DISSOLUTION OF 3D-METAL SILICIDES IN FLUORIDE-CONTAINING ELECTROLYTES

Using scanning electron microscopy combined with electron microprobe a nalysis, changes in the microstructure of iron, cobalt, and nickel sil icides of various compositions, after etching in 1 N H2SO4 that contai ns 50 - 100 mM of NaF were investigated. It is shown that corrosive F- ions attack a SiO2 protective film, which results in local Si dissolu tion in the superficial layers of intermetallic compounds. The resista nce of the silicides to H2SO4 increases with Si content (Me(2)Si < MeS i < MeSi(2)) and is also dependent on the metal type.