Rare earth tantalate / niobate and zirconate composite ceramic powder and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of thermal barrier coating ceramic powder, and particularly relates to rare earth tantalate / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder and a preparation method of the rare earth tantalate / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder. The molecular formula of the rare earth tantalum / niobate and zirconate composite ceramic powder is (RETa / NbO4) x (RE2Zr2O7) 1-x, wherein x is more than 0 and less than 1; rE is one or a mixture of more of Y, Yb, Gd, La, Nd, Lu, Sm, Eu, Dy and Er. By doping rare earth elements, the thermodynamic property of the powder material can be improved; the thermal barrier coating ceramic powder (RETa / NbO4) x (RE2Zr2O7) 1-x can be directly synthesized through a one-step method, the process is simple, and compared with physical mixing after synthesis, the powder synthesized in one step is more uniform in component and more excellent in performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermal barrier coating ceramic powder preparation, and particularly relates to a rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder and a preparation method thereof. BACKGROUND

[0002] Thermal barrier coatings (TBCs) are widely used in the surface of aero-engine, gas turbine and other civil high-temperature hot end parts to prevent the parts from being corroded by high temperature and improve thermal efficiency and service life; currently, domestic and foreign research institutions, colleges and universities and NASA in the United States generally use Y2O3 stabilized ZrO2 (YSZ) material, and a large number of oxygen vacancies of the YSZ material can effectively reduce the thermal conductivity of ZrO2, but the high-temperature problems of the YSZ material, such as (1) phase change easily occurs at a high temperature, and a large volume difference leads to failure; (2) high thermal conductivity, and temperature capacity is limited; (3) high-temperature infrared penetration; (4) environmental corrosion exists at a high temperature, and chemical stability needs to be improved; etc. make the use temperature of the YSZ material not higher than 1200℃; compared with the YSZ, the rare earth zirconate (RE2Zr2O7) is a kind of TBCs candidate material with higher thermal stability and excellent mechanical properties, and the rare earth tantalate ceramic material has a similar ferroelastic toughening effect as the YSZ, and the ceramic material has extremely low thermal conductivity, and is expected to replace the YSZ ceramic as a new generation of thermal barrier coating material. SUMMARY

[0003] The application aims to provide a rare earth tantalum / niobate and zirconate composite ceramic powder and a preparation method thereof, and the tantalum / niobate and zirconate are compounded to prepare a thermal barrier coating ceramic material with high thermal mechanical properties and low thermal conductivity and a preparation method thereof.

[0004] In order to achieve the above application purposes, the application provides the following technical scheme. A rare earth tantalum / niobate and zirconate composite ceramic powder, the molecular formula of the thermal barrier coating ceramic powder is (RETa / NbO4) x (RE2Zr2O7) 1-x , wherein 0

[0005] A preparation method of a rare earth tantalum / niobate and zirconate composite ceramic powder, comprising the following steps: 1) Ta2O5 / Nb2O5, Re2O3, ZrO2 powders with purity of > 99% are weighed according to molar ratio, added into a ball milling solvent, and subjected to planetary ball milling for 12 h at a ball mill speed of 350 r / min, and then dried in an oven, wherein the molar number of Re2O3 is the sum of the molar numbers of Ta2O5 / Nb2O5 and 1 / 2 ZrO2. 2) The powder obtained in step 1) is subjected to high-temperature solid-phase synthesis by setting the temperature, and then subjected to heat preservation at 1200 DEG C for 4 h and then heat preservation at 1450 DEG C for 4 h to obtain a rare earth tantalum / niobate and zirconate composite ceramic powder. 3) The rare earth tantalum / niobate and zirconate composite ceramic powder is subjected to crushing and spray granulation, and then sieved to 150-750 meshes to obtain a spray powder for thermal barrier coating.

[0006] The rare earth tantalum / niobate and zirconate composite ceramic powder and the preparation method thereof provided by the application are advantageous in that the doping of rare earth elements is beneficial to improving the thermodynamic performance of the powder material, and the thermal barrier coating ceramic powder (RETa / NbO4) can be directly synthesized by one-step method. x (RE2Zr2O7) 1-x The process is simple, and the synthesized powder is more uniform in composition and more excellent in performance than the physically mixed powder after synthesis.

