POWDER FOR LASER SINTERING, AND USE

Abstract

A surface-modified powder for laser sintering that allows improved incoupling of the radiation energy of the laser. The surface-modified powder avoids problems arising in the laser sintering of materials having a low absorptance for the laser radiation. The surface-modified powder has particles having particle cores and having laser absorbers bonded to a surface of each particle core, the laser absorbers covering at least 25% of the surface of each particle core and having a higher absorptance for laser radiation for laser sintering than the particle core.

Claims

1.-18. (canceled)

19. A surface-modified powder for laser sintering, comprising particles, each of the particles having a particle core consisting of pure copper; and laser absorbers bound to a surface of each particle core, wherein the laser absorbers occupy the surface of each particle core to an extent of at least 25% and have a higher degree of absorption for laser radiation in the near infrared range for laser sintering with respect to the particle core, wherein the laser absorbers consist of metal hydroxides, are bound by physisorption to the surface of the each particle core, and have a degree of absorption of at least 20% for the laser radiation.

20. The surface-modified powder as claimed in claim 19, wherein the laser absorbers are present in molecular form.

21. The surface-modified powder as claimed in claim 19, wherein the laser radiation has a wavelength of 1064 nm.

22. A method of laser sintering, comprising: providing a surface-modified powder as claimed in claim 19 in a powder bed, and laser sintering the surface-modified powder in the powder bed.

23. The method of laser sintering claimed in claim 22, wherein the step of laser sintering comprises using an Nd:YAG laser or a fiber laser.

24. A method of producing a three-dimensional structure, comprising: providing a surface-modified powder as claimed in claim 19, and conducting selective laser sintering to form the three-dimensional structure.

25. The method of producing a three-dimensional structure claimed in claim 24, wherein the step of conducting selective laser sintering comprises using an Nd:YAG laser or a fiber laser.

26. A method of laser buildup welding, comprising: providing the surface-modified powder as claimed in claim 19; conducting the laser buildup welding using the surface-modified powder.

Description

[0025] The invention will be illustrated below with the aid of the figures. The figures show

[0026] FIG. 1 a schematic depiction of individual particles of the surface-modified powder for laser sintering and

[0027] FIG. 2 a schematic depiction to illustrate the use of the powder of FIG. 1 in selective laser sintering.

[0028] FIG. 1 shows a greatly enlarged, schematic depiction of only a few particles 2 of the surface-modified powder 1. The individual particles 2 have an irregular shape with an equivalent diameter D50 of about 30 μm.

[0029] Each particle 2 of the powder 1 consists of a particle core 3 to the surface 4 of which laser absorbers 5 are attached in molecular form. The laser absorbers 5 cover at least 30% of the surface 4 of each particle core 3.

[0030] The particle cores 3 consist, in particular, of pure copper having a low degree of absorption of about 5% for incident laser radiation having a wavelength of 1064 nm. The laser absorbers 5 are particles of a metal hydroxide, for example dicopper hydroxide phosphate, which has a very high degree of absorption for the incident laser radiation having a wavelength of 1064 nm.

[0031] The laser absorbers 5 are bound to the surface 4 of the particle cores 3 by physisorption. The attachment can, for example, be brought about by a process of mixing the particle cores 3 composed of copper and the laser absorbers 5.

[0032] The powder 1 which has been surface-modified in this way is used for laser sintering, in particular for selective laser sintering. The process of selective laser sintering is illustrated below with the aid of FIG. 2:

[0033] Selective laser sintering is an additive manufacturing process for producing a component 6 from the powder 1 by laser sintering using a laser 7. The geometric data of the component 6 to be produced have to be present as layer data. A laser scanner 10 is controlled by means of the layer data for the component 6 and transmits the laser radiation 11 of the laser 7 line-by-line in an intensity-controlled manner to the powder 1.

[0034] The powder 1 is firstly applied from a powder stock 13 as a layer having a layer thickness of from 20 to 40 μm (powder bed) over the full area of a building platform 8 using a powder-supplying piston 12 and a roller 9. The layer data of the component 6 are then sintered layer-by-layer under computer control in the powder bed so as to correspond to the layer contour of the component 6. The building platform 8 is lowered slightly before each step in order subsequently to apply the next layer of powder 1 from the powder stock using the roller 9. As an alternative, a doctor blade can be used.

[0035] Undercut contours can also be produced by the layerwise production of the component 6. Support structures are not necessary because the component 6 is supported by the surrounding powder 1 while it is being produced.

LIST OF REFERENCE NUMERALS

[0036] 1 Powder [0037] 2 Particle [0038] 3 Particle core [0039] 4 Surface [0040] 5 Laser absorber [0041] 6 Component [0042] 7 Laser [0043] 8 Building platform [0044] 9 Roller [0045] 10 Laser scanner [0046] 11 Laser radiation [0047] 12 Piston [0048] 13 Powder stock