Electrochemical Analysis of Stainless Steel Samples for Use in Pharmaceutical Heat Exchangers
Faculty Mentor Information
Noah Montrose, Boise State University; Brandon King, Boise State University; and Dr. Mike Hurley, Boise State University
Presentation Date
7-15-2026
Abstract
Brazing is a material joining process that uses a filler metal with a lower melting temperature as an adhesive. The high temperatures involved in brazing can leave stainless steels vulnerable to localized chromium depletion, also known as sensitization. Sensitization is detrimental to stainless steel because it can cause regions of the material to lose the “stainless” quality and become much more susceptible to corrosion. The focus of this study is to determine if brazing is a safe method to make heat exchangers for pharmaceutical manufacturing. A double loop-electrochemical potentiokinetic reactivation test (DL-EPR) can be used to quantify a metal alloy’s degree of sensitization. In the test, a 3-electrode electrochemical cell is used with a potentiostat to polarize the working electrode at a constant rate, to strip away the metal’s passive oxide layer. The sample is polarized back down to its original potential, and the chromium rebuilds the protective surface oxide layer. Comparing the peak current during the forward and reverse scans reveal how much of the oxide layer did not reform due to sensitization. The results of this testing were used to determine how the corrosion resistance of stainless steel is impacted by the thermal cycle of a brazing process.
Electrochemical Analysis of Stainless Steel Samples for Use in Pharmaceutical Heat Exchangers
Brazing is a material joining process that uses a filler metal with a lower melting temperature as an adhesive. The high temperatures involved in brazing can leave stainless steels vulnerable to localized chromium depletion, also known as sensitization. Sensitization is detrimental to stainless steel because it can cause regions of the material to lose the “stainless” quality and become much more susceptible to corrosion. The focus of this study is to determine if brazing is a safe method to make heat exchangers for pharmaceutical manufacturing. A double loop-electrochemical potentiokinetic reactivation test (DL-EPR) can be used to quantify a metal alloy’s degree of sensitization. In the test, a 3-electrode electrochemical cell is used with a potentiostat to polarize the working electrode at a constant rate, to strip away the metal’s passive oxide layer. The sample is polarized back down to its original potential, and the chromium rebuilds the protective surface oxide layer. Comparing the peak current during the forward and reverse scans reveal how much of the oxide layer did not reform due to sensitization. The results of this testing were used to determine how the corrosion resistance of stainless steel is impacted by the thermal cycle of a brazing process.