Materials Science Forum, Vol.461-464, 305-312, 2004
High quality aluminide and thermal barrier coatings deposition for new and service exposed parts by CVD techniques
In this work, the performance of CVD aluminide coatings is compared to that of coatings deposited by the classical pack cementation technique using standard SIFCO procedures. The CVD coatings always seem to behave better upon exposure to isothermal and cyclic oxidation conditions. This is explained by a longer term stability of CVD, coatings, with higher Al amounts in the diffusion zone and less refractory element precipitation in the additive layer. The qualities of Pt/Al coatings by out-of-pack and CVD are also compared as a previous step for further thermal barrier coating deposition. As an example, YSZ thermal barrier coatings are deposited by MO-CVD, on Pt/Al CVD bond coats rendering adherent and thick coatings around the surface of turbine blades. This process under development does not require complex manipulation of the component to be coated.