Local Inhibition by 2-mercaptobenzothiazole of Early Stage Intergranular Corrosion of Copper. Issue 16 (30th November 2020)

• Record Type: Journal Article
• Authors: Sharma, Sagar B.; Maurice, Vincent; Klein, Lorena H.; Marcus, Philippe
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 16(2020)
• Publication Date: 2020-11-30
• Subjects: Intergranular corrosion -- corrosion inhibition -- 2-mercaptobenzothiazole -- Copper -- STM -- Nanometer scale; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/abcc36
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Corrosion inhibition by 2-mercaptobenzothiazole (MBT) at the surface termination of various types of grain boundaries (GBs) was studied at the nanometer scale on microcrystalline copper in HCl acid solution using in situ electrochemical scanning tunneling microscopy (ECSTM). Macroscopic electrochemical analysis by cyclic voltammetry showed highly effective inhibition of Cu(I) active dissolution blocked by MBT pre-adsorption in a potential range of 0.15–0.2 V. ECSTM analysis of the initial stages of intergranular corrosion confirmed the mitigation of net intergranular dissolution by the pre-adsorbed MBT surface layer but also revealed the local accumulation of reaction products in the GB regions. For Coincidence Site Lattice boundaries other than coherent twins, intergranular dissolution, mitigated by the pre-adsorbed MBT layer, and protection by intergranular formation of a film of reaction products were observed. For random GBs, protection by reaction products was dominant, in agreement with their more reactive intrinsic character, generating more Cu(I) ions under anodic polarization and thus promoting the formation of a protective film of reaction products. Coherent twins did not show preferential intergranular reactivity compared to adjacent grains, indicating equally strong efficiency than on grains. These results bring new insight on how inhibition operates locally at various types of GBs.