What are lubricants A.K.A LUBRICATING OIL?
A substance that can decrease friction among surfaces that are sliding over each different is referred to as Lubricant.
Petroleum is the primary source of Lubricants, however, synthetic Lubricants have additionally been prepared for unique purposes.
Functions of lubricants
The most important functions of lubrication are:
1. It reduces wear and tear and surface deformation, by avoiding direct contact among the rubbing surfaces.
2. It reduces the loss of energy within the form of heat by performing as a coolant.
3. It reduces the performance of the system by lowering the waste of energy.
Classification Of Lubricants
Lubricants may be widely categorized, on the basis of their physical state, as follows:
(1) Liquid lubricants or lubricating oils;
(2) Semi-solid lubricants or greases, and
(3) Solid lubricants.
Function of lubricants
Lubricating oils lessen friction and wear between moving/sliding metal surfaces by supplying a non-stop fluid film in-between them.
Origins of lubricants
Lubricating oils are in addition labeled as:
(1) Animal and vegetable oils:
Before the appearance of the petroleum industry, oils of the vegetable and animal origins had been the typically used lubricants.
They possess desirable oiliness (a property by which the oil sticks to the surface of gadget parts, even under excessive temperatures and heavy loads).
However, they:
(i) are costly,
(ii) go through oxidation easily
(iii) have a few tendencies to hydrolyze.
(2) Mineral or petroleum oils
are acquired with the aid of using distillation of petroleum.
These are the most broadly used lubricants, due to the fact they are;
(i) cheap,
(ii) available in abundance, and
(iii) quite stable under service situations.
However, they own bad oiliness in comparison to that of animal and vegetable oils.
(3) Blended oils:
Typical properties of petroleum oils are advanced with the aid of using incorporating unique components.
These referred to as blended oils deliver preferred lubricating properties.
The following components are employed;
(i) Oiliness-carriers:
E.g., coconut oil, castor oil) and fatty acids (like palmitic acid, stearic acid, oleic acid. etc.).
(ii) Extreme-pressure components:
They include fatty ester, acids, natural materials, which incorporate sulfur, natural chlorine compounds natural phosphorus compounds.
(iii) Pour-point depressing additives
used are phenol and certain condensation products of chlorinated wax with naphthalene.
These save you the separation of wax from the oil.
(iv) Viscosity-index improvers
are certain excessive molecular weight compounds like hexanol.
(v) Thickeners including polystyrene
(vi) Antioxidants or inhibitors,
The antioxidants are aromatic, phenolic, or amino compounds.
(vii) Corrosion preventers are natural compounds of phosphorus or antimony.
(viii) Abrasion inhibitors like tricresyl phosphate.
(ix) Antifoaming agents (like glycols and glycerol) assist in reducing foam formation.
(x) Emulsifiers including sodium salts of sulphonic acid.
(xi) Deposit inhibitors are detergents including the salts of phenol and carboxylic acids.
(4) Greases Or Semi-solid Lubricants
Lubricating grease is semi-solid, along with a soap dispersed all through liquid lubricating oil.
The liquid lubricant can also additionally be petroleum oil or maybe synthetic oil and it can incorporate any of the components for unique requirements.
But greases have a propensity to split into oils and soaps.
Grease is used :
(i) in conditions in which oil can’t stay in place, because of excessive load, low speed,
(ii) in bearing and gears that work at excessive temperatures ;
(iii) in conditions in which bearing needs to be sealed against the access of dirt, dirt, grit, or moisture,
(iv) in conditions in which dripping or spurting of oil is unwanted etc.
The most important feature of soap is the thickening agent so that grease sticks firmly to the steel surfaces.
(5) Solid Lubricants
Solid lubricants are used where:
(i) working situations are such that a lubricating film can’t be secured by the use of lubricating oils or greases;
(ii) contamination (through the access of dirt or grit particles) of lubricating oil or grease is unacceptable,
(iii) the working temperatures or load is just too high even for a semi-solid lubricant to stay in position; and
(iv) combustible lubricants have to be avoided.
The maximum common solid lubricants hired are graphite and molybdenum disulfide. (a) Graphite (b) Molybdenum disulfide.
(6) Synthetic Lubricants
Petroleum-based lubricants may be used under extraordinary situations like extremely high temperatures, chemically reactive atmosphere, etc.
Important artificial lubricants are given below. (1) Polymerized hydrocarbons
(2) Polyglycols and associated compounds
(3) Organic amines, imines, and amides are desirable artificial lubricants,
(4) Silicones
(5) Fluorocarbon
