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?