Method for preparing orthophosphate thermal barrier coating ceramic material by using co-precipitation method to synthesize powder

Abstract

The present invention belongs to the technical field of the preparation of thermal protection ceramic materials, and particularly relates to a method for preparing a orthophosphate thermal barrier coating ceramic material by synthesizing a powder through a coprecipitation method. The chemical general formula of the orthophosphate is REM₃P₃O₁₂, where RE is a rare earth element and M is an alkaline earth metal. In the present invention, a salt containing RE rare earth and a salt containing alkaline earth metal M are dissolved to obtain a mixed solution, and the phosphate is dissolved to obtain a solution containing P and ammonia water is added to adjust the pH; the mixed solution is dropped into the solution containing P and continuously stirred, and after aging, filtering and washing, a REM₃P₃O₁₂ precursor precipitate is obtained, and after further drying, it is calcined to obtain a REM₃P₃O₁₂ powder. After the REM₃P₃O₁₂ powder is ground and sieved, it is pressed into a green body; the green body is calcined to obtain an orthophosphate thermal barrier coating ceramic material. The powder obtained by the present invention has a small particle size and a uniform distribution, and the synthesis temperature is relatively low. In addition, common inorganic salt reagents are mainly used in the synthesis process, the operation is simple, and the energy consumption is small.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of thermal protection ceramic materials, and particularly relates to a method for preparing orthophosphate thermal barrier coating ceramic materials by using a co-precipitation method to synthesize powders. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Thermal barrier coatings have important application values in the fields of aviation, aerospace, large ships, etc. With the continuous increase of the thrust-to-weight ratio, the inlet temperature of the engine is getting higher and higher. The designed outlet temperature of a turbofan engine with a thrust-to-weight ratio of 10 has reached over 1550 °C, and the designed outlet temperature of a turbofan engine with a thrust-to-weight ratio of over 15 will exceed 1700 °C. However, the upper limit of the service temperature of the current superalloy is about 1150 °C, far from meeting the design and use requirements. Thermal barrier coatings can not only improve the high-temperature corrosion resistance of hot-end components, enabling them to withstand higher operating temperatures, but also have the effect of extending the service life of hot-end components.

[0004] The currently commonly used ceramic material 8wt% Y2O3–ZrO2 (8YSZ) is considered a standard thermal barrier coating material because of its relatively high thermal expansion coefficient (~11.5×10 -6 / °C @ 1000 °C), relatively low thermal conductivity (~2.12 W / m·K @ 1000 °C), and good thermal shock resistance. However, the 8YSZ ceramic material will undergo a phase change at 1200 °C, resulting in the peeling failure of the coating, and the long-term use temperature cannot exceed 1200 °C. Therefore, the development of new thermal barrier coating materials has become a key topic in the research and development of high-performance aero-engines.

[0005] Rare earth-alkaline earth metal orthophosphates REM3P3O 12 (RE: rare earth element, M: alkaline earth metal) have advantages such as good high-temperature stability and relatively low thermal conductivity. In particular, this material has a high thermal expansion coefficient (15 - 22×10 -6 / °C), which can effectively relieve the stress generated by the mismatch of the thermal expansion coefficients between the matrix material and the ceramic layer, and is considered one of the potential thermal barrier coating materials. However, the current synthesis of this rare earth-alkaline earth metal orthophosphate powder uses the solid-phase reaction method, and its disadvantages are that the reaction activities of the raw materials in the synthesis process are low, the migration speed is slow, the uniform mixing of the raw materials at the atomic level cannot be achieved, and the synthesized REM3P3O 12The particles of the powder are relatively large, resulting in a low density of the prepared ceramics. Moreover, the synthesis process includes processes such as raw material pre-sintering, grinding, ball milling, and drying, and the preparation process is cumbersome, affecting the product purity. In addition, the solid-phase reaction method requires calcination synthesis at a relatively high temperature, has strict equipment requirements, and high energy consumption. Summary of the Invention

[0006] In order to solve the deficiencies of the prior art, the object of the present invention is to provide a method for synthesizing a powder by coprecipitation to prepare a orthophosphate thermal barrier coating ceramic material. The present invention uses a simple coprecipitation method to synthesize orthophosphate REM3P3O 12 thermal barrier coating ceramic powder, and further prepares REM3P3O 12 powder into REM3P3O 12 ceramics. The powder particles are small and evenly distributed, and the synthesis temperature is relatively low. During the synthesis process, common inorganic salt reagents are mainly used, the operation is simple, and the energy consumption is small.

