ravyn, welcome!

Something else that can be used in fiction, past, present and future is “tin pest.” Pure tin, when it gets cold, can change from it’s lovely and useful metallic form into a brittle powdery form of tin that no longer is ductile or conducts electricity the same. Cold, in this case, is 13.2 Deg C. And it grows. It’s also called “tin leprosy” or “tin disease.”

Of course, in the past, we didn’t have electronics, but we did have tin utensils and objets d’art. It has corrupted pipe organs.

Check out Wikipedia on this topic for some useful info and examples. It’s fun to learn!

Interestingly enough, the reason I became really immersed in this for a year or so was because, since electronics were pressurized, it was assumed they couldn’t cause metal vapor arcing at 28 VDC. That seemed like a heck of an assumption and I couldn’t find anything that made that so. I asked and they said “the expert told us.” So I asked the expert and he said, “Well, we really don’t know. We could get metal vapor arcing (MVA) at 28VDC in a vacuum but probably not in 1 atm.” Probably sounded too much like speculation to me.

I work for a really cool company that does research and support for the Air Force, NASA and several other space-related organization and, doing research, I’d stumbled upon two scientists who were exploring the minimum voltage level at vacuum for MVA. I called them and asked what the minimum was for 1 atm and they said, “No one knows.” I asked if it could be 28 VDC and they said, “You know, my research money would cover a test, if you wanted.” I wanted.

Not ten minutes later, they scientist call me back and said, “That was great!” Guess what will MVA at 28 VDC? Spectacularly. (I think their papers on are the Goddard Whisker website, too.)

It turns out that the circuits in question weren’t susceptible to MVA because current was clamped down with inductors. They could never pull enough into the system to sustain it. But we never would have found that out without checking.

This is important, though, because many thing MVA is not an issue here on the ground and normal circuit protection is not sufficient to preclude it.

Damn, I’m such a geek.

Would have never guessed that I would be interested in such things!