CN113403594B - High-temperature-resistant, water-oxygen-resistant and low-infrared-emissivity composite film for ceramic matrix composite and preparation method thereof - Google Patents

Abstract

The invention relates to a high temperature resistant, anti-oxyhydrogen and low-infrared-emissivity composite film for a ceramic matrix composite and a preparation method thereof. The film is a high-temperature conductive composite film which is continuously formed, the main components of the film comprise two types, a high-conductivity metal material is used as a component with low infrared emissivity, and an environment barrier coating material for a ceramic matrix composite material is used as a protection component. After the process is optimized, the composite film can realize that the emissivity of 2-22 mu m is less than 0.1 after the composite film is used for 2 hours in a high-temperature air environment at 1000 ℃, has the excellent performances of low emissivity, high temperature resistance, water resistance and the like, and has simple preparation process and simple operation.

Description

Composite films with high temperature resistance, water oxygen resistance and low infrared emissivity for ceramic matrix composite materials and Preparation

technical field

The invention belongs to the field of infrared stealth, and relates to a high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for a ceramic matrix composite material and a preparation method thereof.

Background technique

With the continuous development of the aviation industry, the relevant technical requirements of military aviation gas turbine engines continue to increase. Ceramic matrix composites have become the next generation of high thrust-to-weight ratio aviation gas due to their performance advantages such as high temperature resistance, low density, oxidation resistance, and high specific strength. The key material of the hot end parts of the turbine engine (tail nozzle, etc.). With the rapid development of modern military detection technology, the survival of fighters in modern warfare has been greatly challenged. Stealth technology has become an important research direction in the field of military technology. Infrared stealth occupies a very important position in stealth technology. Therefore, the realization of ceramic Infrared stealth of matrix composites is crucial.

Infrared stealth is to reduce the target's infrared radiation intensity to make it lower than the sensitivity of the infrared detector, reducing the probability of the target being detected by the infrared detector. According to the Stephen-Boltzmann law: the infrared radiation intensity of the target M=εσT ⁴ (ε is the infrared emissivity, σ is the Boltzmann constant, T is the surface temperature of the target). It can be seen that the main factors affecting the infrared radiation energy of an object are the surface temperature and infrared emissivity of the object, so there are two main technical ways to achieve infrared stealth: one is to reduce the surface infrared emissivity of the target, and the other is to control the surface temperature of the target.

In addition, the hot end components of gas turbine engines need to face harsh environmental conditions such as high temperature, water oxygen, and thermal corrosion when working, and the operating temperature often exceeds 1000 °C. Ceramic matrix composites must also resist the erosion of complex environments during application, so it is extremely important to improve the environmental resistance of ceramic matrix composites such as high temperature resistance, water and oxygen corrosion resistance.

In the field of military equipment, the current mainstream infrared stealth materials include low infrared emissivity coatings and films. The low infrared emissivity coating mainly relies on the excellent conductivity of the metal filler to achieve low infrared emissivity, but the hot end parts of the gas turbine engine need to face harsh environmental conditions such as high temperature, water and oxygen. In this environment, metal materials It is easy to oxidize, the conductivity decreases, and the effect of infrared stealth is lost. Patent CN 108913018 B discloses a high-temperature-resistant infrared low-emissivity coating and its preparation method, which uses aluminum/nickel (Al/Ni) core-shell pigments as low-emissivity fillers. The temperature does not exceed 500°C. In addition, low infrared emissivity thin films are mainly classified into metal thin films and semiconductor thin films. Correspondingly, metal thin films are also difficult to meet the needs of high-temperature applications, and new high-temperature-resistant low-emissivity semiconductor oxides and ceramic materials include tin-doped indium oxide (ITO) and aluminum-doped zinc oxide (ZAO), etc., which can be used at room temperature. A lower emissivity is obtained, but there are defects such as inter-substance diffusion and unstable material properties in a complex high-temperature environment, and it is difficult to use it stably. Patent CN 111321382 A discloses a high-temperature-resistant, oxidation-resistant infrared low-emissivity composite film and its preparation method, which uses a high-temperature conductive ceramic film as the low-emissivity functional layer. The film has a certain temperature resistance, and its maximum service temperature Not exceeding 750°C.

