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Is your part in need of a surface coating but you aren’t sure what would work best? My next four blog posts will feature some of the many different choices that Dynacast has to offer. We offer about thirty different coatings, from chrome to electroless nickel and many more. This post will focus on the chrome and chromate surface finishes. If you see a coating that you’d like but it isn’t listed on our site or mentioned in one of my blogs, please reach out to us! We constantly add new surface coating options based on customers needs.
Chrome vs. Chromate
Before I get into the different coatings that are offered, I first want to touch on the differences between chrome and chromate. Chrome, which is short for chromium, is an element and is applied as an electroplated finish. The chrome that you are familiar with on cars or other materials has the shiny, metallic finish that it is most commonly associated. Chromate, on the other hand, is used to describe a corrosion resistant process that is classified as a conversion finish, rather than an additive finish. We have many different options for both of these finishes, which I will now go into more detail.
There are several types of chrome plating that we currently offer, two of which are bright and satin. Bright chrome is the mirror-like finish that you know from automobiles, toys, furniture, and more. It’s a finish that provides corrosion protection and good wear life, as well as a good appearance. Satin chrome has the same characteristics as polished chrome but has a duller finish. Both finishes are rack-plated, with layers of copper and nickel followed by a chrome layer.
Chromate with Zinc
The three types of surface finish for this section are clear, yellow, and black. Zinc surface coating is soft, decorative, and corrosion resistant. It protects the part by corroding before the base metal. For extra corrosion protection, chromates are applied over this zinc coating. Clear chromate with zinc is a slightly iridescent blue color when complete, while yellow and black both give the respective colors to the finished part.
Chromate without Zinc
We have two surface finish options that are chromate and do not contain zinc. These options are black chromate without zinc and yellow chromate without zinc. Black chromate without zinc is an inexpensive type of chromate. It’s typically used for parts that do not require a high amount of corrosion resistance. The coating goes directly onto a zinc die cast part. Yellow chromate parts are chemically milled and then chromated. This gives the part a dull finish. Both of these coating options are very thin and contribute no measureable thickness to the overall coating.
Olive drab chromate and trivalent chromate are two additional chromates that were not covered in the above sections. Olive drab chromate has a dark green finish, and can pass 150 hours to white corrosion.
Trivalent chromate has similar characteristics to a typical chromate, but does not contain hexavalent chromium. This eliminates the issue of chrome reduction in waste treatment, and is not harmful to humans or the environment. The color is bright blue and it exceeds the requirements of automotive specifications.
What questions do you have regarding chrome? Chromate? Is there a particular color you’d like to see that isn’t currently outlined? Let me know, I’d love to hear your thoughts.