Protecting the MoSi2 healing particles for thermal barrier coatings using a sol-gel produced Al2O3 coating |
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| Authors: | AL Carabat MJ Meijerink JC Brouwer EM Kelder JR van Ommen S van der Zwaag WG Sloof |
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| Affiliation: | 1. Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands;2. Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands;3. Department of Chemical Engineering, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands;4. Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, The Netherlands |
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| Abstract: | A successful sol-gel process to encapsulate molybdenum di-silicide MoSi2 particles with a closed and thermally stable Al2O3 layer using aluminium tri-sec-butoxide as a precursor is presented. The processing conditions such as precursor selection and temperature were optimized through analysing the interaction of the MoSi2 particles with the sol. The application of the sol-gel based coating was followed by calcining the coated particles at temperatures between 900 and 1200?°C in Ar. The shell composition and the mechanical stability of the microcapsule were analysed by means of X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. Upon calcining at 1200?°C in Ar, the MoSi2 core remains intact as it is, covered by an α - alumina shell with a thickness of about 0.6?μm. The stability tests proved that the encapsulate particles are about five times more oxidation resistant than the uncoated MoSi2 particles. |
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| Keywords: | Self-healing thermal barrier coatings Alumina shell Sol-gel |
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