Geopolymeric formulations and associated methods for the manufacturing of three-dimensional structures

Patent metadata

Field	Value
Publication number	US-2022089494-A1
Application number	US-202117391976-A
Country	US
Kind code	A1
Filing date	Aug 2, 2021
Priority date	Dec 18, 2015
Publication date	Mar 24, 2022
Grant date	—

Abstract

A geopolymeric ink formulation for direct 3D printing containing a geopolymeric formulation whose components are present in such proportions as to be subjected to a geopolymerization reaction and to provide, at the end of the reaction, a solid geopolymer and wherein the formulation, before and during at least a part of the geopolymerization reaction, wherein three-dimensional chemical bonds have not yet been formed, forms a reversible-gel, non-Newtonian, viscoelastic fluid. The formulation is extruded through a 3D printing tool equipped with nozzle into strands according to a geometry such as to create a three-dimensional structure on one or more layers. The extrusion preferably takes place within a hydrophobic liquid, such as oil.

First claim

1 . A method for manufacturing a three-dimensional solid structure, the method comprising:
preparing an ink formulation for direct 3D printing, the ink formulation comprising a geopolymeric formulation including ingredients comprising metakaolin as a source of polysilicates, a soluble alkaline polysiciate, and an aqueous alkaline solution in proportions such that the formulation in a fluid state has, at a relatively low shear rate equal to or less than 0.11/s, a viscosity of four orders of magnitude greater than a viscosity that the same formation in the fluid state has at a relatively high shear rate equal to or greater than 100 l/s; wherein the ingredients are present in such proportions as to undergo a geopolymerization reaction and produce, at an end of the geopolymerization reaction, a solid geopolymer; and wherein, before and during at least a part of the geopolymerization reaction in which three-dimensional chemical bonds are not yet formed, the formulation reversibly forms a non-Newtonian, viscoelastic gel from a fluid; using the formulation as an ink for a direct 3D printing device which carries out an extrusion of the ink through a nozzle; and forming the three-dimensional solid structure upon a substrate by sequentially extruding upon said substrate strands of said ink.

2 . The method according to claim 1 , wherein the extrusion step is carried out by extruding the ink formulation in a hydrophobic liquid having arranged the substrate immersed in the hydrophobic liquid.

3 . The method according to claim 1 , wherein the composition of the ink formulation is selected in such a way as to obtain strands which once solidified are dense, having a porosity of less than 10%.

4 . The method according to claim 1 , wherein the composition of the ink formulation is selected in such a way as to obtain strands which once solidified are porous, exhibiting a porosity of greater than 10% and up to 90%.

5 . The method according to claim 1 , wherein the method comprises a heating step of the extruded and solidified ink formulation carried out at such a temperature as to produce crystallization of the geopolymer present within the ink.

6 . The method according to claim 1 , wherein the extrusion is carried out in such a way as to subject the ink formulation to a shear rate of between 10 and 80 l/s.

7 . The method according to claim 1 , wherein, when in a fluid state, the formulation has a starting flow-threshold limit or yield stress that is greater than or equal to 20 Pa.

8 . The method according to claim 1 , wherein when in a fluid state, the formulation has a starting flow-threshold limit or yield stress that is greater than 20 Pa, a viscosity measured at a shear rate of 0.1 l/s of about 103 Pa·s, and a viscosity measured at a shear rate of 30 l/s of between about 5 to 20 Pa·s.

9 . The method according to claim 1 , wherein the formulation has an atomic ratio Si:Al of between 1:1 and 35:1 inclusive, a (Na 2 O, K 2 O)/SiO 2 molar ratio of between 0.20 and 0.28 inclusive, a SiO 2 /Al 2 O 3 molar ratio of between 3.5 and 4.5 inclusive, a H 2 O/(Na 2 O, K 2 O) molar ratio of between 10 and 25 inclusive, and a (Na 2 O, K 2 O)/Al 2 O 3 molar ratio of between 0.80 and 1.20 inclusive.

