权利要求：
1. 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 separate second fluid consisting of a second liquid vehicle and latex polymer particles dispersed in the second liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm,
wherein the metal or metal precursor particles have a mean particle diameter ranging from about 1 nm to about 1000 nm and are selected from the group consisting of metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles with a first reducing agent, metal salts, metal salts with a second reducing agent, and combinations thereof.
2. The multi-fluid kit of claim 1, wherein the latex polymer particles are selected from the group consisting of 2-phenoxyethyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, methacrylic acid, and combinations thereof.
3. The multi-fluid kit of claim 1, wherein the latex polymer particles are selected from the group consisting of styrene, methyl methacrylate, butyl acrylate, methacrylic acid, and combinations thereof.
4. The multi-fluid kit of claim 1, wherein the latex polymer particles are present in the second fluid in an amount ranging from about 5 wt % to about 40 wt % based on the total weight of the second fluid.
5. The multi-fluid kit of claim 1, wherein the first liquid vehicle comprises water present in an amount of from about 45 wt % to about 75 wt % based on the total weight of the first liquid vehicle, and wherein the second liquid vehicle comprises is water-present in an amount of from about 45 wt % to about 75 wt % based on the total weight of the second liquid vehicle.
6. The multi-fluid kit of claim 1, wherein the metal nanoparticles are selected from the group consisting of nickel, silver, gold, copper, platinum, and combinations thereof.
7. The multi-fluid kit of claim 1, wherein the metal oxide nanoparticles are selected from the group consisting of oxides of iron, nickel, silver, gold, copper, platinum, cobalt, manganese, vanadium, molybdenum, and combinations thereof.
8. The multi-fluid kit of claim 1, wherein the first reducing agent is selected from the group consisting of aldehydes, hydrazides, hydrazine, ascorbic acid, reducing saccharides, and combinations thereof.
9. 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 separate second fluid comprising a second liquid vehicle and latex polymer particles dispersed in the second liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm and wherein the latex polymer particles are made from:
(A) a co-polymerizable surfactant chosen from polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof; and
(B) styrene, p-methyl styrene, a-methyl styrene, methacrylic acid, acrylic acid, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, methyl methacrylate, hexyl acrylate, hexyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, propyl acrylate, propyl methacrylate, octadecyl acrylate, octadecyl methacrylate, stearyl methacrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, 2-phenoxyethyl methacrylate, benzyl methacrylate, benzyl acrylate, ethoxylated nonyl phenol methacrylate, ethoxylated behenyl methacrylate, polypropyleneglycol monoacrylate, isobornyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, t-butyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, alkoxylated tetrahydrofurfuryl acrylate, isodecyl acrylate, isobornyl methacrylate, isobornyl acrylate, acetoacetoxyethyl methacrylate, or combinations thereof,
wherein the metal or metal precursor particles have a mean particle diameter ranging from about 1 nm to about 1000 nm and are selected from the group consisting of metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles with a first reducing agent, metal salts, metal salts with a second reducing agent, and combinations thereof.
10. A method of printing a three-dimensional object, the method comprising:
(i) depositing a metal powder build material in a powder bed;
(ii) based on a three-dimensional object model, selectively applying a first fluid and a separate second fluid on the metal powder build material in the powder bed,
wherein:
the first fluid comprises a first liquid vehicle comprising metal or metal precursor particles, wherein the metal or metal precursor particles have a mean particle diameter ranging from about 1 nm to about 1000 nm and are selected from the group consisting of metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles with a first reducing agent, metal salts, metal salts with a second reducing agent, and combinations thereof, and
the separate second fluid consists of a second liquid vehicle and latex polymer particles dispersed in the second liquid vehicle, wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm;
(iii) repeating (i), and (ii) at least once to form the three-dimensional object; and
(iv) heating the powder bed to a temperature of up to about 200° C.
11. The method of claim 10 further comprising:
(v) removing the three-dimensional object from the powder bed and heating the three-dimensional object to a temperature of up to about 500° C.
