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Large-size block La2Zr2O7 ceramic material and hot pressed sintering preparation process thereof

A ceramic material, hot pressing sintering technology, applied in the field of ceramic materials, can solve the problems of limiting the preparation of large-size ceramics, less research on ceramic insulation materials, difficult to form thermal stress, etc., to achieve good thermal insulation performance and reliable mechanical bearing performance, Good thermal and mechanical properties, high density effect

Active Publication Date: 2014-05-21
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, studies have focused more on La 2 Zr 2 o 7 Preparation method of thermal barrier coating material, for large size block La 2 Zr 2 o 7 Research on ceramics as thermal insulation materials is less
Block La 2 Zr 2 o 7 The difficulty in the preparation of La 2 Zr 2 o 7 The low thermal conductivity causes the huge thermal stress inside the ceramic, making it difficult to form, which limits the preparation of large-scale ceramics
Therefore, it is difficult to prepare large-sized La by conventional molding and sintering processes. 2 Zr 2 o 7

Method used

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  • Large-size block La2Zr2O7 ceramic material and hot pressed sintering preparation process thereof
  • Large-size block La2Zr2O7 ceramic material and hot pressed sintering preparation process thereof
  • Large-size block La2Zr2O7 ceramic material and hot pressed sintering preparation process thereof

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preparation example Construction

[0032] 1) La 2 Zr 2 o 7 Preparation of powder raw materials: Mix the aqueous solutions of lanthanum nitrate and zirconium oxychloride with a concentration of 0.1~1mol / L and stir for 1h to form La 3+ with Zr 4+ For a mixed solution with a molar ratio of 1:1, add the mixed solution dropwise to the ammonia water precipitant at a rate of 10~60ml / min, continue to stir for 2 hours after the dropwise addition, and then leave it to stand for 24 hours. After standing, the pH of the supernatant When the pH value of the supernatant reaches 10~13, wash and separate with deionized water. When the pH value of the supernatant is 7, wash and separate with ethanol, and dry at 80°C for 24 hours to obtain an amorphous powder. Grind the amorphous powder for 1 hour. Heat treatment at 650~800°C for 4 hours and pass through a 300-mesh screen to obtain a particle size of La 2 Zr 2 o 7 powder raw material;

[0033] 2) Hot pressing and sintering molding: towards La 2 Zr 2 o 7 Add alcohol with...

Embodiment 1

[0037] 1) La 2 o 3 and ZrO 2 The preparation of the mixed powder raw material: La with a particle size of 1 μm is weighed with a La:Zr molar ratio of 1 2 o 3 and ZrO 2 , fully mixed with alcohol as the medium in the tank mill, fully mixed by the impact of zirconium balls and then fully dried, and the dry powder was sieved to obtain a uniformly mixed micron-sized mixed powder.

[0038] 2) Hot press sintering molding: add alcohol with a mass ratio of 8% to the micron-sized mixed powder for granulation to obtain granulated powder, prefabricate the granulated powder into a square green body, put the green body into a sintering mold, At room temperature, apply an initial pressure to the biscuit through the pressure head to prevent material from running out during heating. The initial pressure is 10MPa. When the pressure is kept constant, the temperature is raised to 850°C at a heating rate of 5°C / min. Keep warm for 30 minutes, keep warm at 1350°C for 10 minutes, keep warm at 1...

Embodiment 2

[0041] 1) La 2 o 3 and ZrO 2 The preparation of the mixed powder raw material: take the La:Zr molar ratio as 1 and weigh the La with a particle size of 50nm 2 o 3 and ZrO 2 , fully mixed with alcohol as the medium in the tank mill, fully mixed by the impact of zirconium balls and then fully dried, and the dried powder was sieved to obtain uniformly mixed nano-scale mixed powder.

[0042]2) Hot press sintering molding: add alcohol with a mass ratio of 3% to the nano-scale mixed powder for granulation to obtain granulated powder, preform the granulated powder into a circular green body, and put the green body into a sintering mold At room temperature, the initial pressure is applied to the biscuit through the pressure head to prevent the material from running out during heating. The initial pressure is 30MPa. When the pressure is kept constant, the temperature is raised to 950°C at a heating rate of 10°C / min and kept for 30min. Insulate at 1250°C for 40 minutes, at 1350°C f...

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Abstract

The invention discloses a large-size block La2Zr2O7 ceramic material and a hot pressed sintering preparation process thereof. The process comprises the following steps: sintering and molding a mixed powder raw material of La2O3 and ZrO2 or a La2Zr2O7 powder raw material prepared by a co-precipitation method under the common effects of heat and force to prepare the large-size block La2Zr2O7 ceramic. The essentials of the process are as follows: the cooperative control of a temperature program and a pressure program in a hot pressed sintering process can be used for solving the problem of block ceramic cracking caused by great heat stress generated by low heat conductivity of the La2Zr2O7; temperature adjusting and controlling parameters comprise a heating speed, heat-preservation temperature and time, a cooling rate, and annealing temperature and time; pressure adjusting and controlling parameters comprise a starting pressurizing pressure, a pressurizing and pressure-releasing speed, and pressure maintaining pressure and time. The molding performance of the La2Zr2O7 ceramic prepared by the process is good, the density is high and the appearance specification size is great; the large-size block La2Zr2O7 ceramic material has a high-strength low heat conduction property and can be produced in a large scale.

Description

technical field [0001] The invention relates to the technical field of ceramic materials, in particular to a large-size block La 2 Zr 2 o 7 Ceramic material and its hot pressing sintering preparation process. Background technique [0002] Aerodynamic heating is one of the biggest limiting factors in the development and innovation of aerospace vehicles, which directly affects the realization of the goal of long-endurance and high-speed development of aircraft. Because severe aerodynamic heating causes the surface temperature of the aircraft to rise sharply, heat conduction will affect the thermal deformation of the internal materials of the aircraft, affect the normal operation of the device, and increase the safety hazard of the aircraft. Therefore, the development of thermal protection materials that can serve in complex thermal environments is the key to solving the problem. [0003] Ceramic materials have the advantages of high melting point, low thermal conductivity,...

Claims

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Application Information

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IPC IPC(8): C04B35/48C04B35/50C04B35/645
Inventor 李翔翔洪樟连刘毅黄志威
Owner ZHEJIANG UNIV
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