Binder compositions for additive manufacturing comprising low molecular weight polymers including acrylic acid repeat units
Methods of additive manufacturing, binder compositions for additive manufacturing, and articles produced by and/or associated with methods of additive manufacturing are generally described.
1. A method of additive manufacturing a metal-based composite structure by binder jet printing, the method comprising:
depositing a first layer of metal powder, the metal powder comprising steel;
depositing a binder composition on at least a portion of the first layer of metal powder, the binder composition comprising water and a low molecular weight polymer including an acrylic acid repeat unit, wherein the binder composition has a pH of greater than or equal to 7; and
drying and/or cross-linking at least the binder composition deposited on the first layer of the metal powder, thereby forming a metal-based composite structure.
2. The method of claim 1 , wherein the low molecular weight polymer has a weight average molecular weight of less than or equal to 40 kDa.
3. The method of claim 1 , wherein the metal-based composite structure has a flexural strength of greater than or equal to 2 MPa.
4. The method of claim 3 , wherein the flexural strength is that measured by a three-point bending test.
5. The method of claim 3 , wherein the flexural strength is that measured by a four-point bending test.
6. The method of claim 1 , wherein the binder composition has a viscosity of less than or equal to 20 cP at a printing temperature.
7. The method of claim 1 , wherein the wt % of the low molecular weight polymer in the binder composition is greater than or equal to 1 wt % and less than or equal to 40 wt %.
8. The method of claim 1 , wherein the depositing step comprises thermally depositing the binder composition, and wherein the viscosity of the binder composition is greater than or equal to 1 cP and less than or equal to 10 cP at a printing temperature.
9. The method of claim 1 , wherein the depositing step comprises piezoelectrically depositing the binder composition, and wherein the viscosity of the binder composition is greater than or equal to 3 cP and less than or equal to 30 cP at a printing temperature.
10. The method of claim 1 , comprising cross-linking the binder composition using heat, UV light, and/or microwave radiation.
11. The method of claim 1 , further comprising depositing a second layer of metal powder on the first layer of metal powder after the binder composition has been deposited thereon and prior to drying or cross-linking the binder composition deposited on the first layer of the metal powder.
12. The method of claim 11 , further comprising depositing the binder composition on at least a portion of the second layer of metal powder prior to drying or cross-linking the binder composition deposited on the first layer of the metal powder.
13. The method of claim 1 , further comprising depositing a second layer of metal powder on the first layer of metal powder after drying and/or cross-linking the binder composition deposited on the first layer of the metal powder.
14. The method of claim 13 , further comprising depositing the binder composition on at least a portion of the second layer of metal powder.
15. The method of claim 1 , further comprising heating the metal-based composite structure in an environment having a temperature of greater than or equal to 700° C. and less than or equal to 1400° C.
16. The method of claim 1 , wherein the steel comprises a ferrous alloy having a chromium content of greater than or equal to 2 wt %.
17. The method of claim 1 , wherein the steel comprises a ferrous alloy having a chromium content of less than or equal to 2 wt %.
18. A method of additive manufacturing a metal-based composite structure by binder jet printing, the method comprising:
depositing a first layer of metal powder, the metal powder comprising steel;
depositing a binder composition on at least a portion of the first layer of metal powder, the binder composition comprising water and a low molecular weight polymer including an acrylic acid repeat unit, wherein the binder composition has a pH of greater than or equal to 4; and
cross-linking at least the binder composition deposited on the first layer of the metal powder using heat, UV light, and/or microwave radiation, thereby forming a metal-based composite structure, wherein the acrylic acid repeat unit is esterified during the cross-linking.
19. The method of claim 18 , wherein the cross-linking is performed using heat.
20. The method of claim 18 , wherein the low molecular weight polymer has a weight average molecular weight of less than or equal to 40 kDa.
21. The method of claim 18 , wherein the binder composition has a viscosity of less than or equal to 20 cP at a printing temperature.
22. The method of claim 18 , wherein the wt % of the low molecular weight polymer in the binder composition is greater than or equal to 1 wt % and less than or equal to 40 wt %.
23. The method of claim 18 , wherein the depositing step comprises thermally depositing the binder composition, and wherein the viscosity of the binder composition is greater than or equal to 1 cP and less than or equal to 10 cP at a printing temperature.
24. The method of claim 18 , wherein the depositing step comprises piezoelectrically depositing the binder composition, and wherein the viscosity of the binder composition is greater than or equal to 3 cP and less than or equal to 30 cP at a printing temperature.
25. The method of claim 18 , further comprising heating the metal-based composite structure in an environment having a temperature of greater than or equal to 700° C. and less than or equal to 1400° C.