2 results about "Unidirectional solidification" patented technology

This invention relates to a method for obtaining purified silicon metal, the method comprising the steps of: providing liquid silicon in a crystallization mold, wherein the crystallization mold includes a wall lined with a crucible; solidifying the liquid silicon by unidirectional solidification from the crucible-lined wall of the mold while stirring the liquid silicon by means of electromagnetic stirring (EMS); stopping the unidirectional solidification when a certain percentage of the liquid silicon has solidified; and pouring out excess liquid silicon; wherein the step of pouring out excess unsolidified liquid silicon comprises the steps of: inverting and tilting the crystallization mold under electromagnetic stirring (EMS); and emptying the excess unsolidified liquid silicon from the crystallization mold by turning off the electromagnetic stirring (EMS). The invention also relates to an apparatus comprising: a crystallization mold; an electromagnetic stirrer; and a pouring mechanism. Finally, the invention describes the use of the apparatus in a method for obtaining purified silicon metal.

The silicon ingot (10) is composed of a unidirectionally solidified structure, has a circular cross-section orthogonal to the solidification direction, has a number density of heterogeneous inclusions having an equivalent circle diameter of 3 [mu] m or more of less than 0.01 inclusions / cm2, and has, in the cross-section orthogonal to the solidification direction, a single crystal section (11) composed of a single crystal and a polycrystal section (12) composed of a plurality of crystal grains formed around the single crystal section (11). The area ratio of the single crystal part (11) is 25% or more.