CN111233498A - Environmental barrier coating and preparation method and application thereof - Google Patents
Environmental barrier coating and preparation method and application thereof Download PDFInfo
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Abstract
The environmental barrier coating provided by the invention consists of a SiC bonding layer, a mullite intermediate layer and a ytterbium silicate outer coating which are sequentially arranged from inside to outside and coated on a C/SiC composite material. The coating is prepared into the C/SiC composite material coated by the SiC coating by adopting a secondary chemical vapor deposition method; preparing a mullite intermediate layer by combining a sol-gel process and an air spraying process, and preparing a ytterbium silicate outer coating by combining solid reaction sintering and the air spraying process. According to the invention, through the design of a skillful EBC coating system and a preparation process, the ytterbium silicate outer coating is prepared by combining solid-phase reaction sintering with an air spraying process for the first time, so that the mullite intermediate layer and the ytterbium silicate outer coating are tightly combined, and the coating is compact and has no cracks. The traditional sol-gel process is improved to a great extent, the defects of cracking, peeling and poor binding force of the coating prepared by the traditional sol-gel method in the sintering process are avoided to a great extent, and the use of large-scale components and special-shaped parts can be met.
Description
Technical Field
The invention relates to the technical field of preparation of high-temperature oxidation/corrosion resistant composite coatings, and particularly relates to an environmental barrier coating and a preparation method and application thereof.
Background
The high thrust-weight ratio is one of the measurement marks of the high-performance aircraft engine, and the thrust-weight ratio can be obviously improved by increasing the temperature of a front air inlet of a turbine of the engine and reducing the density of materials. At present, the application temperature of the traditional high-temperature alloy material is close to the limit. Compared with the traditional high-temperature alloy material, the C/SiC composite material has the advantages of low density, high hardness, excellent high-temperature mechanical property, strong thermal shock resistance and the like, has high specific strength, can be kept at 1600 ℃ without reduction, is an ideal high-temperature structural material, and has wide application prospects in the fields of aerospace, energy chemical industry, weaponry, transportation and the like.
However, the carbon fibers in the C/SiC composite material begin to oxidize at 400 ℃ or higher, and the SiC matrix oxidizes at 1200 ℃ or higher to form SiO2The film reacts with water vapor in the environment to generate volatile Si (OH) x, which reduces the mechanical properties. The sensitivity of the C/SiC composite material to oxygen in a high-temperature environment limits the application of the C/SiC composite material to high-performance aircraft engines. Therefore, solving the problem of oxidation of carbon fibers in the C/SiC composite material under a high-temperature aerobic environment becomes a key technology for application of the carbon fibers in the aeroengine. Preparing an Environmental Barrier Coating (EBC) on a Ceramic Matrix Composite (CMC) including a C/SiC composite that ensures an Environmental barrier coatingThe hot-end component can stably operate in a high-temperature aerobic environment for a long time, and becomes one of core technologies for the development of the hot-end component in the future.
At present, the mainstream preparation methods of the EBC coating are a plasma spraying method and a physical vapor deposition method, but the two methods have the disadvantages of complex process, expensive equipment and higher preparation cost. Other common methods such as the sol-gel method have simple preparation process and low cost, but the prepared coating is easy to shrink and crack and is not suitable for preparing large components and special-shaped parts.
Therefore, the development of a novel coating preparation technology which is low in cost, high in efficiency and suitable for large-sized components and special-shaped parts has great significance for the development of the EBC coating in the future. The multilayer EBC coating is prepared on the surface of the C/SiC composite material of a large-scale component and a special-shaped part so as to improve the application capability of the hot end material of the engine in a complex environment, and has important guiding significance for promoting the development of a high-performance aircraft engine.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art, and provides an environmental barrier coating and a preparation method thereof.
The purpose of the invention is realized by the following technical scheme:
discloses an environmental barrier coating, which consists of a SiC bonding layer, a mullite intermediate layer and a ytterbium silicate outer coating which are coated on a C/SiC composite material and are arranged in sequence from inside to outside.
The environmental barrier coating of the present invention consists essentially of a tie layer/intermediate layer/outer coating three layer structure. The SiC coating has a thermal expansion coefficient similar to that of the C/SiC composite material, and the compatibility of the C/SiC composite material and the C/SiC composite material is very good, so that the SiC coating is selected as a bonding and transition layer of the EBC coating, and oxygen can be effectively prevented from diffusing to a matrix. Mullite has the advantages of low heat conduction coefficient and thermal expansion coefficient, good high-temperature phase stability, high-temperature strength and the like, has a thermal expansion coefficient similar to that of a SiC coating, is an ideal EBC coating intermediate layer material, and can prevent oxygen from diffusing to the inside. Ytterbium silicate has the advantages of high melting point, good chemical stability with mullite at high temperature, strong resistance to corrosion in a steam environment and the like, and is used as an outer coating of an environmental barrier coating to improve the corrosion resistance of the coating in a high-temperature water-oxygen environment.
