A dual rare earth oxide doped YSZ ceramic material and coating and method of making and use thereof

Abstract

This invention belongs to the field of thermal protective ceramic coating technology, specifically relating to a dual rare earth oxide-doped YSZ ceramic material and coating, its preparation method, and applications. The invention involves mixing raw materials to obtain a mixed powder; the mixed powder is then subjected to solid-state sintering to obtain the dual rare earth oxide-doped YSZ ceramic material. This invention uses the dual rare earth oxide-doped YSZ ceramic material to prepare a sprayable ceramic powder, which is then used to prepare a ceramic coating using atmospheric plasma spraying technology. The dual rare earth oxide-doped YSZ ceramic material and coating provided by this invention exhibit excellent high-temperature phase stability. The dual rare earth oxide-doped YSZ ceramic material powder possesses the ability to remain unchanged for a long time at a high temperature of 1500 °C; the resulting ceramic coating, as a thermal protective material, exhibits excellent high-temperature phase stability, remaining unchanged for a long time at a high temperature of 1400 °C, and can operate for extended periods above 1200 °C.

Description

Technical Field

[0001] This invention belongs to the field of thermal protection ceramic coating technology, specifically relating to a dual rare earth oxide doped YSZ ceramic material and coating, its preparation method, and its application. Background Technology

[0002] Yttria-stabilized zirconia (YSZ) possesses excellent thermophysical properties, including high melting point, low thermal conductivity, high phase stability, and low sintering rate, as well as superior mechanical properties such as low elastic modulus, high strength, high hardness, and high fracture toughness. It also exhibits good corrosion resistance. YSZ ceramic coatings prepared by atmospheric plasma spraying (APS) or electron beam vapor deposition possess a thermodynamically non-equilibrium tetragonal phase (t′ phase). The t′ phase exhibits a unique ferroelastic toughening mechanism, which ensures that the YSZ coating maintains excellent fracture toughness even at high temperatures. This makes YSZ the only mature, widely used, and commercially viable top-layer material for thermal protective coatings.

[0003] However, as the service temperature of the coating continues to increase, the YSZ coating faces severe challenges. During operation, when the temperature rises to 1200 ℃, the YSZ coating undergoes a phase transformation, with the t phase converting into the m phase, and simultaneously producing a 3%~5% volume expansion. This leads to the coating peeling off due to uneven stress, resulting in premature coating failure.

[0004] Therefore, with the continuous increase in the service temperature of aircraft, YSZ ceramic coatings are no longer able to shoulder the responsibility of surface thermal protection for more advanced aircraft hot-end components at higher temperatures (>1200 ℃). Summary of the Invention

[0005] The purpose of this invention is to provide a YSZ ceramic material and coating doped with two rare earth oxides, as well as its preparation method and application. The YSZ ceramic material doped with two rare earth oxides provided by this invention has excellent high-temperature phase stability as a powder material, and does not undergo phase transformation at 1500 ℃. The YSZ ceramic coating doped with two rare earth oxides provided by this invention has excellent thermal phase stability, and does not undergo phase transformation at 1400 ℃. As a thermal protection material, it can serve for a long time at temperatures above 1200 ℃.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing YSZ ceramic materials doped with two rare earth oxides, comprising the following steps: The raw materials are mixed to obtain a mixed powder, which comprises the following raw materials in the following mass percentages: Yb₂O₃ 9wt%~11wt%, Gd₂O₃ 5wt%~7wt%, Y₂O₃ 5.6wt%, ZrO₂ 76.4wt%~79.4wt%; The mixed powder was subjected to high-temperature solid-state sintering to obtain the YSZ ceramic material doped with two rare earth oxides.

[0007] Preferably, the mixing is wet ball milling, the ball milling medium used in the wet ball milling is ethanol, the ratio of the total mass of the raw materials to the volume of the ball milling medium is 100 g: 100~200 mL; the wet ball milling time is 8~10 h; after the wet ball milling is completed, a wet mixture is obtained; the process further includes drying and sieving the wet mixture sequentially to obtain the mixed powder, the drying temperature is 50~80 ℃, the time is 10~24 h, and the sieve used for sieving is 40 mesh.

[0008] Preferably, the high-temperature solid-state sintering temperature is 1400~1500 ℃ and the time is 5~10 h.

