Oxidation behaviour of a fluorinated beta-stabilized γ-TiAl alloy with thermal barrier coatings in H_2O- and SO_2-containing atmospheres

摘要

The oxidation behaviour of a novel thermal barrier coating (TBC) system on a β-stabilized TiAl alloy was investigated at 900 ℃ in air containing water vapour and sulphur dioxide. This recently developed system consists of a 7 wt.% yttria partially stabilized zirconia topcoat deposited on fluorine-treated and pre-oxidized TNM-B1 substrate material. During thermal cycling at 900 ℃ in atmospheres containing either 10vol.% H_2O or 0.5vol.% SO_2, no spallation of the TBCs was observed for exposure periods exceeding 1000 cycles of 1 h dwell time. Fluorinated samples without TBCs showed similar oxidation behaviour, whereas the untreated TNM-B1 alloy revealed significant oxidation.