Details

Autor(en) / Beteiligte

• des Ligneris, Elise
• Samélor, Diane
• Vergnes, Hugues
• Sekkat, Abderrahime
• Josse, Claudie
• Le Blond du Plouy, Stéphane
• Pugliara, Alessandro
• Descamps-Mandine, Armel
• Ledeuil, Jean-Bernard
• Vahlas, Constantin
• Caussat, Brigitte

Titel

Amorphous Alumina Thin Films Deposited on Carbon Microfibers As Interface Layer for Thermal Oxidation Barriers

Ist Teil von

• ACS Applied Engineering Materials, 2023-10, Vol.1 (10), p.2707-2722

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Carbon microfibers make a promising candidate as textile reinforcement for high temperature composites provided that their limitation of thermal oxidation over 670 K in air is overcome. As such, this study explored the potential of atomic layer deposition (ALD) for the deposition of a substrate-nanolaminate interface layer for the design of a refractory oxygen barrier coating applied to individual carbon microfibers within a woven fabric. To this end, amorphous aluminum hydroxide was deposited at 350 K in a flow-type thermal ALD reactor operating at a pressure of 1.8 Torr, yielding a growth per cycle (GPC) of 1.0 Å/cycle. The conformal aspect of the amorphous films was found to be well preserved below a thickness of 45 ± 5 nm, above which reorganization of the substrate surface by junction of the previously deposited layers resulted in a uniform deposition. Furthermore, a minimal thickness of 20 ± 2 nm was required to obtain self-standing films following the thermal oxidation of the carbon microfibers. Indeed, thermal treatment at 1380 K of the coated woven fabric induced multiple occurrences of neat cracks in the aluminum oxide films, attributed to the increased rigidity and mismatch between the respective thermal expansion coefficients. The dense network of nanograins of aluminum oxide was further characterized by using 4D-STEM, revealing multiple phases and orientations.