Abstract: Apparatus and methods for making metal-connected particle articles. A metal containing fluid is selectively applied to a layer of particles. The metal in the fluid is used to form metal connections between particles. The metal connections are formed at temperatures below the sintering temperature of the particles in the layer of particles.

Abstract: This disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and systems for three-dimensional printing. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and a detailing agent. The fusing agent can include water and metal oxide nanoparticles dispersed therein. The metal oxide nanoparticles can be selected from titanium dioxide, zinc oxide, cerium oxide, indium tin oxide, or a combination thereof. The metal oxide nanoparticles can have an average particle size from about 2 nm to about 500 nm. The detailing agent can include a detailing compound.

Abstract: A three-dimensional (3D) printing device includes a first cylinder. The first cylinder may include a first plurality of holes defined therein. The 3D printing device may include a second cylinder interior and coaxial to the first cylinder that includes a second plurality of holes open to an interior of the first cylinder. The 3D printing device may also include a third cylinder interior to the first cylinder and exterior to the second cylinder, the third cylinder including a longitudinal cutout open to the first cylinder. The 3D printing device may include a supply tube open to the second cylinder, the supply tube to provide an amount of build material to an interior portion of the second cylinder.

Abstract: According to examples, a three-dimensional (3D) fabrication system may include an agent delivery device, an energy generator, and a controller. The agent delivery device may selectively deposit an agent onto a layer of build material particles. In some examples, the agent may include a first substance and a second substance. The controller may control the energy generator to emit energy at selective levels. In some examples, the controller may determine a first energy level tuned to the first substance and a second energy level tuned to the second substance, and may control the energy generator to sequentially emit energy at the first energy level and at the second energy level onto the deposited agent and the layer of build material particles.

Abstract: Apparatus and methods for making metal-connected particle articles. A metal containing fluid is selectively applied to a layer of particles. The metal in the fluid is used to form metal connections between particles. The metal connections are formed at temperatures below the sintering temperature of the particles in the layer of particles.

Abstract: An example of an ultraviolet (UV) light fusing agent for three-dimensional (3D) printing includes a vehicle and a multi-functional antioxidant and UV light absorber dispersed in the vehicle. The vehicle includes water and a water miscible or water soluble organic solvent. The multi-functional antioxidant and UV light absorber includes a metal oxide particle that is to absorb UV radiation having a wavelength within a range from about 330 nm to about 405 nm and a passivating agent complexed with at least a portion of a surface of the metal oxide.

Abstract: In an example of a method for three-dimensional (3D) printing, one or more dispersions is/are sprayed to form a layer including build material particles and a liquid agent. The liquid agent is evaporated from the layer to form a build material layer, and based on a 3D object model, a binder agent is applied on at least a portion of the build material layer.

Abstract: According to examples, an apparatus includes a processor and a memory on which is stored machine readable instructions. The instructions may cause the processor to identify an intended surface property level for a surface of a three-dimensional (3D) object, determine an amount of radiation to be applied as a flash of radiation onto the surface to obtain the intended surface property level, and output the determined amount of radiation to be applied as a flash of radiation, in which a radiation source is to flash apply the determined amount of radiation onto the surface of the 3D object.

Abstract: Described herein are kits, methods, and systems for printing metal three-dimensional objects. In an example, described is a kit for three-dimensional printing comprising: powdered metal build material; and a binding fluid comprising a liquid vehicle, metal or metal precursor particles, and latex polymer particles dispersed in the liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm, and wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.

Abstract: Described herein are kits, methods, and systems for printing metal three-dimensional objects. In an example, described is a multi-fluid kit for three-dimensional printing comprising: a first fluid comprising a first liquid vehicle comprising metal or metal precursor particles; and a second fluid comprising a second liquid vehicle comprising latex polymer particles dispersed therein, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm, and wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.

Abstract: An example method for additive manufacturing of metals includes spreading a build material including a metal in a sequence of layers. Each layer has a respective thickness, a respective sequence position, and a respective exposed surface to receive radiated energy from a flood energy source prior to spreading of a subsequent layer. A energy function is determined based on the metal, the thickness, and the sequence position of an exposed layer. The energy function defines the radiated energy and includes an intensity profile and a fluence sufficient to cause a consolidating transformation of the build material in the exposed layer. The exposed surface of the exposed layer is exposed to the radiated energy from the flood energy source, causing the consolidating transformation of the build material in the exposed layer.

