Investigation of the thermomechanical properties of a plasma-sprayed nanostructured zirconia coating

Yttria partially stabilized nanostructured zirconia coatings were deposited by atmospherical plasma spraying (APS). The microstructure of the as-sprayed nanostructured coating was characterized with Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum (RS). The laser-flash diffusivity method and push-rod method were used to examine the thermomechanical properties of the nanostructured zirconia coatings. The results obtained indicated that the plasma-sprayed zirconia coating possessed nano-structure and its average grain size was about 73 nm. The average thermal expansion coefficients of the nanostructured coating at the first thermal cycle and second thermal cycle from room temperature to 1200 °C are 11.0 and 11.6×10−6 °C−1, respectively. The thermal diffusivity of the nanostructured zirconia coating was 1.80–2.54×10−3 cm2/s between 200 and 1200 °C. The microhardness of the nanostructured zirconia coating was 8.6 GPa, which was 1.6 times as large as that of traditional zirconia coating.