A new strategy was proposed to prepare a composite film using mussel adhesive protein Mefp-1 and graphene to achieve corrosion protection and surface lubrication on carbon steel. The dispersibility of graphene in Mefp-1 solution was firstly investigated and deposition methods of Mefp-1/graphene film were proposed. In-situ confocal Raman micro-spectroscopy and electrochemical impedance spectroscopy measurements were utilized to study the corrosion inhibition effect in NaCl solution. Friction tests were conducted to study the tribological properties. Results show that the Mefp-1/graphene film exhibits strong adhesion to carbon steel, provides improved corrosion- and wear-resistance, and a significantly increased lubricity on carbon steel.
Mefp-1 adhesive protein derived from marine blue mussels, together with the 2D material graphene, was used to build the green composite film with enhanced anti-corrosion property and mechanical strength. The corrosion inhibition of the composite film, formed by different methods, was evaluated by using electrochemical impedance spectroscopy. The non-degraded adhesion of the composite film to the carbon steel substrate was proved by nano-scratch tests. Infrared spectroscopy was utilized to investigate the film formation process and "three-body interactions " between Mefp-1, graphene and carbon steel surface. The results show that the Mefp-1 adsorbs on the carbon steel surface mainly through the covalent bond between catechols and Fe(III). Meanwhile, Mefp-1 can bond to non-adhesive graphene by forming hydrogen bonds and pi-pi interaction non-covalent bonds, which facilitate the formation of a robust Mefp-1/graphene composite film on the carbon steel surface.
This paper focuses on the study of micro-galvanic corrosion of the Cu/Ru couple in KIO4 solution. Practical nobility across the Cu/Ru interface was evaluated by Volta potential mapping, and the morphological changes were monitored by in-situ atomic force microscopy measurements during exposure in a KIO4 solution. Chemical composition of precipitated corrosion product was analyzed by Confocal Raman spectroscopy immediately after the exposure. The results show that Cu is the anode of the Cu/Ru couple, and accelerated dissolution of Cu preferentially occurs near the Cu/Ru interface. However, subsequent formation of insoluble Cu(IO3)2·nH2O leads to precipitation, which impedes further Cu corrosion.
Ruthenium is the most promising material for the barrier layer used for the sub 14 nm technology node in integrated circuits manufacturing. Potassium periodate (KIO4)-based slurry is used in the chemical mechanical planarization (CMP) process of the barrier layer. However, the electrochemical and corrosion properties of ruthenium have not been investigated in such slurry. In this paper, the electrochemical and corrosion behaviors of ruthenium in KIO4 solutions were investigated under static conditions but at different pH values by potentiodynamic polarization and electrochemical impedance spectroscopy measurements, combined with surface chemical analysis using auger electron spectroscopy. Moreover, to study wear enhanced corrosion during CMP, tribocorrosion experiments were carried out to monitor the current density changes during and after mechanical scratching. The results show that at pH 6, ruthenium forms a relatively thick and heterogeneous surface film composed of RuO2 center dot 2H(2)O/RuO3, showing a high corrosion resistance and it exhibits a quick repassivation after mechanical scratching. At pH 4, ruthenium shows a passivation behavior with formation of a uniform and conductive oxide like RuO2 center dot 2H(2)O. It should be noted that there is a possible formation of RuO4 toxic gas under this condition, which should be avoided in the actual production. However, at pH 11, ruthenium exhibits no considerable passivity and the corrosion proceeds uniformly.
A new measurement protocol was used for microscopic chemical analysis of surface oxide films with lateral resolution of 1 mu m. The native air-formed oxide and an anodic passive film on austenite and ferrite phases of a 25Cr-7Ni super duplex stainless steel were investigated using synchrotron hard X-ray photoemission electron microscopy (HAXPEEM). Pre-deposited Pt-markers, in combination with electron backscattering diffraction mapping (EBSD), allowed analysis of the native oxide on individual grains of the two phases and the passive film formed on the same area after electrochemical polarization of the sample. The results showed a certain difference in the composition of the surface films between the two phases. For the grains with (001) crystallographic face // sