A two-step processing was developed to prepare Yb 2 Si 2 O 7 -SiC nanocomposites.Yb 2 Si 2 O 7 -Yb 2 SiO 5 -SiC composites were first fabricated by a solid-state reaction/ hot-pressing method. The composites were then annealed at 1250°C in air for 2 hours to activate the oxidation of SiC, which effectively transformed the Yb 2 SiO 5 into Yb 2 Si 2 O 7 . The surface cracks purposely induced can be fully healed during the oxidation treatment. The treated composites have improved flexural strength compared to their pristine composites. The mechanism for crack healing and silicate transformation have been proposed and discussed in detail. K E Y W O R D Scracks/cracking, nanocomposites, oxidation, silicon carbide, strength

The SiO2 volatility and SiC recession in hydrocarbon‐rich combustion atmosphere is the main problem of SiC‐reinforced ceramics when they are utilized as coating materials for gas turbine blades. The composite of Yb2Si2O7‐Yb2SiO5/SiC is expected as a self‐crack healing material that can avoid this problem because the monosilicate can react with the SiO2 glass to form disilicate and hence further reinforce the composite. In this study, the composites, fabricated with various morphology of SiC nanofillers, were precracked and then heat‐treated in an oxidizing environment to activate their crack healing behavior. The healing effect as a function of filler morphology and annealing time was investigated. Healing mechanism and future applications of these composites were also discussed.

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