Boundary lubrication adsorbed monolayers

In summary, impressive progress has been achieved to understand the role of adsorbed layers in boundary lubrication, but the effect of molecular orientation on tribology performance and the shear strength of adsorbed monolayers are the issues that remain to be clarihed in a long future study of boundary lubrication. 

Lubricity - wear protection and fatigue. The coefficient of friction is a measure of lubricity of a lubricant. The esters, being more polar, are attracted to the metal surfaces and form monolayers. These thin layers reduce the coefficient of friction at the surface. The surface phenomena that determine the behavior of boundary lubricants can be described in the following terms physically and chemically adsorbed layers and tribochemically formed films. 

The adsorption of deposited monolayer films can be very tenacious, especially when the solid substrate can react with the deposited material. Carbox-yhc acid monolayers deposited on metal or metal oxide surfaces, for example, almost certainly form metal soaps that are extremely difficult to remove by any means other than direct chemical etching. For example, such strongly adsorbed films are very useful in friction and wear studies of boundary lubrication (see Chapter 18). 

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