3D infiltration method

Abstract

The invention relates to a method for producing three-dimensional molded parts in two method steps and infiltrating the molded part, as well as a material system.

Claims

1. A method for producing one or more three-dimensional components by means of a layering technique comprising the steps of: applying material layers of the three-dimensional component(s) over a build platform; at least partially solidifying a first portion of the material layers, wherein the first portion at least partially has pores, and a second portion of the material layers is unbound; separating the second portion from the three-dimensional component(s); and contacting the three-dimensional component(s) with a water-containing medium, wherein a particulate material is used to build the material layers, the particulate material including a build material which binds or solidifies due to the introduction of the water-containing medium.

2. A part produced according to the method of claim 1.

3. A method for producing one or more three-dimensional components by means of a layering technique comprising the steps of: applying material layers of the three-dimensional component(s) over a build platform; at least partially solidifying a first portion of the material layers, wherein the first portion at least partially has pores, and a second portion of the material layers is unbound; separating the second portion from the three-dimensional component(s); and contacting the three-dimensional component(s) with a water-containing medium, wherein a particulate material is used to build the material layers, the particulate material including a build material which binds or solidifies due to the introduction of the water-containing medium; wherein the step of contacting includes a series of consecutive steps using different materials which are suitable for solidifying the particulate material and/or essentially filling out the pores.

4. The method according to claim 3, wherein the particulate material used to build the material layers includes a hydraulically binding material.

5. The method according to claim 3, wherein the method includes a step of treating the one or more component(s) with another material or material mixture, the step including essentially filling out the pores.

6. The method according to claim 3, wherein the method includes a step of age-hardening for at least 12 hours after the step of solidifying and before the step of contacting.

7. The method of claim 4, wherein a portion of the hydraulically binding material in the three-dimensional component(s) is unbound after the step of removing and prior to the step of contacting.

8. The method of claim 4, wherein the one or more component are brushed or sprayed with the water-containing medium or dipped in the water-containing medium.

9. The method of claim 8, wherein the method comprises a step of treating the one or more components with heat and/or an air exchange after the step of contacting.

10. The method of claim 8, wherein the method comprises a step of subjecting the one or more components to gassing with CO.sub.2.

11. The method of claim 3, wherein the particulate material used to build the material layers is a hydraulically binding material; the method includes a step of treating the one or more components with another material or material mixture, the step including essentially filling out the pores; and the method includes a step of age-hardening for at least 12 hours after the step of solidifying and before the step of contacting.

12. The method of claim 11, wherein a portion of the hydraulically binding material in the one or more component(s) is unbound after the step of removing and prior to the step of contacting the one or more components are brushed or sprayed with the water-containing medium or dipped in the water-containing medium, and/or additionally treated with heat and/or an air exchange after the contacting step.

13. The method of claim 12, wherein the method includes the step of treating with the air exchange; and includes the subjecting the one or more components to gassing with CO.sub.2.

14. A material system, for producing a three-dimensional part by means of a layering technique, comprising: a first component being a hydraulically hardening material, and a second component being or containing an aqueous solution-containing material, which is hardened by the discharge of water; wherein the material system includes sand or artificial sands; a powdered material; and a polymer dispersion.

15. The material system of claim 14, wherein the a hydraulically hardening material is a cement or a gypsum.

16. The material system of claim 15, wherein the material system includes i) hollow glass balls; or ii) a powdery material selected from a sand, a silica sand, a stone dust, a sodium silicate, a potassium silicate, and a lithium silicate.

17. A method for producing one or more three-dimensional components by means of a layering technique comprising the steps of: applying material layers of the three-dimensional component(s) over a build platform; at least partially solidifying a first portion of the material layers, wherein the solidified areas at least partially have pores, and a second portion of the material layers is unbound; separating the second portion from the three-dimensional component(s); and contacting the three-dimensional component(s) with a water-containing medium, wherein a particulate material is used to build the material layers, the particulate material including a build material which binds or solidifies due to the introduction of the water-containing medium; wherein the particulate material used to build the material layers includes a hydraulically binding material; wherein the hydraulically binding material includes a cement or a gypsum; the water-containing medium is a water glass or a water-based plastic dispersion; the water-containing medium coats the one or more components on the outside; and the water-containing medium contains additional components including a polymer.

