User Contributed Dictionary
Noun
- The quality of being lubric; slipperiness; instability; as, the lubricity of fortune.
- Smoothness; freedom from friction; also, property which diminishes friction; as, the lubricity of oil.
- Lasciviousness; propensity to lewdness; lechery; incontinency.
References
Extensive Definition
Lubricity is the measure of the reduction in
friction of a lubricant. It is due to
chemical action between the lubricant or some components of it and
the rubbing surfaces in the physical conditions there, due to which
a tenatious layer develops, which is able to support the load that
the bulk lubricant alone by virtue of its viscous resistance could
not. The study of lubrication and mechanism wear is called tribology.
Measurement of lubricity
Lubricity of a material cannot be directly measured, so tests are performed to quantify a lubricant's performance. This is done by determining how much wear is caused to a surface by a given friction-inducing object in a given amount of time. Other factors such as surface size, temperature, and pressure are also specified. The greater the wear scar the worse the lubricity. For this reason lubricity is also termed a substance's anti-wear property.Examples of test setups include
"Ball-on-cylinder" and "Ball-on-three-discs" tests.
Lubricity in diesel engines
In a modern diesel
engine, the fuel is part of the engine lubrication process.
Diesel
fuel naturally has sulfur compounds in it that gives
it good lubricity properties, but because of regulations in many
countries (such as the
US and the
EU) this sulfur must be removed. Thus, the reformulated diesel
fuel has a lower lubricity and requires lubricity improving
additives to prevent excessive engine wear.