Preparation method of super-high-entropy complex oxide powder material for thermal barrier coating and application thereof

Abstract

The application discloses a preparation method of super-high-entropy complex oxide powder material for thermal barrier coating and application thereof, and comprises the following steps: S1, uniformly dispersing a rare earth element source and a transition metal element source in deionized water, stirring and treating at 80 DEG C, then adding a complexing agent and a dispersing agent to obtain a mixture A; S2, adjusting the pH of the mixture A system to 4-5 by using ammonia water under stirring at 80 DEG C, continuously stirring and treating to form a gel, and drying to obtain a dry gel; S3, sintering the dry gel at 1400 DEG C for 2h to obtain the super-high-entropy complex oxide powder material. The application makes up the shortcomings of traditional thermal barrier coating YSZ material, can still maintain phase stability near 1500 DEG C, widens the thermal barrier coating material system to the super-high-entropy complex ceramic field, and the material has the characteristics of uniform element distribution, small and uniform powder particle size, high purity and the like, and the method has low requirement on equipment and is simple in synthesis method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrahigh-entropy complex oxide materials, and particularly relates to a preparation method of an ultrahigh-entropy complex oxide powder material for a thermal barrier coating and application thereof. BACKGROUND

[0002] A thermal barrier coating (TBC) is a ceramic coating with good heat insulation performance in a high-temperature environment, and is widely used in the hot end parts of ground-based combustion engines and aero-engines to provide thermal protection and prevent damage to the engine caused by oxidation, corrosion and erosion. The hot end parts bear extreme conditions of high temperature, high pressure and high speed during service, and any failure can cause serious consequences. At present, the most commonly used thermal barrier coating material is Y2O3 stabilized ZrO2 ceramic (Yttria-Stabilized Zirconia, YSZ), which has a high thermal expansion coefficient, high fracture toughness and excellent thermal shock resistance. However, YSZ also has some significant technical problems, such as high thermal conductivity, metastable tetragonal phase degradation and poor sintering resistance, resulting in an upper limit of 1200℃ for its acceptance in long-term use. In addition, in an environment exceeding 1200℃, melted CMAS (CaO, Al2O3, SiO2, etc. sand) will enter the coating and react with Y2O3, causing the failure of the stabilizer, thereby accelerating the failure of the YSZ coating. Therefore, the research on new thermal barrier coating materials has become the key to improving the efficiency of the engine. A2B2O7 ceramic materials with pyrochlore structure, such as La2Zr2O7, have become important candidate materials due to their low thermal conductivity, low oxygen permeability, excellent high-temperature stability and sintering resistance. However, the thermal expansion coefficient of La2Zr2O7 ceramic is relatively low (9.1×10^–6K^–1, 1000℃) and the fracture toughness is relatively low (1.4MPam^1 / 2), resulting in an unsatisfactory thermal cycle life of the coating, which still needs to be further improved.

[0003] In view of the above problems, the present application provides a preparation method of an ultrahigh-entropy complex oxide powder material for a thermal barrier coating and application thereof. SUMMARY

[0004] The present application discloses a preparation method of an ultrahigh-entropy complex oxide powder material for a thermal barrier coating and application thereof, and aims to solve the technical problems in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] A preparation method of an ultrahigh-entropy complex oxide powder material for a thermal barrier coating, comprising the following steps:

[0007] S1, dispersing the rare earth element source and the transition metal element source in deionized water, stirring and treating at 80℃, then adding a complexing agent and a dispersing agent to obtain a mixture A;

[0008] S2, adjusting the pH of the mixture A system to 4-5 with ammonia water under stirring at 80℃, continuing to stir and treat to form a gel, and drying to obtain a dry gel;

[0009] S3, sintering the dry gel at 1400℃ for 2h to obtain an ultra-high-entropy complex oxide powder material.

[0010] The components of the rare earth element are La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Er3+, Yb3+, and Y3+.

[0011] The component of the transition group metal element is Ti4+.

[0012] The rare earth element is introduced in equal molar amount.

[0013] The total molar amount of the rare earth element and the transition group metal element is introduced in equal molar amount, and the introduction amount is allowed to float up and down by 10% on the equal molar ratio.

