Method for preparing low-thermal-conductivity high-temperature thermal barrier ceramic CaWTa2O9 by solid-phase method

A technology of low thermal conductivity and solid-state method, applied in the field of high-temperature ceramic coatings, can solve problems such as low thermal conductivity, coating peeling, coating cracks, etc., and achieve high thermal expansion coefficient, simple preparation process, and good phase stability. Effect

Active Publication Date: 2021-01-22
陕西天璇涂层科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The research of NASA~Lewis shows that in the YSZ system, Y 2 o 3 The optimal content of YSZ is 6-8wt%, but YSZ materials also have some disadvantages, first of all, the problem of phase stability, 6-8wt% of YSZ actually exists in a metastable t' phase, when the temperature is higher than 1200 ℃, the t' phase will be decomposed into a tetragonal phase (t) and a cubic phase (c), and the tetragonal phase will be transformed into a monoclinic phase (m) during the cooling process. Cracks or even peeling of the coating occur in the coating, so the use temperature of YSZ is often limited below 1200 °C
[0003] The rare earth tantalate thermal barrier ceramic coating system developed by Feng Jing's team at Kunming University of Science and Technology studied divalent ions (Ca 2+ , Mg 2+ , Cu

Method used

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  • Method for preparing low-thermal-conductivity high-temperature thermal barrier ceramic CaWTa2O9 by solid-phase method
  • Method for preparing low-thermal-conductivity high-temperature thermal barrier ceramic CaWTa2O9 by solid-phase method
  • Method for preparing low-thermal-conductivity high-temperature thermal barrier ceramic CaWTa2O9 by solid-phase method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Preparation of low thermal conductivity and high temperature thermal barrier ceramics CaWTa by a solid phase method 2 o 9 method, including the following steps:

[0029] Step 1: Follow Ta 2 o 5 with CaWO 4 The molar ratio is 1:1 and weighs tantalum pentoxide (Ta 2 o 5 ) and calcium tungstate (CaWO 4 ), mixed in absolute ethanol, placed in a planetary ball mill for ball milling, the speed of the ball mill was 300r / min, and the ball milling time was 600min, then the milled solution was dried at 80°C for 24h and passed through a 300-mesh sieve for subsequent use.

[0030] Step 2: Compress the powder sieved in step 1 with a mold, wherein the holding pressure is 8 MPa, and the holding time is 30 minutes. After pressing and forming, it is sintered at 1400 ° C for 8 hours to obtain a good firing shape. wxya 2 o 9 ceramics.

[0031] Wherein the reaction equation in the step 2 is:

[0032] wxya 4 (G 1 )+Ta 2 o 5 (G 2 ) = CaWTa 2 o 9 (G 3 )

[0033] Among them...

Embodiment 2~6

[0035] The difference from Example 1 is that the process parameters in Examples 2-6 are different, as shown in Table 1 below for details.

[0036] Table 1 is the technological parameter table of embodiment 2~6

[0037]

[0038]

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Abstract

The invention relates to the technical field of high-temperature ceramic coatings, and particularly discloses a method for preparing low-thermal-conductivity high-temperature thermal barrier ceramic CaWTa2O9 by a solid-phase method, which comprises the following steps: proportioning Ta2O5 and CaWO4 according to a molar ratio of 1: 1, mixing with a ball milling medium, carrying out ball milling, drying, and screening to obtain powder; carrying out compression molding on the powder in a mold, and carrying out pressure-maintaining sintering at 1400-1600 DEG C for 5-10 hours to obtain the thermalbarrier ceramic CaWTa2O9. The thermal conductivity of the thermal barrier ceramic CaWTa2O9 prepared by the method at 800 DEG C reaches 1.25 W.m<-1>.K<-1> at minimum, the thermal expansion coefficientreaches 8.6 K<-1> at 1100 DEG C, the requirements of a high-temperature thermal barrier coating on low thermal conductivity and high thermal expansion coefficient of a ceramic material are met, and the thermal conductivity of the obtained pure CaWTa2O9 ceramic is far lower than that of the existing rare earth tantalate ceramic.

Description

technical field [0001] The invention relates to the technical field of high-temperature ceramic coatings, in particular to a solid phase method for preparing low thermal conductivity high temperature thermal barrier ceramics CaWTa 2 o 9 Methods. Background technique [0002] Yttria-stabilized zirconia (YSZ) is currently the most widely used TBCs material in gas turbines and turbine engines. The research of NASA~Lewis shows that in the YSZ system, Y 2 o 3 The optimal content of YSZ is 6-8wt%, but YSZ materials also have some disadvantages, first of all, the problem of phase stability, 6-8wt% of YSZ actually exists in a metastable t' phase, when the temperature is higher than 1200 ℃, the t' phase will be decomposed into a tetragonal phase (t) and a cubic phase (c), and the tetragonal phase will be transformed into a monoclinic phase (m) during the cooling process. Cracks or even peeling of the coating occur in the coating, so the use temperature of YSZ is often limited to...

Claims

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Application Information

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IPC IPC(8): C04B35/495C04B35/622
CPCC04B35/495C04B35/62222C04B2235/326C04B2235/9607Y02T50/60
Inventor 汪俊利建雨王峰李振军冯晶
Owner 陕西天璇涂层科技有限公司
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