Apr 262017
 

Had a thought for a sci-fi scene: a spaceship has taken a shellacking and needs internal bracing in a hurry. Our Hero leaps to the rescue with a can of Titanium Spray Foam: operates like a can of modern day foam insulation in a can, but the end result is foamed titanium rather than foamed hydrocarbon polymer. Something like this would be pretty obviously handy; with it you could turn a tent into a bomb shelter or, if you are kinda upset with someone, a dandy way to glue your hostage to a chair or bind their hands with something much more sturdy than handcuffs. But there’s a problem: how could this possibly work?

One obvious approach: your can sprays actual liquid hot molten titanium, foamed via the introduction of a high temperature inert gas such as argon. If the temperature is very precisely controlled and the foam comes out *just* above the melting point, as the argon outgasses the bulk temperature should drop just below “freezing” and the foam should solidify. The problems here are pretty obvious, not least of which is laying down foam that’s white hot.

Second obvious approach: it’s not actually titanium but some handwavy futuristic and extremely strong polymer, perhaps infused with carbon fibers or bits of graphene or some such. This is likely workable, but it has a host of potential problems. It might be dissolved with simple chemicals like alcohol, acetone or even water. It might have poor temperature issues… it melts at 100 celcius and bursts into flames at 140 degrees. And, again, it’s not actually titanium.

The goal would be a roughly room-temperature process that lays down titanium foam. Now, if there was some chemical that dissolved titanium like acetone dissolves polystyrene, and when the chemical evaporates  the titanium – like the polystyrene – returns to its solid state, then the process would seem simple. A two-part sprayer, one that has solvent-dissolved titanium in some sort of liquid polymer in one can, and another can with the curative for the polymer. Mix the two together, spray out as a foam; the polymers mix and form the bubbly matrix, viscous enough to hold the liquid titanium in place. The polymer foam sets, the titanium spreads into a thin film covering all the polymer bubbles; the solvent evaporates and leaves the titanium foam behind. Ta-da.

Sounds great, but again there are problems. First up: is there even in a theory an acetone/styrene equivalent solvent for titanium? Sure, there are acids that will dissolve metals, but when the acid evaporates what’s left behind is a sludge of goop that reduces to metal powder, not a solid mass of structural metal.

Secondly: let’s say you’ve got a titanium solvent. What are the chances that it would be a good idea to breathe that stuff in while it evaporates from your work area? If it melts titanium, chances are real good that it’ll glue all the rest of your spaceships metallic moving surfaces together. And, I dunno, reduce your DNA into a pile of constituent atoms.

So… any ideas?

 Posted by at 10:12 am
  • Herp McDerp

    How do you get down off an elephant? You don’t! You get down off a duck.

    Instead of foaming titanium, use an element with a higher atomic number that’s more amenable to being foamed. But be sure to use a radioactive isotope of that element for which the decay product is titanium. The end result will be titanium foam!

    There are some trivial problems with this approach (What if the half-life is on the
    order of picoseconds? How do you store it until you need it? Will anyone be bothered by that pesky radiation
    emission?), but I’m sure they can be overcome with appropriate Clarke’s Third Law technology. A good manager supplies the vision and grants the engineers the freedom to work out the details.

  • allen

    use the stereotypical nanobots. they do one thing…go from “stacked legos” to open-frame shapes that interconnect (pyramids possibly). the “can” is both storage and power source.

    done right it could be reusable. apply power, and they re-stack themselves into the more compact form.

    • Siergen

      Excellent idea! Just pay attention to the expiration date before usage, and make sure that you install all recommended software security updates at least quarterly.

      • allen

        or, place a “can” as part of the interior of every room. sort of like an airbag is hidden in the dashboard of a car. set certain parameters for activation..like exposure to vacuum. this would also work as an anti-boarding measure. fill hallways with “buckyfoam” that collapses on command. your guys can move around, the enemy is using boarding axes to chop every inch of space.

        back when I played a lot of RPG’s, the “traveller” system used something called a “sandcaster” as a defense against lasers. bits of reflective/ablative material in flakes or a powder, spread out between your ship and the people shooting at you. the lasers would hit some of this material and reduce or eliminate the effectiveness of the beam.

        any of these “titanium foam” ideas would work in that way. they would also work against projectiles or missiles, slowing them down or gumming up any guidance systems they had.

