Additives For Lubricants

Additives For Lubricants

There are lack of properties of single lubricating oil so the properties of lubricants may be improved by adding some specific suitable compounds, such type of compounds which are used to improve the properties of lubricants are known as additives for lubricants. Some important additives are listed below.

(i)                 Extreme pressure additives:  These additives either get absorbed on the metal surface or react with the metal to form a layer having low shear strength on the metal surface and prevent wearing and tearing. They also protect them from welding and seizure under extreme pressure conditions. For example fatty ester, acids, organic chlorine compounds, metallic soaps etc.

(ii)               Viscosity Index improves: The prevent the oil from thickening at low temperature and thin at higher temperature. Long chain polymers like polyesters, polystyrene etc are used as viscosity index improves.

(iii)             Anti-Oxidants: These type of additives are used in internal combustion engines, turbines etc. where oxidation of oil is a serious problem. The function of these additives is to get oxidized themselves in to the oil. Hence, these are some times called as inhibitors also. For example- Organic sulphide, amines, phenols etc.

(iv)             Corrosion Inhibitor: Corrosion normally due to water of oxidation products of the oils, such additives protect metal surfaces by preventing contact between the metal and corrosion substances. For Examples, metallic compounds, phosphorized etc.

(v)               Pour-Point Depressing Additives: They maintain the characteristics of lubricating oil in liquid form even at lower temperature and prevents the separation of wax from the oil. For example, phenol, chlorinated was with naphthalene etc.

(vi)             Oiliness improves: It increase the Strength of the oil film and prevent its rupture. For example, fatty amines, fatty acids, vegetables oils etc.

(vii)           Antifoaming Agents or Additives: These additives help in decreasing foam formation. For example, Silicones, glycols etc.

(viii)         Emulsifiers: These additives are used to promote the mixing of oil and water and helps in the formation of emulsion. For example, Sodium salts of Sulphonic acid, fatty amine salts etc.