The important role of lubricant additives
author: Leila
2024-07-13
For lubricant users, the viscosity of lubricant is a familiar concept, because viscosity is the primary indicator for purchasing lubricants. For lubricants that have been put into use, viscosity is also an important indicator that needs to be paid attention to during testing. The components of lubricants are base oil and some additives, and the viscosity is mainly related to the base oil. In addition to the base oil, additives also play an important role in lubricants. This article will give a brief introduction to the role of lubricant additives.
Lubricant additives are some organic or inorganic compounds, some of which are liquid and can be dissolved in lubricants, and some are solid and suspended in lubricants. The content of additives in lubricants is not much. Depending on the type of oil, the content ranges from 0.1% to 30% (volume ratio). Some lubricants contain more additives, such as engine oil, and some lubricants contain fewer additives, such as turbine oil.
The role of lubricant additives can be divided into three aspects:
· Further enhance certain properties of the base oil itself, such as antioxidants, rust inhibitors, antifoaming agents, and anti-emulsifiers.
· Make up for the deficiencies in the performance of the base oil, such as pour point depressants and viscosity index improvers.
· Give the base oil new properties, that is, properties that the base oil itself does not have. These properties are mainly achieved through additives, such as extreme pressure agents (EP), dispersants, and metal passivators.
Polar additives:
Additives are polar, which means that the additives themselves have an attraction. When other polar substances or impurities enter the lubricating oil, this attraction can make the additive molecules adsorb to these foreign substances. Many substances are polar, such as sponges, metals, dust impurities, wood pulp and other hydrophilic substances or water-soluble substances. Non-polar substances include paraffin, Teflon (polytetrafluoroethylene), pure mineral oil, water-resistant substances, duck back hair (hydrophobic), etc.
Lubricating oil additives will be consumed as they are used. When they are exhausted, the additives lose their effect. Therefore, when using lubricating oil, you must pay attention to the conditions of use. For example, if you often come into contact with impurities, dust, water and other polar substances during use, the additives will be adsorbed to the impurities, causing a lot of loss. Correspondingly, the performance of the lubricating oil will be weakened or even lose some properties.
The role of additive polarity:
The mechanism of action of additive polarity has multiple aspects, but for lubricants, we mainly focus on the following aspects: wrapping impurity particles, emulsifying water, and wetting metal surfaces.
Lubricant additives will adsorb to the surface of impurity particles and surround and wrap the impurities. Such additives mainly include metal passivators, detergents, and dispersants. Taking dispersants as an example, they can adsorb small solid particles such as carbon deposits and impurities, disperse them in the oil, and prevent impurity particles from accumulating to form large particle deposits. Detergent dispersants are important additives in automotive engine oils.
Although additives have an enhancing effect on the performance of lubricants, it does not mean that more is better. There are two possible consequences of excessive use of additives in lubricants: one is that it affects the performance of the lubricant. For example, if the concentration of detergent dispersants added is higher than the normal level, the detergent dispersants will surround the anti-wear agent or extreme pressure agent, causing them to suspend in the oil, causing the extreme pressure agent and anti-wear agent to fail to form an effective protective layer when and where they are needed, resulting in increased wear. If the anti-wear agent is used excessively, the performance of the metal anti-rust and anti-corrosion agent will be reduced. As mentioned earlier, additives will be adsorbed on the surface of polar substances, including metals. If the anti-wear agent is excessive, it will be adsorbed on the metal surface, and the rust inhibitor may have no place to adsorb, resulting in a reduction in the anti-rust and anti-corrosion effect. Therefore, additives are not the more the better. Maintaining a balance in the formulation of various additives is a necessary condition for high-quality lubricants.
If the additive is used excessively, another result is that the relevant performance of the lubricant will not be enhanced, but the validity period of the additive will be extended. However, as a user, there is generally no way to understand the consequences of using a certain additive. Therefore, it is not recommended that users add additives by themselves. In some cases, if necessary, you should consult the oil supplier or add it under the guidance of the oil testing laboratory.
When there is water in the lubricant, the polar molecules of the emulsifier are adsorbed on the surface of tiny water droplets to form an emulsion suspension. When the lubricant is found to be emulsified, in addition to removing water, the source of the water must be found. If the lubricant is emulsified by water, the user should be aware that the additives in the oil will be affected because water ingress will lead to additive consumption. Through oil testing, the remaining additives in the lubricant can be determined.
The wetting and penetration of additives refers to the ability of additive molecules to be fixed on the metal surface, such as anti-wear agents (AW), extreme pressure agents (EP), oiliness agents, rust inhibitors, and corrosion inhibitors.
