Ceramic material for high-temperature water-oxygen environment and preparation method thereof

Abstract

The invention discloses a ceramic material for a high-temperature water-oxygen environment and a preparation method of the ceramic material, and belongs to the technical field of environmental barrier coatings. According to the preparation method disclosed by the invention, the Al2O3 modified Yb2Si2O7 powder is prepared into the tablet with a certain size and shape by a dry pressing method, and finally the tablet is sintered into the ceramic material by a pressureless sintering method in the atmosphere, so that the obtained ceramic material for the high-temperature water-oxygen environment can meet the application in the high-temperature water-oxygen environment of 1500 DEG C, has excellent high-temperature environment use performance, and is suitable for being used in the high-temperature water-oxygen environment. And the requirement of a thermal protection component on a C / C composite material high-temperature environment barrier coating is met.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental barrier coatings, and in particular relates to a ceramic material for a high-temperature water-oxygen environment and a preparation method thereof. Background Art

[0002] C / C composites exhibit excellent comprehensive performance at room temperature and high temperature inert environments, and have received extensive attention. They are used in hot end components in the aerospace field, such as aircraft engine nozzles, blades, and carbon-based composites used in combustion chambers. Lightweight thermal protection structures. However, C / C composites fail due to oxidation in oxygen-containing environments at 400°C and above. SiC and C / C composites have good thermal expansion coefficient (CTE) matching and excellent physical and chemical compatibility. The SiC coating prepared by the embedding solid infiltration method reacts with O2 in a high temperature oxidizing environment to form a layer of flowing molten SiO2, which can effectively resist further penetration of O2 and achieve a protective effect on C / C composites (L. Li, HJ Li, HJ Lin, et al. Comparison of the oxidation behaviors of SiC coatings on C / C composites prepared by pack cementation and chemical vapor deposition [J]. Surface and Coatings Technology, 2016, 302: 56-64.). However, as a hot end component, it is inevitable to encounter oxidative corrosion in the high-temperature water-oxygen coupling environment of water vapor generated when the aircraft engine is working. In this environment, water vapor will accelerate the oxidation process of SiC and corrode its oxidation product (SiO2), thus causing material corrosion failure. (XXCao, XGLuan, YLWang, et al. Oxidation and corrosion behavior of 2D laminated SiC / SiC with Si / mullite / BSAS EBC in dry oxygen / watervapor at 1200℃[J]. Corrosion Science, 2023, 219: 111237.).

[0003] Rare earth silicates are important candidate materials for environmental barrier coatings (EBCs) because of their low volatility, excellent phase stability, low thermal conductivity and thermal expansion coefficient matching that of SiC in high temperature environments. Lu2Si2O7 and Yb2Si2O7 do not undergo phase change at high temperatures, and Yb2Si2O7 has relatively better resistance to water and oxygen corrosion, which has attracted widespread attention (N. Maier, KG Nickel, G. Rixecker. High temperature water vapour corrosion of rare earth disilicates (Y, Yb, Lu)2Si2O7 in the presence of Al(OH)3 impurities [J]. Journal of the European Ceramic Society, 2007, 27 (7): 2705-2713.). However, in a long-term high-temperature water-oxygen corrosion experiment at 1316°C, it was found that a porous layer of Yb2SiO5 with a high thermal expansion coefficient was formed on the surface of Yb2Si2O7, and water vapor and the like penetrated into the interior through the pores, resulting in performance degradation (BTRichards, KAYoung, FDFrancqueville, et al. Response of ytterbiumdisilicate-silicon environmental barrier coatings to thermal cycling in watervapor[J]. Acta Materialia, 2016, 106: 1-14.). Therefore, the existing Yb2Si2O7 environmental barrier coating cannot meet the demand for high-temperature environmental barrier coatings of C / C composite materials for thermal protection components. Summary of the invention

[0004] The purpose of the present invention is to provide a ceramic material for high-temperature water-oxygen environment and a preparation method thereof, so as to solve the technical problem that the existing Yb2Si2O7 environmental barrier coating cannot meet the requirements of thermal protection components for C / C composite materials at high-temperature environmental barrier coatings above 1500°C.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a method for preparing a ceramic material for a high-temperature water-oxygen environment, comprising the following steps:

[0007] After mixing Al2O3 powder and Yb2Si2O7 powder, a mixed powder is obtained;

[0008] The mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water are mixed and ball-milled to obtain a granulation slurry;

[0009] The granulation slurry is granulated to obtain Al2O3-modified Yb2Si2O7 powder;

[0010] The Al2O3-modified Yb2Si2O7 powder is placed in a mold and dry pressed to obtain a tablet;

[0011] The pressed tablets are sintered to obtain ceramic materials for high temperature water and oxygen environments.