12. The method of claim 11, wherein the heating to the temperature of up to about 500° C. comprises removing at least about 95 wt % of the latex polymer particles by thermally decomposing the latex polymer particles and initiating binding of metal powder particles of the metal powder build material with the metal or metal precursor particles.
13. The method of claim 11 further comprising:
(vi) heating the three-dimensional object in a sintering oven to a sintering temperature of greater than about 500° C.
14. The method of claim 13, wherein the heating of the three-dimensional object in the sintering oven includes heating the three-dimensional object to a sintering temperature of greater than about 800° C.
15. The method of claim 10, wherein the latex polymer particles are present in the separate second fluid in an amount ranging from about 1 wt % to about 50 wt % based on the total weight of the separate second fluid.
具体实施方式：
[0010]In some examples of three-dimensional (3D) printing, a binder fluid (also known as a liquid functional agent/material) is selectively applied to a layer of build material in a powder bed. The application of a layer of build material and then applying a binder fluid layer with repetition of these steps can lead to form a green part (also referred to as a green body) in the powder bed. The binder fluid may include a binder that holds the build material of the green part together. The green part may then be exposed to electromagnetic radiation and/or heat to sinter the build material in the green part to form the 3D part.
[0011]Examples of the 3D printing kits, methods, and systems disclosed herein utilize a single binder fluid or a multi-fluid binder. The single binder fluid or one of the fluids in the multi-fluid binder include polymer particles, in order to produce a patterned green part from metal powder build material, and also utilize heat to activate the polymer particles and create a cured green part. The cured green part can be removed from the metal powder build material that was not patterned with the binder fluid, without deleteriously affecting the structure of the cured green part. The extracted, cured green part can then undergo de-binding to produce an at least substantially polymer-free gray part, and the at least substantially polymer-free gray part may then undergo sintering to form the final 3D printed part/object.
[0012]The single binder fluid can further include metal or metal precursor particles which can include metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof, in order to produce a patterned green part from metal powder build material, and also utilize heat to form metallic connections and create a cured green part. The cured green part can be removed from the metal powder build material that was not patterned with the binder fluid, without deleteriously affecting the structure of the cured green part. The extracted, cured green part can then undergo de-binding to produce an at least substantially polymer-free gray part, and the at least substantially polymer-free gray part may then undergo sintering to form the final 3D printed part/object.
[0013]The multi-fluid binder can include a separate binder fluid from the polymer particle containing fluid. This separate binder fluid can include metal or metal precursor particles which can include metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof, or combinations thereof, in order to produce a patterned green part from metal powder build material, and also utilize heat to form metallic connections and create a cured green part. The cured green part can be removed from the metal powder build material that was not patterned with the binder fluid, without deleteriously affecting the structure of the cured green part. The extracted, cured green part can then undergo de-binding to produce an at least substantially polymer-free gray part, and the at least substantially polymer-free gray part may then undergo sintering to form the final 3D printed part/object.
[0014]As used herein, the term “bound metal object” or “patterned green part” refers to an intermediate part that has a shape representative of the final 3D printed part and that includes metal powder build material patterned with the binder fluid. In the patterned green part, the metal powder build material particles may or may not be weakly bound together by one or more components of the binder fluid and/or by attractive force(s) between the metal powder build material particles and the binder fluid. In some instances, the mechanical strength of the patterned green part is such that it cannot be handled or extracted from a build material platform. Moreover, it is to be understood that any metal powder build material that is not patterned with the binder fluid is not considered to be part of the patterned green part, even if it is adjacent to or surrounds the patterned green part.
[0015]As used herein, the term “cured green part” refers to a patterned green part that has been exposed to a heating process that initiates melting of the polymer particles and/or initiates melting of the metal or metal precursor particles. The heating process may also contribute to the evaporation of the liquid components of the binder fluid(s). Compared to the patterned green part, the mechanical strength of the cured green part is greater, and in some instances, the cured green part can be handled or extracted from the build material platform.
[0016]It is to be understood that the term “green” when referring to the patterned green part or the cured green part does not connote color, but rather indicates that the part is not yet fully processed and/or completed.
