We’ve written about tank plating on this blog before – the process of plating a metal onto metal items that have been placed into plating tanks. For that process to work, the items to be plated must be electrically charged – in other words, they must be made of metal.
So that leads to an interesting question:
How can metals be plated onto surfaces of non-metallic materials like plastics, ceramics, or composites?
You have doubtless seen non-metallic items that have been plated with metal – they are nearly everywhere. There are metal-plated disposable plastic drink cups, plastic radio knobs, toys with bright shiny metallic coatings, and many other items.
Let’s look at some of the ways that precious and other metals can be coated onto non-metallic surfaces.
Sputtering and Other Vacuum Processes
Sputtering is the process of choice today for depositing thin films of silver and other metals onto plastics, ceramics, and other non-metallic materials. Sputtering is done in the vacuum chamber of a special machine, in which atoms are ejected from a metallic disc called a “target” onto the surface of the material to be coated. Sputtering is now widely used to deposit thin films of silver onto photovoltaic solar panels. (The good news is that used sputtering targets that have outlived their useful lives on production lines contain trace amounts of the silver or other precious metals that they contained. They can be profitably recycled by a qualified precious metals refinery.) Interesting: A variety of other vacuum-coating processes have long been used to coat plastic surfaces with aluminum and other metals; in those processes, atoms of the coating metal are dispersed into a vacuum chamber, where they adhere to the surfaces to be plated.
The word “electroless” looks like a misspelling, but it is actually a word that was invented to describe a chemical process that deposits a metal onto plastic. In it, the plastic items to be coated are “etched” by being immersed in a special chemical solution that prepares their surfaces for plating. The items are then immersed in a chemical bath that contains the metal that will be used to plate them. Interesting: Electroless plating looks a lot like tank plating, only no electricity is used.
Yes, ceramics and plastics can be electroplated with gold or silver. It can be done after those materials undergo the process of electroless plating (see just above). Once they have a thin metallic coating, they can be tank plated, just as metal objects are. Interesting: The items that have been plated using this process are often quite durable. One example? Chrome-plated plastic door handles that are used on automobiles.
Two different spraying processes – arc and flame spraying – can be used to apply metallic plating to nonconductive surfaces. In most cases, a powdered form of the metal is heated and then sprayed, using special equipment. Interesting: Spraying technologies can be used to apply a metal coating to just one part of a ceramic or plastic item; just as a painting technician can mask off parts of an item so they receive no paint, parts of the item to be spray-plated can be masked and receive no coating.
Precious Metals Can Be Recovered from Plastic Items
In virtually all cases, metals that have been applied to inexpensive plastic items are not precious metals. (Think of the shiny chrome-like finish that is applied to the bumpers and other bright pieces that you will find in a kit for a model car.) If, however, you own a quantity of ceramics or higher-end materials that have a coating of what seems to be silver or gold – and you do not know exactly what they are – they could be a source of valuable precious metals that can be extracted by a qualified precious metals refinery. Why not call us at 800-426-2344 to learn more?
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