A method for preparing a si-based multicomponent alloy bond layer in an environmental barrier coating

Abstract

The application provides a preparation method of a Si-based multi-component alloy bonding layer in an environmental barrier coating, and steps are as follows: S1, substrate preparation: taking SiC fiber reinforced SiC composite material as a substrate; S2, preparation of the Si-based multi-component alloy bonding layer: S21, the preparation process is carried out in a directional solidification crystal growth furnace, the furnace comprises a quartz glass tube, a graphite crucible and a heating device; S22, adding silicon material and X metal material into the graphite crucible; S23, fixing the substrate above the graphite crucible; S24, vacuumizing the quartz glass tube; S25, introducing cooling water, turning on the power supply, heating the graphite crucible through the heating device, until the silicon material and the X metal material in the graphite crucible are completely melted into Si-based alloy melt with fluidity; S26, immersing the pre-grown coating composite material substrate into the melt, and then gradually separating the substrate from the Si-based alloy melt through slow downward pulling of the graphite crucible, growing the Si-based alloy on the surface of the composite material uniformly, and preparing the Si-based multi-component alloy bonding layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular, especially relates to a preparation method of Si-based multi-component alloy bonding layer in environmental barrier coating. BACKGROUND

[0002] In the dry high-temperature combustion environment, a dense SiO2 layer is generated on the surface of the ceramic matrix composite material, and the oxidation layer has a certain fluidity and can heal the cracks and pores generated during the oxidation process, which can effectively hinder the entry of oxygen and enhance the oxidation resistance. However, during the actual operation of the aero-engine, 8-10 vol% of water vapor is generated in the combustion process of the hot end components of the aero-engine, SiO2 reacts with high-temperature steam to generate Si(OH)4, and the oxidation layer becomes loose and porous, becoming a channel for O 2 and OH- to enter, which aggravates the material failure. Therefore, it is necessary to prepare an environmental barrier coating on its surface to isolate high-temperature water vapor and inhibit the occurrence of high-temperature water-oxygen corrosion.

[0003] The third-generation environmental barrier coating is mainly composed of Si as the bonding layer and Re2SiO5 (wherein Re=Yb, Y, Gd, Lu, Nd) as the surface layer. Since Re2SiO5 has a large difference in thermal expansion coefficient with SiC, the thermal expansion coefficient of the Si bonding layer is between the two, which can effectively alleviate the thermal stress caused by the volume expansion or shrinkage of the adjacent layer interface during the thermal cycle oxidation process. In addition, Si as the bonding layer material can reduce the permeability of the oxidant, and provide excellent adhesion between adjacent layers; it has good chemical compatibility and can reduce or avoid the chemical reaction of by-products.

[0004] Traditional atmospheric plasma spraying is to realize coating preparation by spraying molten solid particles on the surface of the substrate at high temperature. However, in the atmospheric environment, the molten solid particles are easy to contact air and be partially oxidized, which has been reported in related literature. In addition, the great supercooling degree causes the coating to produce amorphous phase, and "steamed bun peak" can be observed in the XRD diffraction pattern. For this reason, some documents report that the plasma sprayed Si is heat-treated at 1150℃ for 4h to reduce the proportion of amorphous silicon and reduce the surface isolated particles Si that are not completely melted, but the static oxidation experiment obtains an oxidation rate of 0.1622 μm 2 / h, while the oxidation rate of the Si bonding layer obtained by the directional solidification pulling method can be as low as 0.025 μm 2 / h, which is reduced by about 85% compared with the former. This method has broad prospects as a preparation method of Si bonding layer. SUMMARY

[0005] The application provides a preparation method of a Si-based multi-component alloy bonding layer in an environmental barrier coating, and aims to provide a preparation method of a Si-based multi-component alloy bonding layer in an environmental barrier coating.

[0006] The application adopts the following technical means:

[0007] The application provides a preparation method of a Si-based multi-component alloy bonding layer in an environmental barrier coating, and aims to provide a preparation method of a Si-based multi-component alloy bonding layer in an environmental barrier coating.

