# Electrical Metal



## IamIan (Mar 29, 2009)

Nothing new here.
Just some food for thought for some who haven't already seen some of these old ideas before.

I attached a basic picture.

While Copper is used as the dominate metal by far ... there are some interesting possibilities for alternatives... of course you can't have your cake and eat it to... there are trade offs and issues to deal with.

Silver is a slightly better conductor of heat and electricity per volume than Copper but is actually worse per unit weight due to silver's higher density... and is grossly more expensive... a Silver wire to yield the same resistance could be 8% smaller by volume but would end up being 8% heavier by weight ... To conduct the same amount of heat it could be 7% smaller by volume , but would end up weighing 10% heavier... all while the silver wire would cost as much as ~90 times more than the copper.

Copper is a better conductor by volume of heat and electricity than aluminum ... but Aluminum is actually much better by weight ... To result with the same resistance for electricity an Aluminum Wire would be 64% larger than a Copper power by volume... but would weigh 51% less by weight.... To conduct the same amount of heat the aluminum would have to be 69% larger by volume but would be 49% lighter by weight... all while the aluminum would only cost about 17% the cost of the copper wire.

There are other issues people have run into as well... Metal to metal corrosion is an issue with aluminum that caused many fires years ago... some application the additional size / volume needed for equal electrical and or thermal conduction was not followed which also lead to fires ... and Aluminum has different metal fatigue properties that must also be considered where there are stresses and loads.

In application that experience significant skin effect combinations have sometimes been used where the core is aluminum and is coated with a shell of copper.

In motor windings the difference in type of magnetic material needs to be considered as well as the metal fatigue , additional volume for current and cooling... and the needed increase in volume has penalties for magnetic fields which dissipate with distance ...etc...

In short ... there is no free lunch... the way we design many things today is based on the specific properties of the materials we use... nd have been using and learning about these same materials for a very long time... including copper... so while there are alternatives... they can not be effectively just blindly substituted ... to exchange one material for another without very careful consideration and then testing is only inviting undesirable issues and side effects.

Still ... Sometimes I do wonder.

And sometimes I wonder a bit further about some of the much newer discoveries in material science ... even if I might not see some of these possibilities on the market any time soon ... or ever... still sometimes I do find it entertaining to entertain a bit of out of the box thinking.


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## mjcrow (Jan 5, 2008)

How would silver plated copper be? Doesn't silver oxide conduct just as well as "clean" silver, would that be an advantage?


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## PhantomPholly (Aug 20, 2008)

What about stainless steel? While not a superior conductor it is ok; plentiful; cheap (although not as much as aluminum); immune to the corrosion of aluminum; and has some other good structural qualities to boot. I don't know about conductivity per pound....

Remember, even in motor windings we aren't trying to conduct power over many miles.


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## electromet (Oct 20, 2009)

Phantom,

I think that although stainless steel strands feel quite flexible, stainless is a brittle material. I would hesitate to use it in high power electrical applications for fear that heat and vibration cycles could degrade it. Just my opinion.

Mike


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## PhantomPholly (Aug 20, 2008)

Yeah, I don't know that it would matter in the winding process but might be subject to metal fatigue like Aluminum. My point was merely that one of the steel alloys might be both inexpensive and suitable for mass-production winding material, although non-stainless would have to be protected against rust.


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## electromet (Oct 20, 2009)

Phantom,

I thought the original poster was referring to cabling rather than windings. Did I miss something? I'm certainly not a metallurgist, but my experience with stainless cabling is that they ultimately fracture with any continued flexing.

Mike

I just reread the original post. Need to sharpen my comprehension skills.


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## IamIan (Mar 29, 2009)

PhantomPholly said:


> What about stainless steel? While not a superior conductor it is ok; plentiful; cheap (although not as much as aluminum); immune to the corrosion of aluminum; and has some other good structural qualities to boot. I don't know about conductivity per pound....


Stainless steel and Aluminum fluctuate around the same price... there generally is not usually a large price difference between them.

Now normal rusting steel... there is your cost saver... 

The final result would greatly depend on the specific mix in question ...

The issues I see are that allot of the steel alloys are around the same kind of weight as Copper... but are worse conductors of electricity and heat than Aluminum.

Aluminum could potentially make a lighter motor and or wiring for the same current / power but steel would just be heavier.



PhantomPholly said:


> Remember, even in motor windings we aren't trying to conduct power over many miles.


Very true... but I see this as offering a way to reduce motor weight for the same motor power... For instance a Electric motor made using Aluminum instead of copper could be significantly lighter for the same power output... and cost less.

And unlike super conductors going to alloys like Aluminum do not require fancy cooling methods.


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## IamIan (Mar 29, 2009)

mjcrow said:


> How would silver plated copper be? Doesn't silver oxide conduct just as well as "clean" silver, would that be an advantage?


Silver plated copper would make use of silver's better conductivity for skin effect conduction ... but that is all silver would be able to add.

Unfortunately silver oxide / tarnished silver does not conduct as well as 'clean' silver.... which is why despite its higher electrical resistance gold plating is sometimes used on electrical connections due to its non corroding nature.


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