[0007] In order to achieve the above object, the present invention is realized by the following technical solutions:

[0008] In the first aspect, the present invention provides a method for synthesizing orthophosphate thermal barrier coating ceramic powder, and the chemical general formula of the orthophosphate is REM3P3O 12 , where RE is a rare earth element or a combination of rare earth elements, and M is an alkaline earth metal or a combination of alkaline earth metal elements, including the following steps:

[0009] S1. Dissolve the salt containing RE rare earth and the salt containing alkaline earth metal M respectively, and mix them in a certain proportion to obtain a mixed solution; dissolve the phosphate to obtain a solution containing P and add ammonia water to adjust the pH value of the solution;

[0010] S2. Drop the mixed solution containing RE and M into the solution containing P, or drop the solution containing P into the mixed solution containing RE and M, stir continuously, and obtain REM3P3O 12 precursor precipitate through aging, filtration, and washing;

[0011] S3. Dry the REM3P3O 12 precursor precipitate and calcine it to obtain REM3P3O 12 powder.

[0012] Preferably, the RE includes one or a combination of two or more of La, Nd, Gd, Y, Ho, Tm, or Yb.

[0013] Preferably, the M includes one or a combination of two or more of Ca, Sr, or Ba.

[0014] Preferably, the RE-containing rare earth salt is RECl3 or RE(NO3)3, the salt containing alkaline earth metal M is MCl2 or M(NO3)2, the phosphate includes at least one of (NH4)3PO4, NH4H2PO4, NaH2PO4, and KH2PO4, and the molar ratio of the RE salt, M salt, and P salt is 1:3:3.

[0015] Preferably, in step S1, ammonia water is added to adjust the pH of the P-source solution to 9-11.

[0016] Preferably, in step S2, the dropping rate is 5 mL / min or less, and the aging time is 3-10 hours.

[0017] Preferably, in step S3, it is calcined at 1000-1150 °C for 5-15 hours.

[0018] More preferably, the calcination temperature is 1100 °C, and the heating rate is 2-6 °C / min.

[0019] In a second aspect, the present invention provides a positive phosphate thermal barrier coating ceramic powder, and the chemical general formula of the positive phosphate is REM3P3O 12 , where RE is a rare earth element and M is an alkaline earth metal, and it is obtained by the method described in the first aspect.

[0020] In a third aspect, the present invention provides a method for synthesizing a powder by coprecipitation to prepare a positive phosphate thermal barrier coating ceramic material, and the chemical general formula of the positive phosphate is REM3P3O 12 , where RE is a rare earth element and M is an alkaline earth metal, and it includes the following steps:

[0021] S4. After grinding and sieving the positive phosphate thermal barrier coating ceramic powder described in the second aspect, it is pressed into a green body;

[0022] S5. The green body is calcined to obtain a positive phosphate thermal barrier coating ceramic material.

[0023] Preferably, in step S4, the pressure for pressing into a shape is 200-300 MPa, the time is 5-10 min, and the method is cold isostatic pressing.

[0024] Preferably, in step S5, it is calcined at 1400-1600 °C for 2-10 hours.

[0025] In a fourth aspect, the present invention provides a positive phosphate thermal barrier coating ceramic material, and the chemical general formula of the positive phosphate is REM3P3O 12 , where RE is a rare earth element and M is an alkaline earth metal, and it is obtained by the preparation method described in the third aspect.

[0026] The beneficial effects obtained by one or more of the above technical solutions of the present invention are as follows:

[0027] 1. The present invention can obtain REM3P3O powder with a relatively small particle size by using a simple co-precipitation method, and further prepare the powder into a ceramic, and the obtained ceramic has a relatively high density. 12 The powder is further prepared into a ceramic, and the obtained ceramic has a relatively high density.

