Thermal Shock Resistance of Thermal Barrier Coatings with Different Surface Shapes Modified by Laser Remelting
Inspired by the unique structures and shapes of biological organisms, thermal barrier coatings (TBCs) with different shapes including dot, striation and grid were modified by laser remelting. NiCrAlY/ZrO2-7 wt.%Y2O3 double-layer-structured TBCs were prepared. The microstructure, microhardness, phase composition and thermal shock behaviors of the as-sprayed and laser-treated specimens with different shapes were examined. The results indicated that the unit was characterized by the dense columnar crystal structure and the high microhardness. The thermal cycle lifetime of the dotted specimen was about twice that of the as-sprayed specimen. On the one hand, due to the elimination of defects and higher hardness after laser remelting, the dotted unit could resist thermal crack propagation. On the other hand, the columnar grains and segmented cracks in the dotted units were beneficial to increase the strain tolerance. However, due to more continuous segmented cracks and transverse cracks, the striated and grid specimens had relatively poor thermal shock resistance.
Keywordslaser remelting surface shape thermal barrier coatings thermal shock resistance
This work is supported by Guangdong Province Science and Technology Plan Projects (2016A030312015, 2017A070702016, 2017B030314122 and 2017A070701027), Guangzhou Project of Science and Technology (201807010030), Zhongshan Project of Science and Technology (2017G1FC0008), Natural Science Foundation of Guangdong Province (2016A030312015), the National Natural Science Foundation for Youth (51501044) and GDAS’ Project of Science and Technology Development (2018GDASCX-0111, 2017GDASCX-0202, 2017GDASCX-0111 and 2018GDASCX-0402).
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