Friction and wear properties of aligned carbon nanotubes reinforced epoxy composites under water lubricated condition

• Novel continuously aligned carbon nanotubes reinforced epoxy composites were prepared by a capillary-induced moistening method.
• The wear resistance of ACNTs/EP composites with only 1.1 vol% ACNTs increased by 219 times compared to that of pure EP.
• The reinsertion of epoxy pieces adhered to the worn surface improved the wear resistance of ACNTs/EP composites.
• The effect of boundary lubricated film further improved the wear resistance of ACNTs/EP composites.

Novel continuously aligned carbon nanotubes (ACNTs) were synthesized by a floating catalyst Chemical Vapor Deposition (CVD) process. The ACNTs reinforced epoxy (EP) composites were prepared by a capillary-induced moistening method. The tribological properties of pure EP and ACNTs/EP composites in water were comparatively investigated in terms of loads and velocities. Results indicated that both the wear rate and the friction coefficient of ACNTs/EP composites were lower than those of pure EP. ACNTs/EP composites displayed outstanding anti-wear properties, which reduced the wear rate by 219 times as compared to pure EP. Superior performances of ACNTs/EP composites were also observed in rigorous condition (4.0 MPa). The worn and counterpart surfaces were studied by scanning electron microscopy (SEM). SEM observations revealed a slightly abrasive wear behavior for ACNTs/EP composites, while fatigue and abrasive wear behavior for pure EP. In particular, owing to the obstruction of ACNTs tips, part of the debris of epoxy adhered to the worn surface of ACNTs/EP composites. This debris reinsertion behavior further improved the wear resistance of ACNTs/EP composites. Besides, the effect of water on the tribological behaviors of ACNTs/EP composites was discussed as well.