[0028] 2. The present invention only needs to carry out a co-precipitation reaction at room temperature to obtain a precursor and then calcine it once to obtain REM3P3O powder. The reagents used in the preparation process are common inorganic salt reagents, the synthesis temperature is relatively low, the operation is simple, and the energy consumption is small. 12 The powder is further prepared into a ceramic, and the obtained ceramic has a relatively high density. The reagents used in the preparation process are common inorganic salt reagents, the synthesis temperature is relatively low, the operation is simple, and the energy consumption is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0030] Figure 1 X-ray diffraction patterns of REM3P3O powders synthesized by the co-precipitation method in Examples 1 to 5, where (a) is the YBa3P3O powder of Example 1, 12 where (a) is the YBa3P3O powder of Example 1, 12 where (b) is the LaBa3P3O powder of Example 2, 12 where (c) is the NdBa3P3O powder of Example 3, 12 where (d) is the GdBa3P3O powder of Example 4, 12 where (e) is the HoBa3P3O powder of Example 5, 12 and (e) is the HoBa3P3O powder of Example 5;

[0031] Figure 2 Photographs of the physical objects of the REM3P3O series ceramic blocks prepared in Examples 1 to 5, where (a) is the YBa3P3O ceramic block of Example 1, 12 where (a) is the YBa3P3O ceramic block of Example 1, 12 where (b) is the LaBa3P3O ceramic block of Example 2, 12 where (c) is the NdBa3P3O ceramic block of Example 3, 12 where (d) is the GdBa3P3O ceramic block of Example 4, 12 where (e) is the HoBa3P3O ceramic block of Example 5, 12 and (e) is the HoBa3P3O ceramic block of Example 5;

[0032] Figure 3 Photographs of the surface microstructures of the REM3P3O series ceramic blocks prepared in Examples 1 to 5 after surface polishing and thermal etching, where (a) is the YBa3P3O ceramic block of Example 1, 12 where (a) is the YBa3P3O ceramic block of Example 1, 12 where (b) is the LaBa3P3O ceramic block of Example 2, 12Ceramic bulk, (c) is NdBa3P3O of Example 3 12 Ceramic bulk, (d) is GdBa3P3O of Example 4 12 Ceramic bulk, (e) is HoBa3P3O of Example 5 12 Ceramic bulk. Detailed implementation manners

[0033] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific examples and comparative examples.

[0034] Example 1

[0035] Synthesize YBa3P3O ceramic bulk material by coprecipitation method to prepare powder, and the steps are as follows: 12 Ceramic bulk material, the steps are as follows:

[0036] (1) Using yttrium nitrate, barium nitrate and ammonium phosphate as raw materials, weighing according to the molar ratio Y:Ba:P = 1:3:3; dissolving yttrium nitrate and barium nitrate in deionized water to obtain a mixed solution, dissolving ammonium phosphate in deionized water and adjusting the pH to 10 with ammonia water. The mixed solution was dropped into the ammonium phosphate solution at a rate of 3 mL / min and stirred continuously. The pH value was controlled above 9 during the reaction process. After the titration was completed, it was aged for 5 hours. The precipitate was filtered by suction, washed 4 times with deionized water and 2 times with anhydrous ethanol, and dried at 120 °C for 24 hours to obtain a precursor substance.

[0037] (2) Grind the precursor obtained in step (1) and put it into a muffle furnace, calcine at 1150 °C for 10 hours to obtain YBa3P3O powder, and the heating rate is 5 °C / min. The synthesized powder was ground and sieved to obtain powder with uniform particle size. 12 Powder, and the heating rate is 5 °C / min. The synthesized powder was ground and sieved to obtain powder with uniform particle size.

[0038] (3) Adopt the cold isostatic pressing forming process, and obtain the YBa3P3O ceramic green body at 300 MPa and hold the pressure for 5 min. 12 Ceramic green body.

[0039] (4) Sinter the YBa3P3O ceramic green body in an air atmosphere at 1450 °C for 2 hours, and the heating rate is 5 °C / min to obtain the YBa3P3O ceramic bulk material. 12 Ceramic bulk material. 12 Ceramic bulk material.

