5 results about "Unidirectional solidification" patented technology

This silicon ingot 10 has a unidirectionally solidified structure. The silicon ingot is characterized in that, in a cross-section that is orthogonal to the solidification direction, a single crystal region 11 is formed at a center part, and a coincidence boundary region 12 that comprises a plurality of crystal grains and has a ratio of coincidence boundary length to total grain boundary length of at least 80% is formed on the outer circumferential side of the single crystal region 11. The area fraction of the single crystal region 11 in a cross-section that is orthogonal to the solidification direction is preferably at least 25%.

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 is composed of a one-way solidification structure, and the number density of heterogeneous inclusions with the circle equivalent diameter being 3 micrometers or above is smaller than 0.01 / cm < 2 >. In the crucible (20) for silicon ingot production, slurry layers (23) comprising fine silica powder having an average particle diameter of 1 [mu] m to 200 [mu] m and colloidal silica, and plaster layers (24) comprising coarse silica powder having an average particle diameter of 100 [mu] m to 1000 [mu] m are alternately laminated in the thickness direction on the inner surface of a mold (21). The innermost layer in contact with the silicon ingot is a slurry layer (23), and the total number of layers of the slurry layer (23) and the plaster layer (24) after lamination is 6 or more.

To provide a silicon ingot capable of using as a material of a silicon member capable of achieving a long life by suppressing a generation of a local corrosion even in a case of using under a corrosion environment.SOLUTION: A silicon ingot 10 composed of a unidirectional solidification structure has a single crystal region 11 in a center part on a cross-sectional plane orthogonal to a solidification direction. In an outer peripheral side of the single crystal region 11, a corresponding grain boundary region 12 which is constituted with multiple crystal grains and of which a corresponding grain boundary length ratio to a total crystal grain length is 80% or more is formed. In a cross-sectional plane orthogonal to a solidification direction, an area ratio of the single crystal region 11 preferably is 25% or more.SELECTED DRAWING: Figure 1

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.