Three-dimensional printing

Abstract

An example of a kit for three-dimensional (3D) printing includes a host metal and fumed flow additive aggregates to be mixed with the host metal. The fumed flow additive aggregates include flow additive nanoparticles and partially fused necks between at least some of the flow additive nanoparticles. Each of the flow additive nanoparticles consists of a metal containing compound that is reducible to an elemental metal in a reducing environment at a reducing temperature less than or equal to a sintering temperature of the host metal.

What is claimed is: 
     
         1 . A kit for three-dimensional (3D) printing, comprising:
 a host metal; and   fumed flow additive aggregates to be mixed with the host metal, the fumed flow additive aggregates including flow additive nanoparticles and partially fused necks between at least some of the flow additive nanoparticles, each of the flow additive nanoparticles consisting of a metal containing compound that is reducible to an elemental metal in a reducing environment at a reducing temperature less than or equal to a sintering temperature of the host metal.   
     
     
         2 . The kit as defined in  claim 1  wherein the fumed flow additive aggregates have a surface area greater than 50 m 2 /g. 
     
     
         3 . The kit as defined in  claim 1  wherein the fumed flow additive aggregates have a surface area greater than 100 m 2 /g. 
     
     
         4 . The kit as defined in  claim 1  wherein:
 the average host metal particle size is less than 20 μm; and 
 the average flow additive nanoparticle size ranges from about 3 nm to about 200 nm. 
 
     
     
         5 . The kit as defined in  claim 1  wherein:
 the fumed flow additive aggregates, when mixed with the host metal, break into individual flow additive nanoparticles, aggregate fragments, or a combination thereof; and 
 the individual flow additive nanoparticles, the aggregate fragments, or the combination thereof become disposed on a surface of particles of the host metal. 
 
     
     
         6 . The kit as defined in  claim 1  wherein at least one of:
 the fumed flow additive aggregates have an average flow additive aggregate particle size ranging from about 50 nm to about 1000 μm; or 
 the fumed flow additive aggregates have meso-sized pores; or 
 the fumed flow additive aggregates have a density ranging from about 0.1% to 20% of a bulk density of a material of the flow additive nanoparticles. 
 
     
     
         7 . The kit as defined in  claim 1  wherein the metal containing compound is selected from the group consisting of vanadium oxides, chromium oxides, iron oxides, cobalt oxides, nickel oxides, manganese oxides, copper oxides, and mixed transition metal oxides. 
     
     
         8 . The kit as defined in  claim 1  wherein at least some of the fumed flow additive aggregates are agglomerated together. 
     
     
         9 . A method for making a build material composition for three-dimensional (3D) printing, comprising:
 spraying a precursor liquid into a combustion chamber, wherein the precursor liquid is exposed to an external flame or is ignited to generate a flame, whereby fumed flow additive aggregates are formed, the flow additive aggregates including flow additive nanoparticles and partially fused necks between at least some of the flow additive nanoparticles, each of the flow additive nanoparticles consisting of a metal containing compound that is reducible to an elemental metal in a reducing environment at a reducing temperature less than or equal to a sintering temperature of a host metal; and   mixing the fumed flow additive aggregates with the host metal;   wherein the flow additive nanoparticles have an average flow additive particle size ranging from about 1 to about 3 orders of magnitude smaller than an average host metal particle size of the host metal.   
     
     
         10 . The method as defined in  claim 9  wherein the precursor liquid includes a solvent and i) a precursor of a transition metal oxide selected from the group consisting of vanadium oxides, chromium oxides, iron oxides, cobalt oxides, nickel oxides, manganese oxides, and copper oxides, or ii) a precursor of a mixed transition metal oxide. 
     
     
         11 . The method as defined in  claim 10  wherein the precursor is a metal salt that is soluble in the solvent, the metal salt including:
 a cation selected from the group consisting of vanadium, chromium, iron, cobalt, nickel, manganese, and copper; and 
 an anion selected from the group consisting of nitrate, sulfate, halide, an organic carboxylate, and an alkoxide. 
 
     
     
         12 . The method as defined in  claim 10  wherein the precursor is present in the precursor liquid in an amount ranging from about 0.1 wt % to about 5 wt %, based on the total weight of the precursor liquid. 
     
     
         13 . The method as defined in  claim 9  wherein:
 the mixing breaks the flow additive aggregates into individual flow additive nanoparticles, aggregate fragments, or a combination thereof; 
 the individual flow additive nanoparticles, the aggregate fragments, or the combination thereof become disposed on a surface of particles of the host metal; and 
 the mixing forms the build material composition including:
 the host metal present in an amount of at least 99 wt % based on a total weight of the build material composition; and 
 the individual flow additive nanoparticles, the aggregate fragments, or the combination thereof present in an amount of less than 1 wt % based on the total weight of the build material composition. 
 
 
     
     
         14 . The method as defined in  claim 9 , further comprising stopping mixing when the build material composition has a Hausner Ratio less than 1.25. 
     
     
         15 . A method for three-dimensional (3D) printing, comprising:
 applying a build material composition including:
 a host metal present in an amount of at least 99 wt %, based on a total weight of the build material composition; and 
 a flow additive present in an amount of less than 1 wt % based on the total weight of the build material composition, the flow additive including flow additive primary particles that:
 have an average flow additive primary particle size ranging from about 1 to about 3 orders of magnitude smaller than an average host metal particle size; and 
 are metal oxide particles that are reducible to at least one elemental metal in a reducing environment at a reducing temperature less than or equal to a sintering temperature of the host metal, wherein the at least one elemental metal is capable of being incorporated into a bulk metal phase of the host metal in a final metal object; 
 
 wherein the build material composition is spreadable, having a Hausner Ratio less than 1.25; and 
   selectively applying a binder agent on at least a portion of the build material composition.