Influence of porosity on hardness and Young's modulus of nanoporous EB-PVD TBCs by nanoindentation

The hardness and Young's modulus of ZrO2–4 mol% Y2O3 coating layers fabricated by EB-PVD are characterized using a nanoindentation technique. Coatings consist of porous, aligned columnar structure. The porosity of the coatings increased with increasing substrate rotation speed during deposition. The hardness and Young's modulus showed a significant dependence on the porosity and a strong anisotropy due to the columnar microstructure. The hardness and Young's modulus of the surface regions of the coatings is found to be higher than that of the side regions. The hardness and Young's moduli of the surface regions of the coatings have a nearly constant value, whereas those of the side areas decreased with increasing the porosity.