What is it about?
Adsorption and inhibition behavior of 1,2,3-benzotriazole (BTA) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on brazing Cu-Ag alloy was studied in deionized water using potentiodynamic polarization measurement, adsorption isotherm investigation and X-ray photoelectron spectroscopy (XPS). Pure Ag and pure Cu were included to investigate the mere effect of each component on the alloy’s behavior. Results show better inhibition of DMTD for Ag and BTA for Cu, both by chemisorption. BTA was found to follow Langmuir isotherm while DMTD obeyed Temkin adsorption isotherm, despite both acting as a mixed type inhibitor. Combining the two inhibitors increased the inhibition efficiency over 80% for the Cu-Ag alloy. XPS spectra demonstrate the formation of DMTD protective film through DMTD’s functional groups of pyrrolic N from the azole ring and thiol S from the mercapto anchoring group on Ag and thiol S on Cu. Compared to BTA, the higher affinity of DMTD to Ag was attributed to the involvement of two heteroatoms with the Ag surface.
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Why is it important?
The eutectic Cu-Ag alloy is being utilized in cooling systems of data center facilities. In these deionized (DI) water-based systems, copper channels with copper fins brazed with Cu-Ag eutectic alloy are sandwiched between two copper plates and are affixed to thousands of central processing units (CPU). Draining the heat away from the CPUs is the objective of employing such systems. In spite of using benzotriazole (BTA) as an inhibitor, corrosion takes place leading to the detachment of copper fins from the brazing area. The reasoning behind choosing this inhibitor has been based on the fact that BTA protects copper well and Ag as a noble material would be intact. However, it turned out that the Ag rich phase is vulnerable in such conditions raising reliability and safety concerns.
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This page is a summary of: Corrosion Inhibition of Brazing Cu-Ag Alloy with 1,2,3-Benzotriazole and 2,5-Dimercapto-1,3,4-Thiadiazole, CORROSION, October 2020, NACE International, DOI: 10.5006/3642.
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CORROSION, the Journal of Science and Engineering is the premier research journal featuring peer-reviewed technical articles from the world’s top researchers. 75 years and over 7,400 peer-reviewed articles with advances in corrosion science and engineering have been published in CORROSION. The scope of the journal includes the latest developments in areas of corrosion metallurgy, mechanisms, predictors, cracking (sulfide stress, stress corrosion, hydrogen-induced), passivation, and CO2 corrosion.
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