[0009] The present invention provides a YSZ ceramic material doped with two rare earth oxides prepared by the preparation method described above. The YSZ ceramic material doped with two rare earth oxides includes the following phases by mass percentage: c phase 0%, t phase 0%, t′ phase 100%, and m phase 0%.

[0010] This invention provides a method for preparing a YSZ ceramic coating doped with two rare earth oxides, comprising the following steps: The YSZ ceramic material doped with two rare earth oxides as described in the above technical solution is slurried to obtain a slurry; The slurry is subjected to atomization drying, thermal densification, and plasma densification in sequence to obtain a sprayable ceramic powder. The sprayable ceramic powder is sprayed using an atmospheric plasma spraying method to obtain the YSZ ceramic coating doped with two rare earth oxides.

[0011] Preferably, the slurry preparation includes: ball milling the YSZ ceramic material doped with rare earth oxides, a binder, and water to obtain the slurry; the binder is polyvinyl alcohol (PVA), the mass percentage of the binder in the slurry is 0.1%~0.3%, and the solid content of the slurry is 40%~60%; the ball milling process is carried out at a speed of 300~400 rpm for 3~6 h.

[0012] Preferably, the atomization drying and forming is carried out using a spray drying device with an inlet temperature of 240~260 ℃, an outlet temperature of 110~120 ℃, and a feeding rate of 9~15 mL / min; the conditions for the thermal densification treatment include: a calcination temperature of 1380~1430 ℃ and a calcination time of 2~6 h; the conditions for the plasma densification treatment include: a current of 300~400 A and a voltage of 35~45 V.

[0013] Preferably, the average particle size of the sprayable ceramic powder is 30~90 μm, and the powder flowability is less than 45 s / 50g; the atmospheric plasma spraying conditions include: current of 575~585 A, voltage of 68.4~72.4 V, and power of 39.4~42.4 kW.

[0014] The present invention provides a YSZ ceramic coating doped with two rare earth oxides prepared by the preparation method described above.

[0015] This invention provides the application of the dual rare earth oxide-doped YSZ ceramic material or the dual rare earth oxide-doped YSZ ceramic coating described in the above technical solution in the field of thermal protection.

[0016] This invention provides a method for preparing a YSZ ceramic material doped with two rare earth oxides, comprising the following steps: mixing raw materials to obtain a mixed powder, wherein the mixed powder comprises the following raw materials by mass content: Yb₂O₃ 9wt%~11wt%, Gd₂O₃ 5wt%~7wt%, Y₂O₃ 5.6wt%, and ZrO₂ 76.4wt%~79.4wt%; and subjecting the mixed powder to high-temperature solid-state sintering to obtain the YSZ ceramic material doped with two rare earth oxides. This invention, by optimizing the mass ratio of the raw materials in the mixed powder, yields a YSZ ceramic material doped with two rare earth oxides that exhibits excellent high-temperature phase stability, possessing the ability to remain unchanged for an extended period at 1500 °C, particularly without undergoing a phase transition from t phase to m phase.

[0017] This invention provides a method for preparing a YSZ ceramic coating doped with two rare earth oxides, comprising the following steps: preparing a slurry from the YSZ ceramic material doped with two rare earth oxides as described in the above technical solution; subjecting the slurry to atomization drying, thermal densification, and plasma densification in sequence to obtain a sprayable ceramic powder; and spraying the sprayable ceramic powder using an atmospheric plasma spraying method to obtain the YSZ ceramic coating doped with two rare earth oxides. Compared with existing technologies, the dual rare earth oxide-doped YSZ ceramic coating provided by this invention exhibits excellent high-temperature phase stability, possessing the ability to remain unchanged for extended periods at 1400 °C. Its thermal conductivity at 1200 °C is less than 1.2 W / (m·K), significantly lower than that of 8YSZ. The dual rare earth oxide-doped YSZ ceramic coating prepared by this invention, after treatment at 1500 °C for 100 h, exhibits a hardness of 700.0~886.4 HV, higher than that of the 8YSZ coating after the same treatment. This improves upon the issue of 8YSZ coatings developing cracks and decreasing hardness after phase transformation. Furthermore, within the temperature range of 1400~1500 °C, the degree of phase transformation in the coating is significantly improved compared to the 8YSZ coating under the same conditions. As a thermal protection material, it demonstrates excellent high-temperature phase stability and can operate for extended periods above 1200 °C. Attached Figure Description