Similar to the above, a lot of research has been done on low-infrared emissivity materials used in high-temperature environments, but so far, among the reported research results, there are still only a handful of materials that can be used stably in environments exceeding 1000 °C. Therefore, for the ceramic matrix composites used in the hot end parts of aviation gas turbine engines, there is an urgent need for a material that can work stably in complex high-temperature environments and has low infrared emissivity to meet the performance requirements of aerospace vehicles. It will be of great significance to design high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity coatings/films for ceramic matrix composites with high service temperature and stable performance.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials and a preparation method thereof. Aiming at various problems faced by existing materials in harsh working environments, in order to make up for the deficiencies of existing technologies, the composite film of the present invention can be used in high temperature above 1000°C, water and oxygen environments, and has both low infrared emissivity and high temperature resistance , anti-water and oxygen characteristics, and simple structure, easy to prepare.

Technical solutions

A method for preparing a high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for a ceramic matrix composite material. The barrier coating material is mixed and evenly doped on the surface of the target object by magnetron sputtering to form a composite film, in which the content of the highly conductive metal material component is 30-70vol.%.

The preparation method steps are as follows:

Step 1: After cleaning the surface of the target object, fix it on the magnetron sputtering deposition stage;

Step 2: Metal and ceramic targets are used as magnetron sputtering targets, and the sputtering background vacuum is lower than 8×10 ^-1 Pa;

Step 3: Infuse the atmosphere with argon gas with a purity greater than or equal to 99.99%, adjust the sputtering pressure to (3-9)×10 ^-1 Pa, and set the sputtering power to 100-400W;

Step 4: use DC magnetron sputtering metal, adopt radio frequency magnetron sputtering ceramic target material, sputter for 30-60 minutes, sputtering rate is 10-50nm/min, prepare low infrared emissivity composite thin film. The highly conductive metal material includes, but is not limited to, gold, silver, titanium or platinum.

The environmental barrier coating materials for ceramic matrix composites include but not limited to mullite, barium strontium aluminum silicon and yttrium silicate, scandium silicate or rare earth silicate.

The sputtering rate of the direct current magnetron sputtering metal and radio frequency magnetron sputtering ceramic target depends on the control of the metal material component content between 30-70vol.%.

The thin film is a high-temperature conductive composite thin film formed continuously, and the thickness is more than or equal to 100nm.

Beneficial effect

The invention proposes a composite film with high temperature resistance, water oxygen resistance and low infrared emissivity for ceramic matrix composite materials and its preparation method. structure, just cover the surface of the target object when in use. The film is a continuous film-forming high-temperature conductive composite film, which contains two main components. The high-conductivity metal material is used as a low-infrared emissivity component, and the environmental barrier coating material for ceramic matrix composite materials is used as a protective component. After the process is optimized, the composite film can realize the emissivity of 2-22μm is less than 0.1 after being used in a high-temperature air environment of 1000°C for 2 hours, and has excellent properties such as low emissivity, high temperature resistance, and water and oxygen resistance, and its preparation process is simple. , easy to operate.

It is a single-layer multi-phase structure, which is characterized in that: a high-conductivity metal material is used as a low-infrared emissivity component, and an environmental barrier coating material for ceramic matrix composite materials is used as a protective component, which is covered on the surface of the target object when used.

The present invention is based on the principle of complementary functional advantages of composite thin films. Firstly, high conductive metal materials are used as low infrared emissivity functional components, and secondly, environmental barrier coating materials for ceramic matrix composite materials are used as protective components to solve the problem of metal thin films. Not resistant to oxidation, water and oxygen corrosion. The two components complement each other, and by regulating the relative ratio of the two components, the content of the low infrared emissivity component is controlled at 30-70vol.% (the optimal content varies according to the difference between the low infrared emissivity component and the protective component selection), and finally achieve the coordination and unity of low infrared emissivity, high temperature resistance, and water and oxygen resistance. While maintaining low infrared emissivity, it has excellent high temperature resistance, water and oxygen resistance. The composite film prepared by it is used as the infrared stealth material of the hot end part of the aviation gas turbine engine, and it can work stably in the high temperature above 1000 ℃, water and oxygen environment, and the infrared emissivity is kept at a low level.

