Extreme pressure additives (EP additives) are a type of oil additive specifically designed to protect surfaces under high pressure, such as in gears and bearings. These additives are commonly used in automotive and industrial lubricants to reduce friction and prevent metal-to-metal contact, particularly in high-load and high-pressure applications.
Some examples of extreme pressure additives used in lubricants are:
Table of Contents
Phosphorus compounds:
Phosphorus-based additives, such as zinc dithiophosphate (ZDDP), are commonly used as extreme pressure additives. They form a protective film on metal surfaces, preventing direct contact and reducing wear.
Sulfur compounds:
Sulfur-containing additives, like sulfurized olefins, react with metal surfaces under extreme pressure and temperature to form a protective layer of iron sulfide. This layer reduces friction and wear.
Chlorinated compounds:
Chlorinated additives, such as chlorinated paraffins, react with metal surfaces to form a lubricating film. They have excellent extreme pressure properties and are commonly used in heavy-duty applications.
Molybdenum disulfide (MoS2):
MoS2 is a solid lubricant that can be used as an extreme pressure additive. It has excellent anti-wear and load-carrying properties, even under high temperatures and pressures.
Graphite:
Graphite is another solid lubricant often used as an extreme pressure additive. It forms a protective film on metal surfaces, reducing friction and preventing wear.
These additives are often used in combination with other additives to enhance the overall lubricating performance of oils and greases under extreme pressure conditions.
It’s important to note that the use of extreme pressure additives should be done according to manufacturers’ recommendations and with the specific application in mind. Proper lubrication and choosing the right additive for the intended purpose are crucial for ensuring maximum performance and protection.