[0018] Figure 1 The XRD patterns of the powder materials prepared in the embodiments of the present invention under different sintering processes are shown. Figure 2 SEM image of the sprayable powder prepared in Example 1; Figure 3 This is a particle size distribution diagram of the sprayable powder prepared in Example 1; Figure 4 The XRD pattern of the powder and coating prepared in Example 2, which were kept at 1400 °C for 100 h; Figure 5 The XRD pattern of the sample of powder prepared in Example 3 after being kept at 1500 °C for 100 h; Figure 6 The XRD pattern of the sample with the coating prepared in Example 4 after being kept at 1500 °C for 100 h; Figure 7 The thermal conductivity curves of the coating prepared in Example 4 and the 8YSZ coating in the temperature range from room temperature to 1200 °C are shown. Figure 8 The hardness of the coating prepared in Example 4 and the 8YSZ coating in the sprayed state and the sample kept at 1500 °C for 100 h. Detailed Implementation

[0019] This invention provides a method for preparing YSZ ceramic materials doped with two rare earth oxides, comprising the following steps: The raw materials are mixed to obtain a mixed powder, which comprises the following raw materials in the following mass percentages: Yb₂O₃ 9wt%~11wt%, Gd₂O₃ 5wt%~7wt%, Y₂O₃ 5.6wt%, ZrO₂ 76.4wt%~79.4wt%; The mixed powder was subjected to high-temperature solid-state sintering to obtain the YSZ ceramic material doped with two rare earth oxides.

[0020] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0021] The YSZ ceramic material doped with two rare earth oxides prepared in this invention is a ceramic powder.

[0022] The present invention mixes the raw materials to obtain a mixed powder, wherein the mixed powder comprises the following raw materials in the following mass contents: Yb2O3 9wt%~11wt%, Gd2O3 5wt%~7wt%, Y2O3 5.6wt%, ZrO2 76.4wt%~79.4wt%.

[0023] In this invention, the raw materials for preparation include Yb₂O₃, Gd₂O₃, Y₂O₃, and ZrO₂. By mass content, the mixed powder includes 9wt%~11wt% Yb₂O₃, which in the examples can be 9%, 10%, or 11%. The mixed powder includes 5wt%~7wt% Gd₂O₃, which in the examples can be 6%, 7%, or 5%. The mixed powder includes 5.6wt% Y₂O₃. The mixed powder includes 76.4wt%~79.4wt% ZrO₂, which in the examples can be the balance ZrO₂.

[0024] In this invention, the mixing is preferably wet ball milling. The wet ball milling is performed in a ball mill. The ball milling medium used in the wet ball milling is preferably ethanol. The ratio of the total mass of the raw materials to the volume of the ball milling medium is preferably 100 g: 100-200 mL, and in the examples, it can be 100 g: 125 mL. The wet ball milling does not require heating or cooling. The wet ball milling time is preferably 8-10 h, and in the examples, it can be 10 h.

[0025] In this invention, after the wet ball milling and mixing is completed, a wet mixture is obtained; the process further includes drying and sieving the wet mixture sequentially to obtain the mixed powder. The drying can be oven drying. The drying temperature is preferably 50-80°C, and in this embodiment, it can be 80°C. The drying time is preferably 10-24 hours, and in this embodiment, it can be 20 hours. The sieve used for sieving is preferably 40 mesh. Preferably, the undersize material from the sieve is used to obtain the mixed powder.

[0026] After obtaining the mixed powder, the present invention performs high-temperature solid-state sintering on the mixed powder to obtain the YSZ ceramic material (ceramic powder) doped with dual rare earth oxides. In the present invention, the solid-state sintering temperature is preferably 1400~1500℃, and in the embodiment it can be 1500℃. The solid-state sintering time is preferably 5~10 h, and in the embodiment it can be 10 h.

[0027] The present invention provides a YSZ ceramic material doped with two rare earth oxides prepared by the preparation method described above. The YSZ ceramic material doped with two rare earth oxides includes the following phases by mass percentage: c phase 0%, t phase 0%, t′ phase 100%, and m phase 0%.

