What is a Lubricant Antioxidant?
Lubricant Antioxidant Additives are chemicals that can improve the antioxidant properties of lubricating oil, (e.g. motor oil, grease) and extend its use or storage life.
How do the Antioxidant Additives extend the lifespan of lubricants?
Various hydrocarbons in lubricating oil are oxidized and converted into various oxidation products under the action of oxygen in the air, especially at high temperatures and metal catalysis.
Antioxidants can be divided into three types: free radical terminators, peroxide decomposers, and metal deactivators.
(1) Free radical terminator.
Common free radical terminators are of two types: phenolic type and amine type. Among them, phenolic antioxidants have good antioxidant effects, but their use temperature is low, while amine-type antioxidants have higher use temperatures and better durability, but are prone to discoloration and precipitation. These two types of antioxidants are usually added to turbine oil.
(2) Peroxide decomposer.
The function of the peroxide decomposer is to decompose these peroxides and reduce their content, thus delaying the oxidation branch. Zinc dialkyl dithiophosphate, also known as ZDDP, is a peroxide decomposer. Hydraulic oil and engine oil usually contain such antioxidants.
(3) Metal deactivator. The function of metal deactivators is to prevent metals from catalyzing the oxidation of oils. Usually used in turbine oil, compressor oil, machine tool oil, etc.
Usually, these types of antioxidants are used in combination. Free radical terminators are often used as primary antioxidants, while peroxide decomposers and metal passivators are used as secondary antioxidants. These additives play a positive role in improving the quality of lubricating oil, improving the oil's antioxidant properties, and extending the service life of the oil.
