The pure aluminum target and the nickel-based target correspond to different sputtering sources, respectively, and are used to deposit the aluminum oxide film 3 and the nickel-based film 4. By adjusting the distance between the substrate 1 and the target material, the deposition rate and uniformity of the film can be controlled. Next, the vacuum operation is performed to draw the vacuum degree of the coating chamber to 3×10 -4 Pa to remove impurities and moisture in the air and create a clean environment for film deposition.

[0093] Then, argon gas is introduced and the gas flow rate and the pressure in the coating chamber are adjusted to control the sputtering process and the growth rate of the film.

[0094] Set the power of sputtering target A and target B. After the glow is stable, set the program to make the substrate 1 stay directly above the sputtering target A and target B for 35 seconds respectively for pre-sputtering to remove oxides and contaminants on the surface of the target material to ensure the stability of the sputtering process and the purity of the film. Then, sputter target B first, control the sputtering time of target B, and obtain a thicker film.

[0095] Then, target A and target B are sputtered in sequence. When target A is sputtered, oxygen is introduced into the coating chamber through an independent flow controller, and oxygen is introduced into the vacuum chamber at a specific flow rate. The flow rate of oxygen is controlled between 5sccm and 50sccm to control the oxygen content during the sputtering process. The target-substrate distance of target A is 130mm; the power of target A is preferably 200W; and the gas pressure of target A is preferably 1Pa.

[0096] Then, the B target is sputtered. The B target is preferably a nickel-based target. The target-substrate distance of the B target is preferably 125 mm. The power of the B target is preferably 250 W. The gas pressure of the B target is preferably 1 Pa.

[0097] Sputtering deposition is performed according to three pre-set deposition cycles, and the aluminum oxide film 3 and the nickel-based film 4 are deposited alternately in each cycle. By controlling the time of plating target A and target B, the target-substrate distance, power, gas pressure and temperature, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be precisely controlled, thereby obtaining structures with different modulation thickness ratios X.

[0098] The deposition temperature is selected as 300°C. By controlling the sputtering time in each cycle, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be accurately controlled. Adjacent single layers of aluminum oxide and single layers of nickel-based are one cycle, and the thickness ratio X of aluminum oxide and nickel-based is 1:2, 1:4, and 1:8, respectively.

[0099] After the deposition is completed, the sputtering gas is stopped and the vacuum degree in the coating chamber is kept the same as that during deposition to avoid contamination of the film surface; then, the deposited sample is taken out as the coating chamber cools to room temperature, namely, a nickel-based high-temperature nano multilayer film.

[0100] The prepared film samples were placed in SEM for observation and the following results were obtained: Figure 2 Microscopic imaging shown.

[0101] Embodiment 2-6

[0102] The raw material ratios of the multilayer composite films provided in Examples 2-6 are shown in Table 1:

[0103] Table 1 Summary of raw material ratios in the examples

[0104]

[0105] Table 2 Summary of preparation conditions of examples

[0106]

[0107]

[0108] When the thickness ratio X is 1:2, the sputtering time of the aluminum target is 60 min, and the sputtering time of the nickel-based target is 100 min.

[0109] When the thickness ratio X is 1:3, the sputtering time of the aluminum target is 40 min, and the sputtering time of the nickel-based target is 65 min.

[0110] When the thickness ratio X is 1:4, the sputtering time of the aluminum target is 40 min, and the sputtering time of the nickel-based target is 120 min.

[0111] When the thickness ratio X is 1:5, the sputtering time of the aluminum target is 35 min, and the sputtering time of the nickel-based target is 70 min.

[0112] When the thickness ratio X is 1:6, the sputtering time of the aluminum target is 25 min, and the sputtering time of the nickel-based target is 80 min.

[0113] When the thickness ratio X is 1:7, the sputtering time of the aluminum target is 20 min, and the sputtering time of the nickel-based target is 85 min.

[0114] When the thickness ratio X is 1:8, the sputtering time of the aluminum target is 30 min, and the sputtering time of the nickel-based target is 130 min.

[0115] When the thickness ratio X is 1:9, the sputtering time of the aluminum target is 10 min, and the sputtering time of the nickel-based target is 95 min.

[0116] When the thickness ratio X is 1:10, the sputtering time of the aluminum target is 5 min, and the sputtering time of the nickel-based target is 100 min.