[0028] This invention provides a method for preparing a YSZ ceramic coating doped with two rare earth oxides, comprising the following steps: The YSZ ceramic material doped with two rare earth oxides as described in the above technical solution is slurried to obtain a slurry; The slurry is subjected to atomization drying, thermal densification, and plasma densification in sequence to obtain a sprayable ceramic powder. The sprayable ceramic powder is sprayed using an atmospheric plasma spraying method to obtain the YSZ ceramic coating doped with two rare earth oxides.

[0029] This invention involves preparing a slurry from the YSZ ceramic material doped with two rare earth oxides as described in the above technical solution. Preferably, the slurry preparation includes ball milling the YSZ ceramic material doped with two rare earth oxides, a binder, and water to obtain the slurry. Preferably, the binder is polyvinyl alcohol (PVA). The water can be deionized water. The preferred mass percentage of the binder in the slurry is 0.1% to 0.3%. The preferred solid content of the slurry is 40% to 60%. The ball milling process is performed using a planetary ball mill to obtain a uniformly dispersed slurry. The preferred ball mill speed is 300 to 400 rpm, and the preferred milling time is 3 to 6 hours.

[0030] After obtaining the slurry, the present invention sequentially performs atomization drying and shaping, thermal densification treatment, and plasma densification treatment on the slurry to obtain sprayable ceramic powder. In the present invention, the atomization drying and shaping is preferably performed using a spray drying device. The inlet temperature of the spray drying device is preferably 240~260 ℃. The outlet temperature of the spray drying device is preferably 110~120 ℃. The feed rate of the spray drying device is preferably 9~15 mL / min.

[0031] The present invention involves subjecting the powder product obtained by atomization drying to thermal densification treatment. The preferred conditions for the thermal densification treatment include: a calcination temperature of 1380–1430 °C and a calcination time of 2–6 h.

[0032] The present invention involves subjecting the powder product obtained by the thermal densification treatment to plasma densification treatment. The preferred conditions for the plasma densification treatment include: a current of 300-400 A and a voltage of 35-45 V.

[0033] In this invention, after the plasma densification treatment is completed, the powder product obtained by the plasma densification treatment is preferably dried to obtain the sprayable ceramic powder. The drying can be oven drying, and this invention does not have special requirements for the specific implementation method of the oven drying.

[0034] In this invention, the average particle size of the sprayable ceramic powder is preferably 30~90 μm, and the powder flowability is preferably less than 45 s / 50 g.

[0035] After obtaining the sprayable ceramic powder, the present invention employs atmospheric plasma spraying to spray the sprayable ceramic powder to obtain the YSZ ceramic coating doped with dual rare earth oxides. In the present invention, the preferred conditions for atmospheric plasma spraying include: a current of 575~585 A, a voltage of 68.4~72.4 V, and a power of 39.4~42.4 kW.

[0036] The present invention provides a YSZ ceramic coating doped with two rare earth oxides prepared by the preparation method described above.

[0037] This invention provides the application of the dual rare earth oxide-doped YSZ ceramic material described above in the field of thermal protection.

[0038] This invention provides the application of the dual rare earth oxide doped YSZ ceramic coating described above in the field of thermal protection.

[0039] In this invention, the dual rare earth oxide-doped YSZ ceramic coating can be a thermal barrier coating or a thermal protection coating.

[0040] To further illustrate the present invention, 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.

[0041] Example 1 This example prepared 10Yb2O3-6Gd2O3-5.6Y2O3-ZrO2 ceramic powder (hereinafter referred to as 10Y6GY). The specific preparation method of 10Y6GY powder is as follows: (1) Weigh out commercial powders of Yb2O3, Gd2O3, Y2O3, and ZrO2 according to their mass ratio; (2) Mix the powder with ethanol. Add 125 mL of ethanol to every 100 g of powder. Mill the mixture in a ball mill for 10 h. Pause for 10 min every 30 min of rotation of the planetary ball mill. The total time is 800 min. (3) Place the ball-milled ethanol powder mixture into an oven to dry at a temperature of 80 °C for 20 h. (4) Pass the ball-milled powder through a 40-mesh sieve to obtain sieved powder; (5) The sieved powder was subjected to solid-state sintering at a temperature of 1400 °C and a sintering time of 5 h to obtain 10Y6GY powder product. (6) The sieved powder was subjected to solid-state sintering at a temperature of 1400 °C for 10 h to obtain 10Y6GY powder product. (7) The sieved powder was subjected to solid-state sintering at a temperature of 1500 °C for 5 h to obtain 10Y6GY powder product. (8) The sieved powder was subjected to solid-state sintering at a temperature of 1500 °C for 10 h to obtain 10Y6GY powder product. XRD tests were performed on 10Y6GY powders sintered using different processes, and the results are as follows: Figure 1 As shown in the figure, the optimal sintering process, as determined by the four XRD patterns, is as follows: sintering temperature of 1500 ℃ and sintering time of 10 h.