[0014] The rare earth element source is La(NO3)3·6H2O, Ce(NO3)3·6H2O, Pr(NO3)3·6H2O, Nd(NO3)3·6H2O, Sm(NO3)3·6H2O, Eu(NO3)3·6H2O, Gd(NO3)3·6H2O, Dy(NO3)3·6H2O, Er(NO3)3·6H2O, Yb(NO3)

[0015] 3·6H2O, Y(NO3)3·6H2O, and the transition metal element source is C16H36O4Ti.

[0016] The ratio of the total metal cation molar amount of the rare earth element source and the transition metal element source to the amount of deionized water is 0.8-1.2 mol:1L.

[0017] The ratio of the total molar amount of metal elements of the rare earth element source to the total molar amount of metal elements of the transition metal element source is 1:1±0.1, and the molar amount of each metal element in the rare earth element source is equal.

[0018] The complexing agent is citric acid, and the dispersing agent is polyethylene glycol.

[0019] The ratio of the total metal cation molar amount of the rare earth element source and the transition metal element source to the molar amount of citric acid is 1:2, and the addition amount of polyethylene glycol is 10% of the mass of the mixture A.

[0020] The application of the super high entropy complex oxide powder material for thermal barrier coating, the super high entropy complex oxide powder material, the main phase of which is pyrochlore structure, and the second phase of which is fluorite structure, is ground by using agate mortar, sieved by using a 300 mesh screen, and the super high entropy complex oxide powder with fine and uniform particle size is obtained, the ground and sieved super high entropy oxide powder is filled in a graphite mold, and is subjected to discharge plasma sintering at 30 Mpa and 1500 DEG C, and the sintering time is 15 min, and the ceramic bulk material is obtained.

[0021] The application of the super high entropy complex oxide powder material for thermal barrier coating provided by the application has the following advantages:

[0022] 1. According to the service requirement of the thermal barrier coating, a super high entropy complex oxide ceramic new material suitable for the thermal barrier coating of the hot end part of the aero-engine is designed, the synthesis of the powder of the new material is completed by using the sol-gel method, and the discharge plasma sintering technology is proposed to complete the preparation of the thermal barrier coating test material. The new material makes up for the shortcomings of the traditional thermal barrier coating YSZ material and can still maintain phase stability near 1500 DEG C, and the thermal barrier coating material system is widened to the super high entropy complex ceramic field.

[0023] 2. The pyrochlore structure of Y2Ti2O7 is introduced with 11 rare earth elements, the traditional single rare earth titanate ceramic is directly expanded to the super high entropy ceramic system (12 main elements) to complete the design and preparation of the super high entropy pyrochlore oxide ceramic. A large number of cations with different radii cause very obvious lattice distortion, reduce the average free path of phonons in the internal propagation, increase the phonon scattering, and greatly reduce the thermal conductivity of the high-entropy oxide material. The high-entropy oxide has high thermal stability and very low thermal conductivity in a high-temperature environment, and still maintains a stable phase structure and the grain growth phenomenon is not obvious. At the same time, ion diffusion is also delayed, atomic migration energy and diffusion energy are improved, and the chemical stability of the high-entropy oxide material is also greatly improved.

[0024] 3. The second phase is generated in-situ by oxidation of Ce3+, and the second phase is precipitated in the form of particles under high-temperature environment and thermal shock, releases thermal stress, avoids crack initiation, makes up for the deficiency of poor fracture toughness of the ceramic material, and has a self-toughening effect.

[0025] 4、The present application selects rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb, transition group metal elements Y and the like as components of the super high entropy oxide, and each element has excellent properties of high thermal stability, good mechanical properties, corrosion resistance, stable chemical properties, radiation resistance and the like when existing as an oxide alone.

[0026] 5、The present application uses a sol-gel method in the synthesis of the super high entropy complex oxide powder material, and the oxide synthesized by the method has the characteristics of uniform element distribution, small and uniform powder particle size, high purity and the like, and the method has low requirements on equipment and simple synthesis method. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A flowchart of a preparation method of the super high entropy complex oxide powder material for thermal barrier coatings according to the present application.

