7/30/2019 Interfacial characterization for UNS S32760, UNS S30815, UNS N08367 and UNS 2205 in solutions simulating the r

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Interfacial characterization for UNS

S32760, UNS S30815, UNS N08367 and UNS 2205

in solutions simulating the reinforced concrete inpresence of chloride ions

Yenny Paola Cubides Gonzalez

National Center for Education and Research in Corrosion and Materials Performance.

Chemical & Biomolecular Enginerring Department

The University of Akron

Corrosion-induced deterioration in reinforced concrete structures is a major problem thatleads to high repair costs. The study of the mechanism of corrosion and prevention

alternatives in these systems has generated great interest among researchers worldwide. One

of the most important causes of damage in reinforced concrete structures is associated with

the presence of chlorides ions, which are normally in seawater and deicing salts. In the case of

deicing salts, chloride concentration depends on amount of salt spread on the road and the

precipitation of the study place. Thus, among the alternatives to reduce corrosion in

reinforced concrete structures is the use of corrosion resistant alloys (CRA), which can be less

sensitive to attack by chloride ions and can expand the durability during service. UNS S32760,

UNS S30815, UNS N08367 and UNS 2205 are stainless steel alloys used in aggressive

environments, especially in applications including seawater, preventing crevice and pitting

corrosion. In order to analyze the corrosion behavior in these alloys, electrochemical

measurements in field are required. Therefore, a titanium rod is proposed as counterelectrode, since it is chemically and biologically stable in environments that content chloride

ions.

The aim of this work is to characterize the interfacial effect of chloride ions at the

metal/electrolyte interface behavior for different CRAs in solutions that simulate reinforced

concrete. Electrochemical measurements were performed by using electrochemical

impedance spectroscopy (EIS) and cyclic polarization. UNS S32760, UNS S30815, UNS N08367

and UNS 2205 are the working electrodes; they are immersed in 2 g/L calcium hydroxide

solutions at room temperature and pH equal to 12.5. Four different sodium chloride

concentrations are considered: 0, 0,05 wt%, 0,7 wt% and 3,5 wt%. The experimental set up

includes the comparison between two different counter electrodes in the electrochemical

system described above. Thus, two systems are characterized and analyzed, in the first, theCRA is the working electrode and graphite as the counter electrode, and the second, the alloy

is the working electrode in an electrochemical cell with a titanium rod as the counter

electrode. Finally, the corrosion products in the surface of the alloys highly resistant to

corrosion are analyzed by means of Scanning Electron Microscope (SEM).

Keywords: Corrosion Resistant Alloys (CRA), Electrochemical Impedance Spectroscopy (EIS),

Cyclic Polarization.