High temperature solid particle erosion is a critical degradation process affecting boiler components in energy systems operating under thermo-mechanical conditions. The current work systematically investigates the erosion behavior of unreinforced plasma-sprayed CoNiCrAlY coatings and CoNiCrAlY coatings reinforced with Al 2 O 3 and yttria stabilized zirconia (YSZ), deposited on T91 steel. The erosion tests were conducted at a temperature of 800 o C using impact angles of 30 o and 90 o . The as-sprayed coatings were comprehensively characterized in terms of their microstructure, phase composition, elemental distribution and microhardness. Subsequently, erosion-induced damage was evaluated through volumetric erosion loss measurements, surface and cross-sectional SEM analysis with elemental mapping, X-ray diffraction of the eroded samples and 3-D optical profiling. A significant dependence of erosion behavior on impact angle was observed, with considerably higher material loss at 30 o due to the dominance of ductile erosion mechanisms such as cutting and ploughing. Among the investigated coatings, the unreinforced CoNiCrAlY coating exhibited the highest erosion loss, while the incorporation of ceramic reinforcements led to a significant improvement in erosion resistance. The CoNiCrAlY+Al 2 O 3 coating exhibited higher hardness and reduced material loss, whereas the CoNiCrAlY+YSZ coating demonstrated the best overall performance, characterized by high phase stability, enhanced splat cohesion, suppressed subsurface damage, and minimum crater depth. Overall, the experimental findings indicate the critical role of microstructural integrity, elemental stability, and the type of reinforcement in governing high-temperature erosion resistance, thereby, establishing CoNiCrAlY+YSZ coatings as a promising surface engineering solution for mitigating high-temperature erosion damage in the advanced boiler systems.
Shetty et al. (Sun,) studied this question.