Compared with the prior art, the invention proposes a high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials and its preparation method. Compared with the prior art, the invention has the following advantages:

1. The high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composites obtained in the present invention can be used stably in a high-temperature environment above 1000°C by optimizing the component ratio, and has excellent water-oxygen resistance and Infrared emissivity remains low. It is of great significance to realize the infrared stealth of ceramic matrix composites to meet the complex working environment faced in the use of ceramic matrix composites.

2. The high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials of the present invention has a simple structure and is convenient for large-scale preparation and application. Most of the multi-layer films or coating structures in the prior art have interlayer bonding The problems of force difference and thermal expansion mismatch, and the simple single-layer thin film structure in the present invention can realize the functions of low infrared emissivity and complex high temperature environment, without considering the above problems.

3. The preparation process of the high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials of the present invention is simple and feasible, with good repeatability and low equipment requirements.

Description of drawings

Figure 1. Schematic cross-sectional view of a low-infrared emissivity composite film in an embodiment of the present invention.

Figure 2. Infrared emissivity diagrams of 2-22 μm before and after heat treatment of the barium-strontium-aluminum-silicon/platinum composite film at different temperatures in Example 1 of the present invention. The emissivity is 0.10, 0.07, 0.09, respectively.

Fig. 3. The photo of the barium-strontium-aluminum-silicon/platinum composite film before heat treatment in Example 1 of the present invention, the surface is smooth and flat.

Figure 4. The photo of the barium-strontium-aluminum-silicon/platinum composite film in Example 1 of the present invention after heat treatment at 1000°C for 2 hours. The surface of the film has no obvious change, and the structure is preserved intact.

Figure 5. Infrared emissivity diagrams of the scandium silicate/titanium composite film in Example 2 of the present invention before and after heat treatment at different temperatures at 2-22 μm, the infrared emissivity before heat treatment is as low as 0.28, and the infrared emission after 2 hours of air heat treatment at 600, 800, and 1000°C The ratios are 0.24, 0.19, 0.26 respectively.

Figure 6. Infrared emissivity diagrams of 2-22 μm before and after heat treatment of titanium thin film (comparative example) at different temperatures in Example 3 of the present invention. Increased to 0.37, 0.46, 0.68.

Detailed ways

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

Various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

Example 1: Preparation of a barium strontium aluminum silicon/platinum composite thin film with a thickness of 150 nm.

A high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials as shown in Figure 1, the main component of which is barium strontium aluminum silicon/platinum (BSAS/Pt). The thin film has a single-layer multi-phase structure, 1 is the surface of the target object, and 2 is the prepared BSAS/Pt composite thin film, and the main bonding method between the thin film and the substrate is mechanical bonding. The low infrared emissivity film in this embodiment is deposited on the SiO ₂ (1) substrate.

In the embodiment, the thickness of BSAS/Pt film is 150nm, wherein the protective component is prepared by radio frequency magnetron sputtering method, the target material used is BSAS ceramic target (purity 99.95%), and the low infrared emissivity component adopts DC magnetron sputtering method Preparation, the target material used is Pt metal target (purity 99.99%).

After the ratio optimization of previous experiments, the preparation method of the low infrared emissivity composite film in this embodiment comprises the following steps:

(1) Place the SiO ₂ substrate with a size of Φ30mm×2mm in acetone, absolute ethanol, and deionized water for 5 minutes for ultrasonic cleaning, and then use compressed air to blow off the deionized surface of the SiO ₂ substrate. water, set aside.

(2) Fix the _SiO2 substrate dried in step 1 on the magnetron sputtering stage, fix the BSAS and Pt sputtering targets at the same time, and evacuate the sputtering chamber until the pressure in the chamber reaches 8× 10 ^-4 Pa.

(3) Introduce argon gas with a purity greater than or equal to 99.99% into the sputtering chamber, adjust the sputtering pressure to 0.8Pa, direct current sputtering power to 50W, radio frequency sputtering power to 200W, and control the sputtering time to 30min.

(4) After the sputtering time is over, close the gas circuit and voltage, keep the water-cooled state and vacuumize for 30 minutes, then open the chamber and take out the sample.

