Ingeniare. Revista chilena de ingeniería
versión On-line ISSN 0718-3305
MARTINEZ D, Enrique J; ORTEGA DE LA ROSA, Rubin y TORRES C, Gerardo. STUDY OF MODIFIER EFFECT OF SODIUM ARISING FROM NaCl UPON THE MORPHOLOGY OF SILICON IN AN HYPOEUTECTIC Al-Si ALLOY. Ingeniare. Rev. chil. ing. [online]. 2006, vol.14, n.3, pp.238-244. ISSN 0718-3305. http://dx.doi.org/10.4067/S0718-33052006000200007.
This work, comprehends a study about the effect of sodium obtained from NaCl (halita) upon the morphology of eutectic silicon in a cast hypoeutectic Al-Si alloy. The melting was carried out in two furnaces, the first was done using LP gas combustion with a graphite crucible for increasing the content of Si in the alloy from 0.13 to 5% wt, using metallic silicon with a purity of 99.35% wt. The second melting was done using electric resistances with the same kind of crucible to control the temperature at 750o C. The melting material was cast into molds of shell sand, to avoid sludge and interaction in the study areas. To add the salt to the metallic bath, two techniques were used; one with injection by means of argon gas and the other one by gravity. In both cases three quantities of salt were used, 0.5, 1.5 and 2.5% in weight respectively, powdered and preheated at 150o C during 60 min. The content of NaCl in the salt, 95% wt was determined by chemical analysis. The theoretical quantity of necessary salt was calculated with this data. The obtained samples were analyzed metallographically, evidencing the modification of the eutectic Si in the scale #2 at #4, in agreement with the literature, presenting the best results the samples with 1.5 & 2.5% wt of salt added by gravity. Finally, by means of scanning electron microscopy, the precipitate present was characterized in the samples.
Palabras clave : Na; modification; Al-Si; NaCl; solidification.