Penetration of corrosive species into copper exposed to simulated O2-free groundwater by time-of-flight secondary ion mass spectrometry (ToF-SIMS)

Characterization of Surface Films that Develop on Pre-Oxidized Copper in Anoxic Simulated Groundwater with Sulphide

“…in the specimen. This suggests that a sulphur-rich layer exists beneath the oxygen-rich layer, consistent with our recent results obtained by time-of-flight secondary ion mass spectroscopy [16]. The maximum mass concentration of both elements, 33% in the case of oxygen and 41% in the case of sulphur, was detected at the depth of 43 nm.…”

“…The experimental results by Hollmark et al [15] are in agreement with the findings by Stenlid et al [14] in that when a pre-oxidized copper is subjected to a sulphide containing solution, the resulting film is an admixture of Cu 2 O and Cu 2 S. This research is motivated by the aim to shed light in the role of the pre-existing oxide layer on copper in the development of the sulphide film. Our recent work [16] already demonstrated that in the pre-oxidized surfaces exposed to simulated O 2 -free groundwater, oxygen and sulphur often coexist. In fact, the results showed that a sulphur-rich inner layer existed between the oxygen-rich outer layer and the copper substrate, indicating that the oxide film does not act as an effective barrier to the sulphide-induced corrosion.…”

“…The GDOES data originates from area of approximately 2.5 mm in diameter, hence the obtained response likely originates from several grains (the grain structure is shown in ref. [16]) in lateral dimension, but likely from one grain only in the depth direction. As revealed by GDOES examinations, both pre-oxidized and ground specimens contained oxygen in the surface film along with sulphur.…”

“…10 and 11. However, it is evident that more research is needed in this area, to prove the mechanism of conversion of Cu 2 O into Cu 2 S. More importantly, further work is needed to explore the ingress of reactive species, such as oxygen, sulphur, and hydrogen, into the copper substrate and the possible consequences, e.g., embrittlement [16].…”

“…As copper is an inherent element in the corrosion product film, we define the solution/film interface at the first depth point with signal from Cu. In the other extreme, the concentration profiles for both oxygen and sulphur are quite smooth, likely because of several overlapping reasons: surface roughness of the film, possible roughness in the film/substrate interface across the grains, and ingress of corrosive elements into copper [16]. However, small amounts (1-5%) of oxygen were detected at depths where the sulphur signal was attenuated.…”