[0012] Furthermore, the mass ratio of the Al2O3 powder to the Yb2Si2O7 powder is (0.1-4.5): (95.5-99.9).

[0013] Furthermore, the preparation method of the polyvinyl alcohol aqueous solution is: after mixing polyvinyl alcohol particles and deionized water, heating in a water bath, and keeping the water bath heated for at least 1 hour after the water bath heating is completed, to obtain the polyvinyl alcohol aqueous solution.

[0014] Furthermore, the mass ratio of the polyvinyl alcohol particles to deionized water is (1.5-5): (95-98.5);

[0015] The water bath heating temperature is 75-95°C.

[0016] Furthermore, the mass ratio of the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water is (3-4): (3-4): (1-3): (1-4).

[0017] Furthermore, the ball milling treatment time is not less than 2 hours; before the Al2O3-modified Yb2Si2O7 powder is placed in a grinding tool for dry pressing, the Al2O3-modified Yb2Si2O7 powder is sieved and dried in sequence.

[0018] Furthermore, the pressure of the dry pressing treatment is 10-30 MPa, and the pressure holding time is not less than 2 minutes.

[0019] Furthermore, the sintering process is carried out in an atmospheric sintering furnace; the process parameters of the sintering process are: at 1500-1600° C., keeping warm for 5-20 hours and then cooling to room temperature.

[0020] Furthermore, the Al2O3 powder and the Yb2Si2O7 powder are both spherical powders, and the particle size of the spherical powders is 30 to 50 μm;

[0021] The granulator used in the granulation process has an inlet temperature of 330-350° C., an outlet temperature of 90-110° C., and a rotation speed of 15-25 r / min.

[0022] The invention also discloses a ceramic material for high-temperature water-oxygen environment prepared by the preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The invention discloses a method for preparing a ceramic material for a high-temperature water-oxygen environment. The Al2O3-modified Yb2Si2O7 powder is made into a pressed piece with a certain size and shape by a dry pressing method. Finally, the pressed piece is sintered into a ceramic material by a pressureless sintering method under atmosphere. Yb3Al5O 12 The protective layer enables the obtained ceramic material for high-temperature water and oxygen environment to meet the application of high-temperature water and oxygen environment at 1500°C, has excellent performance in high-temperature environment, and meets the technical problems of thermal protection components' requirements for C / C composite material high-temperature environment barrier coating.

[0025] The present invention also discloses a ceramic material for high-temperature water-oxygen environment prepared by the above-mentioned preparation method. According to relevant experimental results, when the ceramic is used in a high-temperature water-oxygen environment of 1500°C, no significant changes occur during the application process, and a Yb3Al5O4-containing ceramic material with a height of about 1 μm is preferentially formed at the ceramic grain boundary. 12 As the main component of the protrusion, and then diffuse to the surrounding, and finally form a layer of Yb3Al5O on the surface of the ceramic 12 The protective layer with quartz as the main component further enhances the ceramic material's ability to resist water and oxygen corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The surface macroscopic morphology of the pressed tablets obtained from the Al2O3-modified Yb2Si2O7 powder prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after sintering;

[0027] Figure 2 The surface XRD patterns of the ceramic materials for high temperature water oxygen environment prepared in Examples 1 to 3 and Comparative Example 1 of the present invention before and after being oxidized at 1500°C in a 90% H2O-10% O2 environment for 225 hours;

[0028] Among them: a-front; b-back;

[0029] Figure 3 The macroscopic morphology of the ceramic material for high temperature water oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after being oxidized at 1500°C and 90% H2O-10% O2 for 225 hours;

[0030] Figure 4The material cross-sectional backscattering morphology diagram of the ceramic material for high temperature water oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after being oxidized in a 90% H2O-10% O2 environment at 1500°C for 225 hours;