[0017]As used herein, the term “at least substantially polymer-free gray part” refers to a cured green part that has been exposed to a heating process that initiates thermal decomposition of the polymer particles so that the polymer particles are at least partially removed. In some instances, volatile organic components of or produced by the thermally decomposed polymer particles are completely removed and a very small amount of nonvolatile residue from the thermally decomposed polymer particles may remain (e.g., <1 wt % of the initial binder). In other instances, the thermally decomposed polymer particles (including any products and residues) are completely removed. In other words, the “at least substantially polymer-free gray part” refers to an intermediate part with a shape representative of the final 3D printed part and that includes metal powder build material bound together as a result of i) weak sintering (i.e., low level necking between the particles, which is able to preserve the part shape), or ii) a small amount of the cured polymer particles remaining, or iii) capillary forces and/or Van der Waals resulting from polymer particle removal, and/or iv) any combination of i, ii, and/or iii.
[0018]It is to be understood that the term “gray” when referring to the at least substantially polymer-free gray part does not connote color, but rather indicates that the part is not yet fully processed.
[0019]The at least substantially polymer-free gray part may have porosity similar to or greater than the cured green part (due to polymer particle removal), but the porosity is at least substantially eliminated during the transition to the 3D printed part.
[0020]As used herein, the terms “three-dimensional object,”“3D object,”“3D printed part,”“3D part,” or “metal part” refer to a completed, sintered part.
[0021]In the examples disclosed herein, the single binder fluid or multi-fluid binders when applied to a layer of metal powder build material, the liquid vehicle in the fluid(s) is capable of wetting the build material and the polymer particles and/or the metal or metal precursor particles are capable of penetrating into the microscopic pores of the layer (i.e., the spaces between the metal powder build material particles).
3D Printing Kits
Multi-Fluid Kits
[0022]In the examples disclosed herein, a multi-fluid kit for three-dimensional printing is described. The multi-fluid kit can comprise 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.
[0023]The latex polymer particles can be made from (A) a co-polymerizable surfactant chosen from polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof, and (B) styrene, p-methyl styrene, α-methyl styrene, methacrylic acid, acrylic acid, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, methyl methacrylate, hexyl acrylate, hexyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, propyl acrylate, propyl methacrylate, octadecyl acrylate, octadecyl methacrylate, stearyl methacrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, 2-phenoxyethyl methacrylate, benzyl methacrylate, benzyl acrylate, ethoxylated nonyl phenol methacrylate, ethoxylated behenyl methacrylate, polypropyleneglycol monoacrylate, isobornyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, t-butyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, alkoxylated tetrahydrofurfuryl acrylate, isodecyl acrylate, isobornyl methacrylate, isobornyl acrylate, acetoacetoxyethyl methacrylate, or combinations thereof.
[0024]The latex polymer particles can comprise 2-phenoxyethyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, methacrylic acid, or combinations thereof.
[0025]The latex polymer particles can comprise styrene, methyl methacrylate, butyl acrylate, methacrylic acid, or combinations thereof.
[0026]The latex polymer particles can be present in the second fluid in an amount ranging from about 5 wt % to about 40 wt % based on the total weight of the second fluid.
[0027]The first liquid vehicle and the second liquid vehicle can comprise water each in an amount of from about 45 wt % to about 75 wt % based on the total weight of the first liquid vehicle and the second liquid vehicle, respectively.
[0028]The metal nanoparticles can comprise, nickel, silver, gold, copper, platinum, or combinations thereof.
[0029]The metal oxide nanoparticles can comprise oxides of iron, nickel, silver, gold, copper, platinum, cobalt, manganese, vanadium, molybdenum, or combinations thereof.
[0030]The reducing agent can be selected from the group consisting of aldehydes, hydrazides, hydrazine, ascorbic acid, reducing saccharides, or combinations thereof.
Single Fluid Kits
[0031]In the examples disclosed herein, is a kit for three-dimensional printing. The kit can comprise 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.
