Thermal barrier coatings (TBCs) are suffering from severe degradations by the melted Ca-Mg-Al-silicates (CMAS) deposits during high-temperature operation. The present study evaluated the CAMS-induced degradation to the sintered gadolinium magnesium hexaaluminate (GdMgAl11O19, GdMA) ceramic bulk at 1260-1500 degrees C for 48 h to 100 h, and compared its CMAS resistance with the air plasma sprayed GdMA coating counterpart at 1350 degrees C. Results indicate that the well crystallized GdMA ceramic bulk suffered from more and more serious infiltration of the melted CMAS and microstructure destructions with extended exposure time and enhanced temperature. No barrier layer consisted of corrosion products formed to prevent the melted CMAS penetration during such a process. While, the APS GdMA coating with more amorphous phase as a chemical active component seemed much better to behave as a barrier layer to stop the melted CMAS penetration and corrosion degradation by sacrificing a thin surface layer of the GdMA coating.
NSTL
Elsevier