6 The Sponge electrode is then positioned in a very vacuum arc furnace for melting. With this water-cooled, copper container, An electrical arc is used to soften the sponge electrode to type an ingot. In terms of its output, silicon is used mostly for a substrate to improve the graphene. https://jaidenabyup.blogstival.com/57470598/how-cupric-oxide-can-save-you-time-stress-and-money