[0031] Among them: a-cross-sectional backscattering morphology of pure Yb2Si2O7 ceramics; b-cross-sectional backscattering morphology of 1.5wt.% Al2O3-modified Yb2Si2O7 ceramics; c-cross-sectional backscattering morphology of 3wt.% Al2O3-modified Yb2Si2O7 ceramics; d-cross-sectional backscattering morphology of 4.5wt.% Al2O3-modified Yb2Si2O7 ceramics;

[0032] Figure 5 The mass change of the ceramic material for high temperature water oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after being oxidized in a 1500°C, 90% H2O-10% O2 environment for 225 hours. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0035] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0036] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] The present invention provides a method for preparing a ceramic material for a high-temperature water-oxygen environment, comprising the following steps:

[0039] Step 1: Al2O3 powder and Yb2Si2O7 powder are mixed evenly in a mass ratio of (0.1-4.5): (95.5-99.9) to obtain a mixed powder, which is placed in a beaker;

[0040] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of (1.5-5): (95-98.5), pour into a beaker, put into a magnetic stirring water bath, set the temperature to 75-95°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0041] Step 3: Weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol, and deionized water in a mass ratio of (3-4): (3-4): (1-3): (1-4), pour them into a ball mill, roll them on a ball mill for not less than 2 hours, and then take them out to obtain a granulation slurry;

[0042] Step 4: granulating the granulated slurry to obtain Al2O3-modified Yb2Si2O7 powder; passing the Al2O3-modified Yb2Si2O7 powder through a 200-mesh sieve to remove impurities, and fully drying it in a constant temperature oven for later use;

[0043] Step 5: placing the obtained Al2O3-modified Yb2Si2O7 powder in a mold and performing dry pressing treatment, the pressure is set to 10-30Mpa, the pressure holding time is not less than 2min, and then slowly unloading, taking out the block in the mold, and obtaining a pressed tablet;

[0044] Step 6: Place the obtained pressed tablet in an atmospheric sintering furnace at 1500-1600°C, keep it warm for 5-20 hours, then cool it to room temperature and take it out to obtain a ceramic material for high-temperature water-oxygen environment.

[0045] Preferably, Yb2Si2O7 powder and Al2O3 powder are both spherical powders with a particle size of 30 to 50 μm.

[0046] Preferably, the purity of Yb2Si2O7 powder, Al2O3 powder, polyvinyl alcohol particles and anhydrous ethanol are all analytically pure.

[0047] Preferably, the inlet temperature of the granulator used in the granulation treatment is maintained at 330-350° C., the outlet temperature is maintained at about 90-110° C., and the rotation speed is 15-25 r / min.

[0048] Preferably, the pressed tablet should be placed in a corundum crucible with a zirconium oxide plate underneath to reduce breakage.

[0049] The invention also discloses a ceramic material for high-temperature water-oxygen environment prepared by the preparation method.

[0050] Also disclosed is the application of the ceramic material for high temperature water and oxygen environment in a 1500°C, 90% H2O-10% O2 environment, and a water and oxygen corrosion test.

[0051] Preferably, during the assessment, when the water-oxygen corrosion furnace is heated to 1500° C., the ceramic materials for high-temperature water-oxygen environment are directly placed into the furnace from the room temperature environment, and the ceramic materials for high-temperature water-oxygen environment are taken out after being kept warm for a certain period of time.

[0052] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0053] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0054] Example 1

[0055] A method for preparing a ceramic material for a high-temperature water-oxygen environment comprises the following steps:

[0056] Step 1: Mix Al2O3 powder and Yb2Si2O7 powder in a mass ratio of 1.5:98.5 to obtain a mixed powder, and place it in a beaker;

[0057] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of 3:97, pour into a beaker, put into a magnetic stirring water bath, set the temperature to 75°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0058] Step 3: Weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water in a mass ratio of 4:4:1:2, pour them into a ball mill, roll them on the ball mill for 4 hours and then take them out to obtain a granulation slurry;

[0059] Step 4: The granulation slurry is granulated, the inlet temperature of the granulator is maintained at 330°C, the outlet temperature is maintained at about 100°C, and the rotation speed is 25r / min to obtain Al2O3 modified Yb2Si2O7 powder, the obtained powder is sieved through a 200-mesh sieve to remove impurities, and is fully dried in a constant temperature oven for standby use;

[0060] Step 5: placing the obtained Al2O3-modified Yb2Si2O7 powder in a mold and performing dry pressing, the pressure is set to 15 MPa, the pressure holding time is not less than 2 minutes, and then slowly unloading, taking out the block in the mold, and obtaining a pressed tablet;

[0061] Step 6: Place the obtained pressed tablets in an atmospheric sintering furnace at 1500°C, keep the temperature for 20 hours, then cool to room temperature and take out to obtain a ceramic material for high-temperature water-oxygen environment (the added Al2O3 is 1.5wt%).