[0040] Through testing, Figure 1 (a) in is the X-ray diffraction pattern of the synthesized YBa3P3O powder material. As can be seen from (a) in 12 >, the YBa3P3O powder is a pure-phase cubic structure. Figure 1 >, the YBa3P3O powder is a pure-phase cubic structure. 12 Powder is a pure-phase cubic structure. Figure 2(a) in it is the obtained YBa3P3O 12 Physical photo of the ceramic block. Figure 3 (a) in it is the obtained YBa3P3O 12 Microscopic structure photo of the surface of the ceramic block after surface polishing and thermal etching. As can be seen from Figure 3 (a) in it, the grain size of the obtained ceramic is between 2μm and 10μm, and there are a small number of micropores in the ceramic grains and at the grain boundaries.

[0041] Example 2

[0042] Synthesize LaBa3P3O ceramic block material by coprecipitation method to prepare powder, the steps are as follows: 12

[0043] (1) Use lanthanum chloride, barium chloride and ammonium dihydrogen phosphate as raw materials, and weigh according to the molar ratio La:Ba:P = 1:3:3; dissolve lanthanum chloride and barium chloride in deionized water to obtain a mixed solution, and dissolve ammonium dihydrogen phosphate in deionized water and adjust the pH to 9.8 with ammonia water. Drop the mixed solution into the ammonium dihydrogen phosphate solution at a speed of 4 mL / min, and stir constantly. Control the pH value above 9.6 during the reaction process. After the titration is completed, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water to remove reaction by-products, and then wash it 2 times with absolute ethanol to prevent serious agglomeration during the drying process. Dry it at 120°C for 24 hours to obtain the precursor material.

[0044] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1150°C for 10 hours to obtain LaBa3P3O 12 powder, and the heating rate is 5°C / min. The synthesized powder is ground and sieved to obtain a powder with uniform particle size.

[0045] (3) Adopt the cold isostatic pressing forming process, and obtain the LaBa3P3O 12 ceramic green body at 300 MPa and keep the pressure for 10 min.

[0046] (4) Sinter the LaBa3P3O 12 ceramic green body in air atmosphere at 1500°C for 2 hours, and the heating rate is 5°C / min to obtain LaBa3P3O 12 ceramic block material.

[0047] Through testing, Figure 1 (b) in it is the X-ray diffraction pattern of the synthesized LaBa3P3O 12 powder material. As can be seen from Figure 1 (b) in it, the synthesized powder is a pure-phase cubic structure. Figure 2 ​In (b), the obtained LaBa3P3O 12 is a physical photo of the ceramic block. Figure 3 In (b), the obtained LaBa3P3O 12 is a surface microstructure photo of the ceramic block after surface polishing and thermal etching. As can be seen from Figure 3 (b), the grain size of the obtained ceramic is between 1μm and 8μm, and there are a small number of micropores inside and at the grain boundaries of the ceramic.

[0048] Example 3

[0049] Synthesize NdBa3P3O powder by coprecipitation method to prepare 12 ceramic block material, the steps are as follows:

[0050] (1) Using neodymium chloride, barium chloride and potassium dihydrogen phosphate as raw materials, weigh according to the molar ratio Nd:Ba:P = 1:3:3; dissolve neodymium chloride and barium chloride in deionized water to obtain a mixed solution, dissolve potassium dihydrogen phosphate in deionized water and adjust the pH to 9.7 with ammonia water. Drop the potassium dihydrogen phosphate solution into the mixed solution at a speed of 3 mL / min and stir continuously. Control the pH value above 9 during the reaction process. After titration, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120°C for 24 hours to obtain the precursor substance.

[0051] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, calcine it at 1150°C without pressure for 10 hours, with a heating rate of 5°C / min, and cool it to room temperature with the furnace to obtain NdBa3P3O 12 powder. Grind and sieve the synthesized powder to obtain a powder with uniform particle size.

[0052] (3) Adopt the cold isostatic pressing forming process, and obtain NdBa3P3O 12 ceramic green body at 300 MPa for 10 minutes of pressure holding.

[0053] (4) Sinter the NdBa3P3O 12 ceramic green body in air atmosphere at 1450°C for 2 hours, with a heating rate of 5°C / min, to obtain NdBa3P3O 12 ceramic block material.