[0007] The technical solution provided by the application significantly improves the mechanical properties of the material due to the refined grain and atomic solid solution strengthening effect.

[0008] The technical solution provided by the application produces interface thermal resistance at the interface between the two phases due to the significant crystal structure difference between the two phases, which leads to the enhancement of phonon scattering and the reduction of thermal conductivity.

[0009] The purity of the powder raw material is > 99%, which is beneficial to reducing the influence of impurities on the preparation of the powder.

[0010] The solid-phase synthesis temperature is divided into two steps, i.e., heat preservation at 1200 DEG C for 4 h and then heat preservation at 1450 DEG C for 4 h, to form a pure rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder without raw material oxides.

[0011] A 150-750 mesh sieve is used for sieving; larger particles are avoided, and different particle sizes of the powder are used according to different uses, such as sieving by a sieve with a mesh size of more than 300 for spray vertical crack, and sieving by a sieve with a mesh size of more than 150 for spray porous coating. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is an XRD pattern of the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder obtained in Example 1 of the application.

[0013] Figure 2 SEM images and crack fracture of the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic material obtained in Example 1.

[0014] Figure 3 Thermal expansion coefficient of the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder obtained in Example 1. DETAILED DESCRIPTION

[0015] The applicant has carried out a large number of experiments on the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder and its preparation method during the research process. The present application will be further described below in combination with examples, and the modes of the present application include but are not limited to the following examples. Example 1:

[0016] The preparation method of the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic material of the present embodiment is as follows: Ta2O5 powder, Y2O3 powder and ZrO2 powder raw materials (the purity of the raw materials used is ≥99%) are weighed according to a molar ratio of 1:2:2, and the powders are placed in alcohol. Zirconia balls are used as the ball milling medium, and then the solution is mixed and subjected to planetary ball milling. The ball milling time is 12 h, and the rotation speed is 350 r / min. After ball milling, the powders are dried in an oven at a drying temperature of 85°C for 12 h. Then, the obtained powders are placed in a high-temperature furnace and subjected to heat treatment at a set temperature of 1200°C for 4 h and then at 1450°C for 4 h to obtain the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder. After cooling in the furnace, the powder is broken and subjected to spray granulation, and then sieved through a 500-mesh sieve. Finally, the spray granulation powder that meets the requirements of thermal barrier coating is obtained. The powder is subjected to XRD and thermal expansion coefficient tests, and the results are as follows: Figure 1 It can be seen that the pure rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder is synthesized, and the thermal expansion coefficient is 10.7×10 Figure 3 -6 K -1 After shaping and sintering in a high-temperature furnace at 1800°C, the Vickers hardness tester is used for measurement, and the crack propagation is observed, and the results are as follows: Figure 2 It can be seen that the grain is refined, the crack is divided into intergranular fracture and transgranular fracture, and there are ferroelastic phase domains, which improves the fracture toughness.

[0017] Example 2 is as follows: ​The rare earth tantalum / niobate and zirconate (RETa / Nb04 and RE2Zr207) composite ceramic material of the present embodiment is prepared by taking Ta205 powder, Y203 powder and Zr02 powder raw materials (the purity of the raw materials used is ≥99%) in a molar ratio of 1:1.1:0.2, placing the powders in alcohol, using zirconia balls as the ball milling medium, then mixing the solution and performing planetary ball milling, the ball milling time being 12 h and the rotation speed being 350 r / min. After ball milling, the mixture is placed in an oven for drying, the drying temperature being 90°C and the drying time being 6 h. Subsequently, the obtained powder is placed in a high-temperature furnace, the temperature is set to 1200°C, and the temperature is maintained for 4 h, then the temperature is set to 1450°C, and the temperature is maintained for 4 h, to obtain the rare earth tantalum / niobate and zirconate (RETa / Nb04 and RE2Zr207) composite ceramic powder. After cooling in the furnace, the mixture is broken up and spray granulated, then sieved through a 750-mesh sieve, and finally the spray granulated powder that meets the requirements of thermal barrier coatings is obtained.

