A rare earth medium-high entropy zirconium oxide-based thermal barrier coating ceramic material and a preparation method thereof

Abstract

The application provides a rare earth medium-high-entropy zirconia-based thermal barrier coating ceramic material and a preparation method thereof, and belongs to the technical field of thermal barrier coating ceramic materials. 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y x La 0.2‑x )O 1.8 , wherein 0<=x<=0.2. The rare earth medium-high-entropy zirconia-based ceramic material obtained by the application has lower thermal conductivity than traditional zirconia-based ceramic materials, and can still maintain low thermal conductivity at 1500 DEG C.

Description

Technical Field

[0001] This invention relates to the field of thermal barrier coating ceramic materials technology, and in particular to a rare earth high-entropy zirconia-based thermal barrier coating ceramic material and its preparation method. Background Technology

[0002] Thermal barrier coatings (TBCs) are a key technology for supporting the thermal protection of blades, driven by the service environment and with multi-performance synergy. They are the core technology for the protection of hot-end components of power plants in aerospace, shipbuilding and marine engineering, and directly determine the thermal efficiency, service life and reliability of aero engines and gas turbines. At present, electron beam physical vapor deposition (EB-PVD) and plasma spraying (APS) are the two mainstream technologies for preparing thermal barrier coatings. The thermal barrier coating system represented by the 7-8wt% YSZ / MCrAlY double-layer structure thermal barrier coating prepared by EB-PVD is considered to have the best comprehensive performance and is widely used in the thermal protection of turbine blades of many types of in-service aero engines. However, when in long-term service in environments above 1000℃, many core problems that cannot be ignored are gradually exposed: (1) poor high-temperature phase stability: the high-temperature t→m phase transformation causes 4-6% volume expansion, leading to TBC cracking failure; (2) poor high-temperature sintering resistance: leading to reduced thermal insulation effect and decreased mechanical properties; (3) increased high-temperature thermal conductivity. Therefore, the existing thermal barrier coating materials have problems such as high high-temperature thermal conductivity, high-temperature sintering failure and poor phase stability, and there is an urgent need to develop a new generation of ultra-high temperature thermal barrier coating ceramic materials. Summary of the Invention

[0003] The purpose of this invention is to provide a rare earth high-entropy zirconia-based thermal barrier coating ceramic material and its preparation method, so as to solve the problems of high high-temperature thermal conductivity leading to high-temperature sintering failure and poor phase stability of existing thermal barrier coating ceramic materials.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a rare-earth high-entropy zirconia-based thermal barrier coating ceramic material, comprising the following molar proportions:

[0006] (Zr 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y x La 0.2-x )O 1.8 , where 0≤x≤0.2.

[0007] This invention provides a method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic materials, comprising the following steps:

[0008] (1) Each raw material powder is preheated separately;

[0009] (2) After mixing the preheated raw material powder, the first ball milling, drying, solid-phase synthesis, second ball milling and pressing are carried out in sequence to obtain ceramic block blanks;

[0010] (3) The ceramic block blank is calcined to obtain rare earth high-entropy zirconia-based ceramic material.

[0011] Furthermore, the temperature of the preheating treatment is independently 900-1000℃, and the preheating time is independently 1-2h.

[0012] Furthermore, the dispersion medium used in the first ball milling is anhydrous ethanol, and the mass ratio of the dispersion medium to the raw material powder is 1.2 to 2.0:1;

[0013] The first ball milling process involves a ball-to-material mass ratio of 1.0 to 2.0:1, a rotation speed of 600 to 1000 r / min, and a milling time of 12 to 24 h.

[0014] Furthermore, the drying temperature is 60–80°C, and the drying time is 15–30 hours;

[0015] The solid-phase synthesis is carried out under calcination at a temperature of 1400–1650 °C for 3–12 h.

[0016] Furthermore, the dispersion medium used in the second ball milling is anhydrous ethanol, and the mass ratio of the dispersion medium to the raw material powder is 1.5 to 2.0:1.

[0017] The second ball milling process involves a material-to-ball mass ratio of 1.5–2.5:1, a rotation speed of 800–1200 r / min, and a milling time of 15–30 h.

[0018] Furthermore, the grinding media used in both the first and second ball milling processes are zirconia ceramic balls.