[0117] Comparative Example 1

[0118] A multi-layer composite film, comprising: a transition layer 2 deposited and fixed on a substrate 1, and an aluminum oxide film 3 and a nickel-based film 4 alternately deposited on the transition layer 2;

[0119] The adjacent aluminum oxide film 3 and nickel-based film 4 are one processing cycle;

[0120] The film was set for three cycles;

[0121] The single layer thicknesses of the aluminum oxide film 3 are 0.6; 0.6; 0.6;

[0122] The single layer thickness of the nickel-based film 4 is 1.2; 1.2; 1.2;

[0123] The thickness ratio of the aluminum oxide film 3 to the nickel-based film 4 is 1:2; 1:2; 1:2.

[0124] The method for preparing the multilayer composite film comprises the following steps:

[0125] First, a nickel-based alloy is selected as the substrate 1, and it is cleaned to remove surface dirt and impurities to ensure the adhesion and quality of the film. Then, the cleaned substrate 1 material is mounted on a sample tray of a magnetron sputtering device to prepare for subsequent sputtering deposition.

[0126] The washing reagents are preferably acetone, ethanol and water; the specific steps of washing are: washing the substrate 1 with acetone, ethanol and water in turn; the time for each washing is preferably 25 minutes; the drying temperature is preferably 50°C; and the drying time is preferably 75 minutes.

[0127] In the magnetron sputtering equipment, the sputtering target A is set to be a pure aluminum target, and the sputtering target B is set to be a nickel-based target. The pure aluminum target and the nickel-based target correspond to different sputtering sources, respectively, and are used to deposit the aluminum oxide film 3 and the nickel-based film 4. By adjusting the distance between the substrate 1 and the target material, the deposition rate and uniformity of the film can be controlled. Next, the vacuum operation is performed to draw the vacuum degree of the coating chamber to 3×10 -4 Pa to remove impurities and moisture in the air and create a clean environment for film deposition.

[0128] Then, argon gas is introduced and the gas flow rate and the pressure in the coating chamber are adjusted to control the sputtering process and the growth rate of the film.

[0129] Set the power of sputtering target A and target B. After the glow is stable, set the program to make the substrate 1 stay directly above the sputtering target A and target B for 35 seconds respectively for pre-sputtering to remove oxides and contaminants on the surface of the target material to ensure the stability of the sputtering process and the purity of the film. Then, sputter target B first, control the sputtering time of target B, and obtain a thicker film.

[0130] Then, target A and target B are sputtered in sequence. When target A is sputtered, oxygen is introduced into the coating chamber through an independent flow controller, and oxygen is introduced into the vacuum chamber at a specific flow rate. The flow rate of oxygen is controlled between 5sccm and 50sccm to control the oxygen content during the sputtering process. The target-substrate distance of target A is preferably 130mm; the power of target A is preferably 200W; and the gas pressure of target A is preferably 1Pa.

[0131] Then, the B target is sputtered. The B target is preferably a nickel-based target. The target-substrate distance of the B target is preferably 125 mm. The power of the B target is preferably 250 W. The gas pressure of the B target is preferably 1 Pa.

[0132] Sputtering deposition is performed according to the pre-set three deposition cycles, and the aluminum oxide film 3 and the nickel-based film 4 are deposited alternately in each cycle. By controlling the time of plating target A and target B, the target-substrate distance, power, gas pressure and temperature, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be precisely controlled, thereby obtaining structures with different modulation thickness ratios X.

[0133] The deposition temperature is selected as 300°C. By controlling the sputtering time in each cycle, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be accurately controlled; a single layer of aluminum oxide and a single layer of nickel-based film is one cycle, and the thickness ratio X of aluminum oxide and nickel-based film is 1:2, 1:2, and 1:2 respectively.

[0134] After the deposition is completed, stop the sputtering gas and keep the vacuum degree in the coating chamber the same as that during deposition to avoid contamination of the film surface. Then, take out the deposited sample as the coating chamber cools to room temperature.

