Ultrafast laser reconstructed PS-PVD thermal barrier coatings with superior silicophobic triple-scale micro/nano structure

Abstract

Silicate material from environmental dust melts and adheres to the surfaces of thermal barrier coatings (TBCs) on hot-components of turbine engines accelerating their eventual failure. To mitigate against the wettability and spreadability of such molten deposits on TBCs, dual-scale structured (Gd0.9Yb0.1)2Zr2O7 TBCs with “lotus leaf” like surface morphology were fabricated using novel PS-PVD technology, which revealed an enhanced resistance to the wetting of molten silicate but experienced some degradation at high temperatures. By the ultrafast laser direct writing technology, the surface of the PS-PVD TBC was re-constructed, obtaining a triple-scale structure, consisting of conical micro-pillars, cauliflower-like domed micro-protuberances and nanoparticles. The contact angle of molten deposits at 1200 °C on this TBC was measured to be ∼ 127.2°, and after exposure to 1300 °C for 10 h, the TBC is still silicophobic (i.e., contact angle of ∼ 124.7°). This superior silicate phobicity is largely attributed to the increased surface roughness of the triple-scale structure. Further, the reaction layer appears to resist effectively further melt penetration. We thus propose that PS-PVD technology together with ultrafast laser direct writing may have great potential for the fabrication of molten silicophobic TBCs for turbine engines.

Keywords

• Thermal barrier coatings
• plasma spray physical vapor deposition (PS-PVD)
• Ultrafast laser
• Silicophobicity
• Structure design