A transition layer for a c / sic composite substrate thin film sensor and a method of manufacturing the same

Abstract

The application belongs to the technical field of thin film sensor design and production, and particularly relates to a transition layer for a C / SiC composite material substrate thin film sensor and a preparation method thereof. x C 1‑x The Zr element in the ZrC thin film diffuses to the C / SiC composite material substrate direction under the diffusion effect of the Zr element in the high-temperature environment, and a ZrC transition layer with gradually decreasing Zr content and gradually increasing C content from top to bottom is formed x C 1‑x The ZrSi2 is oxidized at a high temperature above 1400 DEG C to produce a self-repairing effect of the SiO2-ZrSiO4 glass phase ceramic, the cavities and micro-cracks generated in the high-temperature oxidation process of the ZrSi2 thin film are repaired, the heat shock resistance and heat corrosion resistance of the sensor are improved, and the heat shock resistance of the insulation layer and the high-temperature stability of the sensor are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thin film sensor design and production, and particularly relates to a transition layer for a C / SiC composite material substrate thin film sensor and a preparation method thereof. BACKGROUND

[0002] With the development of aerospace technology, the speed of aircraft will be faster and faster, and the thermal protection coating and the internal working temperature of the engine will be higher and higher, gradually approaching the limit working temperature of existing materials. In order to ensure the safe and reliable operation of the aircraft, one of the methods is to use high-temperature-resistant materials to manufacture high-temperature components on the aircraft.

[0003] C / SiC composite material is a kind of silicon carbide fiber reinforced ceramic matrix composite material, which has the characteristics of high strength, high toughness, high temperature stability and low density, etc. It is a new generation of high-temperature-resistant composite material, which has been widely used in aerospace engine, solid / liquid rocket engine, aerospace vehicle thermal protection and deep space exploration system. In the process of rapid temperature rise, the complex strain load seriously affects the performance and safety of the aircraft. Therefore, it is of great significance to develop stable, reliable and suitable for aircraft high temperature, high pressure, strong vibration and other harsh working environment temperature and strain measurement sensors.

[0004] The sensitive thin film is directly deposited on the surface of the hot end component by using vacuum coating technology such as magnetron sputtering or electron beam evaporation, to form a temperature and strain thin film sensor. Neither the mechanical structure of the component itself is damaged, nor the adhesive is used for pasting, avoiding the error and limitation of the adhesive in high temperature test. The thickness of this kind of thin film sensor is only microns, which has little disturbance to the airflow field of the aerospace vehicle and increases the mass little by little. These characteristics make the thin film sensor have faster response speed, higher accuracy and reliability, and can be applied to harsh environments such as high temperature.

[0005] Since the output of the thin film sensor is an electrical signal, if the substrate is conductive, the sensitive layer of the sensor is directly deposited on the surface of the substrate, and the output electrical signal will be shunted through the substrate and even short-circuited, which will seriously affect the performance of the sensor. Therefore, an insulating layer must be prepared between the substrate and the sensitive functional layer to realize the electrical isolation of the sensitive layer and the substrate. The insulating layer material is usually high-temperature insulating ceramic material such as alumina and other oxide ceramic thin film materials. Because the thermal expansion coefficient of C / SiC composite material (2.8-4.5x10 -6 / K) is different from that of alumina (8x10 -6The difference is large, and when the temperature is high and changes greatly, the film sensor is prone to warping or even falling off, affecting the working stability. Therefore, it is necessary to prepare a transition layer with a low thermal expansion coefficient to a high thermal expansion coefficient between the C / SiC composite material substrate and the alumina insulating layer, so as to improve the adhesion strength of the alumina insulating layer and the C / SiC composite material. SUMMARY

[0006] The purpose of the present application is to provide a transition layer for a C / SiC composite material substrate film sensor and a preparation method thereof, to solve the problems of poor high-temperature adhesion, poor thermal shock resistance and poor stability of the existing C / SiC composite material substrate film sensor.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A transition layer for a C / SiC composite material substrate film sensor, comprising a transition layer and a ZrSi2 sacrificial layer arranged on a C / SiC composite material substrate in sequence, the transition layer is a gradient ceramic layer formed by high-temperature annealing process of ZrC film, and the upper surface of the ZrSi2 sacrificial layer is provided with a self-repairing layer formed by annealing process; wherein the annealing temperature for the ZrC film is 1400-2000 DEG C, and the annealing temperature for the ZrSi2 sacrificial layer is 1400-1800 DEG C.

[0009] Further, the thickness of the ZrC film is 2-10 microns, and the thickness of the ZrSi2 film layer is 1-7 microns.