[0008] S1, substrate preparation: taking SiC fiber reinforced SiC composite material as the substrate, polishing, cleaning and drying the substrate;

[0009] S2, preparation of the Si-based multi-component alloy bonding layer:

[0010] S21, the preparation process is carried out in a directional solidification crystal growth furnace, the directional solidification crystal growth furnace comprises a quartz glass tube and a heating device, a water platform is arranged in the quartz glass tube, a graphite crucible used for smelting experiments is arranged on the water platform, and the water platform can also realize the function of moving up and down; the heating device is arranged outside the quartz glass tube and used for heating the graphite crucible;

[0011] S22, silicon material and X metal material are added into the graphite crucible;

[0012] S23, the substrate is fixed above the quartz glass tube and directly above the mouth of the graphite crucible;

[0013] S24, the inside of the quartz glass tube is vacuumized;

[0014] S25, cooling water is introduced, the power supply of the equipment is turned on, the heating power is set, the graphite crucible is heated, and the silicon material and the X metal material in the graphite crucible are completely melted into Si-based alloy melt with fluidity;

[0015] S26, the composite material substrate of the pre-grown coating is immersed in the melt, then the composite material substrate is gradually separated from the Si-based alloy melt, the Si-based alloy is uniformly and directionally grown on the surface of the substrate, and the Si-based multi-component alloy bonding layer is prepared.

[0016] Further, the specific steps of the step S1 are as follows:

[0017] S11, using SiC fiber reinforced SiC composite material as a matrix, using diamond sand disc to polish the matrix sample into a rounded corner, and then cleaning;

[0018] S12, ultrasonic cleaning in ethanol solution for 5-10 min, and then ultrasonic cleaning in deionized water for 5-10 min, after cleaning, taking out and placing in a drying oven at 50-70℃ for 2-3 hours.

[0019] Further, in step S22, 25-35g of pure silicon block with a purity of 99% is added to the graphite crucible, and a certain amount of X metal material is added to the graphite crucible to form Si-X alloy, i.e. Si-based alloy, wherein X metal is at least one of Ti, Mo, Zr, Yb, Ni or Cr, or a combination of one or more.

[0020] Further, in step S23, the matrix is clamped and fixed by the graphite clamp, the graphite clamp is fixed at the top of the quartz glass tube through the graphite rod with M6 thread at the end, and is located directly above the mouth of the graphite crucible, the height and position of the graphite clamp are adjusted to ensure that the whole body does not touch the graphite crucible during lifting.

[0021] Further, in step S24, the air inside the quartz glass tube is pumped out by the vacuum pump, and after the vacuum pump is disabled, the internal cavity of the quartz glass tube is filled with argon; the argon washing process is repeated three times to ensure that the air is completely removed; argon is kept flowing continuously throughout the preparation process to prevent oxidation and discharge volatile products.

[0022] Further, the quartz glass tube is also provided with a thermocouple, which is located in the pulling rod supporting the water platform and directly connected to the bottom of the graphite crucible.

[0023] Further, in step S25, the temperature of the bottom of the graphite crucible is measured by the thermocouple, and during heating, the melt temperature in the graphite crucible is rapidly increased to 1600-1700℃ and maintained for 10 minutes to ensure the uniformity of the melt in the graphite crucible and the stability of the thermal field.

[0024] Further, the heating device and the water platform both have up and down movement function.

[0025] Further, the specific steps of step S26 are as follows:

[0026] S261, the heating device and the graphite crucible are lifted up at the same time at a speed of 20-60 mm / min, so that the composite material matrix of the pre-grown coating is immersed in the melt;

[0027] S262、reduce the heating power of the heating device, keep warm for two minutes, when the temperature decreases to 1450-1550 ℃, slowly pull down the heating device and the graphite crucible containing the alloy melt at a constant speed of 20~60mm / min, slowly pull the composite matrix from the Si-based alloy melt, the Si-based alloy grows uniformly on the surface of the matrix, and the Si-based multi-component alloy bonding layer is prepared.

[0028] Further, the heating device adopts an induction coil mounted on the outer wall of the quartz glass tube through a lifting structure for generating a 30-80 kHz high-frequency induction current to heat the graphite crucible.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. The present application can prepare Si-based multi-component alloy bonding layers of different thicknesses at different pulling speeds, and the coating thickness increases exponentially as the pulling speed decreases.

[0031] 2. The present application can prepare high-density, dendritic growth Si-based multi-component alloy coatings, and high vacuum can avoid oxidation of the coating during preparation, while improving the bonding strength of the coating and the substrate.

[0032] 3. The multi-component bonding layer prepared by the present application has excellent crystallinity and does not contain amorphous Si. The silicon grains exhibit excellent orientation, and show a very strong single diffraction peak in the XRD results.

[0033] 4. The bonding layer obtained by the present application has no obvious pores and cracks on the surface, and ions exchange at the grain boundaries. The large average grain size has a small grain boundary length, which greatly reduces the permeation and diffusion rate of O 2- and OH - , and significantly improves the oxidation resistance.