The role of anti-wear agents is to play an anti-wear and friction-reducing role on metals under the condition of boundary lubrication. Anti-wear agents generally work at medium temperatures (65℃~110℃) and can form a tough gray film on the metal to avoid direct dry friction between metals. ZDDP (dialkyldithiophosphate) is a relatively common anti-wear agent.
Lubricant additives are some organic or inorganic compounds, some of which are liquid and can be dissolved in lubricants, and some are solid and suspended in lubricants. The content of additives in lubricants is not much. Depending on the type of oil, the content ranges from 0.1% to 30% (volume ratio). Some lubricants contain more additives, such as engine oil, and some lubricants contain fewer additives, such as turbine oil.
The role of lubricant additives can be divided into three aspects:
· Further enhance certain properties of the base oil itself, such as antioxidants, rust inhibitors, antifoaming agents, and anti-emulsifiers.
· Make up for the deficiencies in the performance of the base oil, such as pour point depressants and viscosity index improvers.
· Give the base oil new properties, that is, properties that the base oil itself does not have. These properties are mainly achieved through additives, such as extreme pressure agents (EP), dispersants, and metal passivators.
Polar additives:
Additives are polar, which means that the additives themselves have an attraction. When other polar substances or impurities enter the lubricating oil, this attraction can make the additive molecules adsorb to these foreign substances. Many substances are polar, such as sponges, metals, dust impurities, wood pulp and other hydrophilic substances or water-soluble substances. Non-polar substances include paraffin, Teflon (polytetrafluoroethylene), pure mineral oil, water-resistant substances, duck back hair (hydrophobic), etc.
Lubricating oil additives will be consumed as they are used. When they are exhausted, the additives lose their effect. Therefore, when using lubricating oil, you must pay attention to the conditions of use. For example, if you often come into contact with impurities, dust, water and other polar substances during use, the additives will be adsorbed to the impurities, causing a lot of loss. Correspondingly, the performance of the lubricating oil will be weakened or even lose some properties.
The role of additive polarity:
The mechanism of action of additive polarity has multiple aspects, but for lubricants, we mainly focus on the following aspects: wrapping impurity particles, emulsifying water, and wetting metal surfaces.
Lubricant additives will adsorb to the surface of impurity particles and surround and wrap the impurities. Such additives mainly include metal passivators, detergents, and dispersants. Taking dispersants as an example, they can adsorb small solid particles such as carbon deposits and impurities, disperse them in the oil, and prevent impurity particles from accumulating to form large particle deposits. Detergent dispersants are important additives in automotive engine oils.
Although additives have an enhancing effect on the performance of lubricants, it does not mean that more is better. There are two possible consequences of excessive use of additives in lubricants: one is that it affects the performance of the lubricant. For example, if the concentration of detergent dispersants added is higher than the normal level, the detergent dispersants will surround the anti-wear agent or extreme pressure agent, causing them to suspend in the oil, causing the extreme pressure agent and anti-wear agent to fail to form an effective protective layer when and where they are needed, resulting in increased wear. If the anti-wear agent is used excessively, the performance of the metal anti-rust and anti-corrosion agent will be reduced. As mentioned earlier, additives will be adsorbed on the surface of polar substances, including metals. If the anti-wear agent is excessive, it will be adsorbed on the metal surface, and the rust inhibitor may have no place to adsorb, resulting in a reduction in the anti-rust and anti-corrosion effect. Therefore, additives are not the more the better. Maintaining a balance in the formulation of various additives is a necessary condition for high-quality lubricants.
If the additive is used excessively, another result is that the relevant performance of the lubricant will not be enhanced, but the validity period of the additive will be extended. However, as a user, there is generally no way to understand the consequences of using a certain additive. Therefore, it is not recommended that users add additives by themselves. In some cases, if necessary, you should consult the oil supplier or add it under the guidance of the oil testing laboratory.
When there is water in the lubricant, the polar molecules of the emulsifier are adsorbed on the surface of tiny water droplets to form an emulsion suspension. When the lubricant is found to be emulsified, in addition to removing water, the source of the water must be found. If the lubricant is emulsified by water, the user should be aware that the additives in the oil will be affected because water ingress will lead to additive consumption. Through oil testing, the remaining additives in the lubricant can be determined.
The wetting and penetration of additives refers to the ability of additive molecules to be fixed on the metal surface, such as anti-wear agents (AW), extreme pressure agents (EP), oiliness agents, rust inhibitors, and corrosion inhibitors.
The role of anti-wear agents is to play an anti-wear and friction-reducing role on metals under the condition of boundary lubrication. Anti-wear agents generally work at medium temperatures (65℃~110℃) and can form a tough gray film on the metal to avoid direct dry friction between metals. ZDDP (dialkyldithiophosphate) is a relatively common anti-wear agent.
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