Electrochemical Behavior and Surface Characteristics of Pure Titanium during Corrosion in Simulated Desulfurized Flue Gas Condensates

Corrosion behavior of pure titanium in simulated desulfurized flue gas condensates in thermal power plant chimneys is investigated by electrochemical measurements and surface observations. Existence of fluoride ion leads to the breakdown of oxide film and promotes activation dissolution of Ti. Both anodic and cathodic reactions are enhanced by the increase of temperature, following an Arrhenius relationship. The participation of fluoride ion leads to low activation energy values. The corrosion process presents a two-step mechanism, in which dissolution of the adsorbed intermediate species is the rate determining step. Increase of temperature accelerates both of the two steps, especially the latter, and results in the low surface coverage of adsorbed species at high temperatures. Preferential dissolution occurs on specific grains and grain boundaries. Increase of temperature facilitates the crystallographic characteristics and aggravates the failure risk of the chimneys.