10 . The method according to claim 1 wherein the formulation includes at least one filler selected from a group consisting of rubber, organic resins, alumina, silicates, glass, mineral fillers, polymeric and inorganic short fibers.

11 . The method according to claim 1 wherein the formulation further includes at least one geopolymerization reaction retarding agent, the retarding agent being present within the formulation in an amount between 0.1 and 5% by weight on the total weight.

12 . The method according to claim 1 wherein the formulation further includes at least one fluidifying agent, the fluidifying agent being present within the formulation in an amount between 0.1 and 5% by weight on the total weight.

13 . The method according to claim 1 wherein the formulation further includes at least one gelling agent, the gelling agent being present within the formulation in an amount between 0.1 and 20% by weight on the total weight.

14 . A method for manufacturing a three-dimensional solid structure, the method comprising:
preparing an ink formulation for direct 3D printing, the ink formulation comprising a geopolymeric formulation in a fluid state, the geopolymeric formulation comprising:
at least one inorganic compound comprising silicon and aluminum, the at least one inorganic compound selected from a group consisting of: a silicon-aluminate compound, a compound containing polysilicates, polysiloxane, polysilicon-aluminates and polysialates; and
at least one alkaline activator and water;
wherein the ingredients are present in such proportions as to undergo a geopolymerization reaction and produce, at an end of the geopolymerization reaction, a solid geopolymer;
wherein, before and during at least a part of the geopolymerization reaction in which three-dimensional chemical bonds are not yet formed, the formulation reversibly forms a non-Newtonian, viscoelastic gel from a fluid; and
wherein the formulation further comprises at least one geopolymerization reaction retarding agent, the retarding agent being present within the formulation in an amount between 0.1 and 5% by weight on the total weight;
using the formulation as an ink for a direct 3D printing device which carries out an extrusion of the ink through a nozzle; and forming the three-dimensional solid structure upon a substrate mounted on the support by sequentially extruding upon said substrate strands of said ink.

15 . The method according to claim 14 , wherein the extrusion is carried out in such a way as to subject the ink formulation to a shear rate of between 10 and 80 l/s.

16 . The method according to claim 14 , wherein the extrusion is carried out by extruding the ink formulation in a hydrophobic liquid having arranged the substrate immersed in the hydrophobic liquid.

17 . A method for manufacturing a three-dimensional solid structure, the method comprising:
preparing an ink formulation for direct 3D printing, the ink formulation comprising a geopolymeric formulation in a fluid state, the geopolymeric formulation comprising:
at least one inorganic compound comprising silicon and aluminum, the at least one inorganic compound selected from a group consisting of: a silicon-aluminate compound, a compound containing polysilicates, polysiloxane, polysilicon-aluminates and polysialates; and
at least one alkaline activator and water;
wherein the ingredients are present in such proportions as to undergo a geopolymerization reaction and produce, at an end of the geopolymerization reaction, a solid geopolymer;
wherein, before and during at least a part of the geopolymerization reaction in which three-dimensional chemical bonds are not yet formed, the formulation reversibly forms a non-Newtonian, viscoelastic gel from a fluid; and
wherein the formulation further comprises at least one fluidifying agent, the fluidifying agent being present within the formulation in an amount between 0.1 and 5% by weight on the total weight;
using the formulation as an ink for a direct 3D printing device which carries out an extrusion of the ink through a nozzle; and forming the three-dimensional solid structure upon a substrate mounted on the support by sequentially extruding upon said substrate strands of said ink.

18 . The method according to claim 17 , wherein the extrusion is carried out in such a way as to subject t

Assignees

• Itt Italia Srl

Inventors

• Colombo Paolo
• Franchin Giorgia
• Elsayed Hamada Said Abdelwahab
• Sin Xicola Agustin

Classifications

• B33Y70/10

  Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials · CPC title

• B33Y70/00

  Materials specially adapted for additive manufacturing · CPC title

• C04B28/006 Primary

  containing mineral polymers, e.g. geopolymers of the Davidovits type · CPC title

• C04B28/34

  containing cold phosphate binders · CPC title

• B28B1/001

  Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material (selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00) · CPC title