简介:The electrochemical corrosion behavior of X65 pipeline steel in the
simulated oil/water emulsion was investigated under controlled
hydrodynamic and electrochemical conditions by rotating disk electrode technique.
Res简介:The electrochemical corrosion behavior of X65 pipeline steel in the
simulated oil/water emulsion was investigated under controlled
hydrodynamic and electrochemical conditions by rotating disk electrode technique.
Results demonstrated that mass-transfer of
oxygen plays a significant role in the cathodic process of steel in
both oil-free and oil-containing solutions. Electrode rotation
accelerates the oxygen diffusion and thus the cathodic reduction.
The higher limiting diffusive current density measured in
oil-containing solution is due to the elevated solubility of oxygen
in oil/water emulsion. The anodic current density decreases with the
increase of electrode rotating speed, which is attributed to the
accelerated oxygen diffusion and reduction, enhancing the steel
oxidation. Addition of oil decreases the anodic dissolution of steel
due to the formation of a layer of oily phase on steel surface,
increasing the reaction activation energy. The steel electrode
becomes more active at the elevated temperature, indicating that the
enhanced formation of oxide scale is not sufficiently enough to
offset the effect resulting from the enhanced anodic dissolution
reaction kinetics. The corrosion reaction mechanism is changed upon oil addition,
and the interfacial reaction is activation-controlled,
rather than mass-transfer controlled. When sand particles are added
in oil/water emulsion, there is a significant increase of corrosion of the steel.
The presence of sands in the flowing slurry would
impact and damage the oxide film and oily film formed on the steel
surface, exposing the bare steel to the corrosive solution.详细>