[0010] A preparation method of a transition layer for a C / SiC composite material substrate film sensor, comprising the following steps:

[0011] Step 1, treating the C / SiC composite material substrate to make its surface clean and dry;

[0012] Step 2, using ZrC particles with a purity of greater than or equal to 99.99wt% as plating material, and using electron evaporation method to deposit ZrC film layer on the C / SiC substrate obtained in step 1;

[0013] Step 3, high-temperature annealing the structure obtained in step 2, so that the Zr element in the ZrC film layer diffuses to the C / SiC composite material substrate, to form a gradient ceramic layer composed of ZrC and ZrSi2, and the annealing temperature is 1400-2000 DEG C; x C 1-x The annealing temperature is 1400-2000 DEG C;

[0014] Step 4, using ZrSi2 target with a purity of greater than or equal to 99.99wt% as sputtering target material, and using magnetron sputtering method to deposit ZrSi2 film layer on the gradient ceramic layer obtained in step 3;

[0015] Step 5, annealing the structure obtained in step 4 to oxidize the upper surface of the ZrSi2 thin film layer to obtain a ZrO2 skeleton and a SiO2-ZrSiO4 self-repairing layer, thereby completing the preparation of the transition layer for the C / SiC composite substrate thin film sensor.

[0016] Further, the treatment method of the C / SiC composite substrate in step 1 is as follows: the C / SiC composite substrate is sequentially placed in acetone, ethanol and deionized water for ultrasonic cleaning, each for 10 minutes, and then dried with a nitrogen gun and finally dried to remove residual water.

[0017] Further, the conditions for the electron beam evaporation deposition of the ZrC thin film in step 2 are as follows:

[0018] 2.1, the vacuum degree of the cavity back of the electron beam evaporation device is less than 5x10 -4 Pa, and the temperature of the C / SiC composite substrate is controlled in the range of 250-350℃.

[0019] Further, the high-temperature annealing conditions in step 3 are as follows:

[0020] The structure obtained in step 2 is placed in an annealing furnace for annealing treatment in an argon environment, the annealing temperature is 1400-2000℃, and the annealing time is 2-5h.

[0021] Further, the sputtering conditions in step 4 are as follows:

[0022] The vacuum degree of the cavity back of the sputtering device is less than 8x10 -4 Pa, the power is 200-350W, the sputtering gas is argon, the argon gas flow is 23-48sccm, and the sputtering gas pressure is 0.35Pa-0.5Pa.

[0023] Further, the method for obtaining the ZrO2 and SiO2-ZrSiO4 self-repairing layer by annealing in step 5 is as follows:

[0024] The temperature is raised to 1400-1800℃ in a vacuum environment below 8x10 -4 Pa, oxygen is introduced for oxidation annealing treatment, and the annealing time is 1-8h, thereby obtaining the ZrO2 skeleton and the SiO2-ZrSiO4 self-repairing layer.

[0025] A C / SiC composite substrate thin film sensor comprises a C / SiC composite substrate, a transition layer and an insulating layer stacked from bottom to top, the transition layer is the transition layer for the C / SiC composite substrate thin film sensor, and the insulating layer is an Al2O3 insulating layer.

[0026] The application utilizes the diffusion of Zr element in a high-temperature environment, diffuses the Zr element in the ZrC film to the C / SiC composite material base direction, forms a ZrC film with gradually reduced Zr content and gradually increased C content from top to bottom x C 1-x amorphous ceramic phase, so as to realize the transition from the low thermal expansion coefficient (2.8-4.5*10 -6 / K) of the C / SiC composite material to the high thermal expansion coefficient (6.7*10 -6 / K) of the ZrC; and then utilizes the ZrSi2 with the similar thermal expansion coefficient (6.5*10 -6 / K) to the ZrC to oxidize at a high temperature above 1400 DEG C, forms the self-repairing effect of the SiO2-ZrSiO4 glass phase ceramic, repairs the cavities and micro-cracks generated in the high-temperature oxidation process of the ZrSi2 film, realizes the improvement of the heat shock resistance and heat corrosion resistance of the sensor, and the ZrO2 formed after oxidation can improve the heat shock resistance of the insulation layer, has good adhesion with the Al2O3, and improves the high-temperature stability of the sensor.

