Corrosion inhibition of copper in glycol-based heat transfer fluids: A comparative gravimetric and electrochemical study

The corrosion behavior of metallic copper (Cu) was investigated in the presence and absence of corrosion inhibitors in 33.33 vol.% ethylene glycol and propylene glycol heat transfer solutions under aerated conditions at 75 ◦C. Dipotassium hydrogen phosphate and potassium dichromate were evaluated as inorganic corrosion inhibitors, while benzotriazole, tolyltriazole, indazole and benzimidazole were studied as representative organic corrosion inhibitors using gravimetric and electrochemical techniques. Motivated by increasing regulatory constraints on conventional inhibitors, this work aims to establish robust and efficient screening methodologies for identifying sustainable alternatives that provide comparable or enhanced corrosion protection. Weight- loss measurements, time-resolved electrochemical polarization and impedance techniques, and complementary physicochemical analyses were integrated to elucidate corrosion and inhibition mechanisms in glycol-based systems. Comparative analysis of 112 h medium-term and 336 h long-term gravimetric data with 24 h short-term electrochemical results was conducted to bridge the gap between these approaches. Notable discrepan- cies between gravimetric and electrochemical outcomes were observed, highlighting the need for careful interpretation of short-term electrochemical metrics when assessing long-term inhibitor performance