Abstract: According to an example, an apparatus may include a processor and a memory on which is stored instructions. The instructions may cause the processor to control at least one energy source to apply energy at a certain low energy level onto a layer of metallic particles, in which the metallic particles have micron-level dimensions, and in which application of the certain low energy level may sinter the metallic particles and may cause formation of physical connections between adjacent ones of the metallic particles. The instructions may also cause the processor to control the at least one energy source to apply energy at a certain high energy level onto the layer of metallic particles, in which application of the certain high energy level energy may melt and fuse the sintered metallic particles.

Abstract: An example method for additive manufacturing of metals includes spreading a build material including a metal in a sequence of layers. Each layer has a respective thickness, a respective sequence position, and a respective exposed surface to receive energy from a flood energy source prior to spreading of a subsequent layer. Each respective exposed surface has a surface area of at least 5 square centimeters (cm2). Layer-by-layer, the exposed surface of each layer is exposed to the radiated energy from the flood energy source. The energy is radiated at an intensity profile and a fluence sufficient to cause a consolidating transformation of the build material in the exposed layer.

Abstract: A three-dimensional (3D) printing device may include a pulsed electromagnetic radiation source; a build platform to maintain a number of layers of build material thereon and receive pulsed electromagnetic radiation from the pulsed electromagnetic radiation source; a micromirror array to selectively direct the pulsed electromagnetic radiation from the pulsed electromagnetic radiation source to the build material on the build platform; and a coolant tank with coolant therein to cool the micromirror array.

Abstract: Some examples include a method of producing a three-dimensional object including successively forming a plurality of layers within a print area. The successively forming the plurality of layers within the print area includes depositing a first material including first solid particles, selectively spraying a second material on the first material, the second material including second solid particles suspended in a liquid medium, wherein the first material has a different chemical composition than the second material, and applying fusing energy to the first material and the second material in each of the plurality of layers to form the three-dimensional object including a first region comprised of the first material, a second region comprised of the second material, and a transition region comprised of the first material and the second material extending between the first and second regions.

Abstract: According to examples, an apparatus includes a processor and a memory on which is stored machine readable instructions. The instructions may cause the processor to identify an intended surface property level for a surface of a three-dimensional (3D) object, determine an amount of radiation to be applied as a flash of radiation onto the surface to obtain the intended surface property level, and output the determined amount of radiation to be applied as a flash of radiation, in which a radiation source is to flash apply the determined amount of radiation onto the surface of the 3D object.

Abstract: In a three-dimensional printing method example, a metallic build material is applied. A positive masking agent is selectively applied on at least a portion of the metallic build material. The positive masking agent includes a radiation absorption amplifier that is compatible with the metallic build material. The metallic build material is exposed to radiation from a spatially broad, high energy light source to melt the portion of the metallic build material in contact with the positive masking agent to form a layer. The radiation absorption amplifier i) has an absorbance for the radiation that is higher than an absorbance for the radiation of the metallic build material, or ii) modifies a surface topography of the at least the portion of the metallic build material to reduce specular reflection of the radiation off of the at least the portion of the metallic build material, or both i) and ii).

Abstract: A three-dimensional (3D) printing device includes a first cylinder. The first cylinder may include a first plurality of holes defined therein. The 3D printing device may include a second cylinder interior and coaxial to the first cylinder that includes a second plurality of holes open to an interior of the first cylinder. The 3D printing device may also include a third cylinder interior to the first cylinder and exterior to the second cylinder, the third cylinder including a longitudinal cutout open to the first cylinder. The 3D printing device may include a supply tube open to the second cylinder, the supply tube to provide an amount of build material to an interior portion of the second cylinder.

Abstract: A powder bed material can include from 80 wt % to 100 wt % metal particles having a D50 particle size distribution value from 4 ?m to 150 ?m. From 10 wt % to 100 wt % of the metal particles can be surface-activated metal particles having in intact inner volume and an outer volume with structural defects. The structural defects can exhibit an average surface grain density of 50,000 to 5,000,000 per mm2.

Abstract: An in-situ monitoring device for selective laser melting (SLM) additive manufacturing may include at least one coherent electromagnetic wave source to produce a detection beam, an interferometer interposed between the electromagnetic wave source and a target detection area, a photodetector to detect displacement measuring interference between electromagnetic waves from the electromagnetic wave source and reflected electromagnetic waves from the target detection area through the interferometer, and control logic to cause the detection beam to follow a print path of a material forming laser at a distance behind the material forming laser. The detection beam is placed on a laser-melted and at least partially solidified portion of a layer of a three-dimensional (3D) object formed by the material forming laser.