Enhanced steam thermal cycle resistance of Yb2Si2O7 environmental barrier coatings via Al modification

SiC-based ceramic matrix composites are susceptible to performance losses in steam environments, necessitating the use of environmental barrier coatings for their protection. The high Si activity of Yb₂Si₂O₇ material may induce the emergence of Si(OH)₄ in steam environments, resulting in the development of a pore structure within Yb₂Si₂O₇. This pore structure weakens the service life of the coating, highlighting the importance of enhancing the steam corrosion resistance of environmental barrier coatings as a key factor in improving their overall longevity. In the present study, we employed Al modification technique to improve the steam corrosion resistance of Yb₂Si₂O₇ coatings. The results indicated that Al-modified Yb₂Si₂O₇ coatings exhibited superior steam thermal cycle corrosion resistance compared to the non-modified Yb₂Si₂O₇ coatings after testing performed at 1523 K for 1000 h (10 h per cycle). This improvement was attributed to the presence of Yb₃Al₅O₁₂ and Al₂O₃ composite phases within the Al-modified Yb₂Si₂O₇ coatings, which exhibited low steam activity and effective steam corrosion resistance. Moreover, Al-modified Yb₂Si₂O₇ coatings obtained the dual excellent performance of improving the steam corrosion resistance of Yb₂Si₂O₇ coating and not weakening the thermal cycle ability, providing a guarantee for the longer life of Yb₂Si₂O₇ coating.