A new double layer oxidation resistant coating based on Er2SiO5/LaMgAl11O19 deposited on C/SiC composites by atmospheric plasma spraying

A new coating with Er2SiO5 as inner layer and LaMgAl11O19 (LMA) as top layer was designed and deposited on C/SiC composites by atmospheric plasma spraying to improve the oxidation resistance of the substrate at high temperature. Microstructure, oxidation protection and failure mechanism of the Er2SiO5/LMA coating during dynamic thermal cycling (DTC) were investigated. The results showed that a good interfacial bonding between the substrate and the coating was present before and after DTC test. Weight loss for the sample coated on one-side was 4.5% after 11 cycles of heating for 85 min, and for the uncoated sample was as high as 20.6%. Failure mechanism of the coating resulted from the liquid sintering of the coating and the formation of bubbles between the substrate and the coating.

► A new Er2SiO5/LMA coating was designed and fabricated on C/SiC composites by APS.
► Microstructure, oxidation protection and failure of the coating were investigated.
► The coating significantly improves the oxidation resistance of substrate at 2273 K.
► The sintering of the coating and formation of bubbles make the coating fail.