Abstract: Methods of additive manufacturing, binder compositions for additive manufacturing, and articles produced by and/or associated with methods of additive manufacturing are generally described.

Abstract: A metering apparatus and corresponding method meter a powder material in a three-dimensional (3D) printing system. The metering apparatus comprises a hopper with walls configured to contain a powder material, a metering roller, and a tool. The metering roller is located beneath an opening of the hopper. The metering roller and a given wall of the walls of the hopper are spaced apart by a gap therebetween at the opening; the gap in combination with rotation of the metering roller causes the powder material to flow from under the given wall of the hopper at a substantially predictable rate. The tool is positioned at the given wall where the flow emerges and is configured to force the powder material off of the metering roller to supply the 3D printing system with the powder material for printing a 3D object.

Abstract: Techniques for depowdering additively fabricated parts are described. The techniques utilize various mechanisms to separate powder from parts. For instance, techniques for depowdering described herein may include fabrication of auxiliary structures in addition to fabrication of parts. Certain auxiliary structures may aid with depowdering operations, and may be fabricated along with parts during an additive fabrication process. The auxiliary structures may be shaped and/or have positional and/or geometrical relationships to the parts during fabrication. For instance, an auxiliary structure may include a cage structure fabricated around one or more parts.

Abstract: Techniques for depowdering in additive fabrication are provided. According to some aspects, techniques are provided that separate powder from parts through vibration of the powder, the parts, and/or structures mechanically connected to the powder and/or parts. For instance, the application of vibration may dislodge, aerate and/or otherwise increase the flowability of regions of the powder, thereby making it easier to remove the powder with a suitable means. Techniques for depowdering through vibration may be automated, thereby mitigating challenges associated with manual depowdering operations.

Abstract: A method is provided for printing a three-dimensional object. The method comprises, depositing a layer of metal powder onto a powder bed of a three-dimensional printer. A liquid is heated to generate a vapor. The liquid is removed from the vapor to dry the vapor by heating the vapor above a condensation temperature of the liquid. The dry vapor is deposited onto the powder bed of the three-dimensional printer.

Abstract: Techniques for depowdering additively fabricated parts are described in which powder is separated from parts by creating a large pressure differential between the powder and parts and a nearby location. The pressure differential may cause gas to quickly flow into and/or around the powder and parts, thereby producing a force against the powder and parts. Since the powder is generally much lighter than the parts, this force may be much more effective at moving the powder than moving the parts. As a result, the powder and parts may be separated from one another. The pressure differential may be created in various ways, such as by holding the parts and part in a chamber that is pressurized with air and/or other gas(es). Rapid depressurization of the chamber may produce the aforementioned pressure differential, leading to powder movement away from the parts.

Abstract: Techniques for depowdering additively fabricated parts are described in which powder is separated from parts by creating a large pressure differential between the powder and parts and a nearby location. The pressure differential may cause gas to quickly flow into and/or around the powder and parts, thereby producing a force against the powder and parts. Since the powder is generally much lighter than the parts, this force may be much more effective at moving the powder than moving the parts. As a result, the powder and parts may be separated from one another. The pressure differential may be created in various ways, such as by holding the parts and part in a chamber that is pressurized with air and/or other gas(es). Rapid depressurization of the chamber may produce the aforementioned pressure differential, leading to powder movement away from the parts.

Abstract: A furnace may include an outer wall defining a chamber, the chamber including an internal cavity configured to receive one or more parts, at least one heater positioned within the chamber, the at least one heater being configured to generate temperatures of at least about 800 degrees Celsius within the internal cavity, and a vacuum pump configured to apply a vacuum to at least a portion of the chamber. The furnace may also include at least one layer of inner insulation and at least one layer of outer insulation disposed outward of the inner insulation with respect to the chamber, the at least one layer of outer insulation being sealed with respect to the at least one layer of inner insulation.

Abstract: Techniques for depowdering additively fabricated parts are described in which powder is separated from parts by creating a large pressure differential between the powder and parts and a nearby location. The pressure differential may cause gas to quickly flow into and/or around the powder and parts, thereby producing a force against the powder and parts. Since the powder is generally much lighter than the parts, this force may be much more effective at moving the powder than moving the parts. As a result, the powder and parts may be separated from one another. The pressure differential may be created in various ways, such as by holding the parts and part in a chamber that is pressurized with air and/or other gas(es). Rapid depressurization of the chamber may produce the aforementioned pressure differential, leading to powder movement away from the parts.

Abstract: Techniques for depowdering additively fabricated parts are described. The techniques utilize various mechanisms to separate powder from parts. For instance, techniques for depowdering described herein may include fabrication of auxiliary structures in addition to fabrication of parts. Certain auxiliary structures may aid with depowdering operations, and may be fabricated along with parts during an additive fabrication process. The auxiliary structures may be shaped and/or have positional and/or geometrical relationships to the parts during fabrication. For instance, an auxiliary structure may include a cage structure fabricated around one or more parts.

