Of the many things I love about the Space Shuttle program, one of the sillier ones is that a significant part of the launch profile calls for "throttle at 104%".
Turned out the engine could safely run at higher power than expected, but the engineers kept the original scale. One abort scenario for multiple engine failure specifies throttle at 109%.
@starkatt The basic copper wire that you get from essentially any source (called "ETP" or "Electrolytic tough-pitch" copper) has a conductivity rating of 101% IACS (International annealed copper standard (conductivity)), simply because purer, slightly higher-conductivity copper has become economically available since the standard was made (originally defined such that 100% was the conductivity of generic copper wire on the market)
@starkatt incidentally I have no idea why it's called electrolytic tough-pitch. there is probably a reason.
@Felthry One thing I've noticed is that the residential copper wire I use at work comes in a few slightly different colors. I'm guessing it's loose controls on purity from recyclers :)
@Felthry gosh it makes me really happy to find another fan of copper :)
@Felthry (Silver is pretty wonderful too, though it's a shame about the oxidization.)
@starkatt It's ironic, silver oxidation would be much less of a problem in a pre-industrial society, but it would only be useful as a high-conductivity metal in a post-industrial society.
This is because oxygen doesn't corrode silver very fast if at all; tarnishing is the formation of silver sulfide caused by sulfur pollutants (sulfur dioxide I think is a major offender, along with hydrogen sulfide)
@starkatt and on the topic of high-conductivity metals aluminum is just, wow. So useful in so many ways, it's lightweight, has a very high conductivity (the highest conductivity per weight of any air-stable metal; only sodium and lithium beat it), it's very strong, it doesn't corrode easily due to the formation of a protective layer of sapphire, and if you alloy it with copper you get a super-strong metal that gets stronger with age (called duralumin)
@Felthry ALUMINUM IS HECKING MAGIC.
@starkatt It does unfortunately have downsides! It's notoriously difficult to solder and weld (this is due in part to the same sapphire layer that protects it from corrosion), and getting good electrical contact to aluminum is a pain. Plus, there's the whole problem of spontaneous amalgamation with mercury and gallium (granted a lot of other metals have this problem too)
@Felthry it makes me so happy that "transparent aluminum" (sapphire) is literally a consumer-accessible engineering material these days.
@Felthry what bugs me is how overrated titanium is. Yeah it can do some really cool stuff (lovely thin-layer oxide colors!) but in absolute terms it's not actually stronger than a good steel. Magnesium is where my heart's at for light structural metals.
@starkatt The key thing about titanium as a strong material is how light it is, isn't it? It's about as strong as steel, and around the weight of aluminum.
(also thin-layer oxide colors happen in every metal! Bismuth is well known for it)
@Felthry Yeah, about as strong as steel with the weight of aluminum. Which is *pretty great*, but it's not the super-material that a lot of public consciousness seems to think it is.
@Felthry I've mostly worked with silver in a jewelry context. I know the tarnishing was hastened by sulfur, but I didn't realize it was actually forming silver sulfide.
Now that I actually think about it, it makes sense. You can oxidize silver if you heat it too much for too long, and that creates a nasty purple color that's hard to get out, unlike yellowish tarnishing.
@Felthry There's something about shaping silver that's indescribably wonderful. The malleability and ductility are *just right* and it takes solder really well.
@starkatt A lot of solders contain silver! Mostly lead-free ones. Which are generally a real pain to work with because they just don't melt right like how 63/37 or 60/40 does. Lead is a very useful metal and it's a real shame it's so dangerous.
Honestly the same goes for mercury and cadmium, too. Heavy metals are useful! They're just too dangerous to use in most situations.
@Felthry Jewelry solders are different than electrical solders! Lead-free solders are garbage for electronics but standard for jewelry. With a torch and flux the higher melt temp and lower wettability aren't an issue, and being higher in silver content I think makes tin whiskers not a thing.
@starkatt oh, electrical solders have flux too! It's just that the flux is embedded in the solder. There's a thin inner core of rosin (or several cores, in some cases, though we have no idea why) in electrical solder, so it applies flux as you use it.
The torch though, yeah, you can't really solder electronics with a torch. You'd destroy your microchips!
@Felthry :nod: right, but it's not nearly as effective as a separate liquid or paste flux :)
@starkatt Yeah, but in electronics (unless you're doing rework on an old board) you don't need as much flux!
@starkatt though if you're reworking a really old board......... you're going to go through that solder wick _fast_
@starkatt The sulfide formation is still oxidation! It's just, not oxidation involving oxygen, because chemistry terminology.
@starkatt we're elecctrical engineers, of course we like copper!
@starkatt Could be; could be surface contamination. Could be insulation residue on the surface of the copper. Could be just different lighting you're looking at them under! Who knows.
Copper is good, I know that much. It's fortuitous that such a (comparatively) common metal a) is one of the easiest metals to work with, strong yet ductile and b) has one of the highest conductivities of all metals out there (only silver is better)