18. The method of claim 17, wherein the water-containing medium is an aqueous solution of sodium silicate, potassium silicate or lithium silicate; and the water-containing medium coats the surfaces of the pores.

19. The method of claim 18, wherein the water-containing medium essentially fills out the pores; the quantity of the water-containing medium is selected in such a way that it is sufficient to essentially completely bind and solidify the particulate material used to build the material layers; and the particulate material is essentially no longer water-soluble after the binding.

20. A method for producing one or more three-dimensional components by means of a layering technique comprising the steps of: layering a powder build material containing a hydraulic binder to form a layer; selectively solidifying at least a portion of the layer by applying water to the portion in a quantity insufficient to completely bind the hydraulic binder so that the portion of the layer has unbound hydraulic binder, repeating the layering and selectively solidifying steps until a partially bound product is formed, removing unsolidified powder from the product and then contacting the partially bound product with a water containing medium to react with the unbound hydraulic binder in the partially bound product.

Description

BRIEF DESCRIPTION OF THE FIGURES:

(1) FIG. 1: shows a schematic representation of the components of a powder-based 3D printer in a sectional isometric view;

(2) FIG. 2: shows a schematic representation of a porous body, which includes non-hydrated or only partially hydrated cement particles;

(3) FIG. 3: shows an immersion bath of water glass.

(4) Other details and one preferred exemplary embodiment of the method are discussed below.

EXAMPLE

(5) Producing a molded part using the method according to the invention

(6) In the first step, a particulate material is applied in a thin layer to a building platform. In this preferred specific embodiment, the particulate material comprises silica sand (200) having an average grain size of 140 m. Before being applied, this sand is dried until the residual moisture is less than 0.3 wt. %. A cement grain mixture (201), which is adapted to the pore space, is added to this sand mixture. The reactivity of this cement may be adapted. The layer thickness in this process is 0.25 mm.

(7) Pyrogenic silicic acid in a proportion of 0.5 wt. % is also added to modify the flowability of the particle mixture. The cement may be, for example, a CA270-type calcium aluminate cement from Almatis or an Alphabond 300 from Almatis.

(8) The binding fluid contains a silicate in order to adjust the printability. The latter is present in an aqueous solution. In addition Surfynol 440 surfactants are used to further optimize the fluid for ink-jet print heads.

(9) In total, liquid binder in a proportion of 20 wt. % with respect to the particulate material quantity is added during the build process. The cement suffers from lack of water and thereby only partially hardens (203).

(10) After printing, the building process is paused, and the molded part rests in the powder for 24 hours. No special ventilation measures are taken. The cement continues to dry out, due to the diffusion effects in the powder surrounding the components. This, in turn, is useful for the partial hydration.

(11) Unpacking must take place carefully, since the structural body has only green strength. Deposits are removed with the aid of a hard brush in a first step. Afterward, component (103) is carefully blasted with sand.

(12) This part (103) is dried for another 24 hours in a circulating air oven at a temperature of 40 C. This further reduces the residual moisture.

(13) The infiltration takes place after this step. Potassium silicate 28/30, for example, may be used as infiltrate (300). It may be applied with a brush. The penetration performance may be improved by preheating the mold. Another good option is to dip component (103) into a bath (301) of the infiltrate, since the partially hydrated cement is not water-soluble.

(14) This procedure is repeated directly until the infiltrate exits component (103) again. The strength-increasing effect may be intensified thereby.

(15) Component (103) treated in this manner is age-hardened in air for another day. The strength has now increased significantly. The drying process was completed to a large extent due to subsequent hydration of the cement. This process may be accelerated with the aid of heat. The solidification of the surface may be accelerated by air draft.

(16) According to the invention, component (103) is now solidified and condensed. Other layers having infiltration material may now be easily applied for the purpose of complete sealing or decoration. These layers may be water glass layers, which harden quickly in thin layers. However, polymers which are optimized for outdoor areas may also be used.

LIST OF REFERENCE NUMERALS

(17) 100 Binder dosing device

(18) 101 Powder coater

(19) 102 Building platform

(20) 103 Component (3D molded part)

(21) 104 Build space boundary

(22) 107 Powder layers

(23) 200 Sand particles

(24) 201 Non-hydrated cement

(25) 202 Hydrated cement

(26) 203 Solidified area

(27) 300 Immersion bath

(28) 301 Infiltrate