[0135] like Figure 4 As shown, when the deposition time is 10 min, the sputtering thickness of Comparative Example 1 is 150 nm, and the sputtering thickness of Example 1 is 330 nm; when the deposition time is 20 min, the sputtering thickness of Comparative Example 1 is 340 nm, and the sputtering thickness of Example 1 is 480 nm; when the deposition time is 30 min, the sputtering thickness of Comparative Example 1 is 450 nm, and the sputtering thickness of Example 1 is 650 nm; when the deposition time is 40 min, the sputtering thickness of Comparative Example 1 is 540 nm, and the sputtering thickness of Example 1 is 780 nm; when the deposition time is 50 min, the sputtering thickness of Comparative Example 1 is 630 nm, and the sputtering thickness of Example 1 is 940 nm; when the deposition time is 60 min, the sputtering thickness of Comparative Example 1 is 710 nm, and the sputtering thickness of Example 1 is 1120 nm.

[0136] The present application changes the deposited film thickness ratio so that the thickness of the deposited film is large within the same deposition time, and thus the present application solves the problem of low sputtering rate of aluminum oxide film.

[0137] Comparative Example 2

[0138] A multi-layer composite film, comprising: a transition layer 2 deposited and fixed on a substrate 1, and an aluminum oxide film 3 and a nickel-based film 4 alternately deposited on the transition layer 2;

[0139] The adjacent aluminum oxide film 3 and nickel-based film 4 are one processing cycle;

[0140] The film was set for three cycles;

[0141] The single layer thickness of the aluminum oxide film 3 is 0.6; 0.3; 0.2;

[0142] The single layer thickness of the nickel-based film 4 is 1.2; 1.2; 1.6;

[0143] The thickness ratios of the aluminum oxide film 3 and the nickel-based film 4 are 1:2; 1:4; 1:8.

[0144] The method for preparing the multilayer composite film comprises the following steps:

[0145] First, stainless steel is selected as the substrate 1 and cleaned to remove surface dirt and impurities to ensure the adhesion and quality of the film. Then, the cleaned substrate 1 material is mounted on a sample tray of a magnetron sputtering device to prepare for subsequent sputtering deposition.

[0146] The washing reagents are preferably acetone, ethanol and water; the specific steps of washing are: washing the substrate 1 with acetone, ethanol and water in turn; the time for each washing is preferably 25 minutes; the drying temperature is preferably 50°C; and the drying time is preferably 75 minutes.

[0147] In the magnetron sputtering equipment, the sputtering target A is set to be a pure aluminum target, and the sputtering target B is set to be a nickel-based target. The pure aluminum target and the nickel-based target correspond to different sputtering sources, respectively, and are used to deposit the aluminum oxide film 3 and the nickel-based film 4. By adjusting the distance between the substrate 1 and the target material, the deposition rate and uniformity of the film can be controlled. Next, the vacuum operation is performed to draw the vacuum degree of the coating chamber to 3×10 -4 Pa to remove impurities and moisture in the air and create a clean environment for film deposition.

[0148] Then, argon gas is introduced and the gas flow rate and the pressure in the coating chamber are adjusted to control the sputtering process and the growth rate of the film.

[0149] Set the power of sputtering target A and sputtering target B. After the glow is stable, set the program to make the substrate 1 stay directly above the sputtering target A and B for 35 seconds respectively for pre-sputtering to remove oxides and contaminants on the target surface to ensure the stability of the sputtering process and the purity of the film.

[0150] Sputtering targets A and B in sequence, when sputtering target A, oxygen is introduced into the coating chamber through an independent flow controller, and oxygen is introduced into the vacuum chamber at a specific flow rate, and the flow rate of oxygen is controlled between 5sccm and 50sccm to control the oxygen content during the sputtering process. The target-substrate distance of sputtering target A is preferably 130mm; the power of sputtering target A is preferably 200W; the gas pressure of sputtering target A is preferably 1Pa.

[0151] Then, the B target is sputtered. The B target is preferably a nickel-based target. The target-substrate distance of the B target is preferably 125 mm. The power of the B target is preferably 250 W. The gas pressure of the B target is preferably 1 Pa.

[0152] Sputtering deposition is performed according to the pre-set three deposition cycles, and the aluminum oxide film 3 and the nickel-based film 4 are deposited alternately in each cycle. By controlling the time of plating target A and target B, the target-substrate distance, power, gas pressure and temperature, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be precisely controlled, thereby obtaining structures with different modulation thickness ratios X.

[0153] The deposition temperature is selected as 300°C. By controlling the sputtering time in each cycle, the thickness of the aluminum oxide film 3 and the nickel-based film 4 in each cycle can be accurately controlled; a single layer of aluminum oxide and a single layer of nickel-based film is one cycle, and the thickness ratio X of aluminum oxide and nickel-based film is 1:2, 1:4, and 1:8 respectively.

