Zinc Chromate Plating: Properties And Purpose

by | Dec 11, 2015 | Business

Zinc plating is popular among many manufacturers. It provides an affordable means of protecting objects from exposure to corrosion. As a sacrificial coating, it prolongs the substrate metal effectively, thereby extending its life. Its ability to be effective is this manner can be increased if zinc is combined with another metal or if it is applied as zinc chromate plating.

Zinc Chromate and its Properties

Zinc chromate (ZnCrO4) is a relatively recent discovery. Known also as zinc silver and zinc clear chromate, it dates only back to the final years of the 1920s. The Ford motor Company was the first to employ it. In the following decade, the United States Military as well as the aviation industry also began to employ it. From 1940 to 1950, American military aluminum aircraft wheel wells featured zinc chromate plating. With the addition of a black pigment to provide some UV protection to the light sensitive zinc, the pigmentation took on a greenish hue. The result was an improved safeguard for the components against corrosion.

Zinc chromate plating can also provide the items with other colors including is yellow or rusty red. The latter is the preference for many automotive companies. Zinc chromate is yellow in powder form. It is also:

* Odorless
* Insoluble in water
* Hydrophobic (repels water) over time after application
* An anti-corrosive coating for aluminum in particular
* Helps retain electrical conductivity

These qualities as well as its ability to act as a primer (preparatory coating before painting) and decorative finish, make zinc chromate plating desirable in some industrial applications.

Preparing Zinc Chromate

In order to produce zinc chromate, processors turn to the procedure known as chromate conversion. The method used extensively for zinc chromate is the “Cronak process.” Essentially, what occurs is an absorption of the chromate by the zinc. During zinc chromate plating, the now enhanced characteristics of zinc, are applied to the base or substrate metal. The actual thickness of the coating will vary according to the client’s demands and the requirement of the component.

Colors and Durability

Zinc chromate comes in a wide variety of colors. They do not have color, however, for the sake of appearance. The colors of zinc chromate indicate the durability and strength imparted to the substrate. From clear blue to black and olive drab, they range. The rule of thumb is simple. The darker the color of the zinc chromate plating, the more protection form corrosion it offers. Yet, yellow remains the most popular, according to most finishing companies.

Zinc Chromate Plating

If a company is looking for an affordable and effective means of providing corrosion protection, zinc chromate could be the answer. For industries such as automotive and aircraft, zinc chromate coatings are a viable solution for protecting aluminum. For those who seek to protect their components but want to remain within a tight budget, zinc chromate plating is the obvious answer.

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