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October PhD Defense for Aria Kahyarian
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Aria Kahyarian has successfully defended his dissertation in October 2018. Aria's dissertation topic was Mechanism and Prediction of Mild Steel Corrosion in Aqueous Solutions Containing Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide.
His PhD research was aimed to answer one of long-lasting questions in pipeline corrosion of mild steel: How CO2, H2S and carboxylic acids affect the aqueous corrosion of mild steel? He initiated a kinematic investigation of the
electrochemical behavior of mild steel in such environment. Using polarization data along with detailed quantitative analysis based on comprehensive mathematical models, he showed that neither carbonic acid nor hydrogen sulfide or carboxylic acid are
electrochemically reduced during the corrosion process. His findings showed that all these species act merely as buffers at the vicinity of the metal surface. This process, which is referred to as "buffering effect", is demonstrated to be the cause of
the accelerated corrosion in presence of these species. The buffering effect was shown to be an inherent property of any weak acid. The results and discussions developed during this investigation introduced a new perspective to the corrosion of mild.
He showed that all the above mentioned corrosion scenarios are in fact example of one generic corrosion mechanism: aqueous corrosion in presence of weak acids. Aria showed that the severity of the effect of a weak acid on mild steel corrosion can be readily
predicted based on its chemical properties, and introduced a grouping on that basis, in order from higher to lower aggressivity: strongly buffering weak acids with pKa below 5 such as carbonic acid and acetic acid, mildly buffering weak acids with pKa between
11 and 5, such as hydrogen sulfide and bicarbonate ion, and on-buffering weak acids with pKa above 11, like water and hydrogen bisulfide. The findings of Aria's research are collected in eight peer-reviewed journal publications, with four more in preparation. He is currently with Apple.
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