Crack-Resistance Behavior of an Encapsulated, Healing Agent Embedded Buffer Layer on Self-Healing Thermal Barrier Coatings

• Published in: Coatings (Basel) Vol. 9; no. 6; p. 358
• Main Authors: Song, Dowon, Song, Taeseup, Paik, Ungyu, Lyu, Guanlin, Jung, Yeon-Gil, Choi, Baig-Gyu, Kim, In-Soo, Zhang, Jing
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2019
• Subjects: Buffer layers; Cracks; Design; Embedding; Encapsulation; Fatigue cracks; Fatigue strength; Fatigue tests; Heat treatment; Indentation; Jet engines; Microhardness; Oxidation; Particle size; Plasma; Protective coatings; Raw materials; Scanning electron microscopy; Self healing materials; Shock tests; Thermal barrier coatings; Thermal cycling; Thermal fatigue; Thermal resistance; Thermal shock; United Kingdom > UK; United States > US; Switzerland; Japan; Germany
• ISSN: 2079-6412; 2079-6412
• DOI: 10.3390/coatings9060358

In this work, a novel thermal barrier coating (TBC) system is proposed that embeds silicon particles in coating as a crack-healing agent. The healing agent is encapsulated to avoid unintended reactions and premature oxidation. Thermal durability of the developed TBCs is evaluated through cyclic thermal fatigue and jet engine thermal shock tests. Moreover, artificial cracks are introduced into the buffer layer’s cross section using a microhardness indentation method. Then, the indented TBC specimens are subject to heat treatment to investigate their crack-resisting behavior in detail. The TBC specimens with the embedded healing agents exhibit a relatively better thermal fatigue resistance than the conventional TBCs. The encapsulated healing agent protects rapid large crack openings under thermal shock conditions. Different crack-resisting behaviors and mechanisms are proposed depending on the embedding healing agents.