Electrodeposition and Properties of Water Repellent Metal/Ni-PTFE Composite Films

To improve the corrosion resistance of Ni-PTFE composite film, electrodeposition of Au, Cr and Sn on it to form Metal/Ni-PTFE (polytetrafluoroethylene) composite film was attempted in this study. Ni-PTFE composite film which was water repellent was wet enough under cathodic polarization in the electroplating solution for electrodeposition of the metal to take place. The contact angles of the waster drop of Ni-PTFE and Metal/Ni-PTFE composite films (Meta=Au, Cr, Sn) were 155°, 153°, 145°and 151°, respectively. The electric resistance on the surface of Ni-PTFE and Metal/Ni-PTFE composite films were 1.44×10-3, 5.25×10-4(Au), 3.61×10-1 (Cr), and 9.33×10-4 (Sn) ohm m-1, while that on Ni was 5.41×10-4 ohm m-1. The significantly larger electric resistance of Cr/Ni-PTFE composite film is through to be caused by the formation of an oxide such as Cr2O3 on its surface after the electroplating. This is also reflected in the fact that Cr/Ni-PTFE composite film has the smallest corrosion current among the Metal/Ni-PTFE composite films in this study. From the results of the corrosion test in 1mol dm-3 HCl aq., the amount of Ni dissolved from sample increased in the order of Ni-PTFE, Sn/Ni-PTFE, Cr/Ni-PTFE, Au/Ni-PTFE. The change in the wettability of the sample might affect the corrosion behavior in this case.