Print Email Facebook Twitter Mo(AlxSi1−x)2 healing particles for high temperature ceramics and encapsulation by selective oxidation of aluminium Title Mo(AlxSi1−x)2 healing particles for high temperature ceramics and encapsulation by selective oxidation of aluminium Author Ding, Z. (TU Delft Team Marcel Hermans) Brouwer, J.C. (TU Delft Team Marcel Hermans) Kwakernaak, C. (TU Delft Team Maria Santofimia Navarro) Zhu, Jia-Ning (TU Delft Team Vera Popovich) Popovich, V. (TU Delft Team Vera Popovich) Hermans, M.J.M. (TU Delft Team Marcel Hermans) Sloof, W.G. (TU Delft Team Joris Dik) Date 2023 Abstract To prevent premature triggering of the healing reaction in Mo-Si containing self-healing thermal barrier coating system, an oxygen impenetrable shell (α-Al2O3) around the sacrificial healing particles (MoSi2) is desired. Here an encapsulation method is presented through selective oxidation of Al in Mo(AlxSi1-x)2 particles. Healing particles of Mo(AlxSi1-x)2 is designed in terms of alumina shell thickness, particle size and fraction Al dissolved. By replacing Si by Al in MoSi2 up to the maximum solubility (x = 0.65) a strong crack healing ability is maintained (relative volume expansion ≥ 40 %). The formed exclusive α-Al2O3, featuring a two-layered structure, results from a counter-diffusion process along the grain boundaries, and its oxidation kinetics fits well with the 3D diffusion-Jander model. After 16 h exposure in gaseous ambient with a pO2 of 5 × 10-10 atm. at 1100 °C, a closed and dense shell of α-Al2O3 is formed with a thickness of about 1.3 µm. The oxide shell produced under this condition provided healing particles with significantly improved stability upon exposure to high pO2 of 0.2 atm. at 1100 °C for 50 h. The particles after exposure feature an inner core of MoSi2 with Al completely consumed and an oxide shell of α-Al2O3. Subject Alumina scale growthEncapsulationMo(Al,Si)OxidationSelf-healing thermal barrier coatings To reference this document use: http://resolver.tudelft.nl/uuid:f4769729-0d99-4cf6-88d6-81e93809358d DOI https://doi.org/10.1016/j.matdes.2022.111577 ISSN 0264-1275 Source Materials & Design, 225 Part of collection Institutional Repository Document type journal article Rights © 2023 Z. Ding, J.C. Brouwer, C. Kwakernaak, Jia-Ning Zhu, V. Popovich, M.J.M. Hermans, W.G. Sloof Files PDF 1_s2.0_S026412752201200X_main.pdf 6.08 MB Close viewer /islandora/object/uuid:f4769729-0d99-4cf6-88d6-81e93809358d/datastream/OBJ/view