Zinc is considered by many industries as an economical way of protecting components from the negative effects of corrosion. There are many ways of improving the anti-corrosive qualities of zinc plating. One of them is to combine zinc with another metal such as nickel to create an alloy plating. Another means to use, instead, zinc chromate plating. This is obtained through a process called chromate conversion.
What is Chromate Conversion?
Chromate conversion coating is a process that is described as a type of coating used to passivate various metals including zinc. The name is derived from the chromate acid that is in the bath of chromic acid. During the process, an oxide layer is deposited on the surface. Chromate conversion coatings are usually requested by clients to provide protection to many common items found in hardware stores. These include tools. The distinct yellow color is a giveaway that a chromate conversion process was involved.
Zinc Chromate Plating
Zinc chromate is produced during the chromate coating process. When zinc is involved, the common method is the “Cronak process.” The zinc absorbs the chromate. Zinc chromate plating then takes the characteristics of zinc, enhanced by chromate conversion, and applies them to the substrate metal.
The depth of the ability of the zinc chromate plating is reflected in its color. The colors of the components plated in this fashion can range from a clear blue to black. The rule of thumb is that the darker the color, the greater the protection afforded. As a result, black coatings are more corrosive resistant and stronger than those that are yellow or blue.
Applications of Zinc Chromate Plating
Zinc plating is used for its ability to resist corrosion. It corrodes away while the substrate metal remains intact. To increase the anti-corrosive properties, zinc chromate plating is performed. The chromates integrate themselves into the zinc coating or plating. They do without significantly increasing the overall thickness of the application.
Zinc chromate plating is used primarily in the automotive industry. The process is also a viable treatment for iron and stainless steel supports. It has been used as a covering for aluminum alloy parts in aircraft as well. It is, overall, an inexpensive means of providing corrosion resistance properties to many components and products that will be placed in environments that are hostile. The affordability of zinc chromate plating, in conjunction with its corrosion resistant properties, has resulted in an increase its popularity – a rise that will probably not abate over the coming years.
