3 ms·

As a ceramicist it'd be difficult to 3d print with because the kinds of temperatures you can reach even with heavily fluxed silica is still extremely high. I fi

As a ceramicist it'd be difficult to 3d print with because the kinds of temperatures you can reach even with heavily fluxed silica is still extremely high. I fire bisque at cone 04 which is approximately 1060C / 1940F and that's considered low fire, only extremely heavily fluxed glazes (usually pure frit or equivalent) melt at that level. Putting 3d printing concepts on the table, though, you could definitely see something like a sintered bed printer using a laser to print it, but then you wouldn't get anything close to the standard FDM style print.

Gravityloss 1y ago
I also assume directional solidification is really important for basalt, like for glass fibers and others. That's hard to achieve for bulk objects but easy for fibers.
positron26 1y ago
Fundamentally, if the nozzle temperatures can't possibly withstand what they are extruding without eroding, we can either: - balance an exothermic reaction (self-propagating high-temperature synthesis) to occur just after leaving the nozzle - externally apply the heat with laser or plasma arc etc The limit of externally applying heating is when the heat flux has to be so high that some material vaporizes and pops. An exothermic reaction within the material overcomes this limitation.
- jaggederest 1y ago
  The other alternative is like current state of the art 3d printing ceramics - you either replace some high percentage of the filament with clay and fire it as a post processing step and it burns off the plastic, or print a clay/water slurry directly and fire it after drying. But I don't think we'd end up with the basalt being very filamentous.
  - positron26 1y ago
    If the binder that gives you something printable at low temperature doesn't integrate into the final result through chemical reaction, you are almost assuredly going to get a high porosity mess where the binder had to vaporize out. If instead the binder and precursor can melt, react, and expand into a solid that precipitates out because of a super high melting point, the expansion will ensure that you get a fully dense part that can be machined back down.
kragen 1y ago
Felsic lavas can melt at 750° and even below, and prehistoric terra cotta ceramic is often fired at such low temperatures. That's still quite a bit cozier than nylon or PET, of course.
- jaggederest 1y ago
  Yes, but I think for 3d printing purposes you'd probably have insufficient fusion even at those temperatures. I print well above the melting point or you get layer separation. It'd definitely be a fun experiment to try though!
  - kragen 1y ago
    "Well above the melting point" usually means 60° or less, which is more significant going from 195° to 245° than going from 650° than to 710°. These temperatures make it a significantly trickier engineering problem; ideally, your nozzle would retain its shape at those temperatures despite containing a lot of pressure, not be corroded by the lava you're squeezing through it, not be abraded by any zircon grains that snuck into your melt, and not oxidize on the outside from the temperature when it's exposed to air. I'm pretty sure you could make a zirconia nozzle work if it was thick enough, but I don't think ruby, sapphire, or diamond would last very long. Probably something like inconel would also work, but I don't think 304 or 316 would.
    - jaggederest 1y ago
      It'd be a lot more than 60C - the goal is to keep the material from cooling past the melting point by the time it's been deposited, and thus the important factor is the rate of energy loss, which is dramatically accelerated in a temperature differential of, say, 650C instead of say 145C - so I'd guess you'd want about 150C - 300C difference. I'd bet inconel and other high temperature alloys would be eroded very quickly, anything that's fluxed enough to melt below 1000C is going to be extremely corrosive. Hot molten sodium hydroxide levels of corrosive. Fun to think about though, a serious materials challenge for sure.

Gravityloss 1y ago

I also assume directional solidification is really important for basalt, like for glass fibers and others. That's hard to achieve for bulk objects but easy for fibers.

positron26 1y ago

Fundamentally, if the nozzle temperatures can't possibly withstand what they are extruding without eroding, we can either: - balance an exothermic reaction (self-propagating high-temperature synthesis) to occur just after leaving the nozzle - externally apply the heat with laser or plasma arc etc The limit of externally applying heating is when the heat flux has to be so high that some material vaporizes and pops. An exothermic reaction within the material overcomes this limitation.

jaggederest 1y ago
The other alternative is like current state of the art 3d printing ceramics - you either replace some high percentage of the filament with clay and fire it as a post processing step and it burns off the plastic, or print a clay/water slurry directly and fire it after drying. But I don't think we'd end up with the basalt being very filamentous.
- positron26 1y ago
  If the binder that gives you something printable at low temperature doesn't integrate into the final result through chemical reaction, you are almost assuredly going to get a high porosity mess where the binder had to vaporize out. If instead the binder and precursor can melt, react, and expand into a solid that precipitates out because of a super high melting point, the expansion will ensure that you get a fully dense part that can be machined back down.

kragen 1y ago

Felsic lavas can melt at 750° and even below, and prehistoric terra cotta ceramic is often fired at such low temperatures. That's still quite a bit cozier than nylon or PET, of course.

jaggederest 1y ago
Yes, but I think for 3d printing purposes you'd probably have insufficient fusion even at those temperatures. I print well above the melting point or you get layer separation. It'd definitely be a fun experiment to try though!
- kragen 1y ago
  "Well above the melting point" usually means 60° or less, which is more significant going from 195° to 245° than going from 650° than to 710°. These temperatures make it a significantly trickier engineering problem; ideally, your nozzle would retain its shape at those temperatures despite containing a lot of pressure, not be corroded by the lava you're squeezing through it, not be abraded by any zircon grains that snuck into your melt, and not oxidize on the outside from the temperature when it's exposed to air. I'm pretty sure you could make a zirconia nozzle work if it was thick enough, but I don't think ruby, sapphire, or diamond would last very long. Probably something like inconel would also work, but I don't think 304 or 316 would.
  - jaggederest 1y ago
    It'd be a lot more than 60C - the goal is to keep the material from cooling past the melting point by the time it's been deposited, and thus the important factor is the rate of energy loss, which is dramatically accelerated in a temperature differential of, say, 650C instead of say 145C - so I'd guess you'd want about 150C - 300C difference. I'd bet inconel and other high temperature alloys would be eroded very quickly, anything that's fluxed enough to melt below 1000C is going to be extremely corrosive. Hot molten sodium hydroxide levels of corrosive. Fun to think about though, a serious materials challenge for sure.