Another object of the present invention is to provide a method for preparing an environmental barrier coating, comprising the steps of:
s1, preparing a SiC bonding layer by a secondary chemical vapor deposition method
Grinding the surface of the C/SiC composite material by using sand paper, then ultrasonically cleaning and drying the C/SiC composite material, and placing the C/SiC composite material in a chemical vapor deposition furnace; continuously introducing a deposition gas source, a carrier gas and a diluent gas to control the temperature in the furnace to be 1050-1200 ℃; after the first deposition, turning the sample by 180 degrees in the vertical direction for second deposition, and cooling along with the furnace to obtain a SiC bonding layer coated C/SiC composite material sample;
s2, preparing a mullite middle layer by using a sol-gel combined air spraying process
S21, taking soluble aluminum salt and silicate as raw materials, wherein the molar ratio of Al: si: organic solvent one: the catalyst = 2-3: 1-1.5: 15-25: 0.3-0.5, and carrying out hydrolysis and condensation reaction to obtain mullite precursor sol; respectively preparing mullite micropowder A and mullite precursor gel B by using the mullite precursor sol;
s22, mixing the mullite micropowder A: the mullite precursor gel B is prepared from the following components in a mass ratio of 4-6: 1 preparing a pre-calcined mullite mixture; preparing a film forming aid in an amount of 0.5-1 wt.% and a drying inhibitor I in an amount of 1-3 wt.% based on the total mass of the pre-calcined mullite mixture; adding a second organic solvent, and uniformly ball-milling to obtain mullite coating precursor slurry, wherein the mass ratio of the total mass of the pre-calcined mullite mixture to the second organic solvent is 20-30 wt.%; uniformly coating the mullite coating precursor slurry on the surface of the SiC bonding layer through an air spraying process, and sintering at 1300-1500 ℃ in an air environment to obtain a mullite intermediate layer;
s3, preparing ytterbium silicate outer coating by using solid reaction sintering and air spraying process
S31, taking oxide powder of ytterbium and silicon as a raw material, and mixing the raw material according to a molar ratio of Yb: si = 1.05-1.1: 1, preparing raw materials, performing ball milling to obtain ytterbium and silicon oxide mixed powder, sintering the ytterbium and silicon oxide mixed powder in a muffle furnace at 1400-1600 ℃ for 4-8 hours, and continuously performing ball milling at a rotating speed of 200-300 r/min for more than 10 hours after grinding to obtain ytterbium silicate micro powder C;
s32, preparing a sintering aid in an amount of 0.5-1 wt.% based on the total mass of the ytterbium silicate micro powder C, and preparing a second drying inhibitor in an amount of 0.5-2 wt.%; adding an organic solvent III, performing ball milling uniformly to obtain ytterbium silicate coating precursor slurry, and preparing the mass ratio of the total mass of the pre-calcined ytterbium silicate powder C, the sintering aid and the drying inhibitor II to the organic solvent III to be 40-60 wt%; and uniformly coating the precursor slurry of the ytterbium silicate coating on the surface of the mullite intermediate layer through an air spraying process, and sintering at 1200-1400 ℃ in an air environment to obtain the ytterbium silicate outer coating.
The invention develops a preparation method which is low in cost, high in efficiency and suitable for preparing a large-scale component and a special-shaped component multi-layer EBC coating; according to the functions of each coating in the EBC coating, an EBC coating system and a preparation method of each coating are optimally designed to meet the requirements of practical application.
The SiC bonding layer is prepared by adopting a secondary chemical vapor deposition method, firstly, the microcracks generated in the primary deposition can be covered by the SiC bonding layer deposited for the second time, so that the microcracks of the two layers are staggered, the oxygen-entry blocking capability is improved, and secondly, the thickness of the SiC bonding layer on each surface of the sample is basically the same; the whole SiC bonding layer can realize molecular level densification, and can effectively prevent oxygen from diffusing to a base material; the prepared mullite intermediate layer has low oxygen diffusion rate and can effectively block the diffusion of oxygen; the prepared ytterbium silicate outer coating can effectively prevent the corrosion of a water vapor-oxygen environment.
The ytterbium silicate outer coating adopts a method of combining solid reaction sintering with an air spraying process, has simple process and low preparation cost, meets the preparation requirements of large and special-shaped components, greatly improves the preparation efficiency of the coating, and realizes the aims of controllable coating thickness, high density and no crack.
Further, in step S1, the pressure in the deposition furnace is 0.3-0.6 kPa, the flow rate of the deposition gas source is 800-1000 mL/min, the flow rate of the carrier gas is 1500-2500 mL/min, and the flow rate of the dilution gas is 1500-2500 mL/min; the time of each deposition is 15-25 h. The deposition gas source in the present invention is preferably trichloromethylsilane (MTS), the carrier gas is preferably hydrogen, and the diluent gas is preferably argon.
Further, the soluble aluminum salt is at least one of aluminum nitrate, anhydrous aluminum chloride and aluminum isopropoxide; the silicate is at least one of ethyl orthosilicate, methyl orthosilicate and propyl orthosilicate; the organic solvent I, the organic solvent II and the organic solvent III are at least one of absolute ethyl alcohol and absolute methyl alcohol; the catalyst is at least one of hydrochloric acid, glacial acetic acid and hydrofluoric acid.
Further, the hydrolysis and condensation process specifically comprises: hydrolyzing at 60-80 ℃, adding a catalyst, heating to 80-90 ℃, and carrying out condensation reaction for at least 16 h.
Further, the mullite micro powder A is prepared by drying the mullite precursor sol at 60-80 ℃ for 48-96 h; then ball milling is carried out at the rotating speed of 150-250 r/min, and finally calcining is carried out for 1.5-3 h in the air environment at the temperature of 1100-1300 ℃ to obtain the catalyst; and the mullite precursor gel B is obtained by aging the mullite precursor sol at room temperature for 2-4 months.
Further, in step S22, the drying inhibitor is at least one selected from oxalic acid dihydrate and glycerol; the film-forming assistant is at least one of polyvinylpyrrolidone and polyvinyl butyral.
Further, in steps S22 and S32, in the air spraying process, the spray gun nozzle is perpendicular to the surface of the sample; the diameter of the spray gun is 0.5-1 mm, the spraying pressure is 0.4-0.8 MPa, the spraying distance is 10-25 mm, and the temperature of a sample is 120-140 ℃ during spraying.
Further, the oxide of ytterbium and silicon in step S31 is Yb2O3With SiO2The purity is analytical purity; the sintering aid is Y2O3At least one of CaO and MgO; the organic solventThe third agent is at least one of absolute ethyl alcohol and absolute methyl alcohol; the drying inhibitor is at least one selected from oxalic acid dihydrate and glycerol.
The preparation method of the environmental barrier coating improves the traditional sol-gel process for preparing the environmental barrier coating, combines the traditional sol-gel process with the air spraying method, and can greatly improve the defects of easy cracking, uneven thickness distribution, poor binding force and the like of the coating prepared by the traditional sol-gel method; the addition of the corresponding powder into the coating precursor slurry can improve the ceramic yield in the sintering process, and greatly avoid the volume shrinkage of the pre-sintered coating in the sintering process.
The method combines the solid-phase reaction sintering and the air spraying process for preparing the outer coating for the first time, has simple process and low preparation cost, meets the preparation requirements of large and special-shaped components, greatly improves the preparation efficiency of the EBC coating, realizes the preparation of the mullite intermediate layer and the ytterbium silicate outer coating which have controllable coating thickness, high density and no cracks, and has the potential of practical popularization and industrialization.
