Influence of Ru on Structure and Corrosion Behavior of Passive Film on Ti-6al-4v Alloy in Oil & Gas Exploration Conditions

Abstract

In order to investigate the influence of minor Ru on electrochemical behavior and structural characteristics of passive film on the surface of Ti-6Al-4V alloy in various oil & gas exploration conditions, electrochemical techniques, XPS, SEM and corrosion simulation tests were carried out, and the results revealed that the oil & gas exploration conditions had a serious impact on the electrochemical behavior and corrosion resistance of tested alloys, the passivation film resistance and corrosion potential of tested titanium alloys were significantly reduced with the increasing of acidity and temperature. With the addition of minor ruthenium, the potential of passive film on the Ti-6Al-4V-0.11Ru alloy surface was been risen because of the high surface potential of ruthenium element, the content of metallic ruthenium and tetravalent titanium oxides TiO 2 in the surface film of Ti-6Al-4V-0.11Ru alloy all increased with the increasing of temperature, which led to that the thickness, stability, corrosion resistance and repair ability of passive film on the surface of Ti-6Al-4V-0.11Ru alloy was all better than that of Ti-6Al-4V, these results were also confirmed by corrosion simulation tests.

Keywords: Titanium alloys, Ruthenium, Passive film, Electrochemical behavior, Anti-corrosion properties, Structural characteristics