Premium
Influence of water vapour on the oxidation behaviour of a conventional aluminide and a new thermal barrier coating system sintered from a slurry
Author(s) -
Brossard M.,
Bouchaud B.,
Pedraza F.
Publication year - 2014
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201307106
Subject(s) - aluminide , water vapor , materials science , coating , oxide , thermal barrier coating , chromia , chemical engineering , isothermal process , slurry , sintering , relative humidity , metallurgy , composite material , alloy , intermetallic , chemistry , organic chemistry , thermodynamics , physics , engineering
In this work, the effect of water vapour on a new thermal barrier coating system synthesised from a slurry containing Al microparticles was studied under isothermal regime at 1100 °C for short oxidation times (50 h). Both dry air and argon gas atmospheres were investigated with increasing water vapour contents (0, 5, 10% RH, relative humidity) and the oxidation mechanisms and growth kinetics of the oxide scales were compared to conventional aluminide coatings up to 50% RH. The phase transformations occurring in the coating were characterised by local Raman micro‐spectrometry with complementary analytical techniques (X‐ray diffraction and FEG‐ESEM/EDS). The results demonstrated that water vapour does not exert a great influence on the oxidation of this type of coatings once an α‐Al 2 O 3 scale is stabilised after an appropriate sintering of the coating. In contrast the combined effect of water vapour and oxidation onto oxide scales grown from raw aluminide coatings was shown to trigger delayed transformation of θ into α‐Al 2 O 3 , the appearance of pores and spallation, in particular in air + x %RH.