[0019] Furthermore, the pressing process includes pre-pressing and secondary pressing. The pre-pressing pressure is 5-15 MPa, and the holding time is 30-120 s. The secondary pressing pressure is 100-250 MPa, and the holding time is 10-30 min.

[0020] Furthermore, the target temperature for the calcination treatment is 1400–1600℃, and the holding time is 4–8 hours;

[0021] The heating rate from room temperature to the target temperature is 2–5 °C / min;

[0022] The cooling rate from the target temperature of the calcination treatment to the intermediate temperature T1 is 1-3℃ / min, where the intermediate temperature T1 is 800-1000℃, and the cooling rate from the intermediate temperature T1 to room temperature is 3-5℃ / min.

[0023] The beneficial effects of this invention are:

[0024] Regarding the material system: the currently mature and widely used yttrium oxide-stabilized zirconia-based thermal barrier coating ceramic materials have the disadvantage of high thermal conductivity, especially at service temperatures above 1000℃ where the thermal conductivity increases sharply. Figure 1 The rare-earth high-entropy zirconia-based thermal barrier coating ceramic material proposed in this invention exhibits lower thermal conductivity than traditional zirconia-based ceramic materials, especially maintaining low thermal conductivity even at 1500℃. Furthermore, unlike other thermal barrier coating ceramic material systems, the novel ultra-high temperature, low thermal conductivity material proposed in this invention is based on the existing, widely applied, and mature yttrium-stabilized zirconia coating technology framework, demonstrating strong technical feasibility and low technical risk.

[0025] Regarding material preparation technology: This invention proposes a traditional solid-phase synthesis method, which is easy to engineer and industrialize with controllable preparation, effectively avoiding the Cl- present in traditional liquid-phase methods. -1 Addressing issues such as excessive impurity element content, poor batch stability, and high costs, the production process can achieve zero discharge of "three high" wastewater (high pollution, high energy consumption, and high costs). Furthermore, the material system and preparation method proposed in this invention are easily implemented in the electron beam physical vapor deposition (EB-PVD) process for preparing thermal barrier coatings. Attached Figure Description

[0026] Figure 1 The thermal conductivity curve of the current 8wt% YSZ thermal barrier coated ceramic material is shown.

[0027] Figure 2 The image shows the XRD pattern of the thermal barrier coated ceramic material prepared in Example 1 of this invention.

[0028] Figure 3 This is a thermal conductivity curve of the thermal barrier coated ceramic material prepared in Example 1 of the present invention;

[0029] Figure 4 The image shows the XRD pattern of the thermal barrier coated ceramic material prepared in Example 3 of this invention.

[0030] Figure 5 The thermal conductivity curve of the thermal barrier coated ceramic material prepared in Example 3 of the present invention is shown. Detailed Implementation

[0031] This invention provides a rare-earth high-entropy zirconia-based thermal barrier coating ceramic material, comprising the following molar proportions:

[0032] (Zr 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y x La 0.2-x )O 1.8 , where 0≤x≤0.2.

[0033] In this invention, x is preferably 0, 0.1, or 0.2.

[0034] This invention provides a method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic materials, comprising the following steps:

[0035] (1) Each raw material powder is preheated separately;

[0036] (2) After mixing the preheated raw material powder, the first ball milling, drying, solid-phase synthesis, second ball milling and pressing are carried out in sequence to obtain ceramic block blanks;

[0037] (3) The ceramic block blank is calcined to obtain rare earth high-entropy zirconia-based ceramic material.

[0038] In this invention, the purity of the raw material powder is independently ≥99.9%, preferably ≥99.95%.

[0039] In this invention, the temperature of the preheating treatment is independently 900-1000℃, preferably 920-980℃, and more preferably 950℃; the time of the preheating treatment is independently 1-2h, preferably 1.5h.

[0040] In this invention, the dispersion medium used in the first ball milling is anhydrous ethanol, and the mass ratio of the dispersion medium to the raw material powder is 1.2 to 2.0:1, preferably 1.5 to 1.8:1, and more preferably 1.6:1.

[0041] In this invention, the mass ratio of material to ball in the first ball mill is 1.0 to 2.0:1, preferably 1.2 to 1.8:1, and more preferably 1.5:1; the rotation speed is 600 to 1000 r / min, preferably 700 to 900 r / min, and more preferably 800 r / min; the ball milling time is 12 to 24 h, preferably 15 to 22 h, and more preferably 18 to 20 h.

