Strong-combination wide-temperature-range sunlight selective absorption multilayer composite coating and plating method thereof

Abstract

The invention discloses a strong-combination wide-temperature-range sunlight selective absorption multilayer composite coating which is arranged on a titanium alloy substrate and comprises a light absorption functional layer, an oxidation protection layer and an oxidation protection layer from bottom to top. The plating method comprises the following steps: 1, pretreating the substrate; 2, ion bombardment, cleaning and activation; 3, depositing a light absorption functional layer; 4, depositing an oxidation protection layer; 5, depositing a surface antireflection layer; sixthly, vacuum annealing treatment is conducted; the coating provided by the invention has high absorptivity in a visible light wave band, can keep structural stability and reliable performance in a wide temperature range of 30-600 DEG C, and is particularly suitable for the surface of a titanium alloy matrix.

Description

Technical Field

[0001] This invention relates to the field of functional coating materials technology, specifically to a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating and its coating method. Background Technology

[0002] Solar selective absorption coatings are functional coatings that exhibit high absorptivity in specific bands of the solar spectrum while displaying low emissivity in other bands. They are widely used in solar thermal conversion, aerospace thermal control systems, and military optoelectronic stealth applications. An ideal selective absorption coating should possess high absorptivity, low emissivity, excellent thermal stability, good mechanical properties, and high bonding strength with the substrate.

[0003] Currently, common light-absorbing coatings mainly include black chromium, black nickel, cermet, carbon-based materials, and noble metal nanostructure coatings. These coatings achieve spectral selectivity primarily through intrinsic absorption, interference effects, or surface microstructure design, but the following technical bottlenecks still exist: 1. Poor thermal stability: Most organic-based or certain metal oxide coatings undergo oxidation, decomposition or phase transformation at temperatures exceeding 300°C, resulting in a sharp decline in absorption performance; 2. Low bonding strength: The thermal expansion coefficients between the coating and the metal substrate (especially titanium alloys) do not match, which can easily lead to stress during thermal cycling and cause peeling. 3. Insufficient erosion resistance: Under high wind speed and high speed conditions (such as aircraft engine and gas turbine blades), the coating is easily eroded and peeled off by airflow; 4. Complex preparation process: Wet chemical methods such as sol-gel method and anodizing are difficult to achieve large-area, uniform and environmentally friendly industrial preparation.

[0004] Magnetron sputtering technology has become the mainstream technology for preparing high-performance functional coatings due to its advantages such as dense film formation, good adhesion, and precise controllable process parameters. High-power pulsed magnetron sputtering (HiPIMS) technology, in particular, can generate a sputtered particle stream with high ionization, which is beneficial for forming dense, uniform films with high adhesion strength. However, existing magnetron sputtering-prepared light-absorbing coatings still struggle to achieve both wide-temperature stability and high adhesion, especially on lightweight alloy substrates such as titanium alloys. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a strongly bonded, wide-temperature-range solar selective absorption multilayer composite coating and its coating method; the specific technical solution is as follows: A strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is disposed on a titanium alloy substrate and includes, from bottom to top, a light-absorbing functional layer, an oxidation protection layer, and an oxidation protection layer. The light-absorbing functional layer has a refractive index of 1.8~2.8 and a thickness of 0.5~5.0 μm. It is deposited using heterogeneous dual-target high-power pulsed magnetron sputtering technology to form a dense columnar crystal structure. The oxide protective layer has a refractive index of 1.63~1.67 and a thickness of 0.2~2.0 μm. It is deposited using synchronous pulsed bias high-power pulsed magnetron sputtering technology to form a dense columnar crystal structure. The oxide protective layer has a refractive index of 1.4~1.5 and a thickness of 0.5~2.0 μm. It is deposited using voltage feedback controlled mid-frequency pulse magnetron sputtering technology to form a dense columnar crystal structure.

[0006] The preferred embodiment of the strongly bonded, wide-temperature-range solar selective absorption multilayer composite coating is that the titanium alloy substrate is any one of TC4, TA11, TC17 or Ti60.

