Effects of surface roughness on CMAS corrosion behavior for thermal barrier coating applications

Calcium-magnesium-alumina-silicate (CMAS) corrosion is an important cause for thermal barrier coating (TBC) failure,which has attracted increased attentions.In this study,some thermal barrier coating (TBC) materials including YSZ (yttria partially stabilized zirconia),GdPO_(4),and LaPO_(4) were prepared into bulks,and the effects of their surface roughness on wettability and spreading characteristics of molten CMAS were investigated.As-fabricated and polished bulks with different surface roughness were exposed to CMAS corrosion at 1250 ℃ for 1 and 4 h,following by macro and micro observations.Results revealed that compared with the as-fabricated bulks,molten CMAS on the polished samples had lower wettability and a smaller spreading area,mainly attributable to the reduced capillary force to drive the melt spreading.Meanwhile,GdPO_(4) and LaPO_(4) bulks exhibited lower CMAS wettability than YSZ bulk.It is thus considered that reducing the surface roughness is beneficial to CMAS corrosion resistance of TBCs.