[0042] The specific preparation method of 10Y6GY sprayable powder is as follows: (9) Using deionized water as the liquid phase, prepare the slurry and select 0.2% PVA as the binder to prepare a slurry with a solid content of 50%. (10) A planetary ball mill was used for ball milling to obtain a uniformly dispersed slurry. The ball mill speed was 400 rpm and the ball milling time was 5 h. (11) The uniformly dispersed slurry is atomized and dried to form a shape. The inlet temperature of the spray drying equipment is 250 ℃, the outlet temperature is 120 ℃, and the feeding speed is 10 mL / min. (12) The powder collected in the previous step is subjected to thermal densification treatment. The powder calcination temperature is 1400 ℃ and the calcination time is 5 h. (13) The powder obtained in the previous step is subjected to plasma densification treatment. The current of the plasma spheroidizing equipment is 300 A and the voltage is 40 V. The obtained powder is dried to obtain sprayable spherical ceramic powder 10Y6GY; SEM analysis was performed on the sprayable powder 10Y6GY, and its SEM image is shown below. Figure 2 As shown; the particle size distribution of the sprayable powder 9Y6GY was tested using a laser particle size analyzer, and the results are shown in the figure. Figure 3 As shown.

[0043] Example 2 This example prepared 11Yb2O3-7Gd2O3-5.6Y2O3-ZrO2 ceramic powder and coating (hereinafter referred to as 11Y7GY). The specific preparation method of 11Y7GY powder is as follows: (1) Weigh out commercial powders of Yb2O3, Gd2O3, Y2O3, and ZrO2 according to their mass ratio; (2) Mix the powder with ethanol. Add 125 mL of ethanol to every 100 g of powder. Mill the mixture in a ball mill for 10 h. Pause for 10 min every 30 min of rotation of the planetary ball mill. The total time is 800 min. (3) Place the ball-milled ethanol powder mixture into an oven to dry at a temperature of 80 °C for 20 h. (4) Pass the ball-milled powder through a 40-mesh sieve to obtain sieved powder; (5) The sieved powder was subjected to solid-state sintering at a temperature of 1500 °C and a sintering time of 10 h to obtain 11Y7GY powder product.

[0044] The specific preparation method of the coating is as follows: (6) Using deionized water as the liquid phase, prepare the slurry and select 0.2% PVA as the binder to prepare a slurry with a solid content of 50%. (7) A planetary ball mill was used for ball milling to obtain a uniformly dispersed slurry. The ball mill speed was 400 rpm and the ball milling time was 5 h. (8) The uniformly dispersed slurry is atomized and dried to form a shape. The inlet temperature of the spray drying equipment is 250 ℃, the outlet temperature is 120 ℃, and the feeding speed is 10 mL / min. (9) The powder collected in the previous step is subjected to thermal densification treatment. The powder calcination temperature is 1400 ℃ and the calcination time is 5 h. (10) The powder obtained in the previous step is subjected to plasma densification treatment. The current of the plasma spheroidizing equipment is 300 A and the voltage is 40 V. The obtained powder is dried to obtain sprayable spherical ceramic powder 11Y7GY; (11) The ceramic coating was prepared using sprayable ceramic powder 11Y7GY by atmospheric plasma spraying technology. The current of the atmospheric plasma spraying process was 580 A, the voltage was 70 V, and the power was 40.5 kW.