[0007] A method for depositing a strongly bonded, wide-temperature-range solar selective absorption multilayer composite coating includes the following steps: Step 1: Matrix pretreatment; The titanium alloy substrate is subjected to grinding, wet sandblasting roughening, and ultrasonic cleaning. Step 2: Ion bombardment cleaning and activation; In a vacuum environment, the substrate surface is cleaned by Ar⁺ ion bombardment to activate the surface; Step 3: Deposit a light-absorbing functional layer; A light-absorbing functional layer was deposited on the activated substrate surface using heterogeneous dual-target high-power pulsed magnetron sputtering technology. Step 4: Deposit an oxide protective layer; An oxide protective layer is deposited on the surface of the light-absorbing functional layer using synchronous pulsed bias high-power pulsed magnetron sputtering technology. Step 5: Deposit the surface antireflection layer; A surface antireflection layer is deposited on the surface of the oxide protective layer using medium-frequency pulsed reactive magnetron sputtering technology; Step Six: Vacuum Annealing; The deposited multilayer composite coating is subjected to vacuum annealing to crystallize it.

[0008] The preferred embodiment of the coating method for a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is as follows: in step two, the conditions for ion bombardment cleaning are: background vacuum degree ≤ 1.0 × 10⁻³ Pa, substrate heating temperature 350℃~400℃, Ar gas flow rate 100~200 sccm, working pressure 1.5~2.5 Pa; a DC pulse bias voltage is applied with a frequency of 150 kHz and a bias voltage of -600 V, and the cleaning time is 25 min.

[0009] The preferred embodiment of the coating method for a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is as follows: in step three, the deposition conditions of the light-absorbing functional layer are: using a heterogeneous dual-target HiPIMS system, with the target material being heterogeneous pure metals Cr and Cu. The process gases were Ar and O2, each with a flow rate of 40 sccm; the working gas pressure was 0.5 Pa; the HiPIMS power supply parameters were: pulse width 50 μs, duty cycle 10%, target voltage 550 V; substrate bias voltage -100 V; and deposition time 120 min.

[0010] The preferred embodiment of the coating method for a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is as follows: in step four, the deposition conditions of the oxide protective layer are: using synchronous pulsed bias HiPIMS technology and co-sputtering with dual Al targets. The process gases were Ar 50 sccm and O2 10 sccm; the working pressure was 0.4 Pa; the HiPIMS parameters were: pulse width 35 μs, duty cycle 7%; substrate bias voltage -50 V; and deposition time 180 min.

[0011] The preferred embodiment of the coating method for a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is as follows: in step five, the deposition conditions of the surface antireflection layer are: using mid-frequency pulsed reactive magnetron sputtering (frequency 40kHz) and the target material is SiO2. The process gases were Ar 50 sccm and O2 10 sccm; the working pressure was 0.2~0.4 Pa; the sputtering voltage was 520~550 V; the substrate bias voltage was -50 V; and the deposition time was 180 min.

[0012] The preferred embodiment of the coating method for a strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is as follows: in step six, the conditions for vacuum annealing are: annealing atmosphere is high vacuum, pressure < 2 × 10⁻³ Pa; heating rate is 10℃ / min; annealing temperature is 800℃±10℃, holding time is 120 min; and furnace cooling is carried out to room temperature.

[0013] The preferred embodiment of the strongly bonded, wide-temperature-range solar selective absorption multilayer composite coating is that the composite coating can be used in aerospace, military optoelectronic equipment, or solar thermal conversion systems. Beneficial effects

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Strong interfacial bonding performance: Through the high ion bombardment effect and interfacial activation treatment of HiPIMS technology, the bonding force between the coating and the substrate and between layers is significantly enhanced, with an average tensile bonding strength of 19.31 MPa. 2. Wide temperature range thermal stability: The multi-layer composite structure and ceramic matrix material design enable the coating to work stably for a long time in the temperature range of −30℃ to 600℃, and can withstand high temperature of 800℃ for a short period of time; 3. High absorption rate and spectral selectivity: Through the design of the functional layer refractive index gradient and the optimization of the antireflection layer, the average absorption rate in the visible light band exceeds 80%; 4. Excellent erosion resistance and environmental durability: The dense columnar crystal structure and anti-oxidation layer design effectively resist high-speed airflow erosion and high-temperature oxidation; 5. Process compatibility and scalability: All processes are based on conventional PVD equipment, requiring no wet chemical processes, making them green and environmentally friendly, and suitable for large-area, mass production. Attached Figure Description

[0015] Figure 1 A multi-layer composite coating structure for strong bonding and wide-temperature-range selective absorption of sunlight.

[0016] In the figure: 1-light-absorbing functional layer, 2-oxidation protection layer, 3-oxidation protection layer, 4-titanium alloy substrate. Detailed Implementation

[0017] The following is in conjunction with the appendix Figure 1 The present invention will be described in detail, but the scope of protection of the present invention is not limited by the accompanying drawings.

