Shear thinning build material slurry

1 . A shear thinning build material slurry, comprising:

metallic build material particles selected from the group consisting of steel particles, stainless steel particles, bronze particles, titanium particles and alloys thereof, nickel particles, cobalt particles, iron particles and alloys thereof, gold particles and alloys thereof, silver particles and alloys thereof, platinum particles and alloys thereof, and copper particles and alloys thereof, wherein the build material particles have a particle size ranging from about 5 μm to about 20 μm;

a hydrocolloid present in an amount ranging from about 0.05 percent by volume to less than 0.5 percent by volume of the shear thinning build material slurry, the hydrocolloid having a molecular weight ranging from about 0.5×10 6 g/mol to about 50×10 6 g/mol and is selected from the group consisting of xanthan gum, scleroglucan, diutan gum, rhamsan gum, guar gum, locust bean gum, tara gum, cassia gum, gum tragacanth, welan gum, carrageenan, flaxseed gum, tamarind gum, konjac maanan, agarose, gellan gum, and combinations thereof; and

water,

wherein the build material slurry is a ready-to-use three-dimensional (3D) printing build material.

2 . The shear thinning build material slurry as defined in claim 1 wherein a ratio of a viscosity of the shear thinning build material measured at a shear rate of 0.1 s −1 to a viscosity of the shear thinning build material measured at a shear rate of 100 s −1 is greater than 30.

3 . The shear thinning build material slurry as defined in claim 1 wherein the hydrocolloid has a decomposition temperature of greater than 100° C.

4 . The shear thinning build material slurry as defined in claim 1 wherein the metallic or ceramic particles are present in an amount ranging from about 35 percent by volume to about 70 percent by volume of the shear thinning build material slurry.

5 . The shear thinning build material slurry as defined in claim 1 , further comprising a humectant, an evaporation enhancer, a surfactant, an antimicrobial agent, or combinations thereof.

6 . The shear thinning build material slurry as defined in claim 1 wherein the metallic build material particles are selected from the group consisting of steel particles, stainless steel particles, bronze particles, titanium particles and alloys thereof, nickel particles, cobalt particles, iron particles, gold particles and alloys thereof, silver particles, platinum particles and alloys thereof, and copper particles.

7 . The shear thinning build material slurry as defined in claim 1 , further comprising from 2 percent by volume to 6 percent by volume of a humectant, based on a total weight of the shear thinning build material slurry.

8 . The shear thinning build material slurry as defined in claim 7 wherein the humectant is selected from the group consisting of 1,2-butanediol, 2-pyrrolidone, 2,3-pentanediol, ethylene glycol, propylene glycol, and combinations thereof.

9 . The shear thinning build material slurry as defined in claim 1 wherein the shear thinning build material slurry consists of the metallic particles, the hydrocolloid, the water, and a humectant, and wherein the humectant is 1,2-butanediol.

10 . A three-dimensional printing kit, comprising:

a shear thinning build material slurry, including:

metallic particles having a particle size ranging from about 5 μm to about 20 μm, wherein the metallic particles are selected from the group consisting of steel particles, stainless steel particles, bronze particles, titanium particles and alloys thereof, nickel particles, cobalt particles, iron particles and alloys thereof, gold particles and alloys thereof, silver particles and alloys thereof, platinum particles and alloys thereof, and copper particles and alloys thereof;

a hydrocolloid present in an amount ranging from about 0.05 percent by volume to less than 0.5 percent by volume of the shear thinning build material slurry, the hydrocolloid having a molecular weight ranging from about 0.5×10 6 g/mol to about 50×10 6 g/mol and selected from the group consisting of xanthan gum, scleroglucan, diutan gum, rhamsan gum, guar gum, locust bean gum, tara gum, cassia gum, gum tragacanth, welan gum, carrageenan, flaxseed gum, tamarind gum, konjac maanan, agarose, gellan gum, and combinations thereof; and

water; and

a patterning fluid including a latent binder in a liquid vehicle.

11 . A method for three-dimensional (3D) printing, the method comprising:

exposing the shear thinning build material slurry of claim 1 to a shear rate greater than about 100 s −1 , thereby reducing a viscosity of the build material slurry to less than 10 Pa·s −1 ;

while the viscosity is reduced, applying the build material slurry to form a slurry layer;

evaporating at least some of the water from the slurry layer to form a build material layer; and

selectively applying a patterning fluid on at least a portion of the build material layer, the patterning fluid including a latent binder.

12 . The method as defined in claim 11 wherein the slurry layer is applied across a width of a substantially horizontal build platform.

13 . The method as defined in claim 11 , further comprising:

removing at least some liquid of the patterning fluid from the at least the portion of the build material layer;

activating the latent binder in the at least the portion of the build material layer;

repeating the exposing, the applying, the evaporating, the selectively applying, the removing, and the activating to form a cured intermediate part;

extracting the cured intermediate part from a build material volume to remove any non-patterned metallic or ceramic particles; and

heating the cured intermediate part to form a sintered part.

14 . The method as defined in claim 13 wherein:

the hydrocolloid has a decomposition temperature greater than 100° C.; and

a solid thermal decomposition product of the hydrocolloid in the sintered part is less than 30% of an initial weight of the hydrocolloid in the build material slurry.

15 . The method as defined in claim 11 , further comprising:

removing at least some liquid of the patterning fluid from the at least the portion of the build material layer;

then repeating the exposing, the applying, the evaporating, the selectively applying, and the removing, to form an intermediate part;

activating the latent binder in the intermediate part to form a cured intermediate part;

extracting the cured intermediate part from a build material volume to remove any non-patterned metallic or ceramic particles; and

heating the cured intermediate part to form a sintered part.

16 . The method as defined in claim 15 wherein:

the hydrocolloid has a decomposition temperature greater than 100° C.; and

a solid thermal decomposition product of the hydrocolloid in the sintered part is less than 30% of an initial weight of the hydrocolloid in the build material slurry.

17 . The method as defined in claim 11 wherein the applying of the build material slurry is accomplished using a slot die coater, a doctor blade coater, a rod coater, a knife coater, or combinations thereof.

18 . The shear thinning build material slurry as defined in claim 1 wherein the metallic build material particles are stainless steel particles.

19 . A shear thinning build material slurry, comprising:

metallic build material particles having an average particle size ranging from about 5 μm to about 20 μm;

from about 0.3 percent by volume to less than 0.5 percent by volume of a hydrocolloid selected from the group consisting of xanthan gum, scleroglucan, diutan gum, rhamsan gum, guar gum, locust bean gum, tara gum, cassia gum, gum tragacanth, welan gum, carrageenan, flaxseed gum, tamarind gum, konjac maanan, agarose, gellan gum, and combinations thereof;

from about 2 percent by volume to about 6 percent by volume of a humectant; and

water.