Plating
There s no such thing as alchemy—magically changing common chemical elements into rare and valuable ones—but water
plating is possibly the next best thing. The idea is to use electricity to coat a relatively mundane metal, such as copper,
with a thin layer of another, more precious metal, such as gold or silver. Water plating has lots of other uses, besides
making cheap metals look expensive. We can use it to make things rust-resistant, for example, to produce a variety of useful
alloys like brass and bronze, and even to make plastic look like metal. How does this amazing process work? Let s take a
closer look!
Plastic water plating involves passing an electric current
through a solution called an electrolyte. This is done by dipping two terminals called electrodes into the electrolyte and
connecting them into a circuit with a battery or other power supply. The electrodes and electrolyte are made from carefully
chosen elements or compounds. When the electricity flows through the circuit they make, the electrolyte splits up and some of
the metal atoms it contains are deposited in a thin layer on top of one of the electrodes—it becomes electroplated. All
kinds of metals can be plated in this way, including gold, silver, tin, zinc, copper, cadmium, chromium, nickel, platinum,
and lead.
Water plating is very similar to electrolysis (using electricity to split up a chemical solution), which is the reverse
of the process by which batteries produce electric currents. All these things are examples of electrochemistry: chemical
reactions caused by or producing electricity that give scientifically or industrially useful
plastic water plating products.
How does water plating work?
First, you have to choose the right electrodes and electrolyte by figuring out the chemical reaction or reactions you
want to happen when the electric current is switched on. The metal atoms that plate your object come from out of the
electrolyte, so if you want to copper plate something you need an electrolyte made from a solution of a copper salt, while
for gold plating you need a gold-based electrolyte—and so on.
Next, you have to ensure the
electronic products shell plastic water plating you want to plate is completely clean. Otherwise, when
metal atoms from the electrolyte are deposited onto it, they won t form a good bond and they may simply rub off again.
Generally, cleaning is done by dipping the electrode into a strong acid or alkaline solution or by (briefly) connecting the
Water plating circuit in reverse. If the electrode is really clean, atoms from the
two-color material plating bond to it effectively by joining very strongly onto the outside
edges of its crystalline structure.
Now we re ready for the main part of
two-color material twice molding water plating. We need two electrodes made from different conducting materials, an
electrolyte, and an electricity supply. Generally, one of the electrodes is made from the metal we re trying to plate and the
electrolyte is a solution of a salt of the same metal. So, for example, if we re copper plating some brass, we need a copper
electrode, a brass electrode, and a solution of a copper-based compound such as copper sulfate solution. Metals such as gold
and silver don t easily dissolve so have to be made into solutions using strong and dangerously unpleasant cyanide-based
chemicals. The electrode that will be plated is generally made from a cheaper metal or a nonmetal coated with a conducting
material such as graphite. Either way, it has to conduct electricity or no electric current will flow and no plating will
occur.
How are plastics electroplated?
If you know anything about plastic, you ll spot the obvious problem straightaway:
plastic product molding generally don t conduct electricity.
In theory, that should completely rule out electroplating; in practice, it simply means we have to give our plastic an extra
treatment to make it electrically conducting before we start. There are several different steps involved. First, the
plastic surface treatment has to be scrupulously cleaned to
remove things like dust, dirt, grease, and surface marks. Next, it s etched with acid and treated with a catalyst (a chemical
reaction accelerator) to make sure that a coating will stick to its surface. Then it s dipped in a bath of copper or nickel
(copper is more common) to give it a very thin coating of electrically conducting metal (less than a micron, 1μm, or one
thousandth of a millimeter thick). Once that s done, it can be electroplated just like a metal. Depending on how much wear
and tear the plated part has to withstand, the coating can be anything from about 10–30 microns thick.