[0054] Through testing, Figure 1 In (c), the X-ray diffraction pattern of the synthesized NdBa3P3O 12 powder material is shown. As can be seen from Figure 1 (c), the NdBa3P3O 12 powder is a pure-phase cubic structure. Figure 2In (c), the prepared NdBa3P3O 12 is a physical photo of the ceramic bulk. Figure 3 In (c), the prepared NdBa3P3O 12 is a surface microstructure photo of the ceramic bulk after surface polishing and thermal etching. As can be seen from Figure 3 in (c), the grain size of the prepared NdBa3P3O 12 ceramic is between 2 μm and 10 μm, and there are a small number of micropores inside and at the grain boundaries of the ceramic.

[0055] Example 4

[0056] Synthesize GdBa3P3O 12 ceramic bulk material by coprecipitation method to synthesize powder, and the steps are as follows:

[0057] (1) Using gadolinium chloride, barium chloride and sodium dihydrogen phosphate as raw materials, weigh according to the molar ratio Gd:Ba:P = 1:3:3; dissolve gadolinium chloride and strontium chloride in deionized water to obtain a mixed solution, and dissolve sodium dihydrogen phosphate in deionized water and adjust the pH to 9.8 with ammonia water. Drop the mixed solution into the sodium dihydrogen phosphate solution at a speed of 4 mL / min and stir continuously. Control the pH value above 9 during the reaction process. After the titration is completed, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120 °C for 24 hours to obtain the precursor substance.

[0058] (2) Grind the precursor obtained in step (1) and put it into a muffle furnace, calcine it at 1150 °C for 10 hours to obtain GdBa3P3O 12 powder, and the heating rate is 5 °C / min. Grind and sieve the synthesized powder to obtain powder with uniform particle size.

[0059] (3) Adopt the cold isostatic pressing forming process, and obtain the GdBa3P3O 12 ceramic green body at 300 MPa and keep the pressure for 5 min.

[0060] (4) Sinter the GdBa3P3O 12 ceramic green body in air atmosphere at 1450 °C for 2 hours, and the heating rate is 5 °C / min to obtain the GdBa3P3O 12 ceramic bulk material.

[0061] Through testing, Figure 1 in (d) is the X-ray diffraction pattern of the GdBa3P3O 12 powder material. As can be seen from Figure 1 in (d), the GdBa3P3O 12 powder is a pure-phase cubic structure. Figure 2In (d), the obtained GdBa3P3O 12 is a physical photo of the GdBa3P3O ceramic bulk. Figure 3 In (d), the obtained GdBa3P3O 12 is a surface microstructure photo of the GdBa3P3O ceramic bulk after surface polishing and thermal etching. As can be seen from (d) in Figure 3 the obtained GdBa3P3O 12 ceramic has a grain size in the range of 1μm - 10μm, and there are a small number of micropores inside and at the grain boundaries of the ceramic.

[0062] Example 5

[0063] Synthesize HoBa3P3O ceramic bulk material by coprecipitation method to prepare powder, and the steps are as follows: 12

[0064] (1) Use holmium chloride, barium chloride and sodium dihydrogen phosphate as raw materials, and weigh them according to the molar ratio Gd:Ba:P = 1:3:3; dissolve gadolinium chloride and strontium chloride in deionized water to obtain a mixed solution, and dissolve sodium dihydrogen phosphate in deionized water and adjust the pH to 9.8 with ammonia water. Drop the sodium dihydrogen phosphate solution into the mixed solution at a speed of 4 mL / min, and stir continuously. Control the pH value above 9 during the reaction process. After the titration is completed, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120°C for 24 hours to obtain the precursor substance.

[0065] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1150°C for 10 hours to obtain HoBa3P3O 12 powder, and the heating rate is 5°C / min. Grind and sieve the synthesized powder to obtain powder with uniform particle size.

[0066] (3) Adopt the cold isostatic pressing forming process, and obtain the HoBa3P3O 12 ceramic green body at 300 MPa and keep the pressure for 5 min.

