Evaluation of wear damage in zirconia plasma-sprayed coatings using scanning white light interferometry

The mechanical and tribological properties of thermal barrier coatings (TBCs) can be improved by means of a thermal treatment. The evolution of the mechanical and tribological properties in a NiCr-ZrO₂ TBC with different times of thermal treatment has been measured. In this work, scanning white light interferometry (SWLI) is used to observe and quantify the ZrO₂ wear damage. ZrO₂ shows very poor light reflection, and a sputtering process over the coating has been made to achieve a proper light reflection and make the use of SWLI possible. It has been observed that thermal treatments at 1000 °C produce a decrease of the wear damage and an increase of hardness. The ball-on-disk test and the wear mechanisms are described and include the intersplat delamination of the main wear process in the as-sprayed coatings and thermally treated samples. The volume loss after 18 h at 1000 °C is 38% less than the as-sprayed coating. The erosion test and hardness measures show the same evolution as the ball-on-disk test.