Physical and chemical properties of lubricants

Industrial and automotive lubricants are custom-formulated for various types of vehicle engines (depending on specified requirements from engine manufacturers and end users), drivelines (such as transmissions and gear) and industrial equipment (hydraulic, transformers, compressors) [1, 2]. It is not the intention here to cover the large variety of lubricant formulations in specifically chemical terms, as this area of science and technology is appropriately covered in lubrication-specific reviews and monographs. However, a snapshot of the most important lubricant formulation information in terms of its electrochemical properties is presented below. 

The mechanism by which these additives perform in an engine is quite complex. Simply stated, detergents protect metal surfaces by forming protective films and by neutralizing the acidic products of combustion and thermooxidation. Detergents also actively interact with water, glycol, and other polar contaminants. Overbased detergents are t3q ically -500-5000 molecular- 

Soot formation eventually leads to an increase in oil viscosity and accelerated engine wear. As soot concentration increases beyond a certain level (typically four to eight percent), the dispersants are unable to suspend it, resulting in formation of large soot agglomerates ( 1 pm), which cause abrasive surface 

Contamination by water and/or ethylene glycol caused by coolant leaks from deteriorated seals and moisture from condensation affects all industrial and automotive lubricants, in particular hydraulic equipment. If equipment is 

FIGURE 10-1 Dispersant equilibrium states A. in inverse micelles with other dispersant molecules B. coating a soot particle C. as an associated network of dispersant micelles 

---

Various physical and chemical properties of lubricants are measured and used to determine a lubricant s suitability for different applications. 

---