[0018] Example 3 is as follows: The rare earth tantalum / niobate and zirconate (RETa / Nb04 and RE2Zr207) composite ceramic material of the present embodiment is prepared by taking Ta205 powder, Y203 powder and Zr02 powder raw materials (the purity of the raw materials used is ≥99%) in a molar ratio of 1:1.2:0.4, placing the powders in alcohol, using zirconia balls as the ball milling medium, then mixing the solution and performing planetary ball milling, the ball milling time being 12 h and the rotation speed being 350 r / min. After ball milling, the mixture is placed in an oven for drying, the drying temperature being 75°C and the drying time being 10 h. Subsequently, the obtained powder is placed in a high-temperature furnace, the temperature is set to 1200°C, and the temperature is maintained for 4 h, then the temperature is set to 1450°C, and the temperature is maintained for 4 h, to obtain the rare earth tantalum / niobate and zirconate (RETa / Nb04 and RE2Zr207) composite ceramic powder. After cooling in the furnace, the mixture is broken up and spray granulated, then sieved through a 150-mesh sieve, and finally the spray granulated powder that meets the requirements of thermal barrier coatings is obtained.

[0019] Example 4 thermal barrier coating is as follows: The rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic material of this embodiment is prepared as follows: Ta2O5 powder, Y2O3 powder, and ZrO2 powder raw materials (purity of raw materials ≥99%) are weighed in a molar ratio of 2:2.5:1. The powders are placed in alcohol and milled using zirconium oxide balls as the milling medium. The solution is then mixed and subjected to planetary ball milling for 12 hours at a speed of 350 r / min. After milling, the powder is placed in an oven to dry at 65°C for 18 hours. Subsequently, the obtained powder is placed in a high-temperature furnace and held at 1200°C for 4 hours, followed by holding at 1450°C for 4 hours to obtain the rare earth tantalum / niobate and zirconate (RETa / NbO4 and RE2Zr2O7) composite ceramic powder. After furnace cooling, the powder is crushed and spray-granulated, then sieved through a 350-mesh sieve to obtain a spray powder suitable for thermal barrier coating.

[0020] In summary, the technical solution provided by this invention can directly synthesize the thermal barrier coating ceramic powder (RETa / NbO4) in one step. x (RE2Zr2O7) 1-x The process is simple and the one-step synthesis of powder results in a more uniform composition and superior performance compared to physical mixing after synthesis.

[0021] For those skilled in the art, without departing from the concept of the technical solution of this invention, several modifications and improvements can be made, and these should also be considered within the scope of protection of this invention. These will not affect the effectiveness of the implementation of this patent or the inventiveness of the patent.

Claims

1. A rare earth tantalum / niobate and zirconate composite ceramic powder, characterized by: The thermal barrier coating ceramic powder has a molecular formula (RETa / NbO4) x (RE2Zr2O7) 1-x wherein 0 wherein 0 2. A method for preparing a rare earth tantalum / niobate and zirconate composite ceramic powder as claimed in claim 1, characterized in that: The method comprises the following steps: 1) Ta2O5 / Nb2O5, Re2O3, ZrO2 powder is weighed according to the proportion and added into a ball milling solvent, planetary ball milling is adopted for 12 hours, the rotating speed of the ball mill is 350 r / min, and then the powder is placed into an oven for drying; the mole number of Re2O3 is the sum of the mole number of Ta2O5 / Nb2O5 and 1 / 2 ZrO2; 2) the powder obtained in step 1) is subjected to high-temperature solid-phase synthesis to obtain rare earth tantalum / niobate and zirconate composite ceramic powder; 3) after the rare earth tantalum / niobate and zirconate composite ceramic powder is crushed and spray granulated, the powder is sieved to 150-750 meshes to meet the requirements of the spray powder for thermal barrier coating.

3. The method of claim 2, wherein the method further comprises: The purity of the RE2O3 powder and the Ta2O5 powder / Nb2O5 powder in step (1) is not less than 99%. ​ 4. The method for preparing rare earth tantalum / niobate and zirconate composite ceramic powder as described in claim 2, characterized in that: In step (2), the high-temperature solid-phase synthesis is set at 1200 DEG C for 4 hours and then at 1450 DEG C for 4 hours.

Images