Abstract: A system and corresponding method for additive manufacturing of a three-dimensional (3D) object to improve packing density of a powder bed used in the manufacturing process. The system and corresponding method enable higher density packing of the powder. Such higher density packing leads to better mechanical interlocking of particles, leading to lower sintering temperatures and reduced deformation of the 3D object during sintering. An embodiment of the system comprises means for adjusting a volume of a powder metered onto a top surface of the powder bed to produce an adjusted metered volume and means for spreading the adjusted metered volume to produce a smooth volume for forming a smooth layer of the powder with controlled packing density across the top surface of the powder bed. The controlled packing density enables uniform shrinkage, without warping, of the 3D object during sintering to produce higher quality 3D printed objects.

Abstract: Methods of additive manufacturing, binder compositions for additive manufacturing, and articles produced by and/or associated with methods of additive manufacturing are generally described.

Abstract: A system and corresponding method for additive manufacturing of a three-dimensional (3D) object to improve packing density of a powder bed used in the manufacturing process. The system and corresponding method enable higher density packing of the powder. Such higher density packing leads to better mechanical interlocking of particles, leading to lower sintering temperatures and reduced deformation of the 3D object during sintering. An embodiment of the system comprises means for adjusting a volume of a powder metered onto a top surface of the powder bed to produce an adjusted metered volume and means for spreading the adjusted metered volume to produce a smooth volume for forming a smooth layer of the powder with controlled packing density across the top surface of the powder bed. The controlled packing density enables uniform shrinkage, without warping, of the 3D object during sintering to produce higher quality 3D printed objects.

Abstract: Techniques for depowdering in additive fabrication are provided. According to some aspects, techniques are provided that separate powder from parts through vibration of the powder, the parts, and/or structures mechanically connected to the powder and/or parts. For instance, the application of vibration may dislodge, aerate and/or otherwise increase the flowability of regions of the powder, thereby making it easier to remove the powder with a suitable means. Techniques for depowdering through vibration may be automated, thereby mitigating challenges associated with manual depowdering operations.

Abstract: Methods of additive manufacturing, binder compositions for additive manufacturing, and articles produced by and/or associated with methods of additive manufacturing are generally described.

Abstract: A method is provided for printing a three-dimensional object. The method comprises, depositing a layer of metal powder onto a powder bed of a three-dimensional printer. A liquid is heated to generate a vapor. The liquid is removed from the vapor to dry the vapor by heating the vapor above a condensation temperature of the liquid. The dry vapor is deposited onto the powder bed of the three-dimensional printer.

Abstract: A semiconductor wafer forms on a mold containing a dopant. The dopant dopes a melt region adjacent the mold. There, dopant concentration is higher than in the melt bulk. A wafer starts solidifying. Dopant diffuses poorly in solid semiconductor. After a wafer starts solidifying, dopant can not enter the melt. Afterwards, the concentration of dopant in the melt adjacent the wafer surface is less than what was present where the wafer began to form. New wafer regions grow from a melt region whose dopant concentration lessens over time. This establishes a dopant gradient in the wafer, with higher concentration adjacent the mold. The gradient can be tailored. A gradient gives rise to a field that can function as a drift or back surface field. Solar collectors can have open grid conductors and better optical reflectors on the back surface, made possible by the intrinsic back surface field.

Abstract: Embodiments related to systems and methods of crack detection in wafers (e.g., silicon wafers for photovoltaics, photovoltaic devices including silicon wafers) are disclosed. In some embodiments, an apparatus may include a light source configured to illuminate a side of a wafer and a camera directed towards a first face of the wafer. In some embodiments, a long axis of a field of view of the camera may be angled relative to a propagation direction of the light source. In some embodiments, at least a portion of the field of view of the camera is offset from the path of propagation of light emitted from the light source through the wafer. In some embodiments, at least a portion of a light beam may be oriented at a positive non-zero angle relative to the first face of the wafer, and a dimension of the light beam normal to the first face of the wafer may be larger than a thickness of the wafer.

Abstract: A furnace system includes a heating chamber, a retort assembly, and a waveguide. The heating chamber includes a shell encompassing an insulation layer and a working volume, where the working volume is configured to receive at least one part for heat treatment. The retort assembly is supported within the insulation layer and includes an inner retort surface facing the working volume. The inner retort surface is formed of at least one carbon compound reflective of microwave radiation, and the retort assembly defines a retort aperture. The waveguide is configured to direct microwave radiation from a microwave source to the retort aperture.

Abstract: A workpiece is transported using a porous belt, which belt delivers a workpiece to a chuck, upon which the workpiece is held by vacuum. The belt can be porous PTFE. A flexible stamp is preheated, before it is applied to a workpiece, by drawing the stamp toward a heated plate, for instance by vacuum.