**4. Conclusions**

In this work, a novel TBC system with a bu ffer layer embedded with Si-based crack-healing agents has been developed and evaluated. Using thermal durability tests, the crack-resisting behaviors and mechanisms of Si, and encapsulated Si, and the related mechanisms are presented. The main contributions are as follows.


**Supplementary Materials:** The following are available online at http://www.mdpi.com/2079-6412/9/6/358/s1, Figure S1: EDS mapping analysis around the healing agents in as-coated samples from Figure 6C-1; Figure S2: EDS point-analysis around the healing agents in as-coated samples from Figure 7A,B; Figure S3: EDS pointand mapping analysis around the healing agents after heat treatment from the magnified image in Figure 10C; Table S1: Particle diameters at 10%, 50%, and 90% of the cumulative mass of (A): normal Si, and (B) encapsulated Si from Figure 5.

**Author Contributions:** Conceptualization, D.S., T.S. and Y.-G.J.; Methodology, D.S., T.S., G.L., Y.-G.J. and J.Z.; Formal analysis, D.S. and G.L.; Investigation, D.S., T.S., G.L., Y.-G.J., B.-G.C., I.-S.K. and J.Z.; Writing-Original Draft Preparation, D.S.; Writing-Review and Editing, D.S., T.S., U.P., Y.-G.J., B.-G.C., I.-S.K. and J.Z.; Supervision, T.S., U.P. and Y.-G.J.; Project Administration, T.S., U.P. and Y.-G.J.; Funding Acquisition, T.S., U.P. and Y.-G.J.

**Funding:** This research was funded by "Human Resources Program in Energy Technology (No. 20194030202450)" and "Power Generation & Electricity Delivery gran<sup>t</sup> (No. 20181110100310)" of the Korea Institute of Energy Technology Evaluation and Planning (KETEP); a granted financial resource from the Ministry of Trade, Industry & Energy, Korea; and by Fundamental Research Program of the Korean Institute of Materials Science (KIMS, No. PNK5620).

**Conflicts of Interest:** The authors declare no conflict of interest.
