Metal insulation

I was going to write about how 4x4 vehicles offered the perfect platform for hybrid conversion since you could replace the transfer case with a generator and attach an electric motor to the differential on the rear wheels, but that is that is an obvious thing to do, so that’s as far as I will go with that idea.

Instead I will write about a way to make ultra-high temperature, but very light weight insulation to replace asbestos, by using foamed metals. You might be saying but aren’t metals wonder conductors of heat? Under normal circumstances yes, but with the proper cellular structure, they could basically stop all three forms of heat transfer. Glass conducts heat very well in sheets but in fiberglass it stops it cold. (Pun intended.)

My idea is an extension of the foamed metal technology produced by a Canadian company called Cymet. Their foam is to absorb the energy of impacts; my idea is to make into insulation. The most easily achieved application would be to foam zinc or zinc alloy with xenon or argon on to structural steel. The zinc would protect the metal from corrosion and the heavy gas foam would slow the movement of heat into the metal. The issue with using zinc would be its low melting point. Aluminum has a higher melting point but it reacts with steel.

The application I think would make the prefect insulation, but would be much harder to bring to practice is using a material that boils at temperature lower then is required to make aluminum rigid. This metallic “blowing agent” would allow the metal to be melted and puffed, then as the metal cooled and gained structural integrity the blowing agent would solidify and create partial vacuums in the cells. Nothing insulates like a vacuum.

Having a metal blowing agent would also allow metallic insulation to be sprayed on. (Assuming you could find an insurance company would underwrite a policy for someone spraying 1,300 F molten metal.) This technology could also allow for foamed silicon dioxide insulation, which would be a lot cheaper then metal-based foams, though SiO2 is very viscous near its melting temperature. With a lower temperature blowing agent and the right metal or alloy it should be easy to spray foamed zinc or tin to create impact absorbing, low temperature rated, but ultra-light weight insulation. This would be prefect to line building panels, or insulate pipes (either for steam or cryogenics applications).

Metal foam insulation might have stopped or slowed the collapse of the World Trade Center, since the foam would have absorbed the impact, and since it would be directly fused the structural elements the insulation would not have been shaken off by the impact. With a ceramic (enamel) coating to stop the oxidation and slow the absorption of heat metal insulation could in theory stand up to fire quite well, since it would have to heat up significantly before noticeable failure.

I can also see applications of this foam to superconductor research, since the super conducting alloy could be foamed with nitrogen or at least encased in material foamed with nitrogen. Then once the material is cyro-cooled, with liquid nitrogen or liquid helium, the cells would fill create a partial vacuum and the gas liquefied or froze, which would give the material extremely poor thermal responsiveness, since it would be a self cooling insulator, but still be very electrically conductive..