Methods: NiTi substrate coating with cobalt and IF-WS2 nanoparticles (Co+IF) film was carried out by electroplating procedure. Cobalt solution with dispersed IF (WS2) nanoparticles was used for electroplating of the NiTi archwires and plates which served as the negative electrode. Scanning electron microscopy (SEM) was used for the analysis of the morphology of the coated substrates. The elemental composition of the coating was determined using energy dispersive X-ray spectroscopy (EDS); X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Friction evaluation was done using standard tribological tests (for the plates) and an orthodontic simulator for Instron system (for the wires).
Results: SEM, XRD, EDS and XPS analyses showed stable and well adhered Co+IF coating of the NiTi substrates. Tribological pin on disk tests presented a 66% reduction of the friction coefficient with the coated plates. Friction tests with the wires demonstrated 22% and 34% reduction in the static and kinetic friction coefficients, respectively.
Conclusion: The unique low friction coating of NiTi alloy with IF-WS2 nanoparticles embedded in cobalt matrix provides remarkable advantages such as more efficient orthodontic tooth movement. Since NiTi alloy is widely used in many medical disciplines i.e. stents, staples for foot surgery, and surgical guide wires, this kind of coating can also be beneficiary in other surgical appliances as well, providing better manipulation thus elevating treatment efficiency.