Yellow metals such as bronze, copper, and brass are often overlooked in the quest for corrosion protection because they do not corrode as easily as less noble metals such as steel and zinc. However, that does not mean they are irrelevant or immune to corrosion. Cortec reminds formulators why selecting corrosion inhibiting additives such as M-235 and M-236 for yellow metals can be an important piece to solving the corrosion puzzle. Why Worry About Yellow Metals? It is important to pay attention to yellow metals for three reasons: 1) Some corrosion inhibitors for steel are harmful to yellow metals. 2) Galvanic corrosion can shift the corrosion attack from a yellow metal to a less noble metal when dissimilar metals are together in harsh conditions. 3) Certain environments are harsh enough to corrode yellow metals themselves. How Can I Protect Yellow Metals? Formulators of cleaners, metalworking fluids, water treatments, and protective coatings that will be used in contact with yellow metals can turn to M-235, a powder additive. This extremely versatile corrosion inhibitor forms a complex with copper oxides or yellow metal ions to create an extremely stable physical and electrochemical film barrier against corrosion. M-235 is soluble in both water and glycol and can be used in a variety of applications: ? Direct treatment of copper/brass sheets/coils ? Flash corrosion protection in strong alkali or acid cleaners ? Water treatment in circulating cooling towers or air conditioning systems ? Protective wax or lacquer coatings for metal ? Corrosion protection in hydraulic or metalworking fluids For oil- or solvent-based applications, formulators may use M-236, a liquid additive. This corrosion inhibitor can be added to transformer oil to protect yellow metals without changing the oil’s electrical properties. It also protects in the presence of H2S, SO2, and high temperatures. Don’t Forget Your Yellow Metals It is great to focus on rust prevention for ferrous metals—but not to the neglect of yellow metals. Make sure the yellow component is covered by considering M-235 or M-236 for your next water treatment, hydraulic fluid, cleaner, or oil.