[0067] (4) Sinter the HoBa3P3O 12 ceramic green body in air atmosphere at 1450°C for 2 hours, and the heating rate is 5°C / min to obtain the HoBa3P3O 12 ceramic bulk material.

[0068] Through testing, Figure 1 in (d) is the X-ray diffraction pattern of the HoBa3P3O 12 powder material. As can be seen from (d) in Figure 1 the HoBa3P3O 12 powder is a pure-phase cubic structure. Figure 2 ​In (d), the prepared HoBa3P3O 12 is a physical photograph of the HoBa3P3O ceramic bulk. Figure 3 In (d), the prepared HoBa3P3O 12 is a surface microstructure photograph of the HoBa3P3O ceramic bulk after surface polishing and thermal etching. As can be seen from (d) in Figure 3 the prepared HoBa3P3O 12 ceramic has a grain size in the range of 1 μm to 10 μm, and there are a small number of micropores inside and at the grain boundaries of the ceramic.

[0069] Example 6

[0070] Synthesize GdSr3P3O ceramic bulk materials by the co-precipitation method to prepare powders, and the steps are as follows: 12 (1) Use gadolinium chloride, strontium chloride, and ammonium phosphate as raw materials, and weigh them according to the molar ratio of Gd:Sr:P = 1:3:3; dissolve gadolinium chloride and strontium chloride in deionized water to obtain a mixed solution, and dissolve ammonium phosphate in deionized water and adjust the pH to 9.8 with ammonia water. Drop the mixed solution into the ammonium phosphate solution at a rate of 4 mL / min, and continuously stir. Control the pH value above 9 during the reaction process with ammonia water. After the titration is completed, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120 °C for 24 hours to obtain the precursor substance.

[0071] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1150 °C for 10 hours to obtain GdSr3P3O

[0072] powder, and the heating rate is 5 °C / min. Grind and sieve the synthesized powder to obtain a powder with uniform particle size. 12 (3) Adopt the cold isostatic pressing forming process, and obtain the GdBa3P3O

[0073] ceramic green body at 300 MPa and hold the pressure for 5 min. 12 (4) Sinter the GdSr3P3O

[0074] ceramic green body in an air atmosphere at 1450 °C for 2 hours, and the heating rate is 5 °C / min to obtain the GdSr3P3O 12 ceramic bulk material. 12 (4) Sinter the GdSr3P3O ceramic green body in an air atmosphere at 1450 °C for 2 hours, and the heating rate is 5 °C / min to obtain the GdSr3P3O

[0075] Through testing, Figure 1 in (d) is the X-ray diffraction pattern of the GdSr3P3O 12 powder material. As can be seen from (d) in Figure 1 the GdSr3P3O 12 powder is a pure-phase cubic structure. Figure 2In (d), the obtained GdSr3P3O 12 is a physical photo of the GdSr3P3O ceramic bulk. Figure 3 In (d), the obtained GdSr3P3O 12 is a surface microstructure photo of the GdSr3P3O ceramic bulk after surface polishing and thermal etching. As can be seen from (d) in Figure 3 the obtained GdSr3P3O 12 ceramic has a grain size in the range of 1 μm to 10 μm, and there are a small number of micropores in the ceramic grains and at the grain boundaries.

[0076] Example 7

[0077] Synthesize La 0.5 Yb 0.5 Ba 2.7 Sr 0.3 P3O 12 ceramic bulk materials by coprecipitation method, the steps are as follows:

[0078] (1) Using lanthanum chloride, ytterbium chloride, barium chloride, strontium chloride and ammonium phosphate as raw materials, weigh them according to the molar ratio La:Yb:Ba:Sr:P = 0.5:0.5:2.7:0.3:3; dissolve lanthanum chloride, ytterbium chloride, barium chloride, and strontium chloride in deionized water to obtain a mixed solution, dissolve ammonium phosphate in deionized water and adjust the pH to 9.8 with ammonia water. Drop the mixed solution of lanthanum chloride, ytterbium chloride, barium chloride, and strontium chloride into the ammonium phosphate solution at a rate of 3 mL / min, and stir continuously. Control the pH value above 9 during the reaction process. After titration, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120 °C for 24 hours to obtain the precursor substance.

