Definition - What does Lubricant mean?
Lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles. One of the single largest applications for lubricants, in the form of motor oil, is protecting internal combustion engines in motor vehicles and powered equipment.
Lubricants are used for:
- Keeping moving parts apart
- Reducing friction
- Transferring heat
- Carrying away contaminants & debris
- Transmitting power
- Protecting against wear
- Preventing corrosion
- Seal for gases
- Stopping the risk of smoke and fire
- Preventing rust
Corrosionpedia explains Lubricant
Lubricants are generally composed of 90% base oil (most often petroleum fractions, called mineral oils) and less than 10% of a variety of additives to impart desirable characteristics. Although generally lubricants are based on one type of base oil, mixtures of base oils also are used to meet performance requirements.
Vegetable oils or synthetic liquids such as hydrogenated polyolefins, esters, silicones, fluorocarbons and many others are sometimes used as base oils. Additives deliver reduced friction and wear, increased viscosity, improved viscosity index, resistance to corrosion and oxidation, aging or contamination, etc.
For example, lubricants such as 2-cycle oil are added to fuels like gasoline which has low lubricity. Sulfur impurities in fuels also provide some lubrication properties, which has to be taken into account when switching to a low-sulfur diesel; biodiesel is a popular diesel fuel additive, providing additional lubricity.
Quality lubricants typically possess the following features:
- High boiling point and low freezing point
- High viscosity index
- Thermal stability
- Hydraulic stability
- Corrosion prevention
- High resistance to oxidation
Solid or non-liquid lubricants include grease and powders (dry graphite, PTFE, Molybdenum disulfide, tungsten disulfide, etc.), PTFE tape used in plumbing, air cushion and others. Aqueous lubrication is of interest in a number of technological applications. Strongly hydrated brush polymers such as PEG can act as lubricants at liquid-solid interfaces.
Lubricants, both fresh and used, can cause considerable damage to the environment mainly due to their high potential of serious water pollution.