Coated powder particles for producing three-dimensional bodies by means of a layer constituting method

• US 20060251535A1
• Filed: 02/13/2004
• Published: 11/09/2006
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Jialin Shen, Rolf Pfeifer, Voxeljet AG
• Original Assignee: Daimler AG (Mercedes-Benz Group AG)
• Inventors: Pfeifer, Rolf, Shen, Jialin
• Granted Patent: US 7,722,802 B2
• Time in Patent Office: Days
• US Class Current: 419/36
• CPC Class Codes: B22F 1/102 Metallic powder coated with organic material
• CPC Class Codes: B22F 1/148 Agglomerating
• CPC Class Codes: B22F 1/16 Metallic particles coated with a non-metal coated with lubricating or binding agents or with organic material B22F1/10
• CPC Class Codes: B22F 10/12 by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP]
• CPC Class Codes: B22F 10/16 by embedding the binder within the powder bed
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B29C 41/003 characterised by the choice of material
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/165 using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
• CPC Class Codes: B29C 67/24 characterised by the choice of material
• CPC Class Codes: B29K 2105/0097 Glues or adhesives, e.g. hot melts or thermofusible adhesives
• CPC Class Codes: B29K 2105/045 with open cells
• CPC Class Codes: B29K 2105/251 Particles, powder or granules expandable particles B29K2105/046
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 70/10 Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• CPC Class Codes: C22C 32/0015 with only single oxides as main non-metallic constituents
• CPC Class Codes: C22C 32/0047 with carbides, nitrides, borides or silicides as the main non-metallic constituents
• CPC Class Codes: Y02P 10/25 Process efficiency

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.

Claims

1. A coated powder material for generative rapid prototyping processes, the powder material comprising:

individual particles or granules,

wherein the individual particles or granules are respectively coated, the coating containing an activatable adhesive, and

wherein the coating additionally contains sinterable and/or glass-forming fine-grained material.

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 particles or granules, wherein the individual 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 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 particles or granules, wherein the individual 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.

17. A method for producing a sintered body from a powder material by a rapid prototyping process, 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 particles or granules, wherein the individual 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 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%, wherein

sintering the green compact produced by means of the rapid prototyping process below the sintering temperature or glass transition temperature of the powder material and above that of the fine-grained material contained in the coating.

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.