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 degreesC 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 degreesC is 38% less than the as-sprayed coating. The erosion test and hardness measures show the same evolution as the ball-on-disk test.