Abstract
Thermal growth oxide (TGO) leads to final failure of thermal barrier coatings (TBC) under elevated temperature operation. Researchers have considered preparing different kinds of oxidation barrier coatings for suppressing TGO growth. TiC-based self-healing coatings are one type of possible oxidation barrier coatings for TBC lifetime improvement. According to previous work and recent results, 20-wt% TiC, 40-wt% Al2O3 and 40-wt% YSZ composite self-healing coating (TAZ20) exhibited sealing and filling effects in normal atmosphere above 650 °C. Image analysis and hot corrosion tests both showed that sealing and filling effects led to porosity decline and that even melted hot corrosion salts could not penetrate healed coatings. Then, three types of TiC-based self-healing TBC and traditional TBC were prepared and their oxidation resistance at 1100 °C investigated. The results showed that the TAZ20 coatings in different structural strategies were related to different oxidation resistance. TAZ20 coatings made the protective oxidation process last longer but did not avoid the breakaway oxidation process. The TAZ20/YSZ/TAZ20 structural TBC showed the best oxidation resistance, which reduced TGO by ~50% after 20 h of high temperature oxidation. According to thermal cyclic tests, this enhanced oxidation resistance improved TBC lifetime. The lifetime of TAZ20/YSZ/TAZ20 structural TBC was ~180% that of traditional TBC. In sum, these TiC-self-healing coatings appeared very promising potential and involved a cost-effective method to protect TBC against TGO failure.
Published Version
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