Synthesis of simple and platinum-modified aluminide coatings on cobalt (Co)-base superalloys via a vapor phase aluminizing process

An investigation was conducted to synthesize simple β-CoAl or β-(Co,Ni)Al coatings and platinum (Pt)-modified aluminide coatings on cobalt-base superalloys via an industrial vapor phase aluminizing process. Surface morphology and cross-section microstructure of the developed coatings were studied and compared by using optical microscope, scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Experimental results showed that Al increase in Al–Cr nuggets increases the coating thickness; substrate elements influence the formation of coatings; the increase of the electrodeposited Pt thickness increases the amount of ξ-PtAl2 phase after aluminizing process; and the transformation of ξ-PtAl2 phase into β-(Co,Ni,Pt)Al phase can be obtained via a heat treatment process.