The invention also aims to disclose the application of the coating prepared by the preparation method of the environmental barrier coating, and the coating is suitable for preparing large-scale components and special-shaped components in the fields of aerospace, energy and chemical industry, weaponry, transportation and transportation.
Compared with the prior art, the invention has the beneficial effects that:
(1) the multi-layer EBC coating which is low in cost, high in efficiency and suitable for preparing large-scale components and special-shaped components and the preparation method thereof are developed; according to the functions of each coating in the EBC coating, an EBC coating system and a preparation method of each coating are optimally designed to meet the requirements of practical application.
(2) The traditional sol-gel process for preparing the EBC coating is improved, and the traditional sol-gel process is combined with the air spraying method, so that the defects of easy cracking, uneven thickness distribution, poor binding force and the like of the coating prepared by the traditional sol-gel method can be greatly improved; the addition of the corresponding powder into the coating precursor slurry can improve the ceramic yield in the sintering process, and greatly avoid the volume shrinkage of the pre-sintered coating in the sintering process.
(3) The sol-gel method and the solid-phase reaction sintering method are combined with the air spraying process for the first time to prepare the multi-layer EBC coating system. The method has simple process and low preparation cost, meets the preparation requirements of large and special-shaped components, greatly improves the preparation efficiency of the EBC coating, realizes the preparation of the mullite intermediate layer and the ytterbium silicate outer coating which have controllable coating thickness, high density and no cracks, and has the potential of practical popularization and industrialization.
In conclusion, the ytterbium silicate outer coating is prepared by the ingenious EBC coating system and preparation process through the solid-phase reaction sintering and air spraying process for the first time, so that the mullite intermediate layer and the ytterbium silicate outer coating are tightly combined, and the coating is compact and has no cracks. The traditional sol-gel process is improved to a great extent, and the defects of cracking, peeling and poor binding force of the coating prepared by the traditional sol-gel method in the sintering process are avoided to a great extent.
Drawings
FIG. 1 is a photomicrograph of an environmental barrier coating according to example 2 of the present invention.
FIG. 2 is a surface SEM photograph of a SiC bond coat in an environmental barrier coating described in example 2 of the present invention.
FIG. 3 is an XRD pattern of the surface of a SiC bond coat layer in an environmental barrier coating as described in example 2 of the present invention.
FIG. 4 is a SEM photograph of the surface of a mullite intermediate layer in an environmental barrier coating as described in example 2 of the present invention.
FIG. 5 is an XRD pattern of the surface of a mullite intermediate layer in an environmental barrier coating in accordance with example 2 of the present invention.
FIG. 6 is an SEM photograph of the surface of the ytterbium silicate overcoat in the environmental barrier coating of example 2 of the present invention.
FIG. 7 is a surface XRD pattern of an ytterbium silicate overcoat in an environmental barrier coating described in example 2 of the present invention.
FIG. 8 is a graph showing the constant temperature oxidative weight loss curves at 1400 ℃ of the environmental barrier coatings prepared in example 2 of the present invention and comparative examples 1 to 3.
Detailed Description
The invention discloses an environmental barrier coating, which consists of a SiC bonding layer, a mullite intermediate layer and a ytterbium silicate outer coating which are coated on a C/SiC composite material and are sequentially arranged from inside to outside. The preparation method comprises the following steps:
s1, preparing a SiC bonding layer by a secondary chemical vapor deposition method
Grinding the surface of the C/SiC composite material by using sand paper, ultrasonically cleaning and drying the C/SiC composite material, and then placing the C/SiC composite material in a chemical vapor deposition furnace; continuously introducing a deposition gas source (MTS), a carrier gas (hydrogen) and a diluent gas (argon), and controlling the temperature in the furnace to be 1050-1200 ℃; after the first deposition, turning the sample by 180 degrees in the vertical direction for second deposition, and cooling along with the furnace to obtain a SiC bonding layer coated C/SiC composite material sample; specifically, the pressure in the deposition furnace is 0.3-0.6 kPa, the flow rate of MTS is 800-1000 mL/min, the flow rate of hydrogen is 1500-2500 mL/min, and the flow rate of argon is 1500-2500 mL/min; the time of each deposition is 15-25 h.
S2, preparing a mullite middle layer by using a sol-gel combined air spraying process
S21, taking soluble aluminum salt and silicate as raw materials, wherein the molar ratio of Al: si: organic solvent one: the catalyst = 2-3: 1-1.5: 15-25: 0.3-0.5, and carrying out hydrolysis and condensation reaction to obtain mullite precursor sol; the hydrolysis and condensation process is specifically that after hydrolysis is carried out at 60-80 ℃, a catalyst is added, and the temperature is raised to 80-90 ℃ for condensation reaction for at least 16 h.
Then, respectively preparing mullite micropowder A and mullite precursor gel B by using the mullite precursor sol; the mullite micropowder A is prepared by drying a mullite precursor sol at 80 ℃ for 48-96 h, then ball-milling at 150-250 r/min, and calcining at 1100-1300 ℃ for 1.5-3 h in an air environment; the mullite precursor gel B is obtained by aging the mullite precursor sol at room temperature for 2-4 months.
S22, mixing the mullite micropowder A: mullite precursor gel B = 4-6: 1, preparing a pre-calcined mullite mixture; preparing a film forming aid in an amount of 0.5-1 wt.% and a drying inhibitor I in an amount of 1-3 wt.% based on the total mass of the pre-calcined mullite mixture; adding a second organic solvent, and performing ball milling uniformly to obtain mullite coating precursor slurry, wherein the mass ratio of the total mass of the pre-calcined mullite mixture to the second organic solvent is 20-30 wt.%; uniformly coating the mullite coating precursor slurry on the surface of the SiC bonding layer through an air spraying process, and sintering at 1300-1500 ℃ in an air environment to obtain a mullite intermediate layer; wherein, the organic solvent I and the organic solvent II are selected from at least one of absolute ethyl alcohol and absolute methyl alcohol, and the drying inhibitor I is selected from at least one of oxalic acid dihydrate and glycerol; the film forming assistant is at least one of polyvinylpyrrolidone and polyvinyl butyral.