[0154] After the deposition is completed, the sputtering gas is stopped and the vacuum degree in the coating chamber is kept the same as that during deposition to avoid contamination of the film surface; then, the deposited sample is taken out as the coating chamber cools to room temperature, namely, a nickel-based high-temperature nano multilayer film.

[0155] The prepared samples were placed in SEM for observation. Figure 5 Microscopic imaging shown.

[0156] Depend on Figure 2 and Figure 5 By comparison, it can be seen that Example 1 of the present application adds a thicker nickel-based film as a transition layer 2 on the substrate 1, and its film structure is clear, and there is no columnar growth of the nickel-based film 4, which effectively suppresses the problem of columnar growth of the nickel-based film 4; while Comparative Example 2 directly deposits the aluminum oxide film 3 and the nickel-based film 4 on the substrate 1, and the columnar growth of the nickel-based film 4 is more obvious.

[0157] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A multilayer composite film, characterized in that: include: Depositing a transition layer (2) fixed to a substrate (1), and an aluminum oxide film (3) and a nickel-based film (4) alternately deposited on the transition layer (2); The adjacent aluminum oxide film (3) and the nickel-based film (4) constitute one processing cycle; The single layer thickness of the aluminum oxide film (3) is 0.2 to 0.8 μm; The single layer thickness of the nickel-based film (4) is 1.2 to 2.0 μm; The thickness ratio of the aluminum oxide film (3) to the nickel-based film (4) is 1:2 to 1:

10.

2. A multilayer composite film according to claim 1, characterized in that: The substrate (1) is selected from at least one of aluminum alloy, nickel-based alloy, stainless steel and silicon wafer.

3. A multilayer composite film according to claim 1, characterized in that: The thickness of the film is 4-8 μm.

4. A method for preparing a multilayer composite film according to any one of claims 1 to 3, characterized in that: The following steps are involved: The substrate (1) is cleaned with a cleaning agent, dried and placed in a coating chamber; The coating chamber is evacuated and then introduced with argon gas; In the coating chamber, pre-sputtering is performed on an aluminum target and a nickel-based target in sequence; Re-sputtering the nickel-based target to obtain a thicker nickel-based film, namely the transition layer (2); Introducing oxygen into the coating chamber and controlling its flow rate to sputter the aluminum target, and controlling the sputtering time according to the desired thickness of the aluminum oxide film (3); Sputtering a nickel-based target, and controlling the sputtering time according to the required thickness of the nickel-based film (4); Sputtering deposition is performed according to a preset period and a thickness ratio of the aluminum oxide film (3) to the nickel-based film (4) to obtain a composite film.

5. The method for preparing a multilayer composite film according to claim 4, characterized in that: The pressure of the coating chamber after evacuation is selected from 2×10 -4 ~4×10 -4 Pa.

6. The method for preparing a multilayer composite film according to claim 4, characterized in that: The washing agent is selected from at least one of acetone, ethanol and water.

7. The method for preparing a multilayer composite film according to claim 4, characterized in that: The washing time is 20 to 30 minutes.

8. The method for preparing a multilayer composite film according to claim 4, characterized in that: The drying time is 1 to 1.5 hours.

9. The method for preparing a multilayer composite film according to claim 4, characterized in that: The drying temperature is 40-60°C.

10. The method for preparing a multilayer composite film according to claim 4, characterized in that: The target-substrate distance of the aluminum target during sputtering is 95-200 mm.

11. The method for preparing a multilayer composite film according to claim 4, characterized in that: The power of sputtering the aluminum target is 100-300W.

12. The method for preparing a multilayer composite film according to claim 4, characterized in that: The gas pressure for sputtering the aluminum target is 0.5-2Pa.

13. The method for preparing a multilayer composite film according to claim 4, characterized in that: The target-substrate distance of the nickel-based target during sputtering is 95 to 200 mm.

14. The method for preparing a multilayer composite film according to claim 4, characterized in that: The power of sputtering the nickel-based target is 100-400W.

15. The method for preparing a multi-layer composite film according to claim 4, characterized in that: The gas pressure for sputtering the nickel-based target is 0.5-2Pa.

16. The method for preparing a multilayer composite film according to claim 4, characterized in that: The deposition temperature is 200-400°C.

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