[0027] After the above technical scheme is adopted, the application has the following beneficial effects:

[0028] 1. The application utilizes the Zr x C 1-x amorphous ceramic phase to realize the transition from the low thermal expansion coefficient (2.8-4.5*10 -6 / K) of the C / SiC composite material to the high thermal expansion coefficient (6.7*10 -6 / K) of the ZrC, effectively alleviates the thermal mismatch problem of the C / SiC composite material base and the ZrC, prevents the ZrC film from being warped or peeled off at a high temperature, and can significantly improve the heat shock resistance of the sensor.

[0029] 2. The ZrSi2 sacrificial layer film arranged on the ZrC film has the similar thermal expansion coefficient (6.5*10 -6 / K) to the thermal expansion coefficient (6.7*10 -6 / K) of the ZrC and has the same Zr element, can form a bond transition, realizes the improvement of the adhesion between the ZrSi2 and the ZrC, and prevents the sensor from being peeled off at a high temperature.

[0030] 3、The ZrSi2 sacrificial layer thin in the application can form ZrO2, SiO2 and ZrSiO4 when annealing, wherein the SiO2 is a glass phase and has a certain fluidity at high temperature, which can effectively fill the micro-cracks and holes and other defects generated in the transition layer; ZrO2 forms a eutectic product ZrSiO4 with SiO2 in a high-temperature environment, the molten ZrSiO4 has a suitable viscosity, so that it is not easy to occur mechanical denudation in the oxidation process, and at the same time has a low oxygen diffusion coefficient and plays a role in isolating oxygen. After cooling, the ZrSiO4 particles play a pinning effect in the SiO2 glass phase, so that the SiO2 can better gather near the micro-cracks and holes, and a better repair effect is obtained. In addition, the ZrO2 formed by the oxidation of ZrSi2 has good adhesion with Al2O3, which can prevent Al2O3 from falling off at high temperature. In addition, the oxidation temperature of the ZrSi2 sacrificial layer is not lower than 1400℃, which can prevent the poor fluidity of the oxidation product generated at a low oxidation temperature, which leads to the fact that the micro-cracks cannot be effectively sealed, so that the C / SiC composite material substrate is oxidized, and the performance of the thin film sensor is affected. When it is applied to the C / SiC composite material substrate thin film sensor, the problem of poor stability of the existing C / SiC composite material substrate thin film sensor can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A structure schematic diagram of a C / SiC composite material substrate transition layer based on the application is provided for the embodiment. DETAILED DESCRIPTION

[0032] The application will be described in detail below in combination with the drawings and embodiments of the specification.

[0033] Embodiment 1

[0034] The transition layer for the C / SiC composite material substrate thin film sensor provided in the embodiment comprises a ZrC transition layer film and a ZrSi2 sacrificial layer film which are sequentially arranged on the C / SiC composite material substrate. The ZrC transition layer film is formed by using ZrC particles with a purity of ≥99.99% as plating material, depositing on the C / SiC substrate by electron evaporation method, and annealing at 1600℃. The ZrSi2 sacrificial layer film is formed by using ZrSi2 targets with a purity of ≥99.99wt% as sputtering target material, sputtering and depositing on the ZrC transition layer film by magnetron sputtering method. The thickness of the ZrC as the transition layer will affect the transition effect and sensing performance, therefore the thickness of the ZrC film is controlled in the range of 2-10μm in the embodiment, and preferably 5μm; the thickness of the ZrSi2 film layer is controlled in the range of 1-7μm, and preferably 2μm.

[0035] The preparation method of the above-mentioned transition layer for the C / SiC composite material substrate thin film sensor comprises the following steps:

[0036] Step 1, the C / SiC composite material substrate is sequentially placed in acetone, ethanol and deionized water, and is cleaned by ultrasonic cleaning for 10 minutes respectively to remove organic contaminants and dust particles on the surface of the substrate, and then is dried by nitrogen gun and is dried to keep clean and dry.

[0037] Step 2, an electron beam evaporation device is used to deposit a ZrC film on the C / SiC composite material substrate treated in step 1; the cavity of the device is vacuumed to a vacuum degree of 5x10 -4 Pa, ZrC particles are placed in the crucible as plating material, the voltage is 8KV, the beam current is 120mA, the C / SiC composite material substrate is controlled at 350℃, and a 5μm thick ZrC carbide film is evaporated and deposited.

