Coated powder particles for producing three-dimensional bodies by means of a layer constituting method
First Claim
1. A coated powder material for a two step generative rapid prototyping processes involving a first step of forming a green compact followed by a second step of sintering, the powder material comprising:
- individual core particles or granules,wherein the individual core particles or granules are respectively coated, the coating containing an activatable adhesive,wherein the coating additionally contains sinterable and/or glass-forming fine-grained spacer material,wherein the activatable adhesive is activatable in the first step of forming the green compact without changing the physical properties of the individual core particle or granule or the fine grained spacer material,wherein the average particle size of the fine-grained material lies below 30% of the particle size of the core particles, andwherein the size and/or composition of the sinterable and/or glass-forming fine-grained spacer material is such that upon sintering the fine grained spacer material sinters earlier than the individual core particles or granules.
4 Assignments
0 Petitions
Accused Products
Abstract
The invention relates a powder material consisting of coated particles for a powder-based rapid generative prototyping methods, in particular by compressing a 3D binder. Said powder material consists of individual plastic, metal and/or ceramic particles and/or granules. A coating essentially consists of an adhesive agent which can be activated by a liquid binder, light or laser light, and of sinterable or glass-forming fine-grained material. Said invention also relates to a method for compressing 3D binder with the aid of an organic solvent having a water content less than 45% and to sintered bodies, in particular for moulding or precision mechanical engineering, which are fixed to each other by sintering or glass formation from a fine grained material.
60 Citations
20 Claims
-
1. A coated powder material for a two step generative rapid prototyping processes involving a first step of forming a green compact followed by a second step of sintering, the powder material comprising:
-
individual core particles or granules, wherein the individual core particles or granules are respectively coated, the coating containing an activatable adhesive, wherein the coating additionally contains sinterable and/or glass-forming fine-grained spacer material, wherein the activatable adhesive is activatable in the first step of forming the green compact without changing the physical properties of the individual core particle or granule or the fine grained spacer material, wherein the average particle size of the fine-grained material lies below 30% of the particle size of the core particles, and wherein the size and/or composition of the sinterable and/or glass-forming fine-grained spacer material is such that upon sintering the fine grained spacer material sinters earlier than the individual core particles or granules.
-
-
2. The coated powder material as claimed in claim 1, wherein the sintering temperature and/or the glass transition temperature of the fine-grained material lies below the sintering temperature or glass transition temperature of the powder material.
-
3. The coated powder material as claimed in claim 1, wherein the fine-grained material comprises at least one oxide, carbide or nitride of the elements Si, B, Ti or Al.
-
4. The coated powder material as claimed in claim 3, wherein the fine-grained material contains silicates, borosilicates or alumosilicates.
-
5. The coated powder material as claimed in claim 1, wherein the fine-grained material comprises at least one metal or metal salt.
-
6. The coated powder material as claimed in claim 1, wherein the fine-grained material is formed by nanoparticles and/or microparticles with an average grain size below 5 μ
- m.
-
7. The coated powder material as claimed in claim 1, wherein the sintering temperature and/or glass transition temperature of the fine-grained material is at least 30°
- C. below the sintering temperature and/or glass transition temperature of the powder material.
-
8. The coated powder material as claimed in claim 1, wherein the adhesive comprises an adhesive which is soluble in a binder liquid.
-
9. The coated powder material as claimed in claim 8, wherein the adhesive is composed of organic or organo-metallic polymers of low water solubility.
-
10. The coated powder material as claimed in claim 9, wherein the adhesive is swellable or soluble in a binder liquid of organic solvents with a water content below 45%.
-
11. The coated powder material as claimed in claim 1, wherein the adhesive comprises a polymer which has a melting or sintering temperature in the range from 50 to 250°
- C.
-
12. The coated powder material as claimed in claim 1, wherein the adhesive comprises a light-curing binder.
-
13. A generative rapid prototyping process for producing a body from a powder material, comprising the steps of
discharging a layer of powder on an underlying surface, moistening defined regions of the layer with a binder liquid for the activation of a binder, selecting the binder liquid from organic solvents and having a water content below 45%, wherein the powder material comprises individual core particles or granules, wherein the individual core particles or granules are respectively coated, the coating containing an activatable adhesive, the coating additionally containing sinterable and/or glass-forming fine-grained material, wherein the average particle size of the fine-grained material lies below 30% of the particle size of the core particles, and wherein said fine grained material lying against the contact surfaces of the individual particles or granules inhibits shrinkage of the body upon activation of the binder, and wherein the adhesive: -
(a) comprises an adhesive which is soluble in a binder liquid, (b) is composed of organic or organo-metallic polymers of low water solubility, and/or (c) is swellable or soluble in a binder liquid of organic solvents with a water content below 45%.
-
-
14. The method as claimed in claim 13, wherein the proportion of insoluble constituents in the binder liquid lies below 5% by weight.
-
15. The method as claimed in claim 13, wherein the amount of binder liquid used for moistening the powder lies in the range from 5 to 70% by volume of the powder volume to be coated.
-
16. A generative rapid prototyping process for producing a body from a powder material coated with an adhesive, comprising the steps of:
-
discharging a layer of powder on an underlying surface, irradiating defined regions of the layer of powder with laser light, melting or sintering the adhesive, at least of the discharged layer of powder, by the laser irradiation, the energy of the laser light being insufficient to melt or sinter the powder material, wherein the powder material comprises individual core particles or granules, wherein the individual core particles or granules are respectively coated, the coating containing an activatable adhesive comprising a polymer which has a melting or sintering temperature in the range from 50 to 250°
C., and wherein the coating additionally contains sinterable and/or glass-forming fine-grained material, wherein the average particle size of the fine-grained material lies below 30% of the particle size of the core particles, and wherein said fine grained material lying against the contact surfaces of the individual particles or granules inhibits shrinkage of the body upon melting or sintering of the adhesive.
-
-
17. A method for producing a sintered body from a powder material by a rapid prototyping process followed by sintering, wherein the rapid prototyping process comprises:
-
discharging a layer of powder on an underlying surface, selecting the binder liquid from organic solvents and having a water content below 45%, moistening defined regions of the layer with a binder liquid for the activation of a binder, wherein the powder material comprises individual core particles or granules, wherein the individual core particles or granules are respectively coated, the coating containing an activatable adhesive, the coating additionally containing sinterable and/or glass-forming fine-grained spacer material, wherein the average particle size of the fine-grained material lies below 30% of the particle size of the core particles, such that the fine grained spacer material lies against the contact surfaces of the core particles or granules to minimize shrinkage upon liquification or removal of adhesive, and wherein the adhesive; (a) comprises an adhesive which is soluble in the binder liquid, (b) is composed of organic or organo-metallic polymers of low water solubility, and/or (c) is swellable or soluble in the binder liquid of organic solvents with a water content below 45%, and wherein the sintering process comprises; sintering the green compact produced by means of the rapid prototyping process for a time and temperature sufficient to liberate the coating and to sinter the fine grained spacer material contained in the coating, yet below the sintering or glass transition time and temperature of the core particles or granules.
-
-
18. The method for producing a sintered body as claimed in claim 17, wherein the sintered body is used in foundry practice or in mold making.
-
19. The method for producing a sintered body as claimed in claim 17, wherein the sintered body is used in precision engineering or in tool making.
-
20. The coated powder material as claimed in claim 1, wherein the particle diameter
of the fine particles is from 0.3 to 5% of the particle diameter of the powder particles or granules.
Specification