Deposition of Cr-modified silicide coatings on Nb–Si system intermetallics

In order to improve the oxidation resistance of Nb–Si system intermetallics, silicide was deposited on the substrate by molten salt or by pack cementation, and Cr was deposited by pack cementation. Phase and microstructure were observed by scanning electro microscope (SEM), X-ray diffraction (XRD) and energy diffusion spectrum (EDS). It was found that phases of NbSi2, CrSi2, Cr2Nb were formed. The result showed that the high temperature oxidation resistance of the Nb–Si system intermetallics will be improved by applying the Cr doped Si coatings. Maybe it was attributed by the formation of SiO2 and Cr2O3 which could prevent the penetration of oxygen into the inner coatings and the substrate.