We recently purchased some permalloy nano powders (Ni80Fe70Mo3) I checked the electrical conductivity of these powders using a multimeter which can measure resistance to the order of giga ohm's. I was able to see electrical conductivity in carbonyl iron powders. While we were not expecting to see high electrically conductivity we expected to see some conductivity. I am wondering if I am missing something here or are these powders the issue.
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Nanoparticles are often pyrophoric, and may be coated to prevent spontaneous combustion. The particles' surface might be nitrided, or oxide coated, or coated with an organic chemical. Permalloy itself is quite conductive, but the coatings are insulators.
One doesn't think of a lump of iron as flammable -- but sprinkle iron filings in a flame to make a "sparkler". Steel wool is effective kindling.
Check with the source of your permalloy powder to see if they're coated, and what that coating is.
answered Jun 11, 2023 at 2:53
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$\begingroup$ Thermite: iron oxide powder + aluminum powder + heat = iron + aluminum oxide + lots of heat. $\endgroup$– RonJohnCommented Jun 12, 2023 at 5:40
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$\begingroup$ Also, uranium. It's pyrophoricity + self-sharpening attributes are part of what makes DU soooo effective in cannons. $\endgroup$– RonJohnCommented Jun 12, 2023 at 5:44