[0062] The ceramic material for high temperature water-oxygen environment obtained in Example 1 was subjected to water-oxygen corrosion test at 1500°C and 90% H2O-10% O2 environment. After 225 hours of test, the material weight loss was about 0.03%.

[0063] Example 2

[0064] A method for preparing a ceramic material for a high-temperature water-oxygen environment comprises the following steps:

[0065] Step 1: Mix Al2O3 powder and Yb2Si2O7 powder in a mass ratio of 3:97 to obtain a mixed powder, and place it in a beaker;

[0066] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of 5:95, pour into a beaker, put into a magnetic stirring water bath, set the temperature to 85°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0067] Step 3: Weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water in a mass ratio of 4:4:1:1, pour them into a ball mill, roll them on the ball mill for 10 hours and then take them out to obtain a granulation slurry;

[0068] Step 4: The granulation slurry is granulated, the inlet temperature of the granulator is maintained at 340°C, the outlet temperature is maintained at about 105°C, and the rotation speed is 25r / min to obtain Al2O3 modified Yb2Si2O7 powder. The obtained powder is sieved through a 200-mesh sieve to remove impurities, and is fully dried in a constant temperature oven for standby use;

[0069] Step 5: Place the obtained Al2O3-modified Yb2Si2O7 powder in a mold and perform dry pressing. The pressure is set to 25 MPa and the pressure holding time is not less than 2 minutes. Then, the powder is slowly unloaded and the block in the mold is taken out to obtain a pressed tablet.

[0070] Step 6: Place the obtained pressed tablets in an atmospheric sintering furnace at 1550°C, keep the temperature for 10 hours, then cool to room temperature and take out to obtain a ceramic material for high-temperature water-oxygen environment (the added Al2O3 is 3wt%).

[0071] The ceramic material for high temperature water-oxygen environment obtained in Example 2 was subjected to water-oxygen corrosion test at 1500°C and 90% H2O-10% O2 environment. After 225 hours of test, the material weight loss was about 0.04%.

[0072] Example 3

[0073] A method for preparing a ceramic material for a high-temperature water-oxygen environment comprises the following steps:

[0074] Step 1: Mix Al2O3 powder and Yb2Si2O7 powder in a mass ratio of 4.5:95.5 to obtain a mixed powder, and place it in a beaker;

[0075] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of 4:96, pour into a beaker, put into a magnetic stirring water bath, set the temperature to 95°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0076] Step 3: Weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water in a mass ratio of 4:4:2:1, pour them into a ball mill, roll them on the ball mill for 8 hours and then take them out to obtain a granulation slurry;

[0077] Step 4: The granulation slurry is granulated, the inlet temperature of the granulator is maintained at 335°C, the outlet temperature is maintained at about 100°C, and the rotation speed is 24r / min to obtain Al2O3 modified Yb2Si2O7 powder, the obtained powder is sieved through a 200-mesh sieve to remove impurities, and is fully dried in a constant temperature oven for standby use;

[0078] Step 5: Place the obtained Al2O3-modified Yb2Si2O7 powder in a mold and perform dry pressing. The pressure is set to 30 MPa and the pressure holding time is not less than 2 minutes. Then, the powder is slowly unloaded and the block in the mold is taken out to obtain a pressed tablet.

[0079] Step 6: Place the obtained pressed tablets in an atmospheric sintering furnace at 1600°C, keep the temperature for 5 hours, then cool to room temperature and take out to obtain a ceramic material for high-temperature water-oxygen environment (the added Al2O3 is 4.5wt%).

[0080] The ceramic material for high temperature water-oxygen environment obtained in Example 3 was subjected to a water-oxygen corrosion test at 1500°C and 90% H2O-10% O2. After 225 hours of testing, the material lost weight by about 0.04%.

