Enhancing the performances of EB-PVD TBCs via overlayer Al-modification

Thermal barrier coatings (TBCs) guarantee the service life of high-temperature alloy substrates under harsh service environments. Premature failure of TBCs due to coating fracture, high-temperature oxidation, and calcium oxide-magnesium oxide-aluminum oxide-silicon oxide (CMAS) corrosion, which significantly reduce their service lifespan. In this study, Al film was applied on the surface of EB-PVD TBCs using arc ion plating, and then converted it to alpha-Al2O3 by an in situ reaction between Al and ZrO2. The alpha-Al2O3 have toughening effect resulting in a higher bending resistance of EB-PVD TBCs. Because alpha-Al2O3 could seal the columnar inter-crystal gaps on the surface of EB-PVD TBCs, it reduced oxygen penetration, which enhanced the high-temperature oxidation resistance. CMAS reacted with alpha-Al2O3 to generate spinel and calcium-aluminum yellow feldspar compounds at 1350 degrees C, which prevented following CMAS penetration and corrosion. Furthermore, Al-modification reduced the surface roughness, which made Al-modified TBCs have better wetting resistance.

Automated summary

In this study, an Al film was applied on the surface of EB-PVD TBCs and converted to alpha-Al2O3, which improved the lifespan of the TBCs. Alpha-Al2O3 had a toughening effect, enhanced high-temperature oxidation resistance, and prevented CMAS penetration and corrosion. Moreover, Al modification improved surface roughness and wetting resistance of the TBCs.