Structure, microstructure and disorder in low temperature chemical vapor deposited SiC coatings

H. Plaisantin (1) , J. Danet (1) , I. Berdoyes (2) , G. Laduye (3) , A. Desenfant (4) , Georges Chollon (1)

1 LCTS - Laboratoire des Composites Thermostructuraux
2 Dassault Aviation
3 Campus Innovation Paris - Air Liquide Santé International [Jouy-en-Josas, France]
4 ArianeGroup

Chemical vapor deposited SiC coatings were investigated at different scales by X-Ray diffraction, Raman microspectroscopy and transmission electron microscopy. They were prepared under specific conditions explaining the various (micro)structures obtained. The deposits all have a columnar morphology with a preferential orientation and a faulted cubic structure. They differ in how disorder is incorporated in the structure. Fine XRD analyses and stacking fault density assessment by TEM revealed the one-dimensionally-disordered (ODD) polytype in the < 111 > textured coatings. The frequency and spatial distribution of stacking faults vary and sometimes locally generate periodic alpha sequences. A specific type of disorder was also identified where {111} planes are arranged parallel to the growth direction within the columns. These disorders, more energetic than stacking faults, induce multiple and particularly large Raman modes. Crystal distortions, such as dislocations, are localized at the ODD domain boundaries, which are frequently interrupted as they extend during the growth.

Keywords: Silicon carbide; Chemical vapor deposition; Structure; Raman spectroscopy; Transmission electron microscopy

Domains: Material chemistry

H. Plaisantin, J. Danet, I. Berdoyes, G. Laduye, A. Desenfant, et al.. Structure, microstructure and disorder in low temperature chemical vapor deposited SiC coatings. Journal of the European Ceramic Society, In press, 43 (9), pp.3917-3930. ⟨10.1016/j.jeurceramsoc.2023.02.067⟩. ⟨hal-04049617⟩