Achieving self-enhanced thermal barrier performance through a novel hybrid-layered coating design

Investigation of sintering mechanism for novel composite structural thermal barrier coating

“…As shown in Figure 12A, significant healing occurs at the 2D pores of the intersplats in the conventional coating and the dense matrix in the EMAP coating. During thermal exposure, mass transfer decreases the free energy of the system 28,43,45 . As a typical sintering phenomenon in APS ceramic coatings, multiple bridge‐connections of pores are typically observed between the counter‐surfaces of the splats 16,21,25,27 .…”

“…During thermal exposure, mass transfer decreases the free energy of the system. 28,43,45 As a typical sintering phenomenon in APS ceramic coatings, multiple bridge-connections of pores are typically observed between the counter-surfaces of the splats. 16,21,25,27 These splats are formed by the columnar grains (Figure 12).…”

“…up to 30 nm, whereas the surface faceting occurs at approximately 5-10 nm. 28 Concurrently, 2D micropore tips with widths generally less than 10 nm are connected to one another at the counter-surfaces of these pore tips. Compared with the splat-dominated traditional APS coating, the embedded particle regions in the EMAP coating are not noticeably densified during the entire sintering process.…”

“…Sintering behavior, which is inevitable during TBC service, must be considered in the coating structure design. Recent studies have also indicated that pore healing dominates the structural evolution during sintering behavior 27–29 . In our previous study, we successfully designed a novel embedded micro‐agglomerated particle TBC (EMAP TBC) based on an improved APS process, wherein porous micro‐agglomerated (MA) particles are embedded in the coating matrix.…”

“…Recent studies have also indicated that pore healing dominates the structural evolution during sintering behavior. [27][28][29] In our previous study, we successfully designed a novel embedded micro-agglomerated particle TBC (EMAP TBC) based on an improved APS process, wherein porous micro-agglomerated (MA) particles are embedded in the coating matrix. This novel plasma spraying strategy employs an unconventional powder feeding method wherein two types of powders can be injected and deposited in different molten states.…”