[0045] To test the phase stability of the materials, the powders and coatings prepared in (5) and (11) were respectively placed in a furnace at 1400 °C and kept at that temperature for 100 h. The powders and coatings after the heat treatment were then subjected to XRD tests, and the results are as follows: Figure 4 As shown in the XRD pattern, only the diffraction peaks of ZrO2 were observed, while those of Yb2O3, Gd2O3, and Y2O3 were not observed, indicating that Yb2O3, Gd2O3, and Y2O3 were completely dissolved into the ZrO2 lattice. Furthermore, almost no diffraction peaks of the ZrO2 m-phase were observed, especially the characteristic peaks of the m-phase at 28° and 31° around the strongest peak at 30°. This indicates that the ceramic powder and coating of Example 2 are unlikely to undergo a phase transition to the m-phase at 1400 °C, while the YSZ ceramic undergoes a phase transition from the t-phase to the m-phase at 1200 °C, demonstrating that the phase stability of the ceramic powder and bulk of Example 2 is far superior to that of the YSZ ceramic.

[0046] The phase content of 11Y7GY powder and coating is: 11Y7GY powder products: t' phase: 99.59%, m phase: 0.41%; 11Y7GY coating products: t' phase: 22.67%, c phase: 77.33%.

[0047] Example 3 This example prepared 10Yb2O3-5Gd2O3-5.6Y2O3-ZrO2 ceramic powder (hereinafter referred to as 10Y5GY). The specific preparation method of 10Y5GY powder is as follows: (1) Weigh out commercial powders of Yb2O3, Gd2O3, Y2O3, and ZrO2 according to the proportions; (2) Mix the powder with ethanol. Add 125 mL of ethanol to every 100 g of powder. Mill the mixture in a ball mill for 10 h. Pause for 10 min every 30 min of rotation of the planetary ball mill. The total time is 800 min. (3) Place the ball-milled ethanol powder mixture into an oven to dry at a temperature of 80 °C for 20 h. (4) Pass the ball-milled powder through a 40-mesh sieve to obtain sieved powder; (5) The sieved powder is subjected to solid-state sintering at a temperature of 1500 ℃ and a sintering time of 10 h to obtain 10Y5GY powder product.

[0048] To test the phase stability of the material, the powder prepared in (5) was placed in a furnace at 1500 °C and kept at that temperature for 100 h. XRD phase analysis was then performed on the powder and the bulk material after the heating process. The results are as follows: Figure 5 As shown in the XRD pattern, only the diffraction peaks of ZrO2 were observed, while those of Yb2O3, Gd2O3, and Y2O3 were not observed, indicating that Yb2O3, Gd2O3, and Y2O3 had completely dissolved into the ZrO2 lattice. Furthermore, no diffraction peaks of the ZrO2 m-phase were observed, especially the characteristic peaks of the m-phase at 28° and 31° around the strongest peak at 30°. This indicates that the ceramic powder of Example 3 is unlikely to undergo a phase transition to the m-phase at 1500 °C, while the YSZ ceramic undergoes a phase transition from the t-phase to the m-phase at 1200 °C, demonstrating that the phase stability of the ceramic powder and bulk of Example 3 is far superior to that of the YSZ ceramic.

[0049] The phase content of 10Y5GY powder is: 10Y5GY powder product: t' phase: 99.44%, m phase: 0.56%.

[0050] Example 4 This example prepared a 9Yb2O3-6Gd2O3-5.6Y2O3-ZrO2 ceramic coating (hereinafter referred to as 9Y6GY). The specific preparation method of the 9Y6GY coating is as follows: (1) Weigh out commercial powders of Yb2O3, Gd2O3, Y2O3, and ZrO2 according to the proportions; (2) Mix the powder with ethanol. Add 125 mL of ethanol to every 100 g of powder. Mill the mixture in a ball mill for 10 h. Pause for 10 min every 30 min of rotation of the planetary ball mill. The total time is 800 min. (3) Place the ball-milled ethanol powder mixture into an oven to dry at a temperature of 80 °C for 20 h. (4) Pass the ball-milled powder through a 40-mesh sieve to obtain sieved powder; (5) The sieved powder was subjected to solid-state sintering at a temperature of 1500 °C and a sintering time of 10 h to obtain 9Y6GY powder product.