[0018] A strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating is disposed on a titanium alloy substrate, characterized in that it comprises, from bottom to top, a light-absorbing functional layer 1, an oxide protection layer 2, and an oxide protection layer 3; The light-absorbing functional layer 1 has a refractive index of 2.5 and a thickness of 3.0 μm. It is deposited using heterogeneous dual-target high-power pulsed magnetron sputtering technology to form a dense columnar crystal structure. The oxide protective layer 2 has a refractive index of 1.65 and a thickness of 1.5 μm. It is deposited using synchronous pulse bias high-power pulse magnetron sputtering technology to form a dense columnar crystal structure. The oxide protective layer 3 has a refractive index of 1.4 and a thickness of 1.5 μm. It is deposited using voltage feedback controlled mid-frequency pulse magnetron sputtering technology to form a dense columnar crystal structure.

[0019] The titanium alloy matrix is ​​any one of TC4, TA11, TC17 or Ti60.

[0020] A method for depositing a strongly bonded, wide-temperature-range solar selective absorption multilayer composite coating includes the following steps: Step 1: Matrix pretreatment; TC4 titanium alloy was selected and polished sequentially with 400# to 3000# SiC sandpaper; Wet blowing sand roughening treatment: 180-mesh white corundum abrasive, air pressure 0.3 MPa, water pressure 2.2 kg / cm², spraying distance 80 mm, angle 75°; The sample was ultrasonically cleaned for 10 minutes each in acetone, anhydrous ethanol and deionized water, and then air-dried for later use. Step 2: Ion bombardment cleaning and activation; In a vacuum environment, the substrate surface is cleaned by Ar⁺ ion bombardment to activate the surface; The substrate is placed into the vacuum chamber, and the background vacuum is evacuated to 1.0 × 10⁻⁶. - ³ Pa; heat the sample stage to 350℃ and maintain the temperature; introduce 100 sccm of Ar gas, apply a DC pulse bias voltage with a frequency of 150 kHz and a bias voltage of −600 V, and perform ion cleaning for 25 min.

[0021] Step 3: Deposit a light-absorbing functional layer; A heterogeneous dual-target HiPIMS system was adopted, with the target materials being heterogeneous pure metals Cr and Cu; Process gases: Ar 40 sccm, O2 40 sccm; Working air pressure: 0.5 Pa; HiPIMS power supply parameters: pulse width 50 μs, duty cycle 10%, target voltage 550 V; Substrate bias: −100 V; A deposition time of 120 min yielded a (Cu,Cr)O layer with a thickness of approximately 2.5 μm. x Mixed oxide layer.

[0022] Step 4: Deposit an oxide protective layer; HiPIMS technology with synchronous pulse bias is used for co-sputtering of dual Al targets; Process gases: Ar 50 sccm, O2 10 sccm; Working air pressure: 0.4 Pa; HiPIMS parameters: pulse width 35 μs, duty cycle 7%; Substrate bias: −50 V; The deposition time was 180 min, forming an Al2O3-based protective layer with a thickness of approximately 1.0 μm.

[0023] Step 5: Deposit the surface antireflection layer; The method employed was mid-frequency pulsed reactive magnetron sputtering (frequency 40 kHz), with SiO2 as the target material. Process gases: Ar 50 sccm, O2 10 sccm; Working air pressure: 0.2 Pa; Sputtering voltage: 545 V; Substrate bias: −50 V; A SiO2 antireflection layer with a thickness of approximately 1.2 μm was obtained by deposition time of 180 min.

[0024] Step Six: Vacuum Annealing; Annealing atmosphere: High vacuum (<2×10⁻⁶) -3 Pa); Heating rate: 10℃ / min; Annealing temperature: 800℃ ± 10℃, holding time: 120 min; Cool to room temperature with the furnace.

[0025] Table 1 Tensile bond strength of the prepared films

[0026] Performance test results: As shown in Table 1, the coating bond strength (pull-out method) is an average of 19.31 MPa. Average absorption rate in the visible light band (350–750 nm): 82%; Thermal shock test (600℃ ⇆ room temperature, 200 cycles): No peeling, no cracking; Maximum service temperature: 800℃ (short-term).