The high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composites prepared by the above method is tested for its composition ratio. The volume fraction of Pt is 46vol.%, and its 2-22 μm infrared emissivity is less than 0.2, respectively. After heat treatment in air environment at 600, 800, and 1000°C for 2 hours, the infrared emissivity was all lower than 0.1 (see Figure 2).

The photographs of the film of this embodiment before and after heat treatment in an air environment of 1000°C for 2 hours are shown in Figure 3 and Figure 4 respectively. The structure is well preserved in the environment, not easy to be destroyed, and has excellent anti-oxidation properties. And due to the excellent water and oxygen resistance properties of barium strontium aluminum silicon itself, the film has excellent water and oxygen resistance properties.

Through comparative experiments, the optimal proportion can be achieved when the volume fraction of Pt is around 50vol.%. At this time, the low infrared emissivity and oxidation resistance of the film are optimal. When the volume fraction of Pt decreases, the infrared emissivity of the film increases. , the infrared stealth ability decreases, when the Pt volume fraction increases, the infrared emissivity of the film after high temperature heat treatment increases, and the high temperature resistance ability decreases.

Example 2: Preparation of a scandium silicate/titanium composite film with a thickness of 600 nm.

A high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials as shown in Figure 1, the main component of which is scandium silicate/titanium (Sc ₂ Si ₂ O ₇ /Ti). The film has a single-layer multi-phase structure, 1 is the surface of the target object, and 2 is the prepared Sc ₂ Si ₂ O ₇ /Ti composite film, and the main bonding method between the film and the substrate is mechanical bonding. The low infrared emissivity film in this embodiment is deposited on the SiO ₂ (1) substrate.

In the example, the thickness of the Sc ₂ Si ₂ O ₇ /Ti film is 600nm, and the protective component is prepared by radio-frequency magnetron sputtering. The target used is Sc ₂ Si ₂ O ₇ ceramic target (purity 99.95%), low infrared emission The ratio component is prepared by DC magnetron sputtering method, and the target material used is Ti metal target (purity 99.99%).

The preparation method of the low infrared emissivity composite film in the present embodiment comprises the following steps:

(1) Place the SiO ₂ substrate with a size of Φ30mm×2mm in acetone, absolute ethanol, and deionized water for 5 minutes for ultrasonic cleaning, and then use compressed air to blow off the deionized surface of the SiO ₂ substrate. water, set aside.

(2) Fix the SiO ₂ substrate dried in step 1 on the magnetron sputtering stage, fix the Sc ₂ Si ₂ O ₇ and Ti sputtering targets at the same time, and vacuum the sputtering chamber until the chamber The internal pressure is 8×10 ^-4 Pa.

(3) Introduce argon gas with a purity greater than or equal to 99.99% into the sputtering chamber, adjust the sputtering pressure to 0.6Pa, direct current sputtering power to 200W, radio frequency sputtering power to 200W, and control the sputtering time to 60min.

(4) After the sputtering time is over, close the gas circuit and voltage, keep the water-cooled state and vacuumize for 30 minutes, then open the chamber and take out the sample.

The high-temperature-resistant, water-oxygen-resistant and low-infrared emissivity composite film for ceramic matrix composite materials prepared by the above method, the composition ratio is tested, the volume fraction of Ti is 65vol.%, and the infrared emissivity of 2-22 μm is less than 0.3, respectively. 600, 800, 1000 ℃ air environment heat treatment for 2 hours after testing the infrared emissivity is lower than 0.3 (see Figure 5).

The film of this example has no obvious change before and after heat treatment in 1000°C air environment for 2 hours. The high temperature resistant, water and oxygen resistant low infrared emissivity composite film of the present invention has a complete structure under high temperature environment and has excellent oxidation resistance. And due to the excellent water and oxygen resistance of scandium silicate itself, the film has excellent water and oxygen resistance.

Example 3: Preparation of a titanium thin film with a thickness of 600 nm (comparative example).

As a comparison, a thin film with low infrared emissivity as shown in FIG. 1 was prepared, the main component of which was titanium (Ti). The thin film has a single-layer structure, 1 is the surface of the target object, and 2 is the prepared Ti thin film, and the main bonding method between the thin film and the substrate is mechanical bonding. The low infrared emissivity film in this embodiment is deposited on the SiO ₂ (1) substrate.

