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CN-122010563-A - High-entropy cerite ceramic and preparation method thereof

CN122010563ACN 122010563 ACN122010563 ACN 122010563ACN-122010563-A

Abstract

The invention discloses a high-entropy cerite ceramic and a preparation method thereof, and the chemical composition of the Gao Shangshi acid salt ceramic is represented by the following general formula (A 0.2 B 0.2 Nd 0.2 Gd 0.2 Tm 0.2 ) 2 Ce 2 O 7 ), wherein A and B are independently selected from any one of Y, la, pr, sm, and A and B are different.

Inventors

  • LIU FENG
  • TAN LIMING
  • HUANG LAN
  • WANG FUZHU
  • WU ZEQIAN

Assignees

  • 中南大学

Dates

Publication Date
20260512
Application Date
20260210

Claims (9)

  1. 1. A high-entropy cerite ceramic is characterized in that the chemical composition of the Gao Shangshi acid salt ceramic is represented by the following general formula (A 0.2 B 0.2 Nd 0.2 Gd 0.2 Tm 0.2 ) 2 Ce 2 O 7 ), A and B are each independently selected from any one of Y, la, pr, sm, and A and B are not the same.
  2. 2. The high-entropy cerite ceramic according to claim 1, wherein the ceramic has a single-phase defect fluorite structure, has a thermal conductivity of less than 1.70 W.m -1 ·K -1 at 1000 ℃ and a thermal expansion coefficient of more than 12.5 x 10 -6 /K, and remains structurally stable after heat treatment at 1600 ℃ for 100 hours.
  3. 3. The high entropy cerite ceramic according to claim 1 or 2, wherein A and B are selected from any one of Pr and Y, la and Sm, or Sm and Y.
  4. 4. A method for preparing the high-entropy cerite ceramic according to any one of claims 1 to 3, comprising the following steps: s1, raw material pretreatment, namely carrying out pre-calcination treatment on all raw material powder containing Ce 2 O 3 、Tm 2 O 3 、Nd 2 O 3 、Gd 2 O 3 and oxides corresponding to A, B elements; s2, batching and mixing, namely weighing all raw material powder treated in the step S1 according to the stoichiometric ratio of the general formula of claim 1, and performing ball milling and mixing with a ball milling medium and a dispersing agent to obtain uniform slurry; s3, drying and presintering, namely drying the slurry to obtain mixed powder, and performing primary sintering at the temperature of 1300-1400 ℃; S4, secondary treatment and forming, namely performing secondary ball milling, drying and sieving on the high-entropy ceramic primary powder, adding a binder, and performing dry pressing forming to obtain a ceramic green body; and S5, final sintering, namely performing secondary sintering in an air atmosphere at 1450-1550 ℃ after the ceramic green body is subjected to glue discharging treatment, so as to obtain the Gao Shangshi acid salt ceramic block material.
  5. 5. The method according to claim 4, wherein in the step S2, the rotation speed of the ball milling and mixing is 200 rpm to 300 rpm, and the ball milling time is 2 to 4 hours.
  6. 6. The method according to claim 4, wherein the first sintering is performed for a holding time of 1 to 3 hours in step S3.
  7. 7. The method according to claim 4, wherein the second sintering is performed for a holding time of 4 hours to 8 hours in step S5.
  8. 8. The method according to claim 4, wherein in step S5, the temperature-raising procedure of the paste discharging treatment and the second sintering is to raise the temperature to 800 ℃ at a first temperature-raising rate and to keep the temperature at a second temperature-raising rate lower than the first temperature-raising rate, and then to the target sintering temperature.
  9. 9. The method of claim 8, wherein the first heating rate is controlled to be 4-5 ℃ per minute and the second heating rate is controlled to be 2-3 ℃ per minute.