Claims

1. A strong-bonding wide-temperature-range solar selective absorption multilayer composite coating arranged on a titanium alloy substrate, characterized in that, From bottom to top, it comprises a light absorption functional layer, an oxidation protection layer, and an oxidation protection layer; The refractive index of the light absorption functional layer is 1.8-2.8, and the thickness is 0.5-5.0 μm, which is deposited by using a heterogeneous double-target high-power pulsed magnetron sputtering technology to form a dense columnar crystal structure; The refractive index of the oxidation protection layer is 1.63-1.67, and the thickness is 0.2-2.0 μm, which is deposited by using a synchronous pulsed bias high-power pulsed magnetron sputtering technology to form a dense columnar crystal structure; The refractive index of the oxidation protection layer is 1.4-1.5, and the thickness is 0.5-2.0 μm, which is deposited by using a voltage feedback control intermediate frequency pulsed magnetron sputtering technology to form a dense columnar crystal structure.

2. The strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating according to claim 1, characterized in that, The titanium alloy substrate is any one of TC4, TA11, TC17 or Ti60.

3. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 1 or 2, characterized in that, It comprises the following steps: Step one: substrate pretreatment; Grinding, wet sandblasting and ultrasonic cleaning are performed on the titanium alloy substrate; Step two: ion bombardment cleaning and activation; In a vacuum environment, the surface of the substrate is cleaned and activated by Ar+ ion bombardment; Step three: deposition of light absorption functional layer; The light absorption functional layer is deposited on the activated substrate surface by using a heterogeneous double-target high-power pulsed magnetron sputtering technology; Step four: deposition of oxidation protection layer; The oxidation protection layer is deposited on the surface of the light absorption functional layer by using a synchronous pulsed bias high-power pulsed magnetron sputtering technology; Step five: deposition of surface anti-reflection layer; The surface anti-reflection layer is deposited on the surface of the oxidation protection layer by using an intermediate frequency pulsed reaction magnetron sputtering technology; Step six: vacuum annealing treatment; The vacuum annealing treatment is performed on the deposited multilayer composite coating to make it crystallize.

4. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 3, characterized in that, In step one, the wet sandblasting and roughening treatment uses white corundum abrasive, the air pressure is 0.25-0.35 MPa, the water pressure is 2.2 kg / cm², the spraying distance is 50-150 mm, and the spraying angle is 60°-80°.

5. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 3, characterized in that, In step two, the ion bombardment cleaning conditions are as follows: the base vacuum degree is ≤1.0×10⁻³ Pa, the substrate heating temperature is 350-400℃, the Ar gas flow is 100-200 sccm, the working pressure is 1.5-2.5 Pa, a direct current pulsed bias is applied, the frequency is 150 kHz, the bias is -600 V, and the cleaning time is 25 min.

6. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 3, characterized in that, In step three, the deposition conditions of the light absorption functional layer are as follows: a heterogeneous double-target HiPIMS system is used, the target material is a heterogeneous pure metal Cr and Cu; The process gas is Ar and O2, and the flow rate of each is 40 sccm; the working gas pressure is 0.5 Pa; the HiPIMS power supply parameters are: pulse width 50 μs, duty cycle 10%, target voltage 550 V; the substrate bias is -100 V; and the deposition time is 120 min.

7. The plating method of claim 3, wherein the plating method is characterized by, In step four, the deposition conditions of the oxidation protection layer are as follows: a synchronous pulsed bias HiPIMS technology is used for double Al target co-sputtering; The process gas is Ar 50 sccm and O2 10 sccm; the working gas pressure is 0.4 Pa; the HiPIMS parameters are: pulse width 35 μs, duty cycle 7%; the substrate bias is -50 V; and the deposition time is 180 min.

8. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 3, characterized in that, In step five, the deposition conditions of the surface antireflection layer are as follows: using medium frequency pulse reaction magnetron sputtering (frequency 40 kHz), and the target material is SiO2; The process gas is Ar 50 sccm and O2 10 sccm, the working pressure is 0.2-0.4 Pa, the sputtering voltage is 520-550 V, the substrate bias voltage is-50 V, and the deposition time is 180 min.

9. The plating method of a strong-bonding wide-temperature-range solar selective absorption multilayer composite coating according to claim 3, characterized in that, In step six, the vacuum annealing treatment conditions are as follows: the annealing atmosphere is high vacuum, the pressure is <2×10⁻³ Pa, the heating rate is 10℃ / min, the annealing temperature is 800℃±10℃, the holding time is 120 min, and the furnace cooling is to room temperature.

10. The strong-bonding, wide-temperature-range solar selective absorption multilayer composite coating according to claim 1, characterized in that, The composite coating can be applied in aerospace, military optoelectronic equipment or solar light and heat conversion system.

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