[0032]The latex polymer particles can be made from (A) a co-polymerizable surfactant chosen from polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof, and (B) styrene, p-methyl styrene, α-methyl styrene, methacrylic acid, acrylic acid, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, methyl methacrylate, hexyl acrylate, hexyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, propyl acrylate, propyl methacrylate, octadecyl acrylate, octadecyl methacrylate, stearyl methacrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, 2-phenoxyethyl methacrylate, benzyl methacrylate, benzyl acrylate, ethoxylated nonyl phenol methacrylate, ethoxylated behenyl methacrylate, polypropyleneglycol monoacrylate, isobornyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, t-butyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, alkoxylated tetrahydrofurfuryl acrylate, isodecyl acrylate, isobornyl methacrylate, isobornyl acrylate, acetoacetoxyethyl methacrylate, or combinations thereof.
[0033]The latex polymer particles can comprise 2-phenoxyethyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, methacrylic acid, or combinations thereof.
[0034]The latex polymer particles can comprise styrene, methyl methacrylate, butyl acrylate, methacrylic acid, or combinations thereof.
[0035]The powered metal build material can comprise steels, bronzes, titanium and alloys thereof, aluminum and alloys thereof, nickel and alloys thereof, cobalt and alloys thereof, iron and alloys thereof, nickel cobalt alloys, gold and alloys thereof, silver and alloys thereof, platinum and alloys thereof, copper and alloys thereof, or combinations thereof.
[0036]The metal nanoparticles can comprise nickel, silver, gold, copper, platinum, or combinations thereof.
[0037]The metal oxide nanoparticles can comprise oxides of iron, nickel, silver, gold, copper, platinum, cobalt, manganese, vanadium, molybdenum, or combinations thereof.
[0038]The reducing agent is selected from the group consisting of aldehydes, hydrazides, hydrazine, ascorbic acid, reducing saccharides, or combinations thereof.
[0039]The latex polymer particles can be present in the binding fluid in an amount ranging from about 5 wt % to about 40 wt % based on the total weight of the binding fluid.
3D Printing Methods
Multi-Fluid Methods
[0040]In the examples disclosed herein, a method of printing a three-dimensional object is described. The method can comprise (i) depositing a metal powder build material in a powder bed; (ii) based on a three-dimensional object model, selectively applying a first fluid and a second fluid on the metal powder build material in the powder bed, wherein the first fluid comprises a first liquid vehicle comprising metal or metal precursor particles, wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof, and the second fluid comprises 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;
[0041](iii) repeating (i), and (ii) at least once to form the three-dimensional object; and (iv) heating the powder bed to a temperature of up to about 200° C.
[0042]The method can further comprise (v) removing the three-dimensional object from the powder bed and heating the three-dimensional object to a temperature of up to about 500° C.
[0043]The heating to the temperature of up to about 500° C. can comprise removing at least about 95 wt % of the latex polymer particles by thermally decomposing the latex polymer particles and initiate binding of metal powder particles with the metal or metal precursor particles.
[0044]The latex polymer particles can be present in the second fluid in an amount ranging from about 1 wt % to about 50 wt % based on the total weight of the second fluid.
[0045]The method can further comprise (vi) heating the three-dimensional object in a sintering oven to a sintering temperature of greater than about 500° C.
Single Fluid Methods
[0046]In the examples disclosed herein, a method of printing a three-dimensional object is disclosed. The method can comprise (i) depositing a metal powder build material in a powder bed; (ii) based on a three-dimensional object model, selectively applying a binding fluid on the metal powder build material in the powder bed, wherein the binding fluid comprises a liquid vehicle, metal or metal precursor particles, and latex polymer particles dispersed in the liquid vehicle, wherein the metal or metal precursor particles comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof, and wherein the latex polymer particles have an average particle size of from about 10 nm to about 300 nm; (iii) repeating (i) and (ii) at least one time to form the three-dimensional object; and (iv) heating the powder bed to a temperature of up to about 200° C.
[0047]The method can further comprise (v) heating the three-dimensional object in the powder bed to a temperature of up to about 500° C.
