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Clad metal is metal that uses a thinly bonded layer or layers of dissimilar metals over top of less expensive or less durable base metals to create a stronger, more attractive or otherwise more durable and desirable surface. In many cases, clad metals are a better option than electroplated or galvanized metals, because the capability exists to clad more types of metals than can be electroplated or galvanized. Further, the cladding process used to create clad metal is more durable and lasting than a plating or galvanizing process. There are a number of different types of metal cladding practiced, and each type has its own strengths and weaknesses for different projects.
One type of metal cladding process is known as overlay cladding. To create this clad metal, one layer of metal is bonded to another by extreme heat and pressure. Overlay cladding can bond dissimilar metals, such as nickel and gold or gold and silver, to each other, as well as bonding up to seven different layers of metal to get the strength and durability benefits of all seven in the finished product. Overlay cladding is also useful because it does not require adhesives, fillers, or any welding, and it is a permanent solution that will bond the metal together without any worry of it later coming apart.
Inlay cladding is another type of highly complex and exceedingly useful metal cladding process that is used to create clad metal objects. With inlay cladding, dissimilar metals can be bonded together only where they are necessary to be joined. For example, a piece of copper can be clad into a piece of gold exactly where it needs to be for when a weld is produced that turns the finished product into a sculpture. Inlay cladding also allows the characteristics of the different metals to be used to their maximum benefit in the creation of the finished clad metal product.
Another use of cladding is contact cladding, where certain metals are cladded together using heat and pressure to form perfect conductive metals. An example of this might be a wire that needs to have the tensile strength of steel, but the electrical conductivity and corrosion resistance of copper. Using contact cladding, the two metals can be bonded together to get the benefits of both types of metal, without the chance that a weld or fastener will break or that the material will not be sufficient for the use that is required of it.
@irontoenail - Unfortunately, when gold is layered on top of another metal, the other metal can tend to migrate, eventually leading to the gold becoming tarnished.
Since one of the qualities of gold that people value is that is doesn't tarnish, this is a major shortcoming of clad jewelry.
They end up having to put a couple of layers of different metals in, trying to offset this effect, which drives up the cost of manufacturing the jewelry.
And, unfortunately, the jewelry will eventually wear through to the base metal, as you can't perfectly clad gold onto other metals.
So, I agree that it's got some benefits, but generally pure gold jewelry will last longer (as will pure silver jewelry, and so forth).
@indigomoth - I never realized that our coins weren't just made of a single metal. I thought that the most common way people would experience clad metal would be through jewelry.
I know that a lot of the time gold jewelry is actually only gold on the surface and is something else further in. If you don't mind the snobbery value of "pure gold" this can actually improve the life of your jewelry, since gold is so soft anything made from it is easily deformed.
But, if it has steel inside it, you get the protective qualities of gold, along with the strength of steel.
This is one of the reasons it is such nonsense when people think it's better to get something made from "pure" gold.
Cladding is often used when minting coins. I know that the USA uses cladding to make its coins. And it's not surprising either, as if the coins were made from the metal they are clad with, you could probably make more money by melting them down than by exchanging them for goods.
In fact, that's happened in the past. Sometimes someone will realize that a coin is worth more for the metal it is made from than as a coin and if they are clever about it, they can make some money.
Cladding pretty much ensures that's not going to happen though, but also allows for the coins to be surfaced with a metal that won't corrode.
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