Search

CN-121974685-A - Sintering-resistant pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material and preparation method thereof

CN121974685ACN 121974685 ACN121974685 ACN 121974685ACN-121974685-A

Abstract

The invention relates to the technical field of thermal barrier coating materials, and discloses a sintering-resistant pyrochlore and fluorite dual-phase high-entropy rare earth zirconate thermal barrier coating material and a preparation method thereof. The thermal barrier coating material comprises the chemical components (La 0.2 Sm 0.2 Dy 0.2 Yb 0.2 Sc 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Sm 0.2 Yb 0.2 Sc 0.2 Y 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Nd 0.2 Yb 0.2 Lu 0.2 Sc 0.2 ) 2 Zr 2 O 7 . of the preparation method, wherein the preparation method comprises the steps of S1, preparing a solution according to a molecular formula, S2, preparing a material by adopting reverse coprecipitation of the solution obtained in the step S1, S3, presintering the material obtained in the step S2, and sintering the material for the second time to obtain the high-entropy rare earth zirconate thermal barrier coating material. The grain size and the grain growth speed of the pyrochlore and fluorite biphase high-entropy rare earth zirconate designed by the invention are obviously slowed down, and the sintering resistance is better.

Inventors

  • JIN HONGYUN
  • LI KAIYUN

Assignees

  • 中国地质大学（武汉）

Dates

Publication Date
20260505
Application Date
20251210

Claims (9)

  1. 1. The high-sintering-resistance pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material is characterized in that the chemical composition of the thermal barrier coating material is one of (La 0.2 Sm 0.2 Dy 0.2 Yb 0.2 Sc 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Sm 0.2 Yb 0.2 Sc 0.2 Y 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Nd 0.2 Yb 0.2 Lu 0.2 Sc 0.2 ) 2 Zr 2 O 7 .
  2. 2. The method for preparing the high-sintering-resistance pyrochlore and fluorite dual-phase high-entropy rare earth zirconate thermal barrier coating material according to claim 1, which is characterized by comprising the following steps: s1, preparing a solution by using a rare earth source and a zirconium source according to the molar ratio in one molecular formula of (La 0.2 Sm 0.2 Dy 0.2 Yb 0.2 Sc 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Sm 0.2 Yb 0.2 Sc 0.2 Y 0.2 ) 2 Zr 2 O 7 ,(La 0.2 Nd 0.2 Yb 0.2 Lu 0.2 Sc 0.2 ) 2 Zr 2 O 7 ; S2, dropwise adding the solution obtained in the step S1 into ammonia water, continuously stirring to generate flocculated sediment, standing and aging for a period of time after the sediment is completely precipitated, centrifugally washing the sediment, and drying to obtain a powder material; S3, after presintering the dried powder material obtained in the step S2 for a period of time, sintering for a second time to obtain the pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material.
  3. 3. The method of claim 2, wherein the rare earth source comprises, but is not limited to, rare earth oxides, rare earth chlorides, rare earth nitrates, rare earth sulfates.
  4. 4. The method of claim 2, wherein the zirconium source comprises, but is not limited to, zirconium oxychloride octahydrate, zirconium oxide, zirconium nitrate, zirconium sulfate.
  5. 5. The method of claim 2, wherein the solution is added dropwise to the aqueous ammonia in step S2, and the pH is controlled to be always greater than 10 by continuously adding the aqueous ammonia during the entire reverse co-precipitation titration.
  6. 6. The method of claim 2, wherein the flocculated precipitate obtained in step S2 is aged by standing for at least 24 h.
  7. 7. The process according to claim 2, wherein in step S2, the flocculated precipitate is washed with deionized water repeatedly to neutrality to remove chloride ions, and then washed with ethanol and isopropanol 2 times each.
  8. 8. The method of claim 2, wherein the pre-sintering temperature is 950-1050 ℃ and the sintering time is 5-10 h in step S3.
  9. 9. The method of claim 2, wherein in step S3, the second sintering temperature is 1350-1600 ℃ and the sintering time is at least 6 h.

