Characterization of plasma-sprayed zirconia coatings by X-ray diffraction and Raman spectroscopy

Three zirconia ceramics, ZrO₂−4.5mol.%Y₂O₃, ZrO₂−12mol.%Y₂O₃ and ZrO₂−8mol.%MgO, were investigated using X-ray diffraction before and after plasma spraying. The amounts of monoclinic, tetragonal and cubic phases existing in the three zirconia ceramics were determined from the integrated intensity ratios in the {400} and {111} regions of the X-ray diffraction patterns. The tetragonal-to-monoclinic transformation in the plasma-sprayed coatings caused by indentation, fracture and/or heat treatment with a laser beam was examined using Raman spectroscopy. As a result, this spectroscopic technique is shown to be a powerful tool for the observation of this transformation.