What Does Brass Corrosion Mean?
Brass corrosion refers to the natural electrochemical process that occurs when a brass alloy is exposed to air and moisture. Brass corrosion comes in several different forms and, depending on the corrosion mechanism, this corrosion can be either protective or destructive. In one case, brass can become oxidized due to atmospheric exposure to form a protective corrosion product known as patina. In another case, if the brass contains unfavorable quantities of zinc, a destructive corrosion process known as dezincification can occur.
Corrosionpedia Explains Brass Corrosion
Unlike iron, brass does not form weak, flaky rust when it corrodes. Instead, a firm and durable patina layer appears on the surface of brass when exposed to air and moisture. This layer acts as a barrier that prevents more air and moisture from contacting the brass substrate, thus halting further corrosion. While this type of corrosion is sometimes favorable, it can leave the brass with an unsightly greenish-blue color.
On the other hand, dezincification is a destructive corrosion process that can occur when the quantity of zinc in the alloy is above the recommended value. Dezincification occurs when zinc leaches out of the alloy, leaving behind a copper-rich shell with little mechanical strength. The higher the concentration of zinc in the brass, the more it can be affected by zinc leaching out of the alloy. Dezincification can be avoided in most cases by maintaining the zinc content below 15%.