[0042] In this invention, the drying temperature is 60-80°C, preferably 65-75°C, and more preferably 70°C; the drying time is 15-30 hours, preferably 18-25 hours, and more preferably 20-22 hours.

[0043] In this invention, the solid-phase synthesis is carried out under calcination, with the calcination temperature being 1400–1650°C, preferably 1450–1600°C, and more preferably 1500–1550°C; and the calcination time being 3–12 h, preferably 5–10 h, and more preferably 6–8 h.

[0044] In this invention, the dispersion medium used in the second ball milling is anhydrous ethanol, and the mass ratio of the dispersion medium to the raw material powder is 1.5 to 2.0:1, preferably 1.6 to 1.8:1, and more preferably 1.7:1.

[0045] In this invention, the mass ratio of material to ball in the second ball mill is 1.5–2.5:1, preferably 1.6–2.2:1, and more preferably 2.0:1; the rotation speed is 800–1200 r / min, preferably 900–1100 r / min, and more preferably 1000 r / min; the ball milling time is 15–30 h, preferably 18–25 h, and more preferably 20–22 h.

[0046] In this invention, the grinding media used in the first and second ball milling are preferably zirconia ceramic balls.

[0047] In this invention, the pressing process includes pre-pressing and secondary pressing. The pre-pressing pressure is 5-15 MPa, preferably 8-12 MPa, and more preferably 10 MPa; the holding time is 30-120 s, preferably 50-100 s, and more preferably 60-80 s; the secondary pressing pressure is 100-250 MPa, preferably 120-220 MPa, and more preferably 150-200 MPa; the holding time is 10-30 min, preferably 15-25 min, and more preferably 20 min.

[0048] In this invention, the target temperature for the calcination treatment is 1400–1600°C, preferably 1450–1550°C, and more preferably 1500°C; the holding time is 4–8 h, preferably 5–7 h, and more preferably 6 h.

[0049] In this invention, the heating rate from room temperature to the target temperature is 2 to 5 °C / min, preferably 3 to 4 °C / min.

[0050] In this invention, the cooling rate from the target calcination temperature to the intermediate temperature T1 is 1–3 °C / min, preferably 1.5–2.5 °C / min, and more preferably 2–2.3 °C / min; the intermediate temperature T1 is 800–1000 °C, preferably 850–950 °C, and more preferably 900–920 °C; the cooling rate from the intermediate temperature T1 to room temperature is 3–5 °C / min, preferably 3.5–4.5 °C / min, and more preferably 4–4.2 °C / min.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] (1) Ingredients: Er2O3, Y2O3, ZrO2, CeO2, and HfO2 with a purity greater than 99.9% were used as raw material powders, and then Zr was prepared by preparing the raw materials according to the molar percentage. 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y 0.2 O 1.8 Ceramic materials.

[0054] (2) Ball milling: Zirconia ceramic balls of different diameters were used as grinding media, and anhydrous ethanol was added to a polyurethane ball mill jar as a dispersion medium. The ball milling was carried out for 24 hours at a speed of 1000 r / min. The material-to-ball ratio was 2.0:1, and the mass ratio of dispersion medium to raw material powder was 2.0:1.

[0055] (3) Drying: After ball milling, the slurry is placed in a 75℃ convection constant temperature oven for 24 hours to dry, so as to obtain a uniformly mixed dry powder.

[0056] (4) Solid-phase synthesis of powder: The above uniformly mixed powder is calcined at 1500°C for 12 hours in an air atmosphere muffle furnace.

[0057] (5) Secondary ball milling: The sintered powder was milled using zirconia ceramic balls of different diameters as grinding media and anhydrous ethanol as dispersion media in a polyurethane ball mill jar for 24 hours at a speed of 1200 r / min. The material-to-ball ratio was 2.5:1 and the mass ratio of dispersion media to raw powder was 1.5:1.

[0058] (6) Pre-pressing of ceramic blocks: The granulated powder is pre-pressed at 6MPa using an electric biaxial press. The pre-pressing pressure is 60s and the holding time is 60s. The pre-formed sample is then placed in a cold isostatic press and pressurized to 200MPa for 15min for secondary molding to obtain ceramic block blanks.

[0059] (7) High-temperature calcination of ceramic blocks: The ceramic block blanks are placed in a high-temperature furnace with an air atmosphere and heated to 1550°C at a heating rate of 5°C / min and held for 6 hours. Then, the temperature is reduced to 900°C at a rate of 2°C / min and then cooled to room temperature at a rate of 5°C / min.

