Development of New TBC Coating System by Water Plasma Spraying and HVOF *

摘要

A new Thermal Barrier Coating (TBC) system aiming superior thermal shock resistance and low cost, was developed upon combination of HVOF (JP-5000) sprayed CoNiCrAlY bond coating and Water Plasma Sprayed (WPS) yttria-stabilized zirconia top coating for application to industrial gas turbines. This TBC system was evaluated by thermal cyclic test. The new coating system of WPS/JP-5000 showed excellent thermal shock resistance compared to conventional APS (air plasma-spraying) -TBC system against thermal cyclic test condition of 1,000 deg C approx RT in air. Also the new coating method was confirmed to have good thermal shock resistance even for thick zirconia top coating layer. The superior thermal shock resistance of WPS/JP-5000 coating system was due to formation of micro-crack in the top coating layer by WPS. In addition, the CoNiCrAlY bond coating by JP-5000 had a diffusion zone in between the sprayed particles and the substrate similar to VPS coating layers. The new TBC system of WPS/JP-5000 for application to industrial gas turbines is considered promising because its good thermal shock resistance and low cost.