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

Patent metadata

Field	Value
Publication number	US-2020140332-A1
Application number	US-201616061475-A
Country	US
Kind code	A1
Filing date	Dec 16, 2016
Priority date	Dec 18, 2015
Publication date	May 7, 2020
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 geopolymeric formulation including ingredients comprising:
either:
at least one inorganic compound selected from a first group consisting of:
a compound containing aluminum associated with at least one compound containing silicon, a silicon-aluminate compound, a compound containing polysilicates, polysiloxane, polysilicon-aluminates and polysialates; and
at least one alkaline activator and water;
or:
at least one inorganic compound selected from a second group consisting of: an inorganic oxide and an acidic phosphate;
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 forms a non-newtonian, viscoelastic, gel reversible fluid.

2 . The formulation 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.

3 . The formulation according to claim 1 wherein, when in a fluid state and at a low shear rate less than or equal to 0.1 l/s, the formulation has a viscosity of at least an order of magnitude higher than a viscosity that the same formulation in the fluid state has at a high shear rate equal to or higher than 100 l/s.

4 . The formulation according to claim 1 , wherein the formulation comprises metakaolin, a substance which is a source of polysilicates, a soluble alkaline polysilicate 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 0.1 l/s, a viscosity of four orders of magnitude greater than a viscosity that the same formulation in the fluid state has at a relatively high shear rate equal to or greater than 100 l/s.

5 . The formulation according to claim 4 , 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.

6 . The formulation according to claim 4 , 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.

7 . The formulation 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.

8 . A direct 3D printing ink formulation, wherein the formulation comprises a geopolymeric formulation in a fluid state according to claim 1 .

9 . The direct 3D printing ink formulation according to claim 8 , 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.

10 . The direct 3D printing ink formulation according to claim 8 , 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.

11 . The direct 3D printing ink formulation according to claim 8 , 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.

12 . A method for manufacturing a three-dimensional solid structure, the method comprising:
preparing an ink formulation for direct 3D printing according to claim 8 ; using the formulation as an ink for a direct 3D printing device which carries out an extrusion of the ink through a nozzle by application of a preset pressure, the direct 3D printing device having a support and having a displacing system controlled on three or more axes for the nozzle and/or the support; and forming the three-dimensional solid structure upon a substrate mounted on the support sequentially extruding upon said substrate strands of said ink moving at the same time the nozzle relative to the support in order to create one or more layers formed from one or more strands arranged according to an established geometry; the extrusion being carried out in such a way as to subject the ink formulation to a shear rate of between 10 and 80 l/s.

13 . The method according to claim 12 , 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.

14 . The method according to claim 12 , 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%.

15 . The method according to claim 12 , 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%.

16 . The method according to claim 12 , 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.

Assignees

• Itt Italia Srl

Inventors

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

Classifications

• C04B28/34

  containing cold phosphate binders · CPC title

• C04B2111/00215

  Mortar or concrete mixtures defined by their oxide composition · CPC title

• C04B2111/00181

  Mixtures specially adapted for three-dimensional printing (3DP), stereo-lithography or prototyping · CPC title

• C04B28/006 Primary

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

• B33Y10/00

  Processes of additive manufacturing · CPC title