[0060] Example 2

[0061] (1) Ingredients: Er2O3, Y2O3, ZrO2, CeO2, and HfO2 with a purity greater than 99.9% were used as raw material powders, and then Zr was prepared by preparing the raw materials according to the molar percentage. 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y 0.2 O 1.8 Ceramic materials.

[0062] (2) Ball milling: Zirconia ceramic balls of different diameters were used as grinding media, and anhydrous ethanol was added to a polyurethane ball mill jar as a dispersion medium. The ball milling was carried out for 24 hours at a speed of 1000 r / min. The material-to-ball ratio was 1.5:1, and the mass ratio of dispersion medium to raw material powder was 2.0:1.

[0063] (3) Drying: After ball milling, the slurry is placed in a 60℃ convection constant temperature oven for 24 hours to dry, so as to obtain a uniformly mixed dry powder.

[0064] (4) Solid-phase synthesis of powder: The above uniformly mixed powder is calcined at 1600°C for 12 hours in an air atmosphere muffle furnace.

[0065] (5) Secondary ball milling: The sintered powder was milled using zirconia ceramic balls of different diameters as grinding media and anhydrous ethanol as dispersion media in a polyurethane ball mill jar for 24 hours at a speed of 1200 r / min. The material-to-ball ratio was 2.0:1 and the mass ratio of dispersion media to raw powder was 1.5:1.

[0066] (6) Pre-pressing of ceramic blocks: The granulated powder is pre-pressed at 6MPa using an electric biaxial press. The pre-pressing pressure is 60s and the holding time is 60s. The pre-formed sample is then placed in a cold isostatic press and pressurized to 200MPa for 15min for secondary molding to obtain ceramic block blanks.

[0067] (7) High-temperature calcination of ceramic blocks: The ceramic block blanks are placed in a high-temperature furnace with an air atmosphere and heated to 1550°C at a heating rate of 5°C / min and held for 6 hours. Then, the temperature is reduced to 900°C at a rate of 2°C / min and then cooled to room temperature at a rate of 5°C / min.

[0068] Example 3

[0069] (1) Ingredients: La2O3, Er2O3, ZrO2, CeO2, and HfO2 with a purity greater than 99.9% were used as raw material powders, and then Zr was prepared by preparing the raw materials according to the molar percentage. 0.2 Hf 0.2 Ce 0.2 Er 0.2 La 0.2 O 1.8 Ceramic materials.

[0070] (2) Ball milling: Zirconia ceramic balls of different diameters were used as grinding media, and anhydrous ethanol was added to a polyurethane ball mill jar as a dispersion medium. The ball milling was carried out for 24 hours at a speed of 1000 r / min. The material-to-ball ratio was 2.0:1, and the mass ratio of dispersion medium to raw material powder was 2.0:1.

[0071] (3) Drying: After ball milling, the slurry is placed in a 75℃ convection constant temperature oven and dried at 60℃ for 24 hours to obtain a uniformly mixed dry powder.

[0072] (4) Solid-phase synthesis of powder: The above uniformly mixed powder is calcined at 1500°C for 12 hours in an air atmosphere muffle furnace.

[0073] (5) Secondary ball milling: The sintered powder was milled using zirconia ceramic balls of different diameters as grinding media and anhydrous ethanol as dispersion media in a polyurethane ball mill jar for 24 hours at a speed of 1200 r / min. The material-to-ball ratio was 2.0:1 and the mass ratio of dispersion media to raw powder was 2.0:1.

[0074] (6) Pre-pressing of ceramic blocks: The granulated powder is pre-pressed at 6MPa using an electric biaxial press. The pre-pressing pressure is 60s and the holding time is 60s. The pre-formed sample is then placed in a cold isostatic press and pressurized to 200MPa for 15min for secondary molding to obtain ceramic block blanks.

[0075] (7) High-temperature calcination of ceramic blocks: The ceramic block blanks are placed in an air atmosphere high-temperature furnace and heated to 1500℃ at a heating rate of 5℃ / min and held for 6 hours. Then, the temperature is reduced to 800℃ at a rate of 2℃ / min and then cooled to room temperature at a rate of 5℃ / min.