In the spraying process of the air spraying process, a spray gun nozzle is vertical to the surface of a sample; the diameter of the spray gun is 0.5-1 mm, the spraying pressure is 0.4-0.8 MPa, the spraying distance is 10-25 mm, and the temperature of a sample is 120-140 ℃ during spraying.
S3, preparing ytterbium silicate outer coating by using solid reaction sintering and air spraying process
S31, taking oxide powder of ytterbium and silicon as a raw material, and mixing the raw material according to a molar ratio of Yb: si = 1.05-1.1: 1, preparing raw materials, performing ball milling to obtain ytterbium and silicon oxide mixed powder, placing the ytterbium and silicon oxide mixed powder in a muffle furnace, sintering for 4-8 hours in an air environment at 1400-1600 ℃, and performing ball milling for more than 10 hours at a rotating speed of 200-300 r/min after grinding to obtain ytterbium silicate micro powder C; wherein the oxide of ytterbium and silicon is Yb2O3With SiO2The purity is analytical purity.
S32, preparing a sintering aid in an amount of 0.5-1 wt.% based on the total mass of the ytterbium silicate micro powder C, and preparing a second drying inhibitor in an amount of 0.5-2 wt.%; adding an organic solvent III, performing ball milling uniformly to obtain ytterbium silicate coating precursor slurry, and preparing the mass ratio of the total mass of the pre-calcined ytterbium silicate powder C, the sintering aid and the drying inhibitor II to the organic solvent III to be 40-60 wt%; and uniformly coating the precursor slurry of the ytterbium silicate coating on the surface of the mullite intermediate layer through an air spraying process, and sintering at 1200-1400 ℃ in an air environment to obtain the ytterbium silicate outer coating. Wherein the sintering aid is Y2O3At least one of CaO and MgO; the organic solvent III is at least one of absolute ethyl alcohol and absolute methyl alcohol; the drying inhibitor is at least one selected from oxalic acid dihydrate and glycerol。
The specific embodiment is as follows.
Example 1
The method for preparing the environmental barrier coating of the embodiment comprises the following steps:
s1 preparation of SiC adhesive layer by secondary chemical vapor deposition
Grinding the surface of the C/SiC composite material by using sand paper, ultrasonically cleaning and drying the C/SiC composite material, and then placing the C/SiC composite material in a chemical vapor deposition furnace; continuously introducing trichloromethylsilane (MTS), hydrogen and argon, controlling the temperature in the furnace to be 1100 ℃, the pressure in the furnace to be 0.3-0.6 kPa, the flow rate of the trichloromethylsilane (MTS) to be 800-1000 mL/min, the flow rate of the hydrogen to be 1500-2500 mL/min and the flow rate of the argon to be 1500-2500 mL/min; after 25h of first deposition, the sample is turned 180 degrees in the vertical directionoCarrying out secondary deposition, wherein the total deposition time is 50h, and cooling along with the furnace to obtain a secondary deposited SiC bonding layer coated C/SiC composite material sample;
s2 preparation of mullite intermediate layer by sol-gel combined air spraying process
S21, dissolving 20.83g of ethyl orthosilicate and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, heating in a water bath at 60 ℃ for 4h, heating to 80 ℃ for 16h to obtain mullite precursor sol, drying the sol at 60-80 ℃ for 72h, ball-milling at a rotating speed of 250r/min for 2h, putting the sol into a muffle furnace, setting a heating rate of 5 ℃/min, keeping the temperature at 1200 ℃ for 2h, and cooling to room temperature along with the furnace to obtain mullite micropowder A;
dissolving 20.83g of tetraethoxysilane and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, heating in a water bath at the temperature of 60 ℃, reacting for 4h, heating to 80 ℃, reacting in the water bath for 16h to obtain mullite precursor sol, and standing and aging the sol in a sealed environment at room temperature for 2 months to obtain milky mullite precursor gel B;
s22, weighing 15.4g of mullite micropowder A, 4g of mullite precursor gel B, 0.2g of polyvinylpyrrolidone (PVP) and 0.4g of oxalic acid dihydrate, adding into 48ml of absolute ethanol solution, and ball-milling at the rotating speed of 200r/min for 1.5h to obtain a mullite coating precursor solution; then adding 12ml of acetone solution into the mullite coating precursor solution, and carrying out ball milling for 0.5h at the rotating speed of 200r/min to obtain mullite coating precursor slurry; placing the C/SiC composite material coated with the SiC bonding layer in a drying box, heating to 120 ℃, spraying slurry by using an air spraying process, controlling the spraying pressure to be 0.4-0.8 MPa, the nozzle diameter to be 0.5mm, the spraying distance to be 15-25 mm, and the temperature of a sample during spraying to be 120-140 ℃; and after the spraying is finished, keeping the temperature in a drying box at 80 ℃ for 8h, and then placing the drying box in a tubular furnace to be sintered at 1300 ℃ for 3h to obtain the mullite intermediate layer.
S3 preparation of ytterbium silicate outer coating by using solid reaction sintering and air spraying process
S31 weighing 30g Yb2O3Powder, 4.6g SiO2Mixing the powder, ball milling for 5h at the rotating speed of 250r/min to obtain uniformly mixed Yb2O3+SiO2Mixing the powder; yb of2O3+SiO2Placing the mixed powder in a muffle furnace, sintering for 6h in 1500 ℃ air environment, and continuously performing ball milling for 15h at the rotating speed of 200r/min to obtain ytterbium silicate micro powder C;
s32, weighing 20g of ytterbium silicate micro powder C and 0.2gY g of ytterbium silicate micro powder C2O3Adding 0.3g of oxalic acid dihydrate into 90ml of absolute ethyl alcohol solution, and performing ball milling at the rotating speed of 200r/min for 2 hours to obtain ytterbium silicate coating precursor slurry; placing the C/SiC composite material coated by the mullite intermediate layer/SiC bonding layer in a drying box, heating to 120 ℃, spraying slurry by using an air spraying process, and controlling the spraying pressure to be 0.4-0.8 MPa, the diameter of a nozzle to be 0.5mm and the spraying distance to be 15-25 mm; and after the spraying is finished, preserving the heat for 8 hours in a drying oven at the temperature of 80 ℃, and then placing the drying oven in a tubular furnace to sinter for 3 hours at the temperature of 1300 ℃ to obtain a sample of the ytterbium silicate/mullite/SiC-coated C/SiC composite material. After being oxidized for 100 hours in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is only 0.56 percent, and the composite material has excellent high-temperature oxidation resistance.
