Lubricant anti-wear and extreme pressure additives are two important lubricant additives that play a key role in reducing friction, wear and increasing load-carrying capacity.
Lubricant anti-wear additives are additives that reduce wear on friction surfaces. After adding anti-wear additives to lubricating oil, a protective film can be formed on the metal surface, thereby effectively reducing the friction coefficient and reducing wear. There are many types of anti-wear additives, which can be divided into reactive and non-reactive types according to different adding methods and functions. Generally speaking, reactive anti-wear additives can form a stronger protective film on the friction surface, but require a longer running-in period; non-reactive anti-wear additives have better adaptability and can quickly exert a protective effect.
Extreme pressure additives are additives capable of generating extreme pressure under high load conditions. After adding extreme pressure additives to lubricating oil, a high-shear strength lubricating film can be formed on the friction surface to effectively withstand high temperature, high pressure and wear. Common types of extreme pressure additives include organic compounds containing sulfur, phosphorus, chlorine, etc. These additives can form a chemical reaction film on the metal surface and improve the extreme pressure performance of the lubricant. It should be noted that the use of extreme pressure additives should be appropriate. Excessive use may cause corrosion on the metal surface.
According to different classification standards, lubricant anti-wear and extreme pressure additives can be divided into the following categories:
Classification according to composition: Anti-wear additives mainly include metals, non-metals and metal-non-metal composites. Extreme pressure additives include organic compounds containing sulfur, phosphorus, and chlorine.
Classification according to the method of addition: anti-wear additives can be divided into direct addition type and reactive type, and extreme pressure additives can also be divided into direct addition type and reactive type.
According to functional classification: anti-wear additives can be divided into high temperature resistance type, low temperature resistance type and high and low temperature general type, etc.; extreme pressure additives can be divided into high temperature resistance type, low temperature resistance type and high and low temperature general type, etc.
When selecting anti-wear and extreme pressure additives for lubricants, you need to choose based on actual needs. For example, if you need to reduce friction and wear, you can choose anti-wear additives; if you need to increase load-bearing capacity, you can choose extreme pressure additives. When making a specific choice, you need to consider the following factors:
Usage environment: Different additives are suitable for different usage environments, and appropriate additives need to be selected according to the actual usage environment.
Bearing capacity: For occasions where increased bearing capacity is required, additives with higher extreme pressure properties need to be selected.
High temperature resistance: For lubricants used in high temperature environments, additives with better high temperature resistance need to be selected.
Corrosion resistance: For situations where metal surfaces may be corroded, additives that do not corrode the metal need to be selected.
Lubricant antiwear additives are compounds added to lubricants to reduce friction and wear between interacting surfaces. These additives form a protective layer on metal surfaces, preventing direct metal-to-metal contact and reducing wear.
A common lubricant antiwear additive is zinc dialkyldithiophosphate (ZDDP). ZDDP is a combination of zinc-containing compounds and dialkyl dithiophosphates. When added to lubricants, ZDDP reacts with metal surfaces to form a protective film composed of zinc and phosphate compounds. The film acts as a sacrificial layer, reducing friction between moving parts and preventing wear.
Another lubricant anti-wear additive is molybdenum disulfide (MoS2). MoS2 is a solid lubricant that can be added to lubricants to provide a low friction coating on metal surfaces. It adheres to metal, reducing friction and wear.
Some other examples of lubricant antiwear additives include organophosphates, esters, and amine-based compounds. The function of these additives is to form a protective film on the metal surface, reducing friction and preventing wear.
Extreme pressure additives, on the other hand, are additives added to lubricants to provide protection under high pressure and load conditions. These additives are typically used in applications where there is a risk of metal-to-metal contact and extreme pressure conditions.
A common extreme pressure additive is a sulfur-phosphorus compound. These additives react with metal surfaces under extreme pressure and temperature to form a protective film that helps prevent welding, scratching and pitting of metal surfaces.
Other examples of extreme pressure additives include chlorinated compounds, boron-based compounds, and other compounds containing active sulfur, phosphorus, or chlorine. The purpose of these additives is to react with metal surfaces and form a protective film that provides lubrication and protection under extreme pressure conditions.
Overall, lubricant anti-wear additives and extreme pressure additives play a vital role in extending the service life of lubricants and protecting the surfaces of interacting parts, especially under high loads and extreme conditions.
In summary, lubricant anti-wear and extreme pressure additives are two important lubricant additives that play a key role in reducing friction, wear and increasing load-carrying capacity. Understanding the concepts, functions, classification and selection methods of these two additives is of great significance for the correct use of lubricants and extending the service life of equipment.