65 / 2024-09-23 15:34:10

Improving the durability and investing failure behavior of multi-layer TBCs under thermal cycling-CMAS test

Thermal barrier coatings,Multi-layer coating,Thermal cycling-CMAS lifetime,Failure behavior

Atmospheric plasma spraying (APS) was used to fabricate 4.5 mol% Y₂O₃ stabilized ZrO₂ (YSZ) and 4.0 mol% Yb₂O₃ and 0.5 mol% Y₂O₃ co-stabilized ZrO₂ (YbYSZ) series coatings with different spraying parameters. Effects of particle size of feed powder, substrate temperature and transfer speed on the microstructure and performance of thermal barrier coatings (TBCs) is investigated. Lower substrate temperatures can lead to vertical cracks, finer powders can introduce more microdefects, and conventional sized powders can form larger pores. A coating deposited using a conventional feed powder at a substrate temperature of 800 ℃ shows excellent sintering resistance. A coating deposited using a fine feed powder on 800 ℃ substrate exhibits the best calcium‑magnesium-alumina-silicate (CMAS) corrosion resistance. A series of coatings with embedded micro-agglomerated particles (EMAP) are prepared using different transfer speed. The thermal conductivity of EMAP coatings is lower than that of traditional YSZ coating, with EMAP coating deposited at 200 mm/s transfer speed having the lowest thermal conductivity. The thermal cycling life of EMAP coatings at transfer speeds of 600 mm/s and 800 mm/s is improved by 20.00 % and 58.33 % compared to traditional YSZ coating. On the basis of the above coatings, the multi-layer coating includes the micro-nano dual-scale layer, the dense YbYSZ layer, the porous YbYSZ layer and the laser 3D texturing layer. The lifetime of thermal cycle-CMAS test is 120% longer than that of conventional YSZ coating. In addition, its failure behavior, including fragmentation or bulk-like exfoliation, has been studied. This study emphasizes that combination of materials modification and structure optimization are a promising strategy to extend lifetime of TBCs.