[0034] 5. The Si-based multi-component alloy bonding layer prepared by the present application has good oxidation resistance and water-oxygen corrosion resistance, and does not fall off obviously after 200h of static oxidation and water-oxygen corrosion at 1300℃, which can ensure the integrity of the coating.

[0035] Based on the above reasons, the present application can be widely used in the field of coating preparation. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0037] Figure 1 It is a schematic diagram of experimental equipment of the present application.

[0038] Figure 2 It is a flow chart of the method of the present application.

[0039] In the figure: 1, graphite rod; 2, graphite clamp; 3, ceramic sleeve; 4, carbon felt for heat preservation; 5, graphite crucible; 6, Si-X alloy raw material; 7, induction coil; 8, thermocouple. DETAILED DESCRIPTION

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0042] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0043] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0044] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0045] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0046] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0047] The application provides a preparation method of a Si-based multicomponent alloy bonding layer in an environmental barrier coating, and comprises the following steps:

[0048] 1. Preparation of the substrate:

[0049] The SiC fiber reinforced SiC composite material is used as the substrate (in this embodiment, a pure SiC block (25x10x3mm 3 ) is used as the substrate), and the sample is polished into a rounded corner by using a diamond sand disc, and then is cleaned. The sample is ultrasonically cleaned in an ethanol solution for 5-10 minutes, and then is ultrasonically cleaned in deionized water for 5-10 minutes, and is placed in a drying oven at 50-70 DEG C for 2-3 hours after being taken out.

[0050] 2. Preparation process of the Si-based multicomponent alloy bonding layer (in this experiment, Si-Mo is taken as an example):

[0051] (1) The experiment is carried out in a directional solidification crystal growth furnace (the experiment is carried out by using a heating mode of directional solidification induction melting). The directional solidification crystal growth furnace comprises a quartz glass tube and a heating device, a water platform capable of moving up and down is arranged in the quartz glass tube, a graphite crucible 5 used for melting experiments is arranged on the water platform, the heating device is movable up and down and is arranged outside. A thermocouple 8 and a graphite clamp 2 are further arranged in the quartz glass tube. The thermocouple is arranged at the bottom and is located in a lifting rod supporting the water platform, is directly connected to the bottom of the graphite crucible, the graphite clamp is fixed to the top of the quartz glass tube by a graphite rod 1 with an M6 thread and is located directly above the mouth of the graphite crucible (the graphite rod can be a Mo rod, the graphite rod is only used for fixing the graphite clamp and does not participate in the reaction process), the heating device adopts an induction coil 7, the induction coil is installed on the outer wall of the quartz glass tube by using a lifting structure, and the graphite crucible is heated by using high-frequency induction current (30-80 kHz) generated by the induction coil; a ceramic sleeve 3 is arranged outside the graphite crucible, and the ceramic sleeve 3 and the graphite crucible are provided with heat preservation carbon felt 4 therebetween, and Si-X alloy raw materials 6 are arranged in the graphite crucible;

[0052] (2) 30 grams of pure silicon blocks (with a purity of 99%) are added to the graphite crucible, and a certain amount of X metal materials (in this embodiment, Mo is selected as X, and the addition amount of the X metal materials is about 5-10g, and specifically, 5.4 grams of pure Mo particles are added in this experiment) are added to the graphite crucible, to form Si-X alloy, i.e. Si-based alloy. The content of the alloying element can be selected according to a corresponding Si-X (X is one of Ti, Mo, Zr, Yb, Ni or Cr, or a combination of one or more) binary phase diagram to select a suitable ratio and reaction temperature;

[0053] (3) The substrate is clamped and fixed by using the graphite clamp. The height and position of the graphite clamp are adjusted to ensure that the whole sample does not touch the graphite crucible during the lifting process of the sample;

[0054] (4) The air in the whole system is evacuated using a vacuum pump, and the inner cavity of the quartz glass tube is filled with argon (Ar) after the vacuum pump is disabled. The gas washing process is repeated three times to ensure that the air is completely removed. Argon (1 L / min) is kept flowing continuously throughout the experiment to prevent oxidation and to expel volatile products;

[0055] (5) Cool water is supplied, the power of the device is turned on, the heating power of the induction coil is set to heat the graphite crucible, until the pure silicon block and the X metal material in the graphite crucible are completely melted into a Si-based alloy melt with fluidity, and the temperature at the bottom of the graphite crucible is measured using a thermocouple. The melt temperature is quickly increased to 1550 ℃ and maintained for 10 minutes to ensure the uniformity of the melt in the crucible and the stability of the thermal field; wherein the water supply device of the cooling water is connected to the flanges at the top and bottom of the device to prevent the flanges from being too hot and to function as a cooling device.