[0038] Step 3, the structure obtained in step 2 is placed in a high-temperature annealing furnace and annealed in an argon environment for 2h, the argon flow is 36sccm, and the annealing temperature is 1600℃, so that the Zr element in the ZrC film diffuses to the C / SiC composite material substrate direction through vacancy diffusion and interstitial diffusion, forming a ZrC film gradually decreasing in Zr content and gradually increasing in C content from the ZrC film to the composite material substrate direction. x C 1-x amorphous ceramic phase, as a gradient ceramic layer. Thus, the transition from the low thermal expansion coefficient of the C / SiC composite material to the high thermal expansion coefficient of the ZrC is realized in the ceramic phase, effectively alleviating the thermal mismatch problem of the C / SiC composite material substrate and the ZrC, preventing the ZrC film from warping or falling off at high temperature, and significantly improving the thermal shock resistance of the sensor. The thermal expansion coefficient of the C / SiC composite material is 2.8-4.5x10 -6 / K, and the thermal expansion coefficient of the ZrC is 6.7x10 -6 / K.

[0039] Step 4, the structure obtained in step 3 is placed in a vacuum chamber with a vacuum degree of 8x10 -4 Pa, a ZrSi2 target with a purity of ≥99.99wt% is used as a sputtering target material, the sputtering power is 200W, the sputtering gas is argon, and the sputtering gas pressure is 0.4Pa, wherein the argon gas flow is 48sccm, and a 2μm thick ZrSi2 film is sputtered and deposited.

[0040] In this embodiment, the thermal expansion coefficient of ZrSi2 is similar to that of ZrC, and both have the same Zr element, so after depositing the ZrSi2 film as a sacrificial layer, a bond transition can be formed, improving the adhesion between ZrSi2 and ZrC, and effectively preventing the sensor from falling off and other situations at high temperature. The thermal expansion coefficient of ZrSi2 is 6.5x10 -6 / K, and the thermal expansion coefficient of the ZrC is 6.7x10-6 / K.

[0041] Step 5, the structure obtained in step 4 is placed in a vacuum annealing furnace, the temperature is raised to 1450℃ under a vacuum environment of 8.0x10 -4 Pa, oxygen is introduced, the oxygen flow is 60sccm, the annealing time is 2h, the ZrSi2 thin film surface is oxidized to obtain a ZrO2 skeleton and a SiO2-ZrSiO4 self-repairing layer, thereby completing the preparation of the transition layer for the C / SiC composite material substrate thin film sensor.

[0042] The ZrSi2 thin film in this embodiment forms ZrO2, SiO2 and ZrSiO4 during annealing. The SiO2 is a glass phase and has a certain fluidity at high temperatures, which can effectively fill the micro-cracks and holes and other defects generated in the transition layer; the ZrO2 forms a eutectic product ZrSiO4 with SiO2 under a high temperature environment, the molten ZrSiO4 has a suitable viscosity, so that it is not easy to occur mechanical ablation during oxidation, and at the same time has a low oxygen diffusion coefficient and plays a role of isolating oxygen. After cooling, the ZrSiO4 particles play a pinning effect in the SiO2 glass phase, so that the SiO2 can better gather near the micro-cracks and holes, and a better repair effect is obtained. In addition, the ZrO2 formed by the oxidation of ZrSi2 has good adhesion with Al2O3, which can prevent Al2O3 from falling off at high temperatures. In addition, maintaining the vacuum state of the annealing furnace when the temperature is lower than 1400-1800℃ can prevent the poor fluidity of the oxidation product at a lower temperature, which causes the micro-cracks to be unable to be effectively sealed, so that the C / SiC composite material substrate is oxidized, affecting the performance of the thin film sensor.

[0043] Based on the above-mentioned transition layer for the C / SiC composite material substrate thin film sensor, this embodiment provides a C / SiC composite material substrate thin film sensor, as shown in Figure 1 , the sensor comprises a C / SiC composite material substrate, a transition layer and an Al2O3 insulating layer which are stacked in order from bottom to top; the transition layer comprises a ZrC transition layer thin film, a ZrSi2 sacrificial layer and a SiO2-ZrSiO4 self-repairing layer in order from bottom to top. The preparation of the transition layer is described in detail in the above content, which is not repeated here.

[0044] The Al2O3 insulating layer is arranged on the SiO2-ZrSiO4 self-repairing layer by the following method:

[0045] (1) the transition layer prepared by the above scheme is placed in a vacuum degree of 8x10 -4A 2μm thick Al2O3 film was deposited on the surface of the C / SiC composite material substrate by reactive sputtering method, with the vacuum chamber pressure of 0.4Pa, the Al target with purity ≥99.99wt%, the mixed gas of O2 and Ar as the sputtering gas, the flow ratio of O2 and Ar being 1:24, and the sputtering pressure being 0.4Pa;

[0046] (2) placing the structure obtained in (2) in a vacuum annealing furnace with vacuum degree of 8.0×10 -4 Pa for annealing treatment for 2h, and the annealing temperature being 800℃, thereby obtaining the C / SiC composite material substrate film sensor transition layer structure.

