Cailiao gongcheng (Aug 2022)
Effect of multilayer graphene on tribological property of titanium alloy
Abstract
Multilayer graphene(MLG) and MLG/Fe2O3composite nanomaterials were prepared by liquid-phase stripping. The prepared MLG, MLG/Fe2O3composite nanomaterials and MLG+Fe2O3mechanically mixed nanomaterials were directly added onto the titanium alloy/steel sliding interface. Subsequently, the dry sliding friction and wear tests were performed, and the friction and wear behavior of TC11 alloys was measured. The X-ray diffractometer, laser Raman spectrometer, scanning electron microscopy, 3D laser scanning microscopy and energy spectrometer were employed to analyze the structure, morphology and component of the worn surface and subsurface for TC11 alloys. The results show that, as for the single additive of MLG, the variation tendency of wear loss and friction coefficient for TC11 alloy is similar to that without any additives. There is only Ti and no other phases on the worn surface. The characteristics of adhesive wear and abrasive wear are presented, which are manifested as plastic tearing, adhesive traces and furrows. Underneath the tribo-layer, there exist a plastic layer, which means that TC11 alloy substrate suffers a plastic deformation during sliding. When MLG/Fe2O3composite nanomaterials and MLG+Fe2O3mechanically mixed nanomaterials are selected as the additives, the wear loss and friction coefficient invariably maintain extremely low values and close to zero, in a certain range of sliding revolutions. There retain the phases of MLG and Fe2O3 on the worn surface. The typical black regions and grey regions are observed, and the tribo-layers are presented a double-layer structure. With an increase of cycles to 25000, the double-layer tribo-layer form with the addition of composite nanomaterials disappear, and the severe wear appears. However, as for the addition of mechanically mixed nanomaterials, the double-layer tribo-layer steadily exists. Therefore, the single addition of MLG is unable to improve the friction and wear properties of titanium alloy. With an addition of MLG to the Fe2O3-contained tribo-layer, a new tribo-layer, i.e. double-layer tribo-layer is formed. This layer simultaneously possesses lubrication and bearing function, resulting in a significant improvement for the friction reduction and wear resistance of titanium alloys. Especially, the titanium alloys present more excellent tribological properties with the addition of mechanically mixed nanomaterials, because of more layers and higher content of MLG in the double-layer tribo-layer.
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