Worst Electrical Conductor Metal: What to Know?

[RestlessMind]

Does anybody happen to know what readily-available metal is the worst electrical conductor?

 

[f95toli]

By metal, do you mean an element (e.g. Tungsten) or does that also include alloys?

 

[RestlessMind]

Oh alloys count. For example if steel was it, then I would accept that.

 

[Bob S]

According to this list, plutonium is worst among metallic elements.
http://environmentalchemistry.com/yogi/periodic/electrical.html

 

[RestlessMind]

Er, I was actually hoping for a more readily-available suggestion.

 

[Born2bwire]

Er, I was actually hoping for a more readily-available suggestion.

I'm sure that in 1985 plutonium is available at every corner drug store, but in 1955 it's a little hard to come by.

 

[RestlessMind]

Haha, excellent reference. :P I can't believe I forgot that!

 

[Born2bwire]

Yeah but seriously you really are not going to find a common elemental metal that is a bad conductor. Look at the list, I think the best you could do is titanium and that is only around 100 times less conductive than copper. I'm not aware of any really non-conductive metal alloys either but that's just ignorance. What about forming an oxide layer on the surface of the metal? For example, aluminum oxide is resistive compared to alumin(i)um. According to a random website I found, so you know it must be right (take that CRC), aluminum has a resistivity of 0.00000270 ohm-cm, alumina has a resistivity of 2.5e6 ohm-cm.

Of course the trick would be to form the layer of alumina on the aluminum. Sure, time will do this naturally but who has the patience? You could speed up the process by grinding up the aluminum with iron oxide shavings and then providing the appropriate starting energy by a lit strip of magnesium. Now the gross expulsion of energy in the process is usually undesirable (and unconfinable...) though...

 

[RestlessMind]

Or I could just stick with plastic. This is good information though.

 

[ZapperZ]

Or I could just stick with plastic. This is good information though.

Plastic is not a "conductor metal".

Zz.

 

[Borek]

Plastic is not a "conductor metal".

Nitpicker

 

[Vanadium 50]

Mercury is quite a bad conductor, as is lead. Whether these fall into the category of "readily available" or not is up to you.

 

[Phrak]

Nichrome, 65 to 88 the resistivity of Cu.

 

[DaveC426913]

I'm sure that in 1985 plutonium is available at every corner drug store, but in 1955 it's a little hard to come by.

Oh snap! Awesome reference! Who would have thunk conditions would conflagrate just so to make it relevant!

 

[RestlessMind]

Thank you, Zapper, for reminding me that plastic is not a metal. I'm quite aware of that. :|

 

[Red_CCF]

How do you define readily available?

 

[RestlessMind]

Able to buy it.

 

[f95toli]

Oh alloys count. For example if steel was it, then I would accept that.

But then the question is meaningless. The definition of a metal is a material that has free electrons; i.e. there are no metals or metallic alloys that are VERY bad conductors.
(not counting "exotic" materials such as Mott insulators and superinsulators; which are not really metallic anyway).

If you need a bad conductor (i.e. an insulator) you should just use an insulator of some sort.
Note also that most "metallic" properties (i.e good thermal conductors; the fact that metals are generally "shiny" etc) are only there because of the free electrons; meaning there is e.g. no such thing as a metal that is a good electric conductor but a bad thermal conductor (the exception being superconductors; but they are -again- not really metals).

 

[RestlessMind]

Er, okay then. I was just looking for something hard like metal that didn't conduct very well.

 

[Lambduh]

Are you just looking for something to be used as a heating element? Then definitely just go with nichrome wire. Mainly nickel but with a large amount of chromium (15ish%). It's what I've used in the past to heat things up, but you need a pretty good power supply that can put out quite a bit of current depending on what you want to do.

Just remember the magic rule...

Twinkle, Twinkle, Little Star, Power = I Squared R!

 

[RestlessMind]

Actually, I was just curious about this. I imagine that there could be some applications where a tough material that does not conduct electricity would be useful.

Cute song ^^

 

[f95toli]

Metals are not hard. They are generally quite soft which is why metal surfaces are often protected using ceramics such as titanium oxide (using in e.g. frying pans to avoid scratching etc).
If you need a hard material you should use a ceramic such a quartz (silicon-oxide) or alumina (aluminium oxide). Note, however, that these are quite brittle.

 

[RestlessMind]

Well then, hard and not brittle. :P

 

[Lambduh]

What f95toli said. For good hard insulators ceramics are great. Pretty much all we use in high vacuum environments. Teflon coated wires work great too but can't be heated like ceramics can.

Also fired alumina is extremely hard and I've never actually broken or sheared a piece. I first realized this as an intern when i deposited saw blade on it trying to cut off a piece :) I've always had a problem with the unfired stuff being very brittle.

For a machinable ceramic insulator I've always used Macor: http://en.wikipedia.org/wiki/MACOR

But unless someone is buying it for you it's quite expensive.

 

[RestlessMind]

Haha, I see.

Well thanks for the info guys. =)