[0079] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1100 °C for 20 hours to obtain La 0.5 Yb 0.5 Ba 2.7 Sr 0.3 P3O 12 powder, and the heating rate is 5 °C / min. Grind and sieve the synthesized powder to obtain a powder with uniform particle size.

[0080] (3) Adopt the cold isostatic pressing forming process, and obtain the La 0.5 Yb 0.5 Ba 2.7 Sr 0.3 P3O 12 ceramic green body at 300 MPa for 8 minutes of pressure holding.

[0081] (4) La 0.5 Yb 0.5 Ba2.7 Sr 0.3 P3O 12 The ceramic green body was sintered in air atmosphere at 1550 °C for 2 hours with a heating rate of 5 °C / min to obtain La 0.5 Yb 0.5 Ba 2.7 Sr 0.3 P3O 12 ceramic bulk material.

[0082] Example 8

[0083] To synthesize the powder by coprecipitation method to prepare La 0.8 Yb 0.2 Ba 0.5 Sr 2.5 P3O 12 ceramic bulk material, the steps are as follows:

[0084] (1) Using lanthanum chloride, ytterbium chloride, barium chloride, strontium chloride and ammonium phosphate as raw materials, weighing according to the molar ratio La:Yb:Ba:Sr:P = 0.8:0.2:0.5:2.5:3; dissolving lanthanum chloride, ytterbium chloride, barium chloride, strontium chloride in deionized water to obtain a mixed solution, dissolving ammonium phosphate in deionized water and adjusting the pH to 9.8 with ammonia water, dropping the mixed solution of lanthanum chloride, ytterbium chloride, barium chloride, strontium chloride into the ammonium phosphate solution at a speed of 3 mL / min, and stirring continuously. During the reaction process, control the pH value above 9 with ammonia water. After the titration, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120 °C for 24 hours to obtain the precursor material.

[0085] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1100 °C for 20 hours to obtain La 0.8 Yb 0.2 Ba 0.5 Sr 2.5 P3O 12 powder, with a heating rate of 5 °C / min. Grind and sieve the synthesized powder to obtain powder with uniform particle size.

[0086] (3) Adopt the cold isostatic pressing forming process, and obtain La 0.8 Yb 0.2 Ba 0.5 Sr 2.5 P3O 12 ceramic green body.

[0087] (4) La 0.8 Yb 0.2 Ba 0.5 Sr 2.5 P3O12 The ceramic green body was sintered in air atmosphere at 1550 °C for 2 hours with a heating rate of 5 °C / min to obtain La 0.8 Yb 0.2 Ba 0.5 Sr 2.5 P3O 12 ceramic bulk material.

[0088] Example 9

[0089] Powders of Nd 0.2 Gd 0.2 Y 0.2 Tm 0.2 Yb 0.2 Ba3P3O 12 ceramic bulk material were synthesized by co-precipitation method, and the steps are as follows:

[0090] (1) Using neodymium chloride, gadolinium chloride, yttrium chloride, thulium chloride, ytterbium chloride, barium chloride and ammonium phosphate as raw materials, accurately weighed according to the molar ratio Nd:Gd:Y:Tm:Yb:Ba:P = 0.2:0.2:0.2:0.2:0.2:3:3; Dissolve neodymium chloride, gadolinium chloride, yttrium chloride, thulium chloride, ytterbium chloride, barium chloride in deionized water to obtain a mixed solution, dissolve ammonium phosphate in deionized water and adjust the pH to 9.8 with ammonia water, and add the mixed solution of neodymium chloride, gadolinium chloride, yttrium chloride, thulium chloride, ytterbium chloride, barium chloride to the ammonium phosphate solution at a speed of 3 mL / min, and stir continuously. Control the pH value above 9 during the reaction process. After titration, age for 5 hours, filter the precipitate by suction, wash it 4 times with deionized water and 2 times with absolute ethanol, and dry it at 120 °C for 24 hours to obtain the precursor substance.