[0048]The method can further comprise (vi) heating the three-dimensional object to a sintering temperature of greater than about 500° C.
[0049]A method of using the single fluid kit can comprise applying the powdered build material and then the binding fluid in a three-dimensional printing bed.
3D Printing Systems
[0050]In the examples disclosed herein, a printing system for printing a three-dimensional object is disclosed. The printing system can comprise a supply of one or more binding fluids; a supply of metal powdered build material; a build material distributor; a fluid applicator for selectively dispensing the binding fluid; a heat source;
[0051]a controller; and a non-transitory computer readable medium having stored thereon computer executable instructions to cause the controller to print the three-dimensional object by: utilizing the build material distributor and the fluid applicator to iteratively form at least one layer of powdered metal build material having selective application of the binding fluid, and utilizing the heat source to heat the selectively applied binding fluid on the powdered metal build material to form the three-dimensional object.
[0052]The powered metal build material can comprise steels, bronzes, titanium and alloys thereof, aluminum and alloys thereof, nickel and alloys thereof, cobalt and alloys thereof, iron and alloys thereof, nickel cobalt alloys, gold and alloys thereof, silver and alloys thereof, platinum and alloys thereof, copper and alloys thereof, or combinations thereof.
[0053]In some examples, a first fluid can comprise a first liquid vehicle comprising metal or metal precursor particles. In some examples, a second fluid can comprise 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.
[0054]In the multi-fluid examples, the metal or metal precursor particles can comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.
[0055]In the single fluid examples, the metal or metal precursor particles can comprise metal nanoparticles, metal oxide nanoparticles, metal oxide nanoparticles and a reducing agent, or combinations thereof.
[0056]Referring now to FIG. 1, an example of a 3D printing system 10 is depicted. It is to be understood that the 3D printing system 10 may include additional components and that some of the components described herein may be removed and/or modified. Furthermore, components of the 3D printing system 10 depicted in FIG. 1 may not be drawn to scale and thus, the 3D printing system 10 may have a different size and/or configuration other than as shown therein.
[0057]The three-dimensional (3D) printing system 10 generally includes a supply 14 of metal powder build material 16; a build material distributor 18; a supply of a binder fluid 36; an inkjet applicator 24 for selectively dispensing the binder fluid 36 (FIG. 2C); at least one heat source 32; a controller 28; and a non-transitory computer readable medium having stored thereon computer executable instructions to cause the controller 28 to: utilize the build material distributor 18 and the inkjet applicator 24 to iteratively form multiple layers 34 (FIG. 2B) of metal powder build material 16 which are applied by the build material distributor 18 and have received the binder fluid 36, thereby creating a patterned green part 42 (FIG. 2E), and utilize the at least one heat source 32 to heat the patterned green part 42 creating a cured green part 42′. In some examples, the cured green part 42′ is heated creating an at least substantially polymer-free gray part 48. The at least substantially polymer-free gray part 48 or the cured green part 42′ are heated to a sintering temperature to form a metal part 50.
[0058]As shown in FIG. 1, the printing system 10 includes a build area platform 12, the build material supply 14 containing metal powder build material particles 16, and the build material distributor 18.
[0059]The build area platform (sometimes referred to as the powder bed in this application) 12 receives the metal powder build material 16 from the build material supply 14. The build area platform 12 may be integrated with the printing system 10 or may be a component that is separately insertable into the printing system 10. For example, the build area platform 12 may be a module that is available separately from the printing system 10. The build area platform 12 that is shown is also one example, and could be replaced with another support member, such as a platen, a fabrication/print bed, a glass plate, or another build surface.
[0060]The build area platform 12 may be moved in a direction as denoted by the arrow 20, e.g., along the z-axis, so that metal powder build material 16 may be delivered to the platform 12 or to a previously formed layer of metal powder build material 16 (see FIG. 2D). In an example, when the metal powder build material particles 16 are to be delivered, the build area platform 12 may be programmed to advance (e.g., downward) enough so that the build material distributor 18 can push the metal powder build material particles 16 onto the platform 12 to form a layer 34 of the metal powder build material 16 thereon (see, e.g., FIGS. 2A and 2B). The build area platform 12 may also be returned to its original position, for example, when a new part is to be built.
