Laser nanostructuring of EB-PVD thermal barrier coatings for ultra-low thermal conductivity

Thermally stable uniform nanoparticles and nanoporous structure in electron beam-deposited TBC coating were synthesized by the use of femtosecond laser irradiation followed by a dip in nanostabilizing-slurry. Superalloy sample with a nominal size of 25 mm by 25mm with a bond coat (NiCrALY) thickness of 100μm and top coat (YSZ) thickness of 100μm were acquired from coating manufacturers. A 100 fs pulsed Ti sapphire laser based on the Chirped pulse amplification (CPA) techniques was then used to ablate the coating at very low energy fluence. Femtosecond pulsed laser was chosen over nanosecond pulsed laser for ablation due to reduced thermal effects that in true prevent the formation of non-periodic microstructure. Auger electron spectroscopy (AES) and X-ray diffraction(XRD) analyses revealed that the chemical composition of nanoparticle was same to that of original YSZ). It also disclosed hardness of 20-22 GPa, an increased of 40% over the EB-PVD coating.