Once aluminum metal is exposed to air, it will immediately combine with oxygen in the air to form aluminum oxide, an inert protective layer. In nature, this oxide deposit is only one millionth of an inch deep. Aluminum anodizing is a well known method of thickening the aluminum oxide coating to provide greater protection. It is a restricted oxidation of the surface achieved by immersion in an electrolyte (it will generally be dilute sulfuric acid). Production of anodized aluminum coatings: In the process, the metal is used as the anode and then a very low voltage, high amperage direct current is passed through the metal. A rigid and inert oxide film initially forms on the surface and is followed by a less dense oxide layer in which there are capillary pores. These capillary pores allow oxidation to continue. Unlike paint and plating which are coatings that are added to the lower metal, anodic coatings develop downward on the parent metal and form an integral part of the metal itse...
Nickel plating has smoothness, corrosion resistance, and is reflective.
But chrome is exceptionally thin, measured in millionths of an inch instead of thousandths.
When you look at a chrome accent surface, such as a chrome wheel or truck bumper, what you really see is the effect of nickel plating.
Chrome adds a bluish cast and protects against tarnishing and minimizes scratches.
Some metals, such as zinc die-cast parts, cannot be nickel plated directly, but must first be plated with copper.
Other materials, such as aluminum, cannot be copper plated until they have been zinc plated.
Decorative chrome is applied to many consumer items, including appliances and plumbing fixtures.
This finish is also used on many industrial parts, including medical, motorcycle, automotive, and marine items.
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