[0028] Figure 2 A physical photo of the super high entropy complex oxide powder material prepared in the present application.

[0029] Figure 3 An X-ray diffraction spectrum of the super high entropy complex oxide powder material prepared in the present application.

[0030] Figure 4 A scanning electron microscope backscattering photo of the super high entropy oxide block prepared in the present application.

[0031] Figure 5 A scanning electron microscope secondary electron photo and an energy spectrum distribution diagram of the super high entropy oxide block prepared in the present application after high temperature treatment at 1500 DEG C.

[0032] Figure 6 An X-ray diffraction spectrum of the super high entropy oxide block prepared in the present application after thermal shock test at 1200 DEG C.

[0033] Figure 7 A scanning electron microscope secondary electron photo of the super high entropy oxide block prepared in the present application after thermal shock test at 1200 DEG C. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0035] Embodiment

[0036] A preparation method of an ultra-high-entropy multiphase oxide powder material

[0037] A rare earth element source La(NO3)3·6H2O, Ce(NO3)3·6H2O, Pr(NO3)

[0038] 3·6H2O, Nd(NO3)3·6H2O, Sm(NO3)3·6H2O, Eu(NO3)3·6H2O, Gd(NO3)3·6H2O, Dy(NO3)3·6H2O, Er(NO3)3·6H2O, Yb(NO3)

[0039] 3·6H2O, Y(NO3)3·6H2O) and a transition metal element source (C16H36O4Ti) are uniformly dispersed in deionized water to configure a homogeneous solution with a concentration of 1 mol / L, wherein the molar ratio between each rare earth element source is 1:1, and the total molar ratio of the rare earth element sources to the total molar amount of the transition metal element source is 1:1±0.1. Then, stirring treatment is performed at 80°C with a stirring speed of 300 rpm, and then a complexing agent (citric acid) and a dispersing agent (polyethylene glycol) are added during stirring to obtain a mixture A; wherein the total metal cation molar amount of the rare earth element source and the transition metal element source to the molar amount of citric acid is 1:2, and the addition amount of polyethylene glycol is 10% of the mass of the mixture A. The impurities introduced by citric acid and polyethylene glycol can be removed in the subsequent sintering process. Under stirring at 80°C, an ammonia solution with a concentration of 15%wt is added dropwise to the mixture A system to make the pH of the system 4-5, and the stirring treatment is continued at 80°C, and after all the metal cations are completely complexed, water is continuously evaporated until a gel state is completely formed. The gel is placed in an oven again, dried at 150°C for 24h to obtain a dry gel. The impurity ions introduced by the ammonia water can be removed in the subsequent sintering process. Finally, the dry gel is sintered at 1400°C for 2h to obtain an ultra-high-entropy multiphase oxide powder material with a uniform particle size distribution of 0.1-1μm.

[0040] The application of the super high entropy complex oxide powder material for thermal barrier coating, the super high entropy complex oxide powder material, the main phase of which is pyrochlore structure, and the second phase of which is fluorite structure, is ground by using agate mortar, sieved by using a 300 mesh screen, and the super high entropy complex oxide powder with fine and uniform particle size is obtained, the ground and sieved super high entropy oxide powder is filled in a graphite mold, and is subjected to discharge plasma sintering at 30 Mpa and 1500 DEG C, and the sintering time is 15 min, and the ceramic bulk material is obtained.

[0041] I. Powder photo

[0042] The actual photo of the super high entropy complex oxide powder material prepared in the embodiment 1 of the application is shown in Figure 2 .

[0043] II. X-ray diffraction test

[0044] The super high entropy complex oxide powder prepared in the embodiment 1 of the application is subjected to X-ray diffraction test, and the result is shown in Figure 3 . It can be seen from Figure 3 that the main phase of the prepared super high entropy oxide powder is typical pyrochlore phase, and the second phase is CeO2 fluorite phase.