[0081] Example 4

[0082] A method for preparing a ceramic material for a high-temperature water-oxygen environment comprises the following steps:

[0083] Step 1: Mix Al2O3 powder and Yb2Si2O7 powder in a mass ratio of 0.1:99.9 to obtain a mixed powder, and place it in a beaker;

[0084] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of 1.5:98.5, pour into a beaker, put into a magnetic stirring water bath, set the temperature to 95°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0085] Step 3: weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water in a mass ratio of 3:3:3:1, pour them into a ball mill, roll them on the ball mill for 8 hours and then take them out to obtain a granulation slurry;

[0086] Step 4: granulate the granulation slurry, maintain the inlet temperature of the granulator at 340°C, the outlet temperature at about 110°C, and the rotation speed at 20r / min to obtain Al2O3 modified Yb2Si2O7 powder, sieve the obtained powder through a 200-mesh sieve to remove impurities, and fully dry it in a constant temperature oven for use;

[0087] Step 5: placing the obtained Al2O3-modified Yb2Si2O7 powder in a mold and performing dry pressing, with the pressure set to 10 MPa and the holding time being not less than 2 min, and then slowly unloading and taking out the block in the mold to obtain a pressed tablet;

[0088] Step 6: Place the obtained pressed tablet in an atmospheric sintering furnace at 1600°C, keep the temperature for 5 hours, then cool to room temperature and take out to obtain a ceramic material for high-temperature water-oxygen environment.

[0089] Comparative Example 1

[0090] Step 1: Mix Al2O3 and Yb2Si2O7 powders in a mass ratio of 0:1 to obtain a mixed powder, and place it in a beaker;

[0091] Step 2: Mix the polyvinyl alcohol particles and deionized water in a mass ratio of 4.5:95.5, pour into a beaker, put into a magnetic stirring water bath, set the temperature to 90°C, stir evenly and keep warm for at least 1 hour to obtain a polyvinyl alcohol aqueous solution;

[0092] Step 3: Weigh the mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water in a mass ratio of 4:4:2:2, pour them into a ball mill, roll them on the ball mill for 12 hours and then take them out to obtain a granulation slurry;

[0093] Step 4: granulating the granulation slurry to obtain the desired Al2O3-modified Yb2Si2O7 powder, passing the obtained powder through a 200-mesh sieve to remove impurities, and fully drying it in a constant temperature oven;

[0094] Step 5: placing the obtained Al2O3-modified Yb2Si2O7 powder in a mold, performing dry pressing, setting the pressure to 20 MPa, holding the pressure for not less than 2 minutes, and then slowly unloading and taking out the block in the mold to obtain a pressed tablet;

[0095] Step 6: placing the obtained pressed tablet in an atmospheric sintering furnace at 1550°C, keeping the temperature for 12 hours, then cooling to room temperature and taking it out to obtain a ceramic material (pure Yb2Si2O7 ceramic);

[0096] Step 7: The obtained ceramic material is subjected to a water-oxygen corrosion test at 1500°C and 90% H2O-10% O2 environment. After 225 hours of testing, the material loses weight by about 0.06%.

[0097] In the above embodiments, the Yb2Si2O7 powder and Al2O3 powder used are all spherical powders with a particle size of 30 to 50 μm, and the purity of the Yb2Si2O7 powder, Al2O3 powder, polyvinyl alcohol particles, and anhydrous ethanol are all analytically pure.

[0098] Figure 1 The surface macroscopic morphology of the pressed tablets before and after sintering obtained from the Al2O3-modified Yb2Si2O7 powder prepared in Examples 1 to 3 of the present invention and Comparative Example 1 shows that the volume shrinkage of the Yb2Si2O7 ceramic is more obvious after adding a certain amount of Al2O3, indicating that the addition of Al2O3 helps to improve the sintering performance of the ceramic.

[0099] Figure 2 The surface XRD patterns of the ceramic materials for high temperature water oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after oxidation at 1500°C in a 90% H2O-10% O2 environment for 225 hours show that the main components of the ceramic materials are Yb2Si2O7 and Yb3Al5O 12 Phase, after 225h in water and oxygen environment, Yb3Al5O 12 The phase peak intensity increases, and the pure Yb2Si2O7 ceramics show the Yb2SiO5 phase. No peak of the Yb2SiO5 phase is observed in the ceramics with the addition of Al2O3 after water and oxygen treatment, indicating that the addition of Al2O3 can inhibit the formation of the Yb2SiO5 porous layer, thereby improving the water-oxygen corrosion resistance of the ceramic material.

