Novel Technique for the Application of Azole Corrosion Inhibitors on Copper Surface

et al. 2020

Corrosion Science

Adsorption of 2-mercaptobenzothiazole (2-MBT) at ultra-low pressure and room temperature on metallic and pre-oxidized Cu(111) surfaces and its thermal stability were investigated using X-ray photoelectron spectroscopy in order to better understand the interfacial corrosion inhibiting properties. 2-MBT is lying flat in the monolayer with two sulphur atoms bonded to Cu and decomposes partially yielding atomic sulphur when interacting with metallic copper prior to forming molecular multilayers. Decomposition is prevented by surface pre-oxidation with 2D oxide dissociation accelerating the 2-MBT initial adsorption kinetics. 2-MBT further decomposes and partially desorbs above 100 • C. A pre-adsorbed 2-MBT monolayer on metallic copper inhibits surface corrosion. sulphur in the organic molecule could improve its capacity as corrosion inhibitor by forming coordinative bonds with copper [1]. It has been shown that 2-MBT dissolved in solution can react with copper to form a complex which acts as a protective layer at the copper surface [21]. However, controversy exists on the chemical nature of the complex formed, as well as on the fundamental mechanisms of the inhibiting interaction. The resulting structures of the protective layer formed on copper are also still not clear. Most notably, the exact role of the surface oxide in the inhibiting function remains to be studied. With few exceptions [12], experimental research concerning corrosion inhibitors have been done by immersion into solutions containing the organic compounds [7-24]. However, in order to elucidate the interaction mechanisms, deposition of the molecule evaporated in vacuum could be more insightful, since it allows controlling each step of the deposition process in a well-defined environment and on a well-defined surface. Data have been reported for vacuum evaporation [25, 26] of 1,4-benzenedimethanethiol (BDMT) on Au(111), Au(110), Cu(100) and Cu(111) single crystal surfaces. The authors found that on Cu (100) and Cu(111) surfaces, which are more reactive, BDMT dissociates in the initial stage of adsorption, resulting in atomic S adsorbed on the Cu surface. This phenomenon was not observed for the adsorption of benzotriazole on Cu(100) [27].In this work, the adsorption of 2-MBT at ultra-low pressure (ULP) and room temperature on clean and pre-oxidized Cu(111) surfaces and its effect on the oxidation of copper were investigated using ultra-high vacuum (UHV) spectroscopic techniques. The results were compared to those obtained for ULP deposition on the oxide-covered Cu(111) surface prepared in air. The thermal stability of the adsorbed molecular layer under UHV was also studied. This work brings new insight into the interaction of 2-MBT with copper, which allow us to better understand its corrosion inhibition mechanisms. Material and methodsA high purity (99.999%) Cu(111) single-crystal was used in this work. The surface was mechanically polished to 1/4 µm (diamond paste), successively rinsed with acetone, ethanol, and ultra pure (UP) water (resistivity > 18...

Section: Introductionmentioning

confidence: 99%

2-Mercaptobenzothiazole corrosion inhibitor deposited at ultra-low pressure on model copper surfaces

et al. 2020

Corrosion Science

“…The use of organic inhibiting molecules is one of the most effective and practical ways to protect metals and alloys from corrosion in aggressive environments, hence the intrinsic properties of the molecules and their interaction mechanisms with various substrate surfaces have been studied extensively [1][2][3][4][5][6] . Among all the techniques, X-ray photoelectron spectroscopy (XPS) has been widely used, which gives reliable information on the nature and chemical composition of the inhibitor/substrate interface under various conditions [6][7][8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Molecular scale insights into interaction mechanisms between organic inhibitor film and copper

et al. 2021

npj Mater Degrad

A model experimental approach, providing molecular scale insight into the build up mechanisms of a corrosion inhibiting interface, is reported. 2-mercaptobenzimidazole (2-MBI), a widely used organic inhibitor, was deposited from the vapor phase at ultra-low pressure on copper surfaces in chemically-controlled state, and X-ray photoelectron spectroscopy was used in situ to characterize the adsorption mechanisms upon formation of the inhibiting film. On copper surfaces prepared clean in the metallic state, the intact molecules lie flat at low exposure, with sulfur and both nitrogen atoms bonded to copper. A fraction of the molecules decomposes upon adsorption, leaving atomic sulfur on copper. At higher exposure, the molecules adsorb in a tilted position with sulfur and only one nitrogen bonded to copper, leading to a densification of 2-MBI in the monolayer. A bilayer is formed at saturation with the outer layer not bonded directly to copper. In the presence of a pre-adsorbed 2D oxide, oxygen is substituted and the molecules adsorb intactly without decomposition. A 3D oxide prevents the bonding of sulfur to copper. The molecular film formed on metallic and 2D oxide pre-covered surfaces partially desorbs and decomposes at temperature above 400 °C, leading to the adsorption of atomic sulfur on copper.

“…In order to mitigate corrosion, inhibitors are widely used and developed. On copper, numerous studies [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] have been carried out for a better understanding of the surface interaction with corrosion inhibitors, as well as the inhibition mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…2-mercaptobenzothiazole (2-MBT) is one of the corrosion inhibitors used in industry besides benzotriazole (BTAH) [2][3][4][5][6][7][8][9][10]. Its chemical formula is C 7 H 5 NS 2 , and it exists in two forms: the thione (NH) and the thiol (SH) forms.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and thermal stability of 2-mercaptobenzothiazole corrosion inhibitor on metallic and pre-oxidized Cu(1 1 1) model surfaces

Applied Surface Science

et al. 2020

2-mercaptobenzothiazole (2-MBT) is used for its corrosion inhibition properties. In this study, the adsorption of 2-MBT on metallic and pre-oxidized Cu(111) surfaces was investigated using Auger Electron Spectroscopy and Scanning Tunneling Microscopy. Growth and structure of molecular films adsorbed at ultra low pressure and room temperature on clean and pre-oxidized Cu(111) surfaces were characterized. On clean metallic Cu(111) surface, local triangular (√ 7 × √ 7)R19.1 • structures are formed at low exposures (3-4 L), which are assigned to the adsorption of atomic S resulting from partial decomposition of 2-MBT. At 10 L, a full non-ordered monolayer of 2-MBT is formed, and further exposure leads to the formation of a non-ordered multilayer. The thickness of the outermost 2-MBT layer is 1.3 A, which suggests that the outermost molecules of the multilayer are lying flat. Oxidation of the copper surface prior to exposure to 2-MBT results in more compact and homogeneous molecular films. The initial 2D oxide is dissociated and replaced by 2-MBT. Thermal stability at different temperatures was studied on clean and pre-oxidized copper surfaces saturated with 2-MBT. A (√ 7 × √ 7)R19.1 • structure is observed in both cases for temperatures higher than 100 • C, indicating the decomposition of 2-MBT and a copper surface covered with atomic S.