[0045] III. Scanning electron microscope test

[0046] The obtained actual object is subjected to scanning electron microscope test, and the result is shown in Figure 4 and Figure 5 . Figure 4 It is the scanning electron microscope back scattering photo of the embodiment 2, and it can be seen that the super high entropy oxide ceramic block prepared in the embodiment 2 of the application is dense, and the porosity is low, and the second phase is uniformly distributed in the form of strips between the matrix. Figure 5 It is the scanning electron microscope secondary electron photo and energy spectrum distribution diagram of the embodiment 2 after high temperature treatment at 1500 DEG C, and it can be seen that after high temperature treatment, the second phase is precipitated in the form of particles, and the Ce element is enriched in the precipitate.

[0047] IV. Thermal stability and thermal shock resistance test

[0048] The ceramic block prepared in the embodiment 2 of the application is taken as an example, and the obtained actual object is subjected to thermal stability and thermal shock resistance test at 1200 DEG C, and the result is shown in Figure 6 and Figure 7 . Figure 6 It is the X-ray diffraction result after thermal shock for 50 times and 125 times, and it can be seen that the phase structure of the sample remains stable after thermal shock for 125 times. Figure 7The scanning electron microscope secondary electron photos after different times of thermal shock show that the second phase gradually precipitates in the form of particles to release thermal stress, and no cracks appear in the sample.

[0049] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. The alternatives can be partial structure, device, method step alternatives, or complete technical solutions. According to the technical solutions and inventive concepts of the present application, equivalent replacements or changes are covered within the protection scope of the present application.

Claims

1. A method for producing an ultra-high-entropy complex oxide powder material for thermal barrier coatings, characterized in that The method comprises the following steps: S1, dispersing the rare earth element source and the transition metal element source in deionized water, stirring and treating at 80℃, then adding complexing agent and dispersant to obtain mixture A; the component of the rare earth element source is La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3 + , Gd 3+ , Dy 3+ , Er 3+ , Yb 3+ , Y 3+ ; the component of the transition metal element source is Ti 4+ ; the rare earth element source is introduced in equal molar amount; S2, adjusting the pH of the mixture A system to 4-5 with ammonia water under stirring at 80℃, continuing the stirring treatment to form a gel, and drying to obtain a dry gel; S3, sintering the dry gel at 1400℃ for 2h to obtain an ultra-high-entropy complex oxide powder material; The ratio of the total molar amount of metal elements of the rare earth element source to the total molar amount of metal elements of the transition metal element source is 1:1±0.1; The main phase of the ultra-high-entropy complex oxide powder material is a pyrochlore structure, and the second phase is a fluorite structure.

2. The method of claim 1, wherein the method further comprises: The rare earth element source is La(N03)3-6H20, Ce(N03)3-6H20, Pr(N03)3-6H20, Nd(N03)3-6H20, Sm(N03)3-6H20, Eu(N03)3-6H20, Gd(N03)3-6H20, Dy(N03)3-6H20, Er(N03)3-6H20, Yb(N03)3-6H20, Y(N03)3-6H20, and the transition metal element source is C 16 H 36 O4Ti.

3. The method of claim 1, wherein the method further comprises: The ratio of the total metal cation molar amount of the rare earth element source and the transition metal element source to the amount of deionized water is 0.8-1.2mol:1L.

4. The method of claim 1, wherein the method is characterized by: The complexing agent is citric acid, and the dispersing agent is polyethylene glycol.

5. The method of claim 1, wherein the method further comprises: The ratio of the total metal cation molar amount of the rare earth element source and the transition metal element source to the molar amount of citric acid is 1:2, and the addition amount of polyethylene glycol is 10% of the mass of the mixture A.

6. Use of an ultra-high-entropy complex oxide powder material for thermal barrier coatings, characterized in that According to the preparation method of any one of claims 1-5, the ultra-high-entropy complex oxide powder material with the main phase of a pyrochlore structure and the second phase of a fluorite structure is ground by using an agate mortar, sieved by using a 300-mesh screen, and obtained as an ultra-high-entropy complex oxide powder with fine and uniform particle size. The ground and sieved ultra-high-entropy oxide powder is filled in a graphite mold, and subjected to discharge plasma sintering at 30MPa and 1500℃ for 15min to obtain a ceramic bulk material.

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