Zirconia coatings realized by microwave plasma-enhanced chemical vapor deposition

This study presents an evaluation of a new process microwave plasma-enhanced chemical vapor deposition to deposit thermal barrier coatings (TBCs) consisting of yttria partially stabilized zirconia. A reactor has been designed and realized at ONERA with a view to provide an alternative technique to the processes already in use for depositing TBCs on gas turbine airfoils. It is demonstrated that zirconia coatings having a columnar structure can be deposited with a high rate (up to 5 mu m min(-1)) compatible with production requirements. Plasma study by optical emission spectroscopy has lead to the identification of reactive species and to the determination of the plasma distribution and location with respect with the gas flow and the reactor chamber geometry. A systematic study has been engaged to determine the influence of operating parameters on the structure, the morphology of the coatings and the deposition rate.