Example 2
The method for preparing the environmental barrier coating of the embodiment comprises the following steps:
s1 preparation of SiC adhesive layer by secondary chemical vapor deposition
Grinding the surface of the C/SiC composite material by using sand paper, and then ultrasonically cleaningCleaning and drying, and then placing in a chemical vapor deposition furnace; continuously introducing trichloromethylsilane (MTS), hydrogen and argon, controlling the temperature in the furnace to be 1150 ℃, the pressure in the furnace to be 0.3-0.6 kPa, the flow rate of the trichloromethylsilane (MTS) to be 800-1000 mL/min, the flow rate of the hydrogen to be 1500-2500 mL/min and the flow rate of the argon to be 1500-2500 mL/min; after 25h of first deposition, the sample is turned 180 degrees in the vertical directionoCarrying out secondary deposition, wherein the total deposition time is 50h, and cooling along with the furnace to obtain a secondary deposited SiC bonding layer coated C/SiC composite material sample;
s2, preparing a mullite intermediate layer by a sol-gel combined air spraying process
S21, dissolving 20.83g of ethyl orthosilicate and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, carrying out water bath heating reaction at 80 ℃ for 4h, heating to 90 ℃ for water bath reaction for 16h to obtain mullite precursor sol, drying the sol at 60-80 ℃ for 96h, carrying out ball milling at 200r/min for 2h, putting the sol into a muffle furnace, setting the heating rate to be 5 ℃/min, keeping the temperature at 1300 ℃ for 2h, and cooling to room temperature along with the furnace to obtain mullite micropowder A;
dissolving 20.83g of tetraethoxysilane and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, heating in a water bath at the temperature of 60 ℃, reacting for 4h, heating to 80 ℃, reacting in the water bath for 16h to obtain mullite precursor sol, and standing and aging the sol in a sealed environment at room temperature for 3 months to obtain milky mullite precursor gel B;
s22, weighing 15.4g of mullite micropowder A, 4g of mullite precursor gel B, 0.2g of polyvinylpyrrolidone (PVP) and 0.4g of oxalic acid dihydrate, adding into 48ml of absolute ethanol solution, and ball-milling at the rotating speed of 200r/min for 1.5h to obtain a mullite coating precursor solution; then adding 12ml of acetone solution into the mullite coating precursor solution, and carrying out ball milling for 0.5h at the rotating speed of 200r/min to obtain mullite coating precursor slurry; placing the C/SiC composite material coated with the SiC bonding layer in a drying box, heating to 120 ℃, spraying slurry by using an air spraying process, and controlling the spraying pressure to be 0.4-0.8 MPa, the diameter of a nozzle to be 0.5mm and the spraying distance to be 15-25 mm; and after the spraying is finished, keeping the temperature in a drying box at 80 ℃ for 8h, and then placing the drying box in a tubular furnace to sinter for 3h at 1400 ℃ to obtain the mullite intermediate layer.
S3 preparation of ytterbium silicate outer coating by combining solid reaction sintering and air spraying process
S31 weighing 30g Yb2O3Powder, 4.6g SiO2Mixing the powder, ball milling for 5h at the rotating speed of 250r/min to obtain uniformly mixed Yb2O3+SiO2Mixing the powder; yb of2O3+SiO2Placing the mixed powder in a muffle furnace, sintering for 6h in 1500 ℃ air environment, and continuously performing ball milling for 15h at the rotating speed of 200r/min to obtain ytterbium silicate micro powder C;
s32, weighing 20g of ytterbium silicate micro powder C and 0.2gY g of ytterbium silicate micro powder C2O3Adding 0.3g of oxalic acid dihydrate into 90ml of absolute ethyl alcohol solution, and performing ball milling at the rotating speed of 200r/min for 2 hours to obtain ytterbium silicate coating precursor slurry; placing the C/SiC composite material coated by the mullite intermediate layer/SiC bonding layer in a drying box, heating to 130 ℃, spraying slurry by using an air spraying process, and controlling the spraying pressure to be 0.4-0.8 MPa, the diameter of a nozzle to be 0.5mm and the spraying distance to be 15-25 mm; and after the spraying is finished, preserving the heat for 8 hours in a drying oven at the temperature of 80 ℃, and then placing the drying oven in a tubular furnace to sinter for 3 hours at the temperature of 1400 ℃ to obtain a sample of the ytterbium silicate/mullite/SiC-coated C/SiC composite material. A macroscopic photograph of the environmental barrier coating prepared by the method of this example is shown in fig. 1. The sample of the environmental barrier coating is embedded with a resin material, and the environmental barrier coating is formed by a three-layer structure of a SiC bonding layer, a mullite middle layer and an ytterbium silicate outer coating which are coated with C/SiC. After being oxidized for 100 hours in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is only 0.52 percent, and the composite material has excellent high-temperature oxidation resistance.
Fig. 2 and fig. 3 show the surface microstructure and XRD pattern of the SiC bonding layer prepared by the second chemical vapor deposition in step S1, respectively, and it can be seen that the SiC bonding layer is composed of typical pebble-like fine particles of the coating prepared by the vapor deposition method, and the SiC bonding layer is uniform and dense. The XRD pattern shows that only a single SiC phase exists in the SiC bonding layer, the purity of the SiC is high, and other impurity phases are not generated.
Fig. 4 and 5 show the surface micro-morphology and XRD pattern of the mullite intermediate layer prepared by the sol-gel combined air spraying process in step S2, which shows that the mullite intermediate layer is uniformly distributed without obvious micro-cracks, and some micro-pores are caused by the volatilization of the solvent in the slurry during the coating spraying and sintering processes, and the micro-pores gradually heal along with the sintering process. The XRD pattern shows that only a single mullite phase exists in the mullite intermediate layer, the mullite purity is high, and other impurity phases are not contained.
