Method for the additive laser-induced production of a main part by means of slip casting
A method for the additive production of a ceramic main part has the following steps: providing a slip of ceramic base material particles suspended in a liquid phase; producing a slip layer; orienting the radiation of a laser light source onto a section of the slip layer; evaporating liquid phase out of the slip layer in the section of the slip layer onto which the radiation of the laser light source is oriented or was oriented; forming a section of the ceramic main part in the slip layer in a sinter-free manner; optionally repeating the steps of producing a slip layer, orienting the radiation, evaporating the liquid phase, and forming a section of the main part in a sinter-free manner until the ceramic main part is provided; and separating the ceramic main part from the slip.
1. A process for the additive manufacture of a green ceramic body, the process comprising:
(a) providing a slip formed with particles of a structure-forming ceramic material suspended in a liquid phase,
(b) wherein the slip does not comprise any organic or inorganic additives which are gelled or crosslinked by thermal or optical methods;
(c) producing a slip layer;
(d) directing radiation from a laser light source onto a section of the slip layer, thereby selectively sectionally exposing the slip-layer section to the laser radiation,
(e) wherein said laser radiation vaporizes liquid phase from the slip-layer section onto which the laser radiation from the laser light source is or has been oriented,
(f) wherein the vaporization causes an attractive interaction between particles of the structure-forming ceramic material in the slip-layer section to form agglomerations and the agglomerated particles are not resuspended in the liquid phase in the slip-layer section; and
(g) wherein said laser radiation further results in a sinter-free formation of a section of the green ceramic body in the slip layer;
(h) optionally repeating the steps of producing, directing, vaporizing, and sinter-free formation until the green ceramic body is obtained; and
(i) subsequently separating the non-sintered green ceramic body from the slip.
2. The process according to claim 1 , further comprising drying the non-sintered green ceramic body after the non-sintered green ceramic body has been separated from the slip.
3. The process according to claim 1 , wherein a proportion of the structure-forming ceramic material in the slip is at least 60% by volume.
4. The process according to claim 1 , wherein a proportion of organic and/or inorganic auxiliaries in the slip does not exceed 5% by volume.
5. The process according to claim 1 , wherein a proportion of organic auxiliaries in the slip does not exceed 3% by volume; and/or
the slip is an aqueous slip and is substantially free from organic solvents; or
the liquid phase of the slip comprises an organic solvent that can be vaporized to leave no residue.
6. The process according to claim 1 , wherein the resultant slip layer has a thickness in a range from 25 μm to 2 mm.
7. The process according to claim 1 , which comprises causing the laser light source to emit radiation in a wavelength range from 520 nm to 10 μm.
8. The process according to claim 7 , which comprises causing the laser light source to emit radiation at least of a wavelength in a wavelength range from 600 nm to 3 μm and/or providing a configuration in which the laser light source inputs a proportion of at least 1% of the laser power incident on the slip layer directly into the liquid phase.
9. The process according to claim 8 , which comprises providing a laser light source emitting radiation at least of a wavelength in a wavelength range of 1970 nm±100 nm.
10. The process according to claim 1 , which comprises providing a laser light source selected from the group consisting of an NdYAG laser, a Thulium fiber laser, and a laser diode.
11. The process according to claim 1 , wherein the step of directing radiation comprises focusing laser radiation onto or into the slip layer and/or guiding a directed and/or focused laser beam along an exposure trace that proceeds on or in the slip layer.
12. The process according to claim 11 , wherein the exposure trace is represented, at least in sections, by a continuous and/or interrupted line.
13. The process according to claim 11 , wherein the exposure trace is represented, at least in sections, as a shape selected from the group consisting of a lattice, a grid, a spiral, an ellipse, a circle, a group of lines and a pattern.
14. The process according to claim 1 , where a dimension of oriented and/or focused laser radiation on a surface of the slip layer at least in one direction lies in a range from 25 μm to 25 mm.
15. The process according to claim 14 , which comprises moving the directed and/or focused laser radiation on or in the slip layer with a velocity in a range from 1 mm/s to 20 m/s.
16. The process according to claim 1 , wherein the vaporization step is effected to bring about sinter-free formation of the green-body section in the slip layer, where the liquid phase cannot achieve resuspension of the particles forming the green-body section.
17. The process according to claim 16 , wherein a vaporization is followed by capillary-force-driven flow of the liquid phase into the particle aggregate and/or into the slip-layer section onto which the radiation from the laser light source is or has been directed.
18. The process according to claim 11 , where the exposure trace is derived from data from a virtual slice method.
19. The process according to claim 1 , where the slip layer includes at least an area of 100 mm 2 .
20. The process according to claim 1 , wherein a projection area of an exposure trace followed by the laser radiation for the sinter-free formation of a green-body section in the slip layer on the slip layer or in a plane of the slip layer is at most half as large as the area of the cross section of the resultant green-body section on the slip layer or in the plane of the slip layer.