[0056] (6) The induction coil and the graphite crucible are simultaneously lifted upwards at a speed of 60 mm / min, so that the composite substrate with a pre-grown coating is immersed in the melt;

[0057] (7) The heating power of the induction coil is reduced, and the temperature is maintained for two minutes. When the temperature decreases to 1500 ℃, the induction coil and the graphite crucible are simultaneously and slowly moved downwards at a constant speed, so that the composite substrate is slowly pulled away from the Si-based alloy melt. The Si-based alloy is uniformly and directionally grown on the surface of the substrate, and a Si-based multi-component alloy bonding layer is prepared.

[0058] 3. Oxidation performance test:

[0059] (1) Effect of pulling speed: control the same experimental conditions, and set the speed of separating the substrate from the melt to be 20 mm / min, 40 mm / min and 60 mm / min, and prepare 6 samples for each condition;

[0060] (2) Static oxidation: place three samples obtained at each separation speed in a 1300 ℃ tube furnace under atmospheric conditions, and oxidize them for 60 h, 100 h and 200 h respectively, and observe the microstructure of each sample coating. That is, three samples obtained at a separation speed of 20 mm / min are oxidized for 60 h, 100 h and 200 h respectively, three samples obtained at a separation speed of 40 mm / min are oxidized for 60 h, 100 h and 200 h respectively, and three samples obtained at a separation speed of 60 mm / min are oxidized for 60 h, 100 h and 200 h respectively.

[0061] (3) Water-oxygen corrosion: the remaining three samples obtained under each separation speed are placed at 1300 DEG C, the three samples under the same separation speed are corroded in 90% H2O-10% O2 corrosive gas for 60 hours, 100 hours and 200 hours, and the micro-morphology of the coating of each sample is observed. That is, the remaining three samples obtained under the separation speed of 20 mm / min are respectively corroded for 60 hours, 100 hours and 200 hours, the remaining three samples obtained under the separation speed of 40 mm / min are respectively corroded for 60 hours, 100 hours and 200 hours, and the remaining three samples obtained under the separation speed of 60 mm / min are respectively corroded for 60 hours, 100 hours and 200 hours.

[0062] By the method, the Si-based multi-component alloy bonding layer with different thicknesses can be prepared at different pulling speeds, and the pulling speed is reduced, and the coating thickness increases exponentially.

[0063] The Si-based multi-component alloy coating with high density and dendritic growth can be prepared by the method, oxidation of the coating can be avoided in the preparation process under high vacuum, and the bonding strength of the coating and the substrate is improved.

[0064] The multi-component bonding layer prepared by the method has excellent crystallinity and does not contain amorphous Si. The silicon grains show excellent orientation, and extremely strong single diffraction peaks are shown in the XRD results.

[0065] The bonding layer obtained by the method cannot be observed obvious pores and cracks on the surface, ions are exchanged at the grain boundaries, the large average grain size has small grain boundary length, the penetration and diffusion rate of O and OH is greatly reduced, and the oxidation resistance is significantly improved. 2- and OH -

[0066] The Si-based multi-component alloy bonding layer prepared by the method has good oxidation resistance and water-oxygen corrosion resistance, and is not obviously peeled off after static oxidation at 1300 DEG C and water-oxygen corrosion for 200 hours, so that the integrity of the coating can be ensured.

[0067] The Si-based multi-component alloy bonding layer in the environmental barrier coating system is prepared by the directional solidification pulling method for the first time, the Si-based alloy is melted to form an alloy melt, the SiCf / SiC composite material substrate is immersed in the melt, and the substrate is slowly pulled away from the alloy melt at a fixed speed, so that the Si-based alloy forms a bonding layer on the surface of the substrate by nucleation and growth, and a dense, grain size and morphology controllable Si-based alloy bonding layer coating is prepared.

[0068] ​The present application combines the equipment of induction melting and crystal growth, and through regulating the power of induction coil, the pulling speed, changing the flow state of Si-based alloy melt and the temperature gradient at the interface, the Si-based alloy can be uniformly grown on the surface of SiC.

