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Why are some metals chromium plated?

Updated on September 6, 2015
Electroplated_Spare_Parts
Electroplated_Spare_Parts | Source

Some metals are chromium-plated to make them look attractive and to prevent them from corroding or rusting.

Chromium is a silver-white, hard, brittle metal which was discovered in 1798 by N. L. Vauquelin. Its non-corrosive, high-strength, heat-resistant characteristics are utilized in alloys and as an electroplated coating.

In electroplating, the article to be plated is connected to the negative terminal of a battery and placed in a solution known as electrolyte. Direct electric current is introduced through the anode or positive terminal, which usually consists of the metal with which the article is to be coated.

Metal slowly leaves the anode and forms a deposit on the article. The electrolyte for chromium contains chromic acid and sulphuric acid. It deposits a bright top layer but this is not the only important part of the electroplating. The chromium is only about 0.00002 inches thick.

Under it lays a thick layer of nickel and beneath that again may be a layer of copper. Many household appliances are chromium-plated and so are the bright parts of an automobile. Tools, chemical equipment, electric appliances, gears, packing machinery, and hundreds of other articles are similarly treated to give them brightness, beauty or resistance to wear and rust.

Electroplated and polished chromium is bright bluish-white with a reflecting power which is 77 percent that of silver.

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  • juniorsbook profile image
    Author

    juniorsbook 23 months ago

    Thanks, for reading this out and for the positive feedback. Have a nice day.

  • jbosh1972 profile image

    Jason 5 years ago from Indianapolis, IN. USA

    chromium coatings protect against corrosion because chromium passivates. This "passivation" is what gives stainless steel its anticorrosion property as well.

  • juniorsbook profile image
    Author

    juniorsbook 6 years ago

    Thanks, for reading this out and for the positive feedback along with the advice. Have a nice day.

  • slc334 profile image

    slc334 6 years ago from Canada

    Good topic, very interesting! I think you may want to change the title to something more along the lines of "How to plate metals with chromium", or maybe write some more information on why chromium plating is done, not just the single sentence you have.