Reaction between environmental barrier coatings material Er2Si2O7 and a calcia-magnesia-alumina-silica melt

The suitability of sintered erbium disilicate (Er 2 Si 2 O 7 ) as an environmental barrier coatings (EBCs) for gas turbine applications was assessed by characterizing its high-temperature corrosion behavior in contact with a synthetic calcia-magnesia-alumina-silica (CMAS) melt. Er 2 Si 2 O 7 was fabricated using spark plasma sintering at 1400 °C for 20 min. Corrosion tests were performed by coating sintered Er 2 Si 2 O 7 pellets with CMAS and heating them to 1400 °C for 2, 12, and 48 h. High-temperature X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analysis were used to identify and analyze the reaction products. The two materials were found to react chemically to form an apatite phase, Ca 2 Er 8 (SiO 4 ) 6 O 2 , at their interface. The Ca 2 Er 8 (SiO 4 ) 6 O 2 grains were observed to have shard-like morphologies oriented perpendicular to the Er 2 Si 2 O 7 surface; the reaction layer thickened with increasing heat-treatment time, with the thickness after exposure for 48 h approximately three times the thickness after 2 h.