What’s up guys?!?!?! Michael with Michael Talks Metal back for episode 151. I think it’s time we change up the format of Michael Talks Metals. For the next couple weeks we’re going to take a break from weekly videos while we retool the approach and come back for something even better. So Stay TUNED!!!!! Let’s do this. we’re back for the 151st time and our topic for today is conductivity…. electrical conductivity in the common pure metals.
And it is one of the more common metals that carries electricity to our homes and workplace for us every day. Copper is by far the most common….. owing to excellent conductivity at reasonable cost.
The scientific units of measure for resistance to the flow of electricity are cumbersome so a practical measure of the relative conductivity of metals is useful to make comparisons.
If you recall, in last week’s video, check the card, we explained that the “IACS” conductivity rating is the percentage compared to the “International Annealed Copper Standard”. On this scale, copper is 100% … no surprise there. So everywhere around us we have copper bringing the power from the grid to every outlet and cord.
But is it the highest conductivity??? no its not. Silver has it beat with a rating of 106%. I think you can guess why your extension cords and the power lines are not made of silver….. yep it’s the cost that certainly makes us flinch. Jewelry sure, but not for the power lines. But silver is present in many internal connections in phones, computers, and other electronics.
So if Silver is highest, and Copper is in second place… What’s next?
Third place goes to…..(drum roll) …Gold at 76% Needless to say, we have an even greater cost issue than silver, so why would we use it at all?
We find that it is used sparingly and mainly at contacts since it also has the ability to resist corrosion over long periods of time and that justifies the cost.
Fourth place goes to our old friend.. Aluminum…. at 62% of Copper.
But things look a lot better when we factor in weight. So we see Aluminum used where we can use a larger conductor and still save weight. A downside here is that when aluminum forms an oxide, the oxide is a great insulator. An anodized aluminum surface is for all practical purposes electrically non-conductive. Connections to aluminum require considerable care to prevent degradation over time.
Iron and Nickel are about 20% IACS and Titanium is under 2% IACS so not at all attractive when we want conductivity.
For any of these examples, their individual conductivity increases at lower temperatures and decreases as temperatures increase.
When temperatures get really really low, like a few degrees above absolute zero, a metal can become a “superconductor” and shows essentially no resistance to the flow of electricity.
The problem here is that it takes a lot of energy to achieve temperatures close to absolute zero…… so we find applications only in the physics research labs….. at least for now.
Looks like we are running out of time for today. So for time 151, CHECK THE SPECS. For more information on metals and alloys, please visit our website www.michlinmetals.com. Still here and have not subscribed to the channel….. click here. Missed last weeks’ video, click here. Thanks for tuning in. This is Michael with Michael Talks Metal. I won’t see you next week, but I’ll be back soon enough. I’m out!