Effect of composition on the growth and microstructure of hafnia–zirconia based coatings

Yttria (Y2O3)–stabilized hafnia (HfO2)–zirconia (ZrO2)-based coatings were grown and studied for their growth and microstructure. Composition of the coatings was varied by varying the ratio of HfO2 and ZrO2, from 1:4 to 4:1, while maintaining the Y2O3 stabilizer content fixed at 7.5 mol%. The crystal structure, surface morphology and thermal stability of the grown coatings were evaluated as a function of the coatingsʹ composition. The crystal structure analysis performed by X-ray diffraction (XRD) indicates the hafnia-cubic-phase stabilization in all the coatings. The morphology of the coatings is characterized by the columnar growth coupled with a dense structure as revealed by the scanning electron microscopy (SEM). Thermal stability evaluation performed using high temperature XRD coupled with SEM indicates the enhanced stability of these coatings to 1300 °C. No significant changes were found in the crystal structure and morphology of the coatings.