Corrosion Inhibition (CI) is critical in many grease formulations. Poor corrosion control results in the formation of rust and corrosion on equipment surfaces, which left unchecked can lead to equipment failure and downtime. Afton Chemical has solutions for corrosion testing including salt spray, Emcor dynamic bearings, and yellow metal protection; solutions that are synergistic with other common grease additives and have minimal impact on the thickener system.
What Causes Metal Corrosion?
Corrosion is caused by oxygen and acidic products, and the rate of corrosion increases in the presence of water and polar impurities. Corrosion is an electrochemical reaction that appears in many forms, including rust formation when corroding ferrous metal (such as iron or steel) has been exposed to oxygen and moisture. When iron reacts with oxygen and water, an electrochemical reaction converts oxidized iron (Fe) particles to hydrated iron (III) oxide, also known as iron oxide (Fe2O3), or more commonly called rust.
How Do Corrosion Inhibitors Work?
Corrosion Inhibitors (CI) prevent corrosion from occurring in one of two ways:
Acid Neutralization: neutralize aggressive acidic species and make them innocuous
Film Formation: additives chemically or physically absorb onto the metal surface forming a protective film to prevent corrosive attack
There are several test methods for measuring corrosion, including the EMCOR Dynamic Bearing Test (ASTM D-6138), Bearing Corrosion Test (ASTM D-1743), Fog Spray Test (ASTM B-117), and Copper Corrosion Test (ASTM D-4048). Afton has performance additive solutions to pass all of these test methods.
Afton’s Rust Inhibitor Portfolio
Protection against rust attack on ferrous parts is critical in many grease applications. From static salt spray to dynamic bearing tests, Afton’s portfolio of HiTEC® corrosion inhibitors are engineered to cost-effectively enhance grease performance while maintaining grease stability, extreme pressure and wear protection.
Excellent Protection Against Corrosive/Humid Environments such as ASTM B117 Salt
Low TBN Calcium Sulfonate
HiTEC® 4313: Copper Deactivator
Metal deactivators (also known as metal passivators) extend equipment life by forming a protective film over copper and their alloys (“yellow metals”). This film protects yellow metals from degradation due to sulfur attack. Metal deactivators also prevent metal ions from being introduced into the grease, protecting it from oxidative degradation. HiTEC® 4313 is an ashless alkyl thiadiazole and is an excellent metal passivator and corrosion inhibitor, as well as provides antioxidant and extreme pressure performance.
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