[0100] Figure 3 The macroscopic morphology of the ceramic material for high temperature water and oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after oxidation in a 1500°C, 90% H2O-10% O2 environment for 225 hours showed no obvious change, indicating that the ceramic material has excellent resistance to water and oxygen corrosion.

[0101] Figure 4 The cross-sectional backscattering morphology of the ceramic materials for high temperature water oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after being oxidized at 1500°C in a 90% H2O-10% O2 environment for 225 hours is shown in FIG. Figure 4 (a) The porous reaction layer observed on the surface of pure Yb2Si2O7 ceramics. Figure 4 (bd) No obvious pores were found in the reaction layer observed on the surface of Yb2Si2O7 ceramics modified by adding different mass proportions of Al2O3, which indicates that the addition of Al2O3 should be able to effectively delay the degradation of ceramic materials and improve their resistance to water and oxygen corrosion.

[0102] Figure 5 The mass changes of the ceramic materials for high temperature water and oxygen environment prepared in Examples 1 to 3 of the present invention and Comparative Example 1 before and after oxidation in a 1500°C, 90% H2O-10% O2 environment for 225 hours, and compared with the mass loss rate of pure Yb2Si2O7 ceramics, the mass changes of 1.5 / 3wt.% Al2O3 modified Yb2Si2O7 ceramic materials are only about 0.03% and 0.04%, respectively, which are 53.16% and 44.68% lower than those of pure Yb2Si2O7 ceramics. After adding Al2O3, the water and oxygen corrosion resistance of the ceramic materials is significantly improved.

[0103] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a ceramic material for a high temperature water and oxygen environment, characterized in that: The following steps are involved: After mixing Al2O3 powder and Yb2Si2O7 powder, a mixed powder is obtained; The mixed powder, polyvinyl alcohol aqueous solution, anhydrous ethanol and deionized water are mixed and ball-milled to obtain a granulation slurry; The granulation slurry is granulated to obtain Al2O3-modified Yb2Si2O7 powder; The Al2O3-modified Yb2Si2O7 powder is placed in a mold and dry pressed to obtain a tablet; The pressed tablets are sintered to obtain ceramic materials for high temperature water and oxygen environments.

2. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The mass ratio of the Al2O3 powder to the Yb2Si2O7 powder is (0.1-4.5):(95.5-99.9).

3. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The preparation method of the polyvinyl alcohol aqueous solution comprises: mixing polyvinyl alcohol particles and deionized water, heating the mixture in a water bath, and keeping the mixture warm for at least 1 hour after the water bath heating to obtain the polyvinyl alcohol aqueous solution.

4. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 3, characterized in that: The mass ratio of the polyvinyl alcohol particles to deionized water is (1.5-5): (95-98.5); The water bath heating temperature is 75-95°C.

5. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The mass ratio of the mixed powder, the polyvinyl alcohol aqueous solution, the anhydrous ethanol and the deionized water is (3-4): (3-4): (1-3): (1-4).

6. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The ball milling treatment time is not less than 2 hours; before the Al2O3-modified Yb2Si2O7 powder is placed in a grinding tool for dry pressing, the Al2O3-modified Yb2Si2O7 powder is sieved and dried in sequence.

7. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The pressure of the dry pressing treatment is 10-30 MPa, and the pressure holding time is not less than 2 minutes.

8. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The sintering process is carried out in an atmospheric sintering furnace; the process parameters of the sintering process are: at 1500-1600° C., keeping the temperature for 5-20 hours and then cooling to room temperature.

9. The method for preparing a ceramic material for a high temperature water and oxygen environment according to claim 1, characterized in that: The Al2O3 powder and Yb2Si2O7 powder are both spherical powders, and the particle size of the spherical powders is 30 to 50 μm; The granulator used in the granulation process has an inlet temperature of 330-350° C., an outlet temperature of 90-110° C., and a rotation speed of 15-25 r / min.

10. A ceramic material for high temperature water and oxygen environment, characterized in that: The preparation method is described in any one of claims 1 to 9.

Images