The Effect of Deposition Process Parameters on the Microstructure and Mechanical Properties of Nanostructured Thermal Barrier Coatings

Nanostructured thermal barrier coatings (TBCs, Cr/CoAlY/8 wt% Y₂O_3-ZrO₂ ceramic top coatings) were deposited on superni-718 substrates by the magnetron sputtering method on different process parameters. The effect of magnetron sputtering power on microstructure and mechanical properties of TBC was studied in the present research work. The structural properties of the deposited TBC coatings were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) and chemical composition of thermal barrier coatings was characterized by energy dispersive X-ray spectroscopy (EDS). XRD results showed that the coatings deposited at a low power has much more amorphous nature as compared to coatings deposited at a high power has crystalline nature.The XRD analysis revealed the tetragonal phase which is the stable phase in TBC coating, since the temperature is constant in both depositions. Mechanical properties of the TBC coatings were studied by nano indentation. The results revealed that coatings deposited at lower power exhibited 50% increase in hardness values as compared to coating deposited as higher power. Furthermore, coating thickness has enhanced from 957 nm to 1.34 µm thus there has been 28% enhancement in coating thickness in changing process parameters specifically power of magnetron.