Description

High-entropy cerite ceramic and preparation method thereof Technical Field The invention belongs to the technical field of high-temperature protective materials, and particularly relates to a high-entropy cerite ceramic and a preparation method thereof. Background Thermal Barrier Coatings (TBCs) are key technologies for improving service temperature and service life of hot end components such as aeroengines, gas turbines and the like. Currently, there is a wide range of 6-8 wt% Y 2O3 stabilized zirconia (YSZ) with lower thermal conductivity, higher coefficient of thermal expansion and good fracture toughness below 1200 ℃. However, as engine inlet temperature increases above 1500 ℃, YSZ undergoes a detrimental phase change from tetragonal to monoclinic at high temperatures, with the resulting cracking and spalling of the coating due to volume changes, failing to meet the demands of the next generation of power systems. Rare earth cerates are considered potential thermal barrier coating materials due to their defective fluorite structure, high oxygen vacancy concentration, low thermal conductivity, and high melting point. However, pure ceric acid salts are susceptible to reduction at high temperatures, resulting in lattice instability and reduced sintering resistance. The high-entropy ceramic can form a single solid solution phase through multi-principal element design, has obvious lattice distortion effect and slow diffusion effect, and is beneficial to further improving the thermophysical property and high-temperature stability of the material. However, the prior high-entropy cerite ceramic still has the problems of higher heat conductivity, lower thermal expansion coefficient, insufficient ultrahigh temperature stability and the like compared with high-entropy zirconic acid and hafnate. Disclosure of Invention The invention aims to provide a high-entropy ceric acid salt ceramic material with low thermal conductivity, high thermal expansion coefficient and excellent high-temperature phase stability, and provides a repeatable synthesis method suitable for large-scale preparation, so as to meet the performance requirements of thermal barrier coatings of next-generation aeroengines. For this purpose, the invention provides a high-entropy cerite ceramic, the chemical composition of the Gao Shangshi acid salt ceramic is represented by the following general formula (A 0.2B0.2Nd0.2Gd0.2 Tm0.2)2Ce2O7), wherein, A and B are each independently selected from any one of Y, la, pr, sm, and A and B are not the same. Specifically, the ceramic is of a single-phase defect fluorite structure, the thermal conductivity at 1000 ℃ is lower than 1.70W m -1·K-1, the thermal expansion coefficient is higher than 12.5 multiplied by 1010 -6/K, and the structure is stable after heat treatment for 100 hours at 1600 ℃. Specifically, the A and B are selected from any one of Pr and Y, la and Sm, or Sm and Y. The invention also provides a preparation method of the high-entropy cerite ceramic, which comprises the following steps: s1, raw material pretreatment, namely carrying out pre-calcination treatment on all raw material powder containing Ce 2O3、Tm2O3、Nd2O3、Gd2O3 and oxides corresponding to A, B elements; s2, batching and mixing, namely weighing all raw material powder treated in the step S1 according to the stoichiometric ratio of the general formula of claim 1, and performing ball milling and mixing with a ball milling medium and a dispersing agent to obtain uniform slurry; S3, drying and presintering, namely drying the slurry to obtain mixed powder, and performing primary sintering at the temperature of 1300-1400 ℃ to obtain high-entropy ceramic primary powder; S4, secondary treatment and forming, namely performing secondary ball milling, drying and sieving on the high-entropy ceramic primary powder, adding a binder, and performing dry pressing forming to obtain a ceramic green body; and S5, final sintering, namely performing secondary sintering in an air atmosphere at 1450-1550 ℃ after the ceramic green body is subjected to glue discharging treatment, so as to obtain the Gao Shangshi acid salt ceramic block material. Specifically, in step S2, the rotational speed of the ball-milling mixing is 200 rpm to 300 rpm, and the ball-milling time is 2 to 4 hours. Before final sintering, the powder is sintered for the first time, so that the structural and performance defects of ball milling powder are overcome, the component homogenization, phase structure stabilization and densification of the high-entropy ceramic are realized, and the high-entropy ceramic primary powder meeting the use requirements is obtained. The primary sintering temperature is controlled to 1300-1400 ℃ which is lower than the secondary sintering temperature (1450-1550 ℃), the design is to realize the formation of a main phase of high-entropy ceramic powder, the bonding of a particle neck and the densification of the powder under a relatively mild condition, the secondar