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I would imagine that burning off the polymer binder in the final processing step leads to significant volume change and porosity, which would be a major challen

by blix 6y ago

I would imagine that burning off the polymer binder in the final processing step leads to significant volume change and porosity, which would be a major challenge in many applications. I'm not seeing any information about how they approach these problems.

lucioperca 6y ago
See the publications of Frederik Kotz: https://scholar.google.de/citations?user=TQBKvzsAAAAJ&hl=de https://scholar.google.de/citations?user=TQBKvzsAAAAJ&hl=de Citing from the Nature publication: "The shrinkage of the part during the sintering process is isotropic and dependent on the solid loading (hence can be calculated; see Supplementary Information). The sintering shrinkage for stereo- lithography and microstereolithography does not depend on the scale of the sintered parts (for example, the honeywell structure in Fig. 1a with a solid loading of 37.5 vol% showed the expected linear shrinkage of 27.88% in height from 3.05 mm to 2.2 mm and width from 2.177 cm to 1.57 cm)." "During a final sintering step at 1,300 °C the density of the brown part is increased (ρ final = 2.2 g cm −3 ) to that of high-quality fused silica glass with no remaining porosity and no cracks." But of course these processes could be quite sensitive to hard to control parameters.
- blix 6y ago
  If they can reliably get those densities and shrinkages from this procedure that is quite impressive. After a brief look through the papers, there is some promising evidence but I'd like to see a more thorough characterization, especially demonstrating spatial homogeneity of porosity and shrinkage. It's certainly a very interesting technology, and I think it could potentially be applicable to materials beyond glass.
  - jlokier 6y ago
    > I think it could potentially be applicable to materials beyond glass. It's been used for quite a few years already. Precious metal clay is basically this. You can 3d print with it, then fire it and it turns into solid metal.
    - blix 6y ago
      What's most interesting to me is subtractive manufacturing of ceramics. From what I've seen in metals, there's a preference for powder bed technologies over binder technologies. But it's not like I have a wide scope of current industry or research.

by blix 6y ago

lucioperca 6y ago

See the publications of Frederik Kotz: https://scholar.google.de/citations?user=TQBKvzsAAAAJ&hl=de https://scholar.google.de/citations?user=TQBKvzsAAAAJ&hl=de Citing from the Nature publication: "The shrinkage of the part during the sintering process is isotropic and dependent on the solid loading (hence can be calculated; see Supplementary Information). The sintering shrinkage for stereo- lithography and microstereolithography does not depend on the scale of the sintered parts (for example, the honeywell structure in Fig. 1a with a solid loading of 37.5 vol% showed the expected linear shrinkage of 27.88% in height from 3.05 mm to 2.2 mm and width from 2.177 cm to 1.57 cm)." "During a final sintering step at 1,300 °C the density of the brown part is increased (ρ final = 2.2 g cm −3 ) to that of high-quality fused silica glass with no remaining porosity and no cracks." But of course these processes could be quite sensitive to hard to control parameters.

blix 6y ago
If they can reliably get those densities and shrinkages from this procedure that is quite impressive. After a brief look through the papers, there is some promising evidence but I'd like to see a more thorough characterization, especially demonstrating spatial homogeneity of porosity and shrinkage. It's certainly a very interesting technology, and I think it could potentially be applicable to materials beyond glass.
- jlokier 6y ago
  > I think it could potentially be applicable to materials beyond glass. It's been used for quite a few years already. Precious metal clay is basically this. You can 3d print with it, then fire it and it turns into solid metal.
  - blix 6y ago
    What's most interesting to me is subtractive manufacturing of ceramics. From what I've seen in metals, there's a preference for powder bed technologies over binder technologies. But it's not like I have a wide scope of current industry or research.