Nanomechanical properties of plasma-sprayed nanostructured and conventional 8YSZ thermal barrier coatings

Nanostructured thermal barrier coatings (TBCs) have become a noteble research field for the development of high-performance thermal protection coatings. The mechanical properties are essential for TBCs, which determine the functionality, reliability and durability of coatings. In this article, the nanostructured 8YSZ (n-8YSZ) and conventional 8YSZ (c-8YSZ) coatings were fabricated by atmospheric plasma spraying (APS). The goal of the work is to do an evaluation and comparison of the nanomechanical properties of n-8YSZ and c-8YSZ coatings. The microstructure of coatings was observed by scanning electron microscopy and the nanomechanical properties was characterized using nano-indenter. Results indicate that the microstructure of the n-8YSZ coating exhibits bi-modal distribution while the microstructure of the c-8YSZ coating shows mono-modal distribution. The elastic indentation work (W_e) is 11.952 ± 1.243 nJ and the plastic indentation work (W_p) is 20.266 ± 5.594 nJ for the n-8YSZ coating. Meanwhile, the W_e is 11.753 ± 0.634 nJ and the W_p is 16.508 ± 3.000 nJ for the c-8YSZ coating. The microstructure of the coating has little effect on W_e, but much on W_p. The dissipation ratio of plastic deformation work (η) is 0.621 ± 0.046 for the n-8YSZ coating and 0.579 ± 0.042 for the c-8YSZ coating. Therefore, it can be predicted that the n-8YSZ coating is superior to the c-8YSZ coating in terms of erosion performance.