Fig. 6 and 7 respectively show the surface micro-morphology and XRD pattern of the ytterbium silicate coating prepared by the solid reaction sintering and air spraying processes in step S3, which shows that the ytterbium silicate coating is uniformly distributed without obvious micro-cracks, and some micro-pores are caused by volatilization of the solvent in the slurry during the coating spraying and sintering processes, and the micro-pores gradually heal along with the sintering process. The XRD pattern shows that only a single ytterbium silicate phase exists in the ytterbium silicate outer coating, the ytterbium silicate has high purity and no other impurity phases.
Example 3
The method for preparing the environmental barrier coating of the embodiment comprises the following steps:
s1 preparation of SiC adhesive layer by secondary chemical vapor deposition
Grinding the surface of the C/SiC composite material by using sand paper, ultrasonically cleaning and drying the C/SiC composite material, and then placing the C/SiC composite material in a chemical vapor deposition furnace; continuously introducing a deposition gas source, a carrier gas and a diluent gas, controlling the temperature in the furnace to be 1200 ℃, the pressure in the furnace to be 0.3-0.6 kPa, the flow of trichloromethylsilane (MTS) to be 800-1000 mL/min, the flow of hydrogen to be 1500-2500 mL/min and the flow of argon to be 1500-2500 mL/min; after 15h of first deposition, the sample is turned 180 degrees in the vertical directionoCarrying out secondary deposition, wherein the total deposition time is 30h, and cooling along with the furnace to obtain a secondary deposited SiC bonding layer coated C/SiC composite material sample;
s2, preparing a mullite intermediate layer by a sol-gel combined air spraying process
S21, dissolving 20.83g of ethyl orthosilicate and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, heating in a water bath at 60 ℃ for 4h, heating to 80 ℃ for 16h to obtain mullite precursor sol, drying the sol at 60-80 ℃ for 48h, ball-milling at a rotating speed of 250r/min for 2h, putting the sol into a muffle furnace, setting a heating rate of 5 ℃/min, keeping the temperature at 1100 ℃ for 2h, and cooling to room temperature along with the furnace to obtain mullite micropowder A;
dissolving 20.83g of tetraethoxysilane and 112.53g of aluminum nitrate nonahydrate in 100ml of absolute ethyl alcohol, adding 3.60g of glacial acetic acid, heating in a water bath at the temperature of 60 ℃, reacting for 4h, heating to 80 ℃, reacting in the water bath for 16h to obtain mullite precursor sol, and standing and aging the sol in a sealed environment at room temperature for 2-4 months to obtain milky mullite precursor gel B;
s22, weighing 15.4g of mullite micropowder A, 4g of mullite precursor gel B, 0.2g of polyvinylpyrrolidone (PVP) and 0.4g of oxalic acid dihydrate, adding into 48ml of absolute ethanol solution, and ball-milling at the rotating speed of 200r/min for 1.5h to obtain a mullite coating precursor solution; then adding 12ml of acetone solution into the mullite coating precursor solution, and carrying out ball milling for 0.5h at the rotating speed of 200r/min to obtain mullite coating precursor slurry; placing the C/SiC composite material coated with the SiC bonding layer in a drying box, heating to 120 ℃, spraying slurry by using an air spraying process, and controlling the spraying pressure to be 0.4-0.8 MPa, the diameter of a nozzle to be 0.5mm and the spraying distance to be 15-25 mm; and after the spraying is finished, keeping the temperature in a drying box at 80 ℃ for 8h, and then placing the drying box in a tubular furnace to sinter for 1.5h at 1500 ℃ to obtain the mullite intermediate layer.
S3 preparation of ytterbium silicate outer coating by combining solid reaction sintering and air spraying process
S31 weighing 30g Yb2O3Powder, 4.6g SiO2Mixing the powders, and ball-milling at the rotating speed of 250r/min for 5h to obtain uniformly mixed Yb2O3+SiO2Mixing the powder; yb of2O3+SiO2Sintering the mixed powder in a muffle furnace at 1500 ℃ in an air environment for 6 hours, and continuously performing ball milling at the rotating speed of 200r/min for 15 hours to obtain ytterbium silicate micro powder C;
s32, weighing 20g of ytterbium silicate micro powder C and 0.2gY g of ytterbium silicate micro powder C2O3Adding 0.3g of oxalic acid dihydrate into 90ml of absolute ethyl alcohol solution, and performing ball milling at the rotating speed of 200r/min for 2 hours to obtain ytterbium silicate coating precursor slurry;
placing the C/SiC composite material coated by the mullite intermediate layer/SiC bonding layer in a drying box, heating to 140 ℃, spraying slurry by using an air spraying process, and controlling the spraying pressure to be 0.4-0.8 MPa, the nozzle diameter to be 0.5mm and the spraying distance to be 15-25 mm; and after the spraying is finished, preserving the heat for 8 hours in a drying oven at the temperature of 80 ℃, and then placing the drying oven in a tubular furnace to sinter for 3 hours at the temperature of 1400 ℃ to obtain a sample of the ytterbium silicate/mullite/SiC-coated C/SiC composite material. After being oxidized for 100 hours in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is only 0.63 percent, and the composite material has excellent high-temperature oxidation resistance.
Example 4
The preparation method of the environmental barrier coating of this example is substantially the same as that of example 2, except that, in step S2, 20.83g of methyl orthosilicate and 93.78g of anhydrous aluminum chloride are dissolved in 145.75ml of anhydrous methanol, 2.0g of glacial acetic acid is added, the mixture is heated in a water bath at 70 ℃ for 4 hours to react, and then the temperature is raised to 90 ℃ for 16 hours in a water bath to obtain mullite micropowder a and mullite precursor gel B. The remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 0.68 percent, which is slightly higher than the weight loss of the material sample in the example 2.
Example 5
The preparation method of the environmental barrier coating according to the present embodiment is substantially the same as that of embodiment 2, except that, in step S2, 16.54g of mullite micropowder a, 2.76g of mullite precursor gel B, 0.1g of polyvinylpyrrolidone (PVP), and 0.6g of oxalic acid dihydrate are weighed and added to 48ml of anhydrous ethanol solution to prepare mullite coating precursor slurry. The remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 0.65 percent, which is slightly higher than the weight loss of the material sample in the example 2.
