한국주조공학회

Decarburization phenomena have been studied by plasma in stainless steel, plain carbon steel and cast iron. It was also investigated the movement of impurity element P,S in the plasma jet metal pool. The plasma jet was obtained by Ar-CO_2 gas mixture with 5 kVA DC power source. It produced enough temperature to dissociate into activated oxygen atom by reaction of $CO_2{leftrightarrows}CO+O^+ and it reacted with {underline{C}} in metal pool. Decarburization rate was increased about 5 times in comparing with the conventional induction melted metal pool by CO_2 gas decarburization. Even under the Ar plasma jet, decarburization was obtained by agitation of metal bath by Ar^+ bombardment and dilution phenomena of carbon atom under the very high plasma temperature. But heavy element P and S are not much removed because they are too heavy in mass to be activated by Ar^+ion bombardment. Desulphurization was achieved by Ar;- ;CO_2 plasma in plain carbon steel and cast iron by the reaction of SO_2({\underline{S}}+O^+). But dephosphorization could not be obtained by Ar-CO_2 plasma, because gaseous reaction of phosphorous oxide ({\underline{P}}+O^+) was not existed.