Description

Sintering-resistant pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material and preparation method thereof Technical Field The invention relates to the technical field of thermal barrier coating materials, in particular to a sintering-resistant pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material and a preparation method thereof. Background The thermal barrier coating is a thermal barrier coating material used for protecting the surface of the hot end part of the engine. Under a long-term high-temperature service environment, the ceramic coating material can generate a remarkable sintering phenomenon, and the yttria-stabilized zirconia (YSZ) widely used at present can generate phase transition and rapid sintering at 1200 ℃, so that the change of the microstructure, the mechanical property and the thermal property of the coating is caused, and the thermal barrier effect and the safe service of the coating are seriously affected. Therefore, the high-temperature sintering phenomenon of the ceramic layer is one of the bottlenecks for limiting the long-term service stability and the service life of the thermal barrier coating. The crystal structure of zirconates is related to the cation radius ratio (r A/rB) that fluorite structure (F) is easily formed when r A/rB <1.46, and pyrochlore structure (P) is more easily formed when 1.46< r A/rB < 1.78. The A 2B2O7 rare earth zirconate with a pyrochlore or defective fluorite single-phase structure has the performances of low heat conductivity, larger thermal expansion coefficient, high-temperature phase stability and the like, and is the thermal barrier coating ceramic material with the most potential to replace 8YSZ at present. However, the high-entropy ceramic grain growth speed of the thermal barrier coating ceramic materials of some single-phase rare earth zirconate material systems disclosed in the prior art is relatively high, and the sintering resistance is different from the practical application. Disclosure of Invention The invention aims to provide a sintering-resistant pyrochlore and fluorite dual-phase high-entropy rare earth zirconate thermal barrier coating material and a preparation method thereof, aiming at the defects of the prior art. The high-sintering-resistance pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material has a chemical composition formula of one of (La0.2Sm0.2Dy0.2Yb0.2Sc0.2)2Zr2O7,(La0.2Sm0.2Yb0.2Sc0.2Y0.2)2Zr2O7,(La0.2Nd0.2Yb0.2Lu0.2Sc0.2)2Zr2O7. The preparation method of the high-sintering-resistance pyrochlore and fluorite biphase high-entropy rare earth zirconate thermal barrier coating material comprises the following steps: S1, proportioning and mixing a rare earth source and a zirconium source according to a molar ratio in one molecular formula of (La0.2Sm0.2Dy0.2Yb0.2Sc0.2)2Zr2O7,(La0.2Sm0.2Yb0.2Sc0.2Y0.2)2Zr2O7,(La0.2Nd0.2Yb0.2Lu0.2Sc0.2)2Zr2O7; S2, dropwise adding the solution obtained in the step S1 into ammonia water, continuously stirring to generate flocculated precipitate, standing and aging for a period of time after the precipitation is complete, centrifugally washing the precipitate, and drying to obtain a powder material; s3, presintering the dried mixed powder material obtained in the step S2 for a period of time, and then sintering for a period of time for the second time to obtain the high-entropy rare earth zirconate thermal barrier coating material. Further, the rare earth sources include, but are not limited to, rare earth oxides, rare earth chlorides, rare earth nitrates, rare earth sulfates. Further, the zirconium source includes, but is not limited to, zirconium oxychloride octahydrate, zirconium nitrate, zirconium sulfate, zirconium oxide. Further, in the step S2 titration process, the solution is dropwise added into ammonia water, and the pH value is controlled to be always more than 10 by continuously adding the ammonia water in the whole titration process, so that the flocculation sediment is ensured to be completely generated. Further, in the step S2, the standing and ageing time of the flocculated sediment is not less than 24 h, so that the materials are ensured to fully react, and the flocculated suspended matters are settled. Further, in step S2, the generated flocculated precipitate is repeatedly centrifuged with deionized water to be washed to be neutral, chloride ions are removed, and then ethanol and isopropanol are used for washing 2 times respectively. Further, in step S3, the pre-sintering temperature is 950-1050 ℃ and the sintering time is 5-10 h. Further, in step S3, the second sintering temperature is 1350-1600 ℃ and the sintering time is at least 6 h. After the rare earth zirconate is designed by high entropy, the growth of crystal grains can be promoted due to the movement of oxygen vacancies in the sintering process. In the invention, five equimolar ratio ra