[0047] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the present application.

Claims

1. A transition layer for a C / SiC composite substrate thin-film sensor, characterized in that: The material includes a gradient ceramic layer and a ZrSi2 sacrificial layer sequentially disposed on a C / SiC composite substrate. The gradient ceramic layer is formed by a high-temperature annealing process of a ZrC thin film. The ZrSi2 sacrificial layer has a self-healing layer formed by an annealing process on its upper surface. The annealing temperature for the ZrC thin film is 1400~2000℃, and the annealing temperature for the ZrSi2 sacrificial layer is 1400~1800℃.

2. The transition layer for a C / SiC composite substrate thin-film sensor as described in claim 1, characterized in that: The ZrC thin film has a thickness of 2~10μm, and the ZrSi2 sacrificial layer has a thickness of 1~7μm.

3. A method for preparing a transition layer for a C / SiC composite substrate thin-film sensor, characterized in that, Includes the following steps: Step 1: Treat the C / SiC composite substrate to ensure its surface is clean and dry; Step 2: Using ZrC particles with a purity ≥ 99.99 wt% as the coating material, a ZrC thin film layer is deposited on the C / SiC substrate obtained in Step 1 by electronic evaporation. Step 3: The structure obtained in Step 2 is subjected to high-temperature annealing to allow the Zr element in the ZrC thin film to diffuse toward the C / SiC composite substrate, thereby forming a structure composed of Zr... x C 1-x The gradient ceramic layer composed of amorphous ceramic phase is annealed at a temperature of 1400~2000℃. Step 4: Using a ZrSi2 target with a purity ≥ 99.99 wt% as the sputtering target, a ZrSi2 sacrificial layer is deposited on the gradient ceramic layer obtained in Step 3 by magnetron sputtering. Step 5: Anneal the structure obtained in Step 4 to oxidize the upper surface of the ZrSi2 sacrificial layer to obtain the ZrO2 framework and the SiO2-ZrSiO4 self-healing layer, thereby completing the preparation of the transition layer for the C / SiC composite substrate thin film sensor.

4. The method for preparing a transition layer for a C / SiC composite substrate thin-film sensor as described in claim 3, characterized in that: The treatment method for the C / SiC composite substrate in step 1 is as follows: the C / SiC composite substrate is placed in acetone, ethanol and deionized water in sequence for ultrasonic cleaning, each for 10 minutes. After cleaning, it is dried with a nitrogen gun and then dried to remove residual moisture.

5. The method for preparing a transition layer for a C / SiC composite substrate thin-film sensor as described in claim 3, characterized in that: The conditions for electron beam evaporation deposition of ZrC thin films in step 2 are as follows: 2.1 The vacuum level at the bottom of the electron beam evaporation chamber is less than 5×10⁻⁶. -4 Pa controls the temperature of the C / SiC composite substrate within the range of 250~350℃.

6. The method for preparing a transition layer for a C / SiC composite substrate thin-film sensor as described in claim 3, characterized in that: The high-temperature annealing conditions in step 3 are as follows: The structure obtained in step 2 was placed in an annealing furnace and annealed in an argon atmosphere at a temperature of 1400-2000℃ for 2-5 hours.

7. The method for preparing a transition layer for a C / SiC composite substrate thin-film sensor as described in claim 3, characterized in that: The sputtering conditions for step 4 are as follows: The back-bottom vacuum level of the sputtering device cavity is less than 8×10 -4 Pa, power of 200~350W, sputtering gas is argon, argon gas flow rate is 23~48sccm, sputtering pressure is 0.35Pa~0.5Pa.

8. The method for preparing a transition layer for a C / SiC composite substrate thin-film sensor as described in claim 3, characterized in that: The method for obtaining the ZrO2 framework and the SiO2-ZrSiO4 self-healing layer by annealing in step 5 is as follows: In 8×10 -4 In a vacuum environment below Pa, the temperature is raised to 1400~1800℃, and oxygen is introduced for oxidation annealing treatment. The annealing time is 1~8h, and a ZrO2 framework and a SiO2-ZrSiO4 self-healing layer can be obtained.

9. A C / SiC composite material substrate thin film sensor, comprising a C / SiC composite material substrate, a transition layer and an insulating layer stacked sequentially from bottom to top, wherein the transition layer is the transition layer for a C / SiC composite material substrate thin film sensor as described in claim 1, and the insulating layer is an Al2O3 insulating layer.

Images