Tribomechanical-Chemical Effects and Visualisation of Additive’s Layer Formation in Engine Crankcase Oil Between Sliding Pairs

Examination of worn surfaces by optical, electron microscope detection and X-Ray diffraction analysis indicated that the replacement of the pin (steel 52100) by another pin (steel Stub 51115) facilitated and increased the influence of surface degradation which allows the sliding surface to be satisfactorily reactive to form high percentage of protective additive’s layers and to cover uniformly the whole wear track in boundary lubricated conditions. A few minutes of dry test well determined the production of the surface degradation to promote an optimal layer formation. The same type of tests were repeated using pin (sapphire) on the plate (steel Stub 51115) in order to be able to visualize the formation of layers. High speed camera has got images of layers and demonstrates the layer formation during experiment. This study suggests that the surface deterioration is a mechanical process and promotes chemical reactions at solid surfaces. Satisfactory degradation of the surface permits activating lubricant additives to form protective layers. The temperature has a significant chemical influence on the mechanical effect of the material type on the formation of additive’s layer.