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HITHEX Résumé de rapport

Project ID: G5RD-CT-2000-00218
Financé au titre de: FP5-GROWTH
Pays: France

Multilayer CVD mullite coatings

IMP-CNRS prepared mullite coatings by low pressure CVD in a hot wall reactor on CMC (C/C-SiC) substrates in order to protect them again oxidation at high temperature. The CMC samples were small plates (7x7x3mm3) supplied by SKT and DLR. An experimental study of the deposition conditions was carried out in order to improve the resistance to high temperature air resistance of the coated samples.

The oxidation resistance of these coatings was tested by means thermo-gravimetric “in situ” measurements in the range 1350-1600°C. The cracks formation on the coatings during the cooling stage of the oxidation cycles result in weight losses due to the carbon combustion within the CMC samples.

Two layers coating made of an intermediate porous mullite layer and an outer dense mullite layer were tested seem to show some improvement. In addition, SiO2-rich mullite layers showed also encouraging results.

Reported by

Centre National de la Recherche Scientifique
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