How Does a Corrosion Inhibitor Work?

A corrosion inhibitor is an anti-rusting chemical substance that, when applied to a non-metal or fuel-based fluid, reduces the effective resistance to corrosion by a material, usually an iron or an alloy, which comes into direct contact with the fluid. The effectiveness of such a corrosion inhibitor greatly depends upon the fluid type, amount of dissolved oxygen, and typical flow regime of the application. Commonly used corrosion inhibitors in fluids are oil-water separators and hydrocarbon corrosives. Other types of corrosion inhibitors that are increasingly being used in a wide variety of industries, including the automobile industry, include zinc and platinum.

One of the most widely used and most important types of corrosion inhibitors in today's industry is the cathodic inhibitor. It works by preventing corrosion of the steel or other material being protected. Usually applied as a powder or in a spray form, the cathodic inhibitor protects against heat, moisture, and even rust. The basic function of the cathodic inhibitor is to prevent corrosion of the protective layer, which then causes the protection to wear out more quickly than it would if there was no protection at all. Certain types of cathodic inhibitors are used to prevent corrosion of steel and stainless steel in certain applications, such as brake pads, pipe seals, water pipes, and many others.

A second very important type of corrosion inhibitor, used to protect many metals, is the metal protection shield. Metal protection shields prevent the corrosion of a specific metal from damaging a specific surface. Some examples include anti-rust coatings, which are often used in the auto and power transmission industry. Certain types of metal protection inhibitors are specially formulated to specifically meet the needs of certain metals, such as nickel. In addition, many corrosion inhibitors are used to slow down the corrosion rate of certain types of materials, which includes copper, aluminum, and many others.

Some corrosion inhibitors are made to work on a two-part process. First, a barrier is applied to the metal being protected. Then, an oxidizing agent is applied onto the protected metal. This allows the chemical reaction that occurs between the two to occur more slowly, which in turn slows down the corrosion rate. Some examples of this type of corrosion inhibitors include rust stop coatings, which stop the corrosion rate of aluminum and other metals when exposed to oxidizing agents.

A third type of corrosion inhibitor, sometimes called a catalytic inhibitor, is added to an aluminum plate to create a metallic protective film. This metallic protective film serves the purpose of allowing certain materials to pass through the aluminum plate without being damaged. For example, an aluminum plate that has been coated with a protection film will allow certain corrosive fluids, such as hydrocarbons, to pass through the aluminum. In the past, this type of inhibitor was added to the final coat of aluminum, as well as the penetrations needed to make sure that the protective film did its job. Now, most corrosion inhibitors available for use in the auto industry are coated to protect other metals during the final coatings process.

So what does it mean to say that a particular type of corrosion inhibitor slows down the corrosion rate? The answer depends upon the type of corrosion inhibitor being used. If you are having a discussion about a specific type of corrosion inhibitor, you can check with an auto technical expert at your local auto parts store to explain how each type works. Generally, however, the way that it slows down a corrosion process relates to the material that it is used on. When a technician is explaining the process to you, be sure to ask about the various types of protection additives that the manufacturer uses to protect their products.