[0076] Figure 1The thermal conductivity curve of the existing thermal barrier coating ceramic material (8wt.% Y2O3 partially stabilized ZrO2 ceramic material, 8wt% YSZ) is shown in the figure. (This material is from Aziz HS, Huang M, Li Z, et al. Repressing high-temperature radiative heat transfer in thermal barrier coatings[J]. Journal of the American Ceramic Society, 2022(5):105.DOI:10.1111 / jace.18321.) It can be seen that when the service temperature is higher than 1000℃, there is a problem of increased thermal conductivity at high temperature. This is mainly caused by photon heat conduction, which seriously restricts its application in higher service temperature environments.

[0077] The ceramic materials obtained in Examples 1 and 3 were subjected to performance tests, and the results are as follows: Figure 3 and Figure 5 As shown, the Zr obtained by this invention 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y 0.2 O 1.8 and Zr 0.2 Hf 0.2 Ce 0.2 Er 0.2 La 0.2 O 1.8 Ceramic materials have lower thermal conductivity, especially at 1500℃, they can still maintain low thermal conductivity.

[0078] As can be seen from the above embodiments, the present invention provides a rare-earth high-entropy zirconia-based ceramic material and its preparation method. The rare-earth high-entropy zirconia-based ceramic material obtained by the present invention has a lower thermal conductivity than traditional zirconia-based ceramic materials, especially maintaining a low thermal conductivity even at 1500℃. In addition, unlike other thermal barrier coating ceramic material systems, the novel ultra-high temperature low thermal conductivity proposed in this invention is based on the existing mature yttrium oxide stabilized zirconia coating technology framework, which has strong technical feasibility and low technical risk.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rare earth medium entropy zirconia-based thermal barrier coating ceramic material, characterized in that, Comprise the following molar proportions of materials: (Zr 0.2 Hf 0.2 Ce 0.2 Er 0.2 Y x La 0.2-x )O 1.8 wherein 0≤x≤0.

1.

2. The method for preparing the rare earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 1, characterized in that, It comprises the following steps: (1) preheat each raw material powder respectively; (2) after mixing the preheated raw material powder, sequentially perform first ball milling, drying, solid phase synthesis, second ball milling and pressing forming to obtain ceramic bulk body green body; (3) perform calcination treatment on the ceramic bulk body green body to obtain rare earth medium-high entropy zirconium oxide-based thermal barrier coating ceramic material; The pressing forming comprises pre-pressing and secondary pressing, the pressure of pre-pressing is 5-15 MPa, and the pressure maintaining time is 30-120 s; the pressure of secondary pressing is 100-250 MPa, and the pressure maintaining time is 10-30 min.

3. The method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 2, characterized in that, The temperature of the preheating treatment is independently 900-1000℃, and the preheating treatment time is independently 1-2 h.

4. The method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 2 or 3, characterized in that, The dispersing medium used in the first ball milling is anhydrous ethanol, and the mass ratio of the dispersing medium to the raw material powder is 1.2-2.0:1; The mass ratio of the material ball in the first ball milling is 1.0-2.0:1, the rotation speed is 600-1000 r / min, and the ball milling time is 12-24 h.

5. The method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 4, characterized in that, The temperature of the drying is 60-80℃, and the drying time is 15-30 h; The solid phase synthesis is performed under calcination, the calcination temperature is 1400-1650℃, and the calcination time is 3-12 h.

6. The method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 2, 3, or 5, characterized in that, The dispersing medium used in the second ball milling is anhydrous ethanol, and the mass ratio of the dispersing medium to the raw material powder is 1.5-2.0:1; The mass ratio of the material ball in the second ball milling is 1.5-2.5:1, the rotation speed is 800-1200 r / min, and the ball milling time is 15-30 h.

7. The method for preparing the rare earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 6, characterized in that, The grinding medium used in the first ball milling and the second ball milling is zirconia ceramic ball.

8. The method for preparing rare-earth high-entropy zirconia-based thermal barrier coating ceramic material according to claim 7, characterized in that, The target temperature of the calcination treatment is 1400-1600℃, and the holding time is 4-8 h; The heating rate from room temperature to the target temperature is 2-5℃ / min; The cooling rate from the target temperature of the calcination treatment to the intermediate temperature T1 is 1-3℃ / min, the intermediate temperature T1 is 800-1000℃, and the cooling rate from the intermediate temperature T1 to room temperature is 3-5℃ / min.

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