Example 6
The environmental barrier coating of this example was prepared in substantially the same manner as in example 2, except that 32.71g Yb was weighed in step S312O3Powder, 4.6g SiO2Mixing the powder, ball milling for 5h at the rotating speed of 250r/min to obtain uniformly mixed Yb2O3+SiO2Mixing the powder; s32, weighing 20g of ytterbium silicate micro powder C, 0.1g of CaO and 0.4g of glycerol, adding the materials into 90ml of absolute ethanol solution, and performing ball milling at the rotating speed of 200r/min for 2 hours to obtain ytterbium silicate coating precursor slurry. The remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 0.73 percent, which is slightly higher than the weight loss of the material sample in the example 2.
Comparative example 1
The comparative example discloses an environmental barrier coating, the preparation method of which is basically the same as that of example 2, except that step S1 is that the surface of the C/SiC composite material is ground flat by sand paper, then cleaned by ultrasonic cleaning and dried, and then placed in a chemical vapor deposition furnace; continuously introducing a deposition gas source (MTS), a carrier gas (hydrogen) and a diluent gas (argon), controlling the temperature in the furnace to be 1150 ℃, the pressure in the furnace to be 0.3-0.6 kPa, the flow rate of the MTS to be 800-1000 mL/min, the flow rate of the hydrogen to be 1500-2500 mL/min and the flow rate of the argon to be 1500-2500 mL/min; after deposition is carried out for 50 hours, the deposited SiC bonding layer is cooled along with the furnace to obtain a deposited C/SiC composite material sample; the remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 0.75 percent, which is slightly higher than the weight loss of the material sample in the example 2.
Comparative example 2
The comparative example discloses an environmental barrier coating, the preparation method of which is basically the same as that of the example 2, and the difference is that in the step S2, the mullite intermediate layer is prepared by using the traditional sol-gel method, the C/SiC composite material coated by the SiC bonding layer is placed in a drying box and heated to 120 ℃, the mullite coating precursor slurry is brushed on the C/SiC composite material in a brushing mode, after the brushing is completed, the heat is preserved for 8 hours in the drying box at 80 ℃, and then the C/SiC composite material is placed in a tube furnace and sintered for 3 hours at 1400 ℃ to obtain the mullite intermediate layer; the remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 1.03 percent, which is much higher than the weight loss of the material sample in the example 2.
Comparative example 3
The comparative example discloses an environmental barrier coating, the preparation method of which is basically the same as that of the example 2, and the difference is that the step S3 uses a dipping method to prepare an ytterbium silicate outer coating, the C/SiC composite material coated by the mullite intermediate layer/SiC bonding layer is placed in ytterbium silicate outer coating precursor slurry for dipping treatment, the dipping temperature is 50 ℃, the C/SiC composite material is insulated for 8 hours in a drying box at 80 ℃ after the dipping is finished, and then the C/SiC composite material is placed in a tube furnace and sintered for 3 hours at 1400 ℃ to obtain the mullite intermediate layer; the remaining steps were the same as in example 2. After 100 hours of oxidation in a static air environment at 1400 ℃, the oxidation weight loss rate of the ytterbium silicate/mullite/SiC coated C/SiC composite material sample is 0.96 percent, which is much higher than the weight loss of the material sample in the example 2.
According to the ytterbium silicate/mullite/SiC three-layer oxidation-resistant coatings prepared in the embodiments 1-6 and the comparative examples 1-3, through a 1400 ℃ long-term oxidation-resistant experiment, the coating prepared in the embodiment 2 is found to have the optimal high-temperature oxidation resistance, and after 100 hours of oxidation at 1400 ℃, the weight loss rate of a sample is only 0.52%. Comparative examples 1, 2 and 3 reached 0.75%, 1.03% and 0.96%, respectively, which were higher than example 2.
The oxidation weight loss curve of the ytterbium silicate/mullite/SiC three-layer oxidation resistant coating prepared in the embodiment 2 and the comparative examples 1-3 at the constant temperature of 1400 ℃ is shown in figure 8.
Comparing example 2 with comparative example 1, it is found that the SiC bonding layer prepared by the secondary chemical vapor deposition method in example 2 has better high-temperature oxidation resistance than the SiC bonding layer deposited at the first time, so that the oxidation resistance of the ytterbium silicate/mullite/SiC three-layer oxidation-resistant coating is better. Because the thickness of the SiC bonding layer prepared by the secondary vapor deposition method is more uniform on each surface, and the SiC bonding layer deposited for the second time can cover microcracks in the SiC bonding layer deposited for the first time, the microcracks are staggered, the oxygen diffusion resistance is improved, and the high-temperature oxidation resistance of the coating is improved.
Comparing example 2 with comparative example 2, it is found that the mullite intermediate layer prepared by the sol-gel combined air spraying process in example 2 has better high-temperature oxidation resistance than the mullite intermediate layer prepared by the traditional sol-gel brushing method, so that the ytterbium silicate/mullite/SiC three-layer oxidation-resistant coating has better oxidation resistance. Because the mullite intermediate layer prepared by the brushing method has uneven coating distribution and poor compactness, the coating is easy to crack. The mullite intermediate layer prepared by air spraying has uniform thickness distribution and good compactness, and can improve the capability of blocking oxygen diffusion so as to improve the high-temperature oxidation resistance of the coating.
Comparing example 2 with comparative example 3, it is found that the ytterbium silicate outer coating prepared by adopting the solid-phase reaction sintering and air spraying process in example 2 has better high-temperature oxidation resistance than the ytterbium silicate outer coating prepared by adopting the solid-phase reaction sintering and impregnation method, so that the ytterbium silicate/mullite/SiC three-layer oxidation resistance coating has better oxidation resistance. Because the ytterbium silicate outer coating prepared by the dipping method has uneven thickness distribution in the vertical direction, a thicker coating is easily formed at the edge, so that the coating is easily cracked due to the action of stress in the sintering process. The ytterbium silicate outer coating prepared by air spraying has uniform thickness distribution and good coating compactness, and can improve the capability of blocking oxygen diffusion so as to improve the high-temperature oxidation resistance of the coating.
It should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. The environmental barrier coating is characterized by consisting of a SiC bonding layer, a mullite intermediate layer and a ytterbium silicate outer coating which are coated on a C/SiC composite material and are sequentially arranged from inside to outside.
