Detection of breakaway oxidation with Acoustic Emission during titanium oxide scale growth
Résumé
Extensive in-situ analysis of high temperature breakaway oxidation of titanium metal has been performed using the Acoustic Emission (AE) technique. Depending on temperature and oxidising atmosphere, different model cases were examined: with breakaway (900 degrees C/O-2), without breakaway (750 degrees C/O-2 and 900 degrees C/H2O). Two specific population of AE hits were observed before and after breakaway. Contrary to the pre-breakaway population, the post-breakaway population exhibited low AE activity characterised by high values of energy. A critical energy value of E = 3 fj was determined as a frontier between signals resulting from oxide parabolic growth and signals resulting from rapid linear growth.