Nanostructured coatings of yttria stabilized zirconia (YSZ) deposited by the suspension plasma spraying (SPS)

The outstanding properties of ytria stabilized zirconia (YSZ) coatings allow an excellent performance of these materials for many applications, ranging from dentistry to thermal barriers, including its use as solid electrolytes in fuel cells. In the present work, nanostructured coatings of 8YSZ with a maximum thickness of 75 mu m were deposited on a Haynes 230 superalloy substrate by means of a suspension plasma spraying (SPS) process. The deposited coatings act as a sub-layer between the smooth and unprepared substrate and a thicker microstructured YSZ coating. The effect of the deposited sub-layer thickness and the influence of subsequent heat treatments (TT) at 300 degrees C and 600 degrees C, on its tribological performance at room temperature and 650 degrees C, were studied. During sliding wear tests with a load of 2 N versus alumina, it was determined that reducing the coating thickness from 75 mu m to 25 mu m increases the wear resistance by approximately 5 times. Also, it was found that the heat treatment at 600 degrees C applied to the coating of 25 mu m thickness decreases its wear resistance 6 times with respect to the as-sprayed condition. Similarly, when the tests were performed at 650 degrees C, the tribological behavior was significantly deteriorated. These results have been related to the morphological changes that take place during the heat treatment process. (C) 2018 SECV. Published by Elsevier Espana, S.L.U.