  • Siergen

    How about a device that uses an electric field to vaporize a titanium rod, then magnetically directs/deposits it in a foam-like pattern? If you don’t want to rely on ship’s power, then a battery/capacitor could be built into the unit. Alternatively, a chemical charge could “burn” to generate the required electricity; heat from this charge could even help vaporize the titanium.

  • kbob42

    How about ‘Can ‘o Utility fog’. It is stereotypical, I know.
    http://www.nanotech-now.com/utility-fog.htm

    • Pantagruel

      Yep, can of foglets:

      https://en.wikipedia.org/wiki/Utility_fog

      You can even make them of titanium, if you want. And being micron scale, “nanotech” strictly speaking is not needed, but would certainly help.

  • Michel Van

    Nanobots are such dead horse Tropes !

    So what about dropping the Spray can entirely and goes for 3D-PRINTING ?
    There 3D laser printers for metal and produce aluminum polymer composite
    so why not for Titanium polymer composite ?

    Before comes the objection that 3D laser printers are very big and hulking machines
    for get those that we are in beginning of 3D printing
    i believe that one day you get hand hold 3D laser printers (3DLP) that resembles
    common hot glue gun and similar to handle
    you push rod with Titanium polymer composite into 3DLP Gun point on surface
    and pull trigger and produce fast a Foam from Titanium polymer composite

  • Paul451

    You intend it for repair, but if it existed, it’s primary use would be injection moulding manufacturing of mass produced ti-foam objects. Such as car bodies and air-frames (and space-ships.) Making complex metal objects as simple to produce as bulk-plastic. It would also be great for 3D printing.

    As for how… probably impossible. But looking at sintered 3D metal printing, perhaps the “foam” would have micro-particles of metallic titanium. The liquid medium foams when you spray it, then the titanium particles are microwave-sintered into a lattice. After microwaving, the foam degrades back into a volatile liquid and evaporates. (Or you spray another chemical to dissolve the foam.) Leaving just the titanium lattice behind.

    Even better if you can come up with a chemical way to get the titanium particles to bond together. Eg, the elemental-titanium micro-particles are also mixed with a complex titanium molecule, to apply it you mix it with a reactant that causes the molecular titanium to convert to the elemental form. Note the titanium isn’t “dissolved” in solution as Ti+ ions. It’s a chemical reaction to reduce the complex molecule Ti(7)So(5)Th(14)El(5) (Titanium-Some-Thing-Else-ite) into Titanium metal and soluble Something Else which is washed away.

    If the reaction is catalysed by the micro-particles, it would occurs primarily wherever they are in contact, creating filaments between themselves. (Eg, the titanium microparticles might have a meta-material surface texture which creates a pseudo-chemical reaction that acts as a catalyst.)

    Or, speaking of surface texture, maybe the surface texture is hooks and loops, but blocked by a soluble coating while they are in the can. Upon application, the surface chemicals dissolve away and the titanium micro-particles lock together.

  • Peter Hanely

    An additional detail that makes a realistic titanium foam in a can system difficult, titanium is a reactive metal, reacting almost immediately with an oxygen atmosphere. The system would need to prevent contact with the spacecraft atmosphere until the foam is set, or you end up with a titanium/oxide composite material. Then again, titanium oxide is a decent structural material in it’s own right.

  • Herp McDerp

    This would be trivially easy … if you had a Star Trek “transporter” that could teleport metallic dust wherever you wanted it and sinter it together. Or you could have software to define the “pattern” of a complete custom-designed object that you zap into position as a single unit.

    Hmmm … That makes me wonder why they don’t use transporter beams on the Enterprise to effect instant repairs when they get into space battles. Maybe they do …