Abstract: A method and apparatus for refining metallurgical silicon to produce solar grade silicon for use in photovoltaic cells. A crucible in a vacuum furnace receives a mixture of metallurgical silicon and a reducing agent such as calcium disilicide. The mix is melted in non-oxidizing conditions within the furnace under an argon partial pressure. After melting, the argon partial pressure is decreased to produce boiling and the process ends with directional solidification. The process reduces impurities, such as phosphorus, to a level compatible with solar-grade silicon and reduces other impurities significantly.

Abstract: To reduce the heat input to the bottom of the crucible and to control heat extraction independently of heat input, a shield can be raised between a heating element and a crucible at a controlled speed as the crystal grows. Other steps could include moving the crucible, but this process can avoid having to move the crucible. A temperature gradient is produced by shielding only a portion of the heating element; for example, the bottom portion of a cylindrical element can be shielded to cause heat transfer to be less in the bottom of the crucible than at the top, thereby causing a stabilizing temperature gradient in the crucible.

Abstract: To reduce the heat input to the bottom of the crucible and to control heat extraction independently of heat input, a shield can be raised between a heating element and a crucible at a controlled speed as the crystal grows. Other steps could include moving the crucible, but this process can avoid having to move the crucible. A temperature gradient is produced by shielding only a portion of the heating element; for example, the bottom portion of a cylindrical element can be shielded to cause heat transfer to be less in the bottom of the crucible than at the top, thereby causing a stabilizing temperature gradient in the crucible.

Abstract: A silicon nitride crucible is coated with a crucible release coating for use in directional solidification of multicrystalline silicon ingots. The crucible preferably includes reaction bonded silicon nitride crucible. After removing the silicon ingot, the release coating is easily removed and the crucible can be repeatedly recoated and reused.

Abstract: A cutting machine has a blade mounted for reciprocating movement. A workpiece is rotated while the blade is reciprocated, and then the workpiece is rotated through smaller angles to complete the cut. A holder is attached to partially cut slices of the workpiece.

Abstract: An apparatus for purifying metallurgical grade silicon to produce solar grade silicon has a container for holding molten silicon and one or more torches for providing oxygen and hydrogen gas to heat the molten silicon so that the reaction time is prolonged, to create turbulence, and to introduce silica powder and water vapor for reactions with molten silicon. The molten silicon is then directionally solidified.

Abstract: An apparatus for purifying metallurgical grade silicon to produce solar grade silicon has a container for holding molten silicon and one or more submergible torches for providing a flame surrounded by inert gas to heat the molten silicon so that the reaction time is prolonged, to create turbulence, and to introduce silica powder and water vapor for reactions with molten silicon. The molten silicon is then directionally solidified by providing the container in a coolant tank and controlling the coolant level with controllable valves so that further purification is achieved by segregating impurities.

Abstract: A radial cut profile is achieved while advancing a workpiece at a substantially constant rate in a direction towards a cutting blade by moving the workpiece vertically relative to the blade in synchronization with the oscillation of the workpiece. The vertical movement is provided by a linkage including two links pivotally connected to each other. The other end of one link is pivotally connected to the feed mechanism. The other end of the other link is fixed relative to the oscillating workpiece.

Abstract: A cutting blade the core of which is generally tear-drop shaped in cross-section. The sides of the tear-drop shaped core form an included angle of not less than about 5 degrees (and typically not less than about 9 degrees), and abrasive is provided essentially on only the wide bottom surface of the core.

Abstract: A high temperature heat exchanger is used with the Czochralski crystal growing method to control the heat extraction from crystal silicon ingots as they are grown. The high temperature heat exchanger also acts as a shaping die so that silicon bars, or ingots, of various shapes, including square, circular, rectangular or ribbon, can be produced by shaping during the growth stage.

Abstract: A wafering machine having a multiplicity of wire cutting blades supported by a bladehead reciprocally moving past a workpiece supported by a holder that rocks about an axis perpendicular to the wires at a frequency less than the reciprocation of the bladehead.

Abstract: A wafering machine having a multiplicity of wire cutting blades supported by a bladehead reciprocally moving past a workpiece supported by a holder that rocks about an axis perpendicular to the wires at a frequency less than the reciprocation of the bladehead.

Abstract: A narrow wire blade with abrasive particles plated within a longitudinally-extending, plated cutting portion that extends from only one side of a wire core and has parallel side walls spaced by a controlled width.

Abstract: Making a wire pack in which a plurality of wires of predetermined length extend between a pair of spaced supports by wrapping turns of wire in a helix around a cylindrical roll while maintaining a constant tension on the wire, placing the supports in position adjacent but spaced from each other and extending axially of the roll and clamping the wire to the supports, and then cutting the wire segments extending between the adjacent supports.

Abstract: A cutting process in which a blade under tension is moved relative to a workpiece. The blade has a longitudinally-extending abrasive-holding portion defined by blade material that is softer than the workpiece to be cut and overlies a high tensile strength core. The abrasive-holding portion defines a cutting surface extending between opposite sides of the blade and defining less than one-half the total outer surface of the blade, and abrasive particles are partially embedded into a longitudinally-extending segment of the cutting surface but not into the sides of the blade.

Abstract: In the growing of crystals, the formation of carbide contaminants is prevented by eliminating direct silica-graphite contact.

Abstract: Making a wire pack in which a plurality of wires of predetermined length extend between a pair of spaced supports by wrapping turns of wire in a helix around a cylindrical roll while maintaining a constant tension on the wire, placing the supports in position adjacent but spaced from each other and extending axially of the roll and clamping the wire to the supports, and then cutting the wire segments extending between the adjacent supports.

Abstract: Ingots are cast in silica containers in which the interior surface of the container is defined by a thin skin of high density glass behind which the silica wall varies in density and cristobalite phase content.

Abstract: A cutting process in which a blade under tension is moved relative to a workpiece. The blade has a longitudinally-extending abrasive-holding portion defined by blade material that is softer than the workpiece to be cut and overlies a high tensile strength core. The abrasive-holding portion defines a cutting surface extending between opposite sides of the blade and defining less than one-half the total outer surface of the blade, and abrasive particles are partially embedded into a longitudinally-extending segment of the cutting surface but not into the sides of the blade.

Abstract: Making a wire pack in which a plurality of wires of predetermined length extend between a pair of spaced supports by wrapping turns of wire in a helix around a cylindrical roll while maintaining a constant tension on the wire, placing the supports in position adjacent but spaced from each other and extending axially of the roll and clamping the wire to the supports, and then cutting the wire segments extending between the adjacent supports.