[0051] (6) Using deionized water as the liquid phase, prepare the slurry and select 0.2% PVA as the binder to prepare a slurry with a solid content of 50%. (7) A planetary ball mill was used for ball milling to obtain a uniformly dispersed slurry. The ball mill speed was 400 rpm and the ball milling time was 5 h. (8) The uniformly dispersed slurry is atomized and dried to form a shape. The inlet temperature of the spray drying equipment is 250 ℃, the outlet temperature is 120 ℃, and the feeding speed is 10 mL / min. (9) The powder collected in the previous step is subjected to thermal densification treatment. The powder calcination temperature is 1400 ℃ and the calcination time is 5 h. (10) The powder obtained in the previous step is subjected to plasma densification treatment. The current of the plasma spheroidizing equipment is 300 A and the voltage is 40 V. The obtained powder is dried to obtain sprayable spherical ceramic powder 9Y6GY; (11) The ceramic coating was prepared using sprayable ceramic powder 9Y6GY by atmospheric plasma spraying technology. The current of the atmospheric plasma spraying process was 580 A, the voltage was 70 V, and the power was 40.5 kW.

[0052] To test the phase stability of the material, the coating prepared in (11) was placed in a furnace at 1500 °C and kept at that temperature for 100 h. XRD phase analysis was then performed on the powder and bulk material after the heat treatment. The results are as follows: Figure 6 As shown in the XRD pattern, only ZrO2 diffraction peaks were observed, while diffraction peaks of Yb2O3, Gd2O3, and Y2O3 were not observed, indicating that Yb2O3, Gd2O3, and Y2O3 have been completely dissolved into the ZrO2 lattice. Weak diffraction peaks of the ZrO2 m-phase were observed, especially the characteristic peaks of the m-phase at 28° and 31° on either side of the strongest peak at 30°. This indicates that the ceramic coating of Example 4 undergoes a small amount of m-phase phase transformation at 1500 °C, while the YSZ ceramic undergoes a t-phase to m-phase phase transformation at 1200 °C, demonstrating that the phase stability of the ceramic powder and bulk of Example 4 is better than that of the YSZ ceramic.

[0053] The phase content of the 9Y6GY coating is: 9Y6GY coating product: t' phase: 49.80%, t phase: 10.56%, c phase: 27.60%, m phase: 12.05%.

[0054] The thermal conductivity of the 9Y6GY coating and the 8YSZ coating from room temperature (approximately 25 °C) to 1200 °C is as follows: Figure 7 As shown, the hardness of the two materials before and after being kept at 1500 ℃ for 100 h is as follows: Figure 8 As shown.

[0055] As shown in the above embodiments, this invention provides a method for preparing a YSZ ceramic material and coating doped with two rare earth oxides. This invention modifies YSZ ceramic material by doping with rare earth oxides, introducing Yb₂O₃ and Gd₂O₃ into the YSZ ceramic material to prepare a Yb₂O₃-Gd₂O₃-Y₂O₃-ZrO₂ ceramic material. Through solid-state sintering, Yb₂O₃, Gd₂O₃, and Y₂O₃ dissolve into the ZrO₂ lattice, acting as stabilizers and greatly improving the high-temperature phase stability of the ceramic material. This increases the phase transition temperature of the material from 1200 °C for YSZ material to over 1400 °C for Yb₂O₃-Gd₂O₃-Y₂O₃-ZrO₂ material. This invention involves mixing powders according to a predetermined ratio to obtain a mixed powder, and then performing solid-state sintering on the mixed powder to obtain the YSZ ceramic material doped with two rare earth oxides. In this invention, YSZ ceramic material powder doped with two rare earth oxides is prepared by slurry preparation, atomization drying and forming, thermal densification and plasma densification treatment to obtain a sprayable ceramic powder. The sprayable ceramic powder is then sprayed using atmospheric plasma spraying technology to prepare the ceramic coating. The ceramic powder material provided by this invention exhibits excellent high-temperature phase stability, possessing the ability to remain unchanged for extended periods at 1500 °C, particularly without undergoing a phase transition from t to m. The resulting ceramic coating has a thermal conductivity of less than 1.2 W / (m·K) at 1200 °C, significantly lower than that of 8YSZ. Furthermore, within the temperature range of 1400–1500 °C, the phase transition degree of the coating is significantly improved compared to the 8YSZ coating under the same conditions. As a thermal protection material, it exhibits excellent high-temperature phase stability and can operate for extended periods above 1200 °C. Compared with existing technologies (Chinese Patent CN101012123A, entitled "A High Thermal Expansion Ratio Thermal Barrier Coating Material Doped with Yb₂O₃ and Gd₂O₃ and YSZ"), this invention achieves the effect of no phase transition in powder samples at 1500 °C and no phase transition in atmospheric plasma sprayed coating samples at 1400 °C, even with a lower doping amount. This invention achieves high-temperature phase stability comparable to the existing technology while saving costs. In summary, the high-temperature ceramic powder and coating of this invention have potential applications in the fields of high-temperature thermal protection and thermal protective coatings.

