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Ceramics can be 3D-printed [1]. The printed product is a paste of ceramic powder + binder that must be sintered (heated so the organic binder burns away and the

Ceramics can be 3D-printed [1]. The printed product is a paste of ceramic powder + binder that must be sintered (heated so the organic binder burns away and the ceramic particles fuse together into a strong, dense body). The as-printed part shrinks a bit during sintering, so you've got to account for that as well. [1] http://robocasting.net/index.html http://robocasting.net/index.html

Scaevolus 13y ago
Are there any connective materials that could withstand the sintering process?
- pmahoney 13y ago
  It's been a while since I was in that field... Typical sintering temperatures are around 1000 to 1300 degC. Usually about 2/3 the melting point of the ceramic; enough to promote ionic motion leading to fusing of the powder in a reasonable amount of time (one-two hours for my lab-sized samples). Various techniques for lowering the sintering temperature are: - Increase the sintering time. The time required to achieve a given density (say, 95%) increases somewhat rapidly as you decrease the temperature - Add a glass to the ceramic powder. The glass melts and essentially lubricates things so there is sufficient motion at lower temperature. - Start with finer ceramic powder. This has higher surface area for a given amount, which is an energetically unfavorable state (the fused state has lower surface energy and is thus more favorable). - Apply pressure while sintering [3] - Live with less density. Pottery needn't be 95+% dense. Clay (or playdough) can be useful for some situations (not bullet-proof vest I imagine) if just let to air dry. - Other clever things I don't know about. I know there are metallic substances that can survive sintering processes, as in multi-layer ceramic capacitors, where a sandwich of ceramic/electrode/ceramic/electrode is sintered, but these tend to be the expensive metals that don't react with oxygen [1]. The polymer with the highest melting point I know of is Kapton [2], melting around 400 degC, which is quite a way from the 800 or so degC you might see after adding glass to your ceramic powder... All that said, most ceramics are not that tough in that they shatter when impacted. If you must 3D print bullet-proof armor, and are sure you can't print some kind of Kevlar-reinforced thing, then I'm not really sure what the best option is. [1] https://en.wikipedia.org/wiki/Ceramic_capacitor#Multi-layer_ceramic_capacitors_.28MLCC.29 https://en.wikipedia.org/wiki/Ceramic_capacitor#Multi-layer_... [2] https://en.wikipedia.org/wiki/Kapton https://en.wikipedia.org/wiki/Kapton [3] https://en.wikipedia.org/wiki/Hot_isostatic_pressing https://en.wikipedia.org/wiki/Hot_isostatic_pressing

Scaevolus 13y ago

Are there any connective materials that could withstand the sintering process?

pmahoney 13y ago
It's been a while since I was in that field... Typical sintering temperatures are around 1000 to 1300 degC. Usually about 2/3 the melting point of the ceramic; enough to promote ionic motion leading to fusing of the powder in a reasonable amount of time (one-two hours for my lab-sized samples). Various techniques for lowering the sintering temperature are: - Increase the sintering time. The time required to achieve a given density (say, 95%) increases somewhat rapidly as you decrease the temperature - Add a glass to the ceramic powder. The glass melts and essentially lubricates things so there is sufficient motion at lower temperature. - Start with finer ceramic powder. This has higher surface area for a given amount, which is an energetically unfavorable state (the fused state has lower surface energy and is thus more favorable). - Apply pressure while sintering [3] - Live with less density. Pottery needn't be 95+% dense. Clay (or playdough) can be useful for some situations (not bullet-proof vest I imagine) if just let to air dry. - Other clever things I don't know about. I know there are metallic substances that can survive sintering processes, as in multi-layer ceramic capacitors, where a sandwich of ceramic/electrode/ceramic/electrode is sintered, but these tend to be the expensive metals that don't react with oxygen [1]. The polymer with the highest melting point I know of is Kapton [2], melting around 400 degC, which is quite a way from the 800 or so degC you might see after adding glass to your ceramic powder... All that said, most ceramics are not that tough in that they shatter when impacted. If you must 3D print bullet-proof armor, and are sure you can't print some kind of Kevlar-reinforced thing, then I'm not really sure what the best option is. [1] https://en.wikipedia.org/wiki/Ceramic_capacitor#Multi-layer_ceramic_capacitors_.28MLCC.29 https://en.wikipedia.org/wiki/Ceramic_capacitor#Multi-layer_... [2] https://en.wikipedia.org/wiki/Kapton https://en.wikipedia.org/wiki/Kapton [3] https://en.wikipedia.org/wiki/Hot_isostatic_pressing https://en.wikipedia.org/wiki/Hot_isostatic_pressing