Thermal shock behavior and oxidation resistance of novel SiC nanowires+Si/Yb2Si2O7-Si/Yb2Si2O7 environmental barrier coatings.

The objective of this work is to design environmental barrier coatings with new structure to improve the thermal shock and oxidation resistance. A novel tri-layer SiC nanowires+Si/Yb 2 Si 2 O 7 -Si/Yb 2 Si 2 O 7 coating was designed and fabricated on the surface of C/SiC composites by chemical vapor reaction route and combination of the method of atmospheric plasma spraying. All coated samples were subjected to thermal shock test at 1300 ℃. Results indicated that the interfacial bond among the layers in the coating system and C/SiC composites was still intact without delamination crack. The Si in the Yb 2 Si 2 O 7 -Si layer consumed the oxygen diffused into coating and then reacted with Yb 2 SiO 5 to form Yb 2 Si 2 O 7 , which could decrease the release of tensile stress caused by thermal mismatch. The study also investigates the Yb 2 Si 2 O 7 formation in the Yb 2 SiO 5 -Si system, and finds that the Yb 2 Si 2 O 7 formation was controlled by the diffusion of Yb3+ and Si4+ ions through the Yb 2 Si 2 O 7 layer. [ABSTRACT FROM AUTHOR]