[0091] (2) Grind the precursor obtained in step (1), put it into a muffle furnace, and calcine it at 1100 °C for 20 hours to obtain Nd 0.2 Gd 0.2 Y 0.2 Tm 0.2 Yb 0.2 Ba3P3O 12 powders, with a heating rate of 5 °C / min. Grind and sieve the synthesized powders to obtain powders with uniform particle size.

[0092] (3) Adopt the cold isostatic pressing forming process, and obtain Nd 0.2 Gd 0.2 Y 0.2 Tm 0.2 Yb 0.2 Ba3P3O 12 ceramic green body at 300 MPa for 8 minutes of pressure holding.

[0093] (4) Nd0.2 Gd 0.2 Y 0.2 Tm 0.2 Yb 0.2 Ba3P3O 12 The ceramic green body was sintered in air atmosphere at 1550 °C for 2 hours with a heating rate of 5 °C / min to obtain Nd 0.2 Gd 0.2 Y 0.2 Tm 0.2 Yb 0.2 Ba3P3O 12 ceramic bulk material.

[0094] The REM3P3O 12 series of ceramic bulk materials prepared in the above examples have a thermal expansion coefficient as shown in Table 1. The REM3P3O 12 series of ceramic bulk materials prepared in the present invention all have a high thermal expansion coefficient, meeting the requirements of thermal barrier materials.

[0095] Table 1 Thermal expansion coefficient of the prepared REM3P3O 12 series of ceramics (@1000 °C)

[0096]

[0097]

[0098] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a rare earth orthophosphate thermal barrier coating ceramic material by synthesizing powder through coprecipitation method, the chemical general formula of the rare earth orthophosphate is REM3P3O 12 , RE is a rare earth element, M is an alkaline earth metal, and it is characterized in that It includes the following steps: S1. Dissolve the salt containing RE rare earth and the salt containing alkaline earth metal M to obtain a mixed solution, dissolve the phosphate to obtain a P-containing solution and add ammonia water to adjust the pH; Add ammonia water to adjust the pH of the P-containing solution to 9.7 - 10; S2. Drop the mixed solution containing RE and M into the solution containing P, or drop the solution containing P into the mixed solution containing RE and M, and continuously stir. During the reaction process, control the pH value above 9 with ammonia water, and obtain the REM3P3O 12 precursor precipitate; the dropping rate is 5 mL / min or less; the aging time is 3 to 10 hours; S3. Dry the REM3P3O 12 precursor precipitate and calcine it to obtain REM3P3O 12 powder; S4, REM3P3O 12 After the powder is ground and sieved, it is pressed into a green body; the pressure for pressing is 200 - 300 MPa, the time is 5 - 10 min, and the method is cold isostatic pressing; S5. Calcinate the green body to obtain the orthophosphate thermal barrier coating ceramic material; The RE includes one or more combinations of La, Nd, Gd, Y, Ho, Tm or Yb; the molar ratio of the RE salt, M salt and P salt is 1:3:3; The grain size of the orthophosphate thermal barrier coating ceramic is 1 μm - 10 μm.

2. The method according to claim 1, wherein The M includes one or more combinations of Ca, Sr or Ba; the salt containing RE rare earth is RECl3 or RE(NO3)3, the salt containing alkaline earth metal M is MCl2 or M(NO3)2, and the phosphate includes at least one of (NH4)3PO4, NH4H2PO4, NaH2PO4, KH2PO4.

3. The method according to claim 1, wherein In step S3, calcine at 1000 - 1150 °C for 5 - 15 hours.

4. The method according to claim 3, wherein In step S3, the calcination temperature is 1100 °C and the heating rate is 2 - 6 °C / min.

5. The method according to claim 1, characterized in that In step S5, calcine at 1400 - 1600 °C for 2 - 10 hours.

6. A kind of orthophosphate thermal barrier coating ceramic powder, the chemical general formula of the orthophosphate is REM3P3O 12 , RE is a rare earth element, M is an alkaline earth metal, and its characteristics are that Obtained by the method according to any one of claims 1 - 4.

7. A kind of orthophosphate thermal barrier coating ceramic material, the chemical general formula of the orthophosphate is REM3P3O 12 , RE is a rare earth element, M is an alkaline earth metal, and its characteristics are that Obtained by the method according to any one of claims 1 - 5.

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