Fenomenos de difusion termica combinados con procesos de vaporizacion en reacciones metal liquido-gas

For studying the reactions of liquid drops of Fe-Sn and Fe-Si alloys and pure iron drops with reactive gases such as H₂S-H₂-Ar mixtures with different P_H(2)S/P_H(2) ratios, the levitation melting technique was employed. It was concluded that the adsorption of sulfur by pure iron drops is controlled by the H₂S diffusion through the gaseous boundary surrounding the drop. With regard to the alloys, the formation of volatile species like SnS_(g) and SiS_(g), was verified. Besides, it was thermodynamically predicted that silicon increases the vapor pressure of SnS_(g) and it is concluded that the formation of this sulfide is rate controlled by the H₂S diffusion and a corresponding counterdiffusion of SnS_(g) through the gaseous boundary layer. The results indicate that there is the possibility for a mutual refining of Sn and S assisted by silicon alloying. Finally, it was shown that the levitation melting technique is suitable for the fundamental study of thermal diffusion phenomena during liquid metal-gas reactions under extreme temperature gradiente conditions.