Deposition and properties of a multilayered thermal barrier coating

• A multilayered architecture is introduced, including segmentation cracking, porous and dense layer.
• The thermal cycling lifetime of the multilayered TBCs is higher than the conventional one.
• It is potential to obtain the high performance TBCs by adjusting plasma spraying.

The widely used air plasma sprayed thermal barrier coatings (TBCs) in industrial gas turbine engines are limited by its durability. The failure of plasma sprayed TBCs in thermal cycling is usually induced by the spallation of ceramic coating within the ceramic coating near the top coat/bond coat interface. In this research, a multilayered ceramic coating architecture is introduced comprised of the layers of segmentation cracks, porous and dense. The segmented yttria stabilized zirconia (YSZ) layer was deposited at the substrate temperature of 750 °C without any artificial cooling, which resulted in the formation of YSZ layer with obvious columnar crystal structure and segmentation cracks. And a dense top YSZ layer was also included on the top to restrain the penetration of oxygen and the molten calcium–magnesium–alumina-silicate (CMAS) glass deposits. Additionally, the conventional porous YSZ coating was preserved in order to get the low thermal conductivity. The thermal cycling tests show that the lifetime of the multilayered TBCs increases by a factor of 2 compared with that of the conventional one, which could attribute to the high strain tolerance and fracture toughness of the segmented and columnar microstructure. Oxidation resistance and CMAS corrosion resistance are also better for the multilayered TBCs compared with that of the conventional one, due to the suppression function of dense top YSZ layer. It is potential to obtain the high performance TBCs by adjusting plasma spraying.

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