Description
1st Paragraph: Electrochemical techniques are extensively utilized to characterize corrosion. Although not standardized, metal samples typically are polished so that that the material exhibits stabilized corrosion behavior by removing contaminants and native oxides prior to conducting electrochemical measurements. Effect of surface roughness and the associated microstructure on pitting potential of aluminum alloy is studied, where the rougher surface exhibited two breakdown potential.[1] In addition, scanning Kelvin Probe (SKP) is utilized to study the effects of surface roughness to cathodic delamination and epoxy coatings.[2] The NACE 1/SSPC 5 standard provides general guidance for metal surface preparation, but the surface finish relating to the corrosion heavier is not defined.[3] Corrosion potential, or open circuit potential (OCP), is an indication of the likelihood of corrosion and metal nobility based on thermodynamics. In general, the extent of reaching a stabilized reaction is indicated by a delayed OCP process for a certain amount of time depending on the exposure environment. The ASTM C876 standard specifies corrosion potentials of uncoated reinforcing steel in concrete and the likelihood of corrosion according to the OCP measurement.[4] However, this stabilization process has never been characterized, or quantified, in a standardized manner to determine the OCP delay time. In many cases, the ultimate stabilization may not be reached due to the nature of corrosion, for example, passivation or recurring metastable pitting. The goal of this work is to provide a robust approach to capture the variation introduced by mechanical polishing in simulated pore solutions with different NaCl concentrations then ranking and quantifying the level of variation introduced by each factor to corrosion potential. Since the impact of polishing on corrosion potential is usually ignored or not reported in most work, with statistical analysis the polishing process can be optimized by the robust experimental design, a statistical tool using regression to quantitatively analyze the relationship between the corrosion potential and extent of polishing, chloride concentration, and time.
Authors: A.H.M.E. Rahman, Ma’Moun Abu-Ayyad, Issam Abu-Mahfouz, and Joshua Bachert
Keywords: Recycling, HDPE coating, Adhesion Tape Test, Corrosion, Salt Immersion Test