Nanostructured and conventional titania coatings for abrasion and slurry-erosionresistance sprayed via APS, VPS and HVOF

摘要

In order to characterize the performance of nanostructured coatings during wear, nanostructured and conventionaltitania (TiO2) coatings were sprayed via three different thermal spray processes: APS, VPS and HVOF. Threedistinct types of wear resistance were evaluated: dry-abrasion and slurry-erosion at 30o and 90o. The ranking of thewear performance of the different coatings varied for the three wear tests, except for the HVOF-sprayednanostructured titania. The HVOF-sprayed nanostructured coating exhibited the highest wear resistance in allthree types of wear. The different angles of erosion (30° and 90°) did not cause a change in the wear performance(ranking) of the HVOF-sprayed nanostructured coating, as was observed for the other coatings tested. Thesuperior mechanical performance of the HVOF-sprayed nanostructured titania can be explained by observing themicrostructure of the coating via high magnification SEM. These observations show that the nanostructured zonesin the coating microstructure act as crack arresters, thereby increasing the coating toughness. The wear scars forthe different coatings were also analyzed via SEM and used to help understand the wear performance of thedifferent materials.