Effect of heat treatment on the thermal conductivity of plasma-sprayed thermal barrier coatings

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• 作者：Rollie Dutton (1)
  Robert Wheeler (2)
  K. S. Ravichandran (3)
  K. An (3)
• 关键词：thermal conductivity ; heat treatment ; microcracks ; TBCs
• 刊名：Journal of Thermal Spray Technology
• 出版时间：June 2000
• 出版年：2000
• 期刊代码：pc357_1059-9630
• 类别：ch
• 卷：9
• 期：2
• 页码：204-209
• 数据来源：sp

摘要

The effect of heat treatment on the thermal conductivity of plasma-sprayed Y₂O₃ stabilized ZrO₂ (YSZ) and Al₂O₃ coatings was investigated. A heat treatment of 1300 掳C in flowing argon for 50 h was found to significantly increase the thermal conductivity of the coatings when compared to measurements in the assprayed condition. Transmission electron microscopy (TEM) examination of the microstructures of the coatings in the as-sprayed and heat-treated conditions revealed that sintering of microcracks at the splat interfaces was the main cause for the increase in thermal conductivity. In the YSZ coatings, complete closure of microcracks was frequently observed. In contrast, microcrack closure in the Al₂O₃ coatings was characterized by the isolated necking of particles across a microcrack rather than complete closure. A model for thermal conductivity in a solid containing oriented penny-shaped cracks was used to explain the observed increase in thermal conductivity after heat treatment.