Analysis of wear tracks produced during boundary lubrication of 6082T6 aluminium with polydimethylsiloxane

Polydimethylsiloxane is renowned for its extremely poor boundary lubricating ability when placed between sliding metallic surfaces. In fact, it is not simply a poor boundary lubricant, it is a positive antagonist since, in certain instances, dry sliding can produce lower wear and friction under identical test conditions. The objective of the present investigation was to determine whether the relationship between the wear produced and the respective coefficient of friction followed the traditional theory. The test used a cross-cylinder friction rig and scanning electron microscopy. It was found that when the lowest coefficient of friction was observed (μ = 0’31) the plastic wear involved small area scuffing. A slightly higher coefficient of friction (μ = 0’37) produced large area scuffing, and the highest coefficient (μ = 0’58) caused deep ploughing. It was concluded that although the action of the siloxane under boundary conditions is somewhat unique, the transition from small area scuffing to ploughing associated with an increase in friction follows the convention.