Newbie question or idea - FDM into a non-air medium

I was finding out about different materials, and about some of the limitations on their use in extruders. I am new to 3d printing, but I am familiar with robotics, computing, Microcontrollers and electronics - the sides of this other than the material science stuff involved.

I came to understand about phase change diagrams and different substances - some of the plastics, and with metals how some alloys may have different characteristics, one of the major issues as I understand it are the relatively short phase transitions of metals. The other problem was apparently that the nozzle is dissolved and eroded by heated molten metal or the heat needed rapidly oxidises stuff.

So my question is this - please let me know if it is fundamentally flawed, or I am missing something, but printing is done onto a bed, through air - plain air. What if some other substance, another medium, was used for the print bed - bathed in some kind of fluid. It would require some thought - viscosity, being inert, would this impede the motion of the nozzle, thermal conductivity of it.
Could techniques used for sous vide cooking with Arduino's be used to maintain relatively stable temperatures of this medium and keep stuff just tacky enough coming out of the nozzle?

It just struck me that altering the parameters of the problem might make it easier to consider filament and nozzle types to print in other kinds of material.

My own interest here lies in conductive printing - if a part could be printed with conductors in place with multi-nozzle printing then I can see a multitude of interesting uses. The current conductive filaments have such high resistance to render them pretty useless.

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Reprappro Ormerod2 (528.2, Duet 0.6, firmware 1.18.1 (2017-04-09), web interface Christian Hammacher 1.15a, Cura) & CNC 3020 (GRBL)

My first though was that pushing a molten metal through a liquid (water, oil etc.) had too many problems, but I wonder if the Leidenfrost Effect - which puts a layer of boiling liquid between a hot object and a liquid - may make it a practical proposition. My guess is that you would have to have a very well insulated hot end and extruded metal well above its melting point.

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leadinglights
My first though was that pushing a molten metal through a liquid (water, oil etc.) had too many problems, but I wonder if the Leidenfrost Effect - which puts a layer of boiling liquid between a hot object and a liquid - may make it a practical proposition. My guess is that you would have to have a very well insulated hot end and extruded metal well above its melting point.

The leidenfrost effect only works as long as the metal is above a certain temperature, after that, the water will contact the metal and absorb the heat causing it to cool down, and causing the water to instantly boil, another effect will be un-equal cooling of the metal which will probably cause warp, maybe not detectable with the human eye, but surely the metal will cool down faster on different spots.

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http://www.marinusdebeer.nl/

Hopefully I'm not misunderstanding but have you looked into the technology and materials used in vapor phase reflow soldering? Using a similar setup you should be able to print a tin based alloy that has a melt temperature just a bit higher than the vapor temperature but you would need to insulate the print nozzle to keep it hot enough to to keep the tin alloy flowing. There are several other factors (problems) that would have to be overcome but probably nothing insurmountable.

For printed conductors inside of a printed object wouldn't it be possible to print an object with ceramic clay and use paladium or platinum based thick film inks to print the conductors then just fire the finished object? Or would there be too much solvent in the inks that would need to be evaporated before a firing? If it's possible then you would be able to print the conductor traces, most resistors and some capacitors of your circuit leaving only a few components that would need to be soldered to the printed pads later.

A word of warning, this could get real expensive in a hurry. Back when I used to be involved in thick film printing, the really cheap inks started at a bit over a thousand dollars an ounce. I think the vapor phase chemicals currently run about 25 to 30 dollars an ounce. There is also the fact that you would be playing with some pretty nasty chemicals.

This idea has come up a few times before. It seems like an interesting thing to investigate. You might get some additional info from this thread: Under Water Printing, and also this post by KalleP in a thread about wax printing. There is also this example where structures are made by 3D printing water droplets under oil: Liquid Scaffolds From a 3D Printer.

If you are interested in printing metal structures, you might try using molten flux as the submerging liquid.

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dannystaple
Could techniques used for sous vide cooking with Arduino's be used...?

Yes, but you do not need to invoke sous vide cooking: the plain old Arduino-based temperature controllers used for things like the hot end and heated bed would work fine!