In the embodiment, the thickness of the Ti film is 600 nm, and it is prepared by DC magnetron sputtering method, and the target material used is a Ti metal target (purity: 99.99%).

The preparation method of the low infrared emissivity composite film in the present embodiment comprises the following steps:

(1) Place the SiO ₂ substrate with a size of Φ30mm×2mm in acetone, absolute ethanol, and deionized water for 5 minutes for ultrasonic cleaning, and then use compressed air to blow off the deionized surface of the SiO ₂ substrate. water, set aside.

(2) Fix the _SiO2 substrate dried in step 1 on the magnetron sputtering stage, fix the Ti sputtering target at the same time, and evacuate the sputtering chamber until the pressure in the chamber reaches 8×10 ^{− 4Pa} .

(3) Introduce argon gas with a purity greater than or equal to 99.99% into the sputtering chamber, adjust the sputtering pressure to 0.6Pa, direct current sputtering power to 200W, and control the sputtering time to 100min.

(4) After the sputtering time is over, close the gas circuit and voltage, keep the water-cooled state and vacuumize for 30 minutes, then open the chamber and take out the sample.

The low-infrared emissivity film prepared by the above method is tested to have an infrared emissivity of less than 0.2 at 2-22 μm, and its infrared emissivity gradually increases after being heat-treated at 600, 800, and 1000° C. in an air environment for 2 hours, and its infrared stealth ability drops seriously (see Figure 6).

Ti film is a common single-component low-infrared emissivity film. After heat treatment at 1000 °C for 2 hours in air environment, the infrared emissivity reaches 0.68, and the performance deteriorates seriously. It is found by comparison that the Sc ₂ Si ₂ O ₇ /Ti composite film with the same thickness prepared in Example 2 has excellent oxidation resistance, and the infrared emissivity is 0.26 after heat treatment in air environment at 1000°C for 2 hours. It can be seen that the introduction of the anti-oxidation phase (Sc ₂ Si ₂ O ₇ ) greatly improves the anti-oxidation ability of the film, while maintaining the low infrared emissivity of the film.

In summary, the present invention is based on the principle of functional superposition and complementary advantages of composite thin films, uses highly conductive metal materials as low infrared emissivity functional components, and utilizes ceramic matrix composite materials used when working under high temperature, water and oxygen harsh environmental conditions The environmental barrier coating material is used as a protective component to finally realize the coordination and unity of low infrared emissivity, high temperature resistance, and water and oxygen resistance. It has excellent high temperature resistance and water and oxygen resistance while maintaining low infrared emissivity. Infrared stealth of ceramic matrix composites lays the foundation.

Claims (3)

1. A method for preparing a ceramic matrix composite material with high temperature resistance, water oxygen resistance and low infrared emissivity composite film, characterized in that: the ceramic matrix composite material is used for high temperature resistance, water oxygen resistance and low infrared emissivity composite film. Highly conductive metal materials and environmental barrier coating materials are mixed and uniformly doped on the surface of the target object by magnetron sputtering to form a composite film, in which the high conductive metal material component content is 30-70vol.%. The preparation method steps are as follows: Step 1: After cleaning the surface of the target object, fix it on the magnetron sputtering deposition stage; Step 2: Metal and ceramic targets are used as magnetron sputtering targets, and the sputtering background vacuum is lower than 8×10 ^-1 Pa; Step 3: Infuse the atmosphere with argon gas with a purity greater than or equal to 99.99%, adjust the sputtering pressure to (3-9)×10 ^-1 Pa, and set the sputtering power to 100-400W; Step 4: Use DC magnetron sputtering metal, adopt RF magnetron sputtering ceramic target material, sputter for 30-60 minutes, sputtering rate is 10-50nm/min, and prepare low infrared emissivity composite film; The film is a continuous film-forming high-temperature conductive composite film with a thickness ≥ 100 nm; The environmental barrier coating material is barium strontium aluminum silicon. 2. The method according to claim 1, characterized in that: the sputtering rate of the DC magnetron sputtering metal and RF magnetron sputtering ceramic target depends on the metal material component content and is between 30-70vol.%. control between. 3. The method according to claim 1, characterized in that: the highly conductive metal material is gold, silver, titanium or platinum.

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