Analysis and modelling of the dry-sliding friction and wear behaviour of electrodeposited Ni and Ni-matrix-nanocomposite films

• Novel Ni-matrix-nanocomposite and Ni films were produced by electrodeposition.
• Dry-sliding friction and wear using linearly reciprocating ball-on-flat setup.
• Plastic contact during sliding resulting in ploughing-type abrasive wear.
• Dependence of dynamic friction coefficient on material hardness.
• Numerical modelling of wear volume and instantaneous wear rate.

The work here described aimed to assess the tribological behaviour of a Ni-matrix-nanocomposite film and to gain understanding of the role that the reinforcing phases play in it. The composite consisted of an array of Ag-coated SnO2 nanowires grown onto a substrate, around which the Ni matrix was galvanostatically deposited. Friction and wear were evaluated under dry sliding conditions using a linearly reciprocating ball-on-flat setup, with a diamond ball of 5.8 µm radius as counterbody, subjected to loads ranging from 5 to 30 mN. The surface and cross section of the wear tracks were characterised by scanning electron microscopy, energy-dispersive X-ray spectroscopy and white light interferometry. Ploughing-type abrasive wear was observed, with load-dependent dynamic friction coefficients, being this attributed to scale effect. Numerical models were developed for the analysis of wear volume and wear rate, as function of film hardness, applied load and wear track length. Due to their higher hardness, the composite films exhibited superior wear resistance with respect to Ni films produced using the exact same bath and deposition parameters as the composite׳s matrix. This was evidenced by reductions of up to 74 and 65% in wear volume and rate, respectively.