[0061]The build material supply 14 may be a container, bed, or other surface that is to position the metal powder build material particles 16 between the build material distributor 18 and the build area platform 12. In some examples, the build material supply 14 may include a surface upon which the metal powder build material particles 16 may be supplied, for instance, from a build material source (not shown) located above the build material supply 14. Examples of the build material source may include a hopper, an auger conveyer, or the like. Additionally, or alternatively, the build material supply 14 may include a mechanism (e.g., a delivery piston) to provide, e.g., move, the metal powder build material particles 16 from a storage location to a position to be spread onto the build area platform 12 or onto a previously formed layer of metal powder build material 16.
[0062]The build material distributor 18 may be moved in a direction as denoted by the arrow 22, e.g., along the y-axis, over the build material supply 14 and across the build area platform 12 to spread a layer of the metal powder build material 16 over the build area platform 12. The build material distributor 18 may also be returned to a position adjacent to the build material supply 14 following the spreading of the metal powder build material 16. The build material distributor 18 may be a blade (e.g., a doctor blade), a roller, a combination of a roller and a blade, and/or any other device capable of spreading the metal powder build material particles 16 over the build area platform 12. For instance, the build material distributor 18 may be a counter-rotating roller.
[0063]The metal powder build material 16 may be any particulate metallic material. In an example, the metal powder build material 16 may be a powder. In another example, the metal powder build material 16 may have the ability to sinter into a continuous body to form the metal part 50 (see, e.g., FIG. 2F) when heated to the sintering temperature (e.g., a temperature ranging from about 850° C. to about 1400° C.). By “continuous body,” it is meant that the metal powder build material particles are merged together to form a single part with little or no porosity and with sufficient mechanical strength to meet the requirements of the desired, final metal part 50.
[0064]While an example sintering temperature range is provided, it is to be understood that this temperature may vary, depending, in part, upon the composition and phase(s) of the metal powder build material 16.
[0065]The applicator 24 may be scanned across the build area platform 12 in the direction indicated by the arrow 26, e.g., along the y-axis. The applicator 24 may be, for instance, an inkjet applicator, such as a thermal inkjet printhead, a piezoelectric printhead, or combinations thereof, and may extend a width of the build area platform 12. While the applicator 24 is shown in FIG. 1 as a single applicator, it is to be understood that the applicator 24 may include multiple applicators that span the width of the build area platform 12. In some examples, a single or multiple applicators 24 can be used to apply the single fluid binder or multi-fluid binder.
[0066]Additionally, the applicators 24 may be positioned in multiple printbars. The applicator 24 may also be scanned along the x-axis, for instance, in configurations in which the applicator 24 does not span the width of the build area platform 12 to enable the applicator 24 to deposit the binder fluid 36 over a large area of a layer of the metal powder build material 16. The applicator 24 may thus be attached to a moving XY stage or a translational carriage (neither of which is shown) that moves the applicator 24 adjacent to the build area platform 12 in order to deposit the binder fluid 36 in predetermined areas of a layer of the metal powder build material 16 that has been formed on the build area platform 12 in accordance with the method(s) disclosed herein. The applicator 24 may include a plurality of nozzles (not shown) through which the binder fluid 36 is to be ejected.
[0067]The “binder fluid 36” as used herein refers to the single fluid binder or multi-fluid binders.
[0068]As discussed above, the multi-fluid binder kit for three-dimensional printing comprises 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.
[0069]As discussed above, the single-fluid binder for three-dimensional printing comprises 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.
[0070]The applicator 24 may deliver drops of the binder fluid 36 at a resolution ranging from about 300 dots per inch (DPI) to about 1200 DPI. In other examples, the applicator 24 may deliver drops of the binder fluid 36 at a higher or lower resolution. The drop velocity may range from about 2 m/s to about 24 m/s and the firing frequency may range from about 1 kHz to about 100 kHz. In one example, each drop may be in the order of about 10 picoliters (pl) per drop, although it is contemplated that a higher or lower drop size may be used. For example, the drop size may range from about 1 pl to about 400 pl. In some examples, applicator 24 is able to deliver variable size drops of the binder fluid 36.
