An apparatus to purify a melt is disclosed. A first portion of a melt in a chamber is frozen in a first direction. A fraction of the first portion is melted in the first direction. A second portion of the melt remains frozen. The melt flows from the chamber and the second portion is removed from the chamber. The freezing concentrates solutes in the melt and second portion. The second portion may be a slug with a high solute concentration. This system may be incorporated into a sheet forming apparatus with other components such as, for example, pumps, filters, or particle traps.

A cast work piece includes a cast metal component section and a sprue section connected to the cast metal component section. The cast metal component section and a portion of the sprue section have a first grain orientation and another portion of the sprue section has a second grain orientation such that there is a microstructural discontinuity where the first grain orientation meets the second grain orientation in the sprue section.

A cast work piece includes a cast metal component section and a sprue section connected to the cast metal component section. The cast metal component section and a portion of the sprue section have a first grain orientation and another portion of the sprue section has a second grain orientation such that there is a microstructural discontinuity where the first grain orientation meets the second grain orientation in the sprue section.

Disclosed is a preparation method of a polycrystalline silicon ingot. The preparation method comprises: providing a silicon nucleation layer at the bottom of a crucible, and filling a silicon material above the silicon nucleation layer; heating the silicon material to melt same, adjusting the thermal field inside the crucible to make the melted silicon material to start crystallization on the basis of the silicon nucleation layer; and when the crystallization is finished, performing annealing and cooling to obtain a polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot. Further disclosed are a polycrystalline silicon ingot obtained through the preparation method and a polycrystalline silicon wafer made using the polycrystalline silicon ingot as a raw material.

Disclosed is a preparation method of a polycrystalline silicon ingot. The preparation method comprises: providing a silicon nucleation layer at the bottom of a crucible, and filling a silicon material above the silicon nucleation layer; heating the silicon material to melt same, adjusting the thermal field inside the crucible to make the melted silicon material to start crystallization on the basis of the silicon nucleation layer; and when the crystallization is finished, performing annealing and cooling to obtain a polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot. Further disclosed are a polycrystalline silicon ingot obtained through the preparation method and a polycrystalline silicon wafer made using the polycrystalline silicon ingot as a raw material.

Disclosed is an electromagnetic casting method of polycrystalline silicon which is characterized in that polycrystalline silicon is continuously cast by charging silicon raw materials into a bottomless cold mold, melting the silicon raw materials using electromagnetic induction heating, and pulling down the molten silicon to solidify it, wherein the depth of solid-liquid interface before the start of the final solidification process is decreased by reducing a pull down rate of ingot in a final phase of steady-state casting. By adopting the method, the region of precipitation of foreign substances in the finally solidified portion of ingot can be reduced and cracking generation can be prevented upon production of a polycrystalline silicon as a substrate material for a solar cell.

Disclosed is an electromagnetic casting method of polycrystalline silicon which is characterized in that polycrystalline silicon is continuously cast by charging silicon raw materials into a bottomless cold mold, melting the silicon raw materials using electromagnetic induction heating, and pulling down the molten silicon to solidify it, wherein the depth of solid-liquid interface before the start of the final solidification process is decreased by reducing a pull down rate of ingot in a final phase of steady-state casting. By adopting the method, the region of precipitation of foreign substances in the finally solidified portion of ingot can be reduced and cracking generation can be prevented upon production of a polycrystalline silicon as a substrate material for a solar cell.

The present disclosure provides a polycrystalline silicon ingot, a polycrystalline silicon brick and a polycrystalline silicon wafer. The polycrystalline silicon ingot has a vertical direction and includes a nucleation promotion layer located at a bottom of the polycrystalline silicon ingot, and a plurality of silicon grains grown along the vertical direction, wherein the silicon grains include at least three crystal directions. The coefficient of variation of grain area in a section above the nucleation promotion layer of the polycrystalline silicon ingot increases along the vertical direction.

The present disclosure provides a polycrystalline silicon ingot, a polycrystalline silicon brick and a polycrystalline silicon wafer. The polycrystalline silicon ingot has a vertical direction and includes a nucleation promotion layer located at a bottom of the polycrystalline silicon ingot, and a plurality of silicon grains grown along the vertical direction, wherein the silicon grains include at least three crystal directions. The coefficient of variation of grain area in a section above the nucleation promotion layer of the polycrystalline silicon ingot increases along the vertical direction.

A method comprising introducing a first casting material into a casting mold; applying directional solidification to the first casting material in the casting mold; introducing a second casting material into the casting mold, the second casting material having a different chemical composition than the first casting material; applying directional solidification to the second casting material in the casting mold; and forming a molded article, wherein the molded article comprises a first region