Effect of NaCL Upon an AI-Si Casting Alloy Hipoeutec

Abstract

This work, comprehends the study about the effect of NaCl kind Halite upon the morphology of eutectic Silicon and porosity in a cast hipoeutectic Al-Si alloy. The melting was carried out in two furnaces, the first to combustion of LP gas in graphite crucible to increase the content of Si in the alloy from 0.13 to 5% wt using metallic silicon with a purity of 99.35% wt, and the second of electric resistances in the same kind of crucible to control the temperature at 750º C. The melting material was casting into molds of sand shell. To add the salt into 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% wt respectively, powdered and preheated at 150º C during 60 min. The obtained samples were analyzed metallographily evidencing the modification of the eutectic Si, presenting the best results the samples with 1.5&2.5% wt of salt added by gravity. Too was obtained effect of Salt upon the degassing of bath metallic, where the simples with 1.5% wt presented the best results. Finally, by means of Scanning Electron Microscopy, the precipitates present were characterized in the samples.