[0056] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a YSZ ceramic material doped with two rare earth oxides, characterized in that, Includes the following steps: The raw materials are mixed to obtain a mixed powder, which comprises the following raw materials by mass content: Yb2O3 9wt%~11wt%, Gd2O3 5wt%~7wt%, Y2O3 5.6wt%, ZrO2 76.4wt%~79.4wt%; The mixed powder was subjected to high-temperature solid-state sintering to obtain the YSZ ceramic material doped with two rare earth oxides.

2. The preparation method according to claim 1, characterized in that, The mixing is a wet ball milling mixture, and the ball milling medium used in the wet ball milling mixture is ethanol. The ratio of the total mass of the raw materials to the volume of the ball milling medium is 100 g: 100~200 mL. The wet ball milling mixture is mixed for 8~10 h. After the wet ball milling mixture is completed, a wet mixture is obtained. The mixture further includes drying and sieving the wet mixture in sequence to obtain the mixed powder. The drying temperature is 50~80 ℃, the time is 10~24 h, and the sieve used for sieving is 40 mesh.

3. The preparation method according to claim 1, characterized in that, The high-temperature solid-state sintering temperature is 1400~1500℃, and the time is 5~10 h.

4. The YSZ ceramic material doped with two rare earth oxides prepared by the preparation method according to any one of claims 1 to 3, characterized in that, The YSZ ceramic material doped with two rare earth oxides comprises the following phases by mass percentage: c phase 0%, t phase 0%, t′ phase 100%, and m phase 0%.

5. A method for preparing a YSZ ceramic coating doped with two rare earth oxides, characterized in that, Includes the following steps: The YSZ ceramic material doped with dual rare earth oxides as described in claim 4 is slurried to obtain a slurry; The slurry is subjected to atomization drying, thermal densification, and plasma densification in sequence to obtain a sprayable ceramic powder. The sprayable ceramic powder is sprayed using an atmospheric plasma spraying method to obtain the YSZ ceramic coating doped with two rare earth oxides.

6. The preparation method according to claim 5, characterized in that, The slurry preparation includes: ball milling the YSZ ceramic material doped with rare earth oxides, a binder, and water to obtain the slurry; the binder is polyvinyl alcohol, the mass percentage of the binder in the slurry is 0.1%~0.3%, and the solid content of the slurry is 40%~60%; the ball milling process is carried out at a speed of 300~400 rpm for 3~6 h.

7. The preparation method according to claim 5, characterized in that, The atomization drying and forming process is carried out using a spray drying device with an inlet temperature of 240~260 ℃, an outlet temperature of 110~120 ℃, and a feeding rate of 9~15 mL / min. The conditions for the thermal densification treatment include: a calcination temperature of 1380~1430 ℃ and a calcination time of 2~6 h; the conditions for the plasma densification treatment include: a current of 300~400 A and a voltage of 35~45 V.

8. The preparation method according to claim 5, characterized in that, The sprayable ceramic powder has an average particle size of 30~90 μm and a powder flowability of less than 45 s / 50 g; The conditions for atmospheric plasma spraying include: current of 575~585 A, voltage of 68.4~72.4 V, and power of 39.4~42.4 kW.

9. The YSZ ceramic coating doped with two rare earth oxides prepared by the preparation method according to any one of claims 5 to 8.

10. The application of the dual rare earth oxide-doped YSZ ceramic material of claim 4 or the dual rare earth oxide-doped YSZ ceramic coating of claim 9 in the field of thermal protection.

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