Method and apparatus for additive manufacturing

1. A method for forming a three-dimensional article through successive fusion of parts of at least one layer of a powder bed provided on a work table in a vacuum chamber, which parts corresponds to successive cross sections of the three-dimensional article, said method comprising the steps of:

applying a predetermined thickness of unfused powder particles on said work table in said vacuum chamber;

applying a coating material on at least a portion of said unfused powder particles while said unfused powder particles are inside said vacuum chamber and prior to fusing any portion of said powder particles, wherein said coating material (a) is at least partially covering said unfused powder particles, and (b) has at least one material characteristic that differs from a corresponding material characteristic of the unfused powder particles; and

after applying the coating material, fusing said unfused powder particles on said work table with an energy beam so as to form said at least one layer of said powder bed.

2. The method according to claim 1 , wherein said coating material is applied on said unfused powder particles while said pressure in said vacuum chamber is less than 1×10 −2 mbar.

3. The method according to claim 1 , further comprising the step of vibrating the work table while at least one of applying said coating material on said unfused powder particles or while said unfused powder particles are on said work table.

4. The method according to claim 1 , wherein said coating material is applied by a process selected from the group consisting of: sputtering, chemical vapor deposition, physical vapor deposition, laser ablation, resistive melting of a target, laser beam melting of a target, electron beam melting of a target, and any combination thereof.

5. The method according to claim 1 , wherein said at least one material characteristic of the coating material that differs with a corresponding material characteristic of the unfused powder particles is an electrical conductivity of the coating material.

6. The method according to claim 5 , wherein said electrical conductivity of the coating material is higher than an electrical conductivity of the unfused powder particles, said higher electrical conductivity of said coating material being configured for increasing the electrical conductivity of the unfused powder particles.

7. The method according to claim 1 , wherein said coating material further has at least one material characteristic in common with the material of the unfused powder particles.

8. The method according to claim 1 , further comprising the step of changing the material characteristics for at least one layer of the three-dimensional article by providing a predetermined thickness of said coating material on a predetermined portion of said unfused powder particles.

9. The method according to claim 1 , wherein:

said unfused powder particles are made of at least one of a ceramic material or a polymer material; and

said coating material is made of an electrically conductive material.

10. The method according to claim 1 , wherein said energy beam is at least one of an electron beam or a laser beam.

11. A method for forming a three-dimensional article through successive fusion of parts of at least one layer of a powder bed provided on a work table in a vacuum chamber, which parts corresponds to successive cross sections of the three-dimensional article, said method comprising the steps of:

applying a predetermined thickness of unfused powder particles on said work table in said vacuum chamber;

applying a coating material on at least a portion of said unfused powder particles while said unfused powder particles are inside said vacuum chamber and prior to fusing any portion of said unfused powder particles, wherein said coating material (a) is at least partially covering said unfused powder particles, and (b) has an electrical conductivity that differs from an electrical conductivity of the unfused powder particles; and

after applying the coating material, fusing said unfused powder particles on said work table with an energy beam so as to form said at least one layer of said powder bed.

12. The method according to claim 11 , wherein said coating material is applied on said unfused powder particles while said pressure in said vacuum chamber is less than 1×10 −2 mbar.

13. The method according to claim 11 , further comprising the step of vibrating the work table while at least one of applying said coating material on said unfused powder particles or while said unfused powder particles are on said work table.

14. The method according to claim 11 , wherein said coating material is applied by a process selected from the group consisting of: sputtering, chemical vapor deposition, physical vapor deposition, laser ablation, resistive melting of a target, laser beam melting of a target, electron beam melting of a target, and any combination thereof.

15. The method according to claim 11 , wherein said electrical conductivity of the coating material is higher than an electrical conductivity of the unfused powder particles, said higher electrical conductivity of said coating material being configured for increasing the electrical conductivity of the unfused powder particles.

16. The method according to claim 11 , wherein said coating material further has at least one material characteristic in common with the material of the unfused powder particles.

17. The method according to claim 11 , further comprising the step of changing the material characteristics for at least one layer of the three-dimensional article by providing a predetermined thickness of said coating material on a predetermined portion of said unfused powder particles.

18. The method according to claim 11 , wherein:

said unfused powder particles are made of at least one of a ceramic material or a polymer material; and

said coating material is made of an electrically conductive material.

19. The method according to claim 11 , wherein said energy beam is at least one of an electron beam or a laser beam.