[0069] In view of the problem that the low melting point of Si adhesive layer leads to low use temperature, the present application selects Ti, Mo, Zr, Yb, Ni, Cr and other alloy elements as alloy additives, introduces them into the Si melt to prepare the Si-based alloy melt, thereby growing the Si-based alloy adhesive layer on the surface of the substrate, improving the use temperature of the adhesive layer, and improving the oxidation resistance and water-oxygen corrosion resistance of the adhesive layer.

[0070] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a Si-based multi-component alloy binder layer in an environmental barrier coating, characterized in that, Includes the following steps: S1. Matrix preparation: Using SiC fiber reinforced SiC composite material as the matrix, the matrix is ​​polished, cleaned and dried. Preparation of S2 and Si-based multi-component alloy bonding layers: S21. The preparation process is carried out in a directional solidification crystal growth furnace, which includes a quartz glass tube and a heating device. A water platform is provided inside the quartz glass tube, and a graphite crucible for melting experiments is placed on the water platform. The heating device is placed outside the quartz glass tube to heat the graphite crucible. S22. Add silicon material and X metal material to the graphite crucible; S23. Fix the substrate inside the quartz glass tube and position it directly above the opening of the graphite crucible; S24. Vacuum the inside of the quartz glass tube; S25. Introduce cooling water, turn on the power of the equipment, and set the heating power to heat the graphite crucible until the silicon material and X metal material in the graphite crucible are completely melted into a fluid Si-based alloy melt. S26. The pre-grown coating of the composite matrix is ​​immersed in the melt, and then the composite matrix is ​​gradually separated from the Si-based alloy melt. The Si-based alloy grows uniformly and directionally on the surface of the matrix to prepare a Si-based multi-component alloy bonding layer.

2. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, The specific steps of step S1 are as follows: S11. Using SiC fiber-reinforced SiC composite material as the matrix, the matrix sample is ground into rounded corners using a diamond grinding disc, and then cleaned. S12. Sonicate in ethanol solution for 5-10 minutes, then sonicate in deionized water for 5-10 minutes. After cleaning, remove and place in a drying oven at 50-70℃ for 2-3 hours.

3. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, In step S22, 25-35g of pure silicon block with a purity of 99% is added to the graphite crucible, and a certain amount of X metal material is added to the graphite crucible to form a Si-X alloy, i.e., a Si-based alloy, wherein the X metal is at least one of Ti, Mo, Zr, Yb, Ni or Cr, or a combination of one or more.

4. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, In step S23, the base is clamped and fixed by a graphite clamp. The graphite clamp is fixed to the top of the quartz glass tube by a graphite rod with an M6 thread at the end, and is located directly above the opening of the graphite crucible. The height and position of the graphite clamp are adjusted to ensure that the whole body will not touch the graphite crucible during the lifting and lowering process.

5. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, In step S24, the air inside the quartz glass tube is evacuated by a vacuum pump, and after the vacuum pump is stopped, the cavity inside the quartz glass tube is filled with argon gas. The argon gas washing process is repeated three times to ensure that the air is completely removed. Argon gas is kept flowing continuously throughout the preparation process to prevent oxidation and remove volatile products.

6. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, A thermocouple is also installed inside the quartz glass tube. The thermocouple is located inside the lifting rod supporting the water platform and is directly connected to the bottom of the graphite crucible.

7. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 6, characterized in that, In step S25, the temperature at the bottom of the graphite crucible is measured by a thermocouple. During the heating process, the temperature of the melt inside the graphite crucible is rapidly increased to 1600~1700 ℃ and maintained for 10 minutes to ensure the uniformity of the melt and the stability of the thermal field in the graphite crucible.

8. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1, characterized in that, Both the heating device and the water platform have the function of moving up and down.

9. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 8, characterized in that, The specific steps of step S26 are as follows: S261. Simultaneously lift the heating device and the graphite crucible upwards at a speed of 20~60 mm / min to immerse the pre-grown coating composite matrix into the melt. S262. Reduce the heating power of the heating device and keep it at the temperature for two minutes. When the temperature drops to 1450-1550 ℃, slowly pull down the heating device and the graphite crucible containing the alloy melt at a constant speed of 20~60 mm / min. This will slowly pull the composite matrix out of the Si-based alloy melt, and the Si-based alloy will grow uniformly and directionally on the surface of the matrix to prepare a Si-based multi-component alloy bonding layer.

10. The method for preparing a Si-based multi-component alloy bonding layer in an environmental barrier coating according to claim 1 or 9, characterized in that, The heating device uses an induction coil, which is installed on the outer wall of a quartz glass tube via a lifting structure to generate a 30-80 kHz high-frequency induced current, which heats the graphite crucible.

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