2. A method of preparing the environmental barrier coating of claim 1, comprising the steps of:
s1, preparing a SiC bonding layer by a secondary chemical vapor deposition method
Grinding the surface of the C/SiC composite material by using sand paper, then ultrasonically cleaning and drying the C/SiC composite material, and placing the C/SiC composite material in a chemical vapor deposition furnace; continuously introducing a deposition gas source, a carrier gas and a diluent gas, and controlling the temperature in the furnace to be 1050-1200 ℃; after the first deposition, turning the sample by 180 degrees, performing the second deposition, and cooling along with the furnace to obtain a SiC bonding layer coated C/SiC composite material sample;
s2, preparing a mullite middle layer by using a sol-gel combined air spraying process
S21, taking soluble aluminum salt and silicate as raw materials, wherein the molar ratio of Al: si: organic solvent one: the catalyst = 2-3: 1-1.5: 15-25: 0.3-0.5, and carrying out hydrolysis and condensation reaction to obtain mullite precursor sol; respectively preparing mullite micropowder A and mullite precursor gel B by using the mullite precursor sol;
s22, mixing the mullite micropowder A: the mullite precursor gel B is prepared from the following components in a mass ratio of 4-6: 1 preparing a pre-calcined mullite mixture; preparing a film forming aid in an amount of 0.5-1 wt.% and a drying inhibitor I in an amount of 1-3 wt.% based on the total mass of the pre-calcined mullite mixture; adding a second organic solvent, and uniformly ball-milling to obtain mullite coating precursor slurry, wherein the mass ratio of the total mass of the pre-calcined mullite mixture to the second organic solvent is 20-30 wt.%; uniformly coating the mullite coating precursor slurry on the surface of the SiC bonding layer through an air spraying process, and sintering at 1300-1500 ℃ in an air environment to obtain a mullite intermediate layer;
s3, preparing ytterbium silicate outer coating by using solid reaction sintering and air spraying process
S31 takes oxide powder of ytterbium and silicon as raw materials, and the raw materials are mixed according to the molar ratio of Yb: si = 1.05-1.1: 1, preparing raw materials, performing ball milling to obtain ytterbium and silicon oxide mixed powder, placing the ytterbium and silicon oxide mixed powder in a muffle furnace, sintering for 4-8 hours in an air environment at 1400-1600 ℃, and performing ball milling for more than 10 hours at a rotating speed of 200-300 r/min after grinding to obtain ytterbium silicate micro powder C;
s32, preparing a sintering aid in an amount of 0.5-1 wt.% based on the total mass of the ytterbium silicate micro powder C, and preparing a second drying inhibitor in an amount of 0.5-2 wt.%; adding an organic solvent III, performing ball milling uniformly to obtain ytterbium silicate coating precursor slurry, and preparing the mass ratio of the total mass of the pre-calcined ytterbium silicate powder C, the sintering aid and the drying inhibitor II to the organic solvent III to be 40-60 wt%; and uniformly coating the precursor slurry of the ytterbium silicate coating on the surface of the mullite intermediate layer through an air spraying process, and sintering at 1200-1400 ℃ in an air environment to obtain the ytterbium silicate outer coating.
3. The method for preparing the environmental barrier coating according to claim 2, wherein in step S1, the pressure in the deposition furnace is 0.3 to 0.6kPa, the flow rate of the deposition gas source is 800 to 1000mL/min, the flow rate of the carrier gas is 1500 to 2500mL/min, and the flow rate of the dilution gas is 1500 to 2500 mL/min; the time of each deposition is 15-25 h.
4. The method of preparing the environmental barrier coating of claim 2, wherein the soluble aluminum salt is at least one of aluminum nitrate, anhydrous aluminum chloride, aluminum isopropoxide; the silicate is at least one of ethyl orthosilicate, methyl orthosilicate and propyl orthosilicate; the organic solvent I, the organic solvent II and the organic solvent III are at least one of absolute ethyl alcohol and absolute methyl alcohol; the catalyst is at least one of hydrochloric acid, glacial acetic acid and hydrofluoric acid.
5. Method for the preparation of an environmental barrier coating according to claim 2, characterized in that the hydrolysis and condensation process is in particular: hydrolyzing at 60-80 ℃, adding a catalyst, heating to 80-90 ℃, and carrying out condensation reaction for at least 16 h.
6. The preparation method of the environmental barrier coating according to claim 2, wherein the mullite micropowder A is prepared by drying the mullite precursor sol at 60-80 ℃ for 48-96 h; then ball milling is carried out at the rotating speed of 150-250 r/min, and finally calcining is carried out for 1.5-3 h in the air environment at the temperature of 1100-1300 ℃ to obtain the catalyst; and the mullite precursor gel B is obtained by aging the mullite precursor sol at room temperature for 2-4 months.
7. The method for preparing an environmental barrier coating according to claim 2, wherein in step S22, the drying inhibitor is at least one selected from oxalic acid dihydrate and glycerol; the film-forming assistant is at least one of polyvinylpyrrolidone and polyvinyl butyral.
8. The method for preparing an environmental barrier coating according to claim 2, wherein in the air spraying process, the spray gun nozzle is perpendicular to the surface of the test piece in steps S22 and S32; the diameter of the spray gun is 0.5-1 mm, the spraying pressure is 0.4-0.8 MPa, and the spraying distance is 10-25 mm.
9. The method for preparing the environmental barrier coating according to claim 2, wherein the oxide of ytterbium and silicon is Yb in step S312O3With SiO2The purity is analytical purity; the sintering aid is Y2O3At least one of CaO and MgO; the drying inhibitor is at least one selected from oxalic acid dihydrate and glycerol.
10. The application of the coating prepared by the preparation method of the environmental barrier coating according to any one of claims 2 to 9 is characterized by being suitable for preparing large-sized components and special-shaped components in the fields of aerospace, energy and chemical engineering, weaponry, transportation and transportation.
Priority Applications (1)
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| CN112573943A (en) * | 2020-12-09 | 2021-03-30 | 江西信达航科新材料科技有限公司 | High-temperature-resistant composite coating and preparation method thereof |
| CN114853494A (en) * | 2022-06-02 | 2022-08-05 | 中国人民解放军国防科技大学 | Composite ceramic powder with self-repairing capability and preparation method and application thereof |
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