Influence of Ru-Ni-Nb combined cathode modification on corrosion behavior and passive film characteristics of Ti-6Al-4V Alloy used for oil country tubular goods

A new Ru-Ni-Nb combined cathode modification for Ti-6Al-4V alloy was investigated. There was a multiple blocking mechanism existed in the passivation film of Ru-Ni-Nb modified Ti-6Al-4V alloy, which not only increased the surface potential, but also greatly decreased the number of metastable oxides and point defects in the passive film, and reduced the transport and diffusion process of titanium ions and/or oxygen in the passive film, thus effectively reducing destruction of the passive film and maintaining the stability and integrity of the oxide film, which has excellent corrosion resistance in harsh oil &gas exploration environments.