Surface alloying of Si into AISI 304L austenitic stainless steel (SS) and CK10 structural steel to increase their corrosion and acid resistance was attempted by employing pack cementation process. The process parameters, i.e. time and powder mixture, were considered for optimization of case depth, surface quality and the hardness profile by Taguchi approach. The coating was carried out at 850, 950 and 1050?C for 2, 5 and 10 hours in several powder mixtures of Si, Al 2 O 3 and NH 4 Cl halide activator. The coatings were characterized by means of standard metallography, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction methods and corrosion tests. The experimental results showed that Si in the coatings mainly present in the form of secondary phase including Fe 3 Si and Fe 5 Si 3. Compositional and structural analyses showed that the coating was adherent, porous and had ~8-23wt.% Si. Both the coating and substrate near the coating /substrate interface were turned into layered structure and the structure of substrate was remained face-centered cubic while coating was turned to body-centered cubic. Tests result showed that siliconization treatment improves acid resistance for CK10 but has not significant effect on 304L SS. Keywords: ck10 ; AISI 304L stainless steel; siliconizing; pack cementation; acid resistance