[0071]Each of the previously described physical elements may be operatively connected to a controller 28 of the printing system 10. The controller 28 may control the operations of the build area platform 12, the build material supply 14, the build material distributor 18, and the applicator 24. As an example, the controller 28 may control actuators (not shown) to control various operations of the 3D printing system 10 components. The controller 28 may be a computing device, a semiconductor-based microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), and/or another hardware device. Although not shown, the controller 28 may be connected to the 3D printing system 10 components via communication lines.
[0072]The controller 28 manipulates and transforms data, which may be represented as physical (electronic) quantities within the printer's registers and memories, in order to control the physical elements to create the 3D part 50. As such, the controller 28 is depicted as being in communication with a data store 30. The data store 30 may include data pertaining to a 3D part 50 to be printed by the 3D printing system 10. The data for the selective delivery of the metal powder build material particles 16 and/or the binder fluid 36 may be derived from a model of the 3D part 50 to be formed. For instance, the data may include the locations on each layer of metal powder build material particles 16 that the applicator 24 is to deposit the binder fluid 36. In one example, the controller 28 may use the data to control the applicator 24 to selectively apply the binder fluid 36. The data store 30 may also include machine readable instructions (stored on a non-transitory computer readable medium) that are to cause the controller 28 to control the amount of metal powder build material particles 16 that is supplied by the build material supply 14, the movement of the build area platform 12, the movement of the build material distributor 18, the movement of the applicator 24.
[0073]As shown in FIG. 1, the printing system 10 may also include a heater 32. In some examples, the heater 32 includes a conventional furnace or oven, a microwave, or devices capable of hybrid heating (i.e., conventional heating and microwave heating). This type of heater 32 may be used for heating the entire build material cake 44 (see FIG. 2E) after the printing is finished or for heating the cured green part 42′ or for heating the at least substantially polymer-free gray part 48 after the cured green part 42′ is removed from the build material cake 44 (see FIG. 2F). In some examples, patterning may take place in the printing system 10, and then the build material platform 12 with the patterned green part 42 thereon may be detached from the system 10 and placed into the heater 32 for the various heating stages.
[0074]In other examples, the heater 32 may be a conductive heater or a radiative heater (e.g., infrared lamps) that is integrated into the system 10. These other types of heaters 32 may be placed below the build area platform 12 (e.g., conductive heating from below the platform 12) or may be placed above the build area platform 12 (e.g., radiative heating of the build material layer surface). Combinations of these types of heating may also be used. These other types of heaters 32 may be used throughout the 3D printing process. In still other examples, the heater 32 may be a radiative heat source (e.g., a curing lamp) that is positioned to heat each layer 34 (see FIG. 2C) after the binder fluid 36 has been applied thereto. In the example shown in FIG. 1, the heater 32 is attached to the side of the applicator 24, which allows for printing and heating in a single pass.
[0075]It is to be understood that an example of the method 300 shown in FIG. 3 is discussed in detail herein, e.g., in FIGS. 2A-2F and the text corresponding thereto.
[0076]Referring now to FIGS. 2A through 2F, an example of the 3D printing method is depicted. Prior to execution of the method or as part of the method (which could be method 300), the controller 28 may access data stored in the data store 30 pertaining to a 3D part 50 that is to be printed. The controller 28 may determine the number of layers of metal powder build material particles 16 that are to be formed, and the locations at which binder fluid 36 from the applicator 24 is to be deposited on each of the respective layers.
[0077]As shown in FIGS. 2A and 2B, the 3D printing method can include applying the metal powder build material 16. In FIG. 2A, the build material supply 14 may supply the metal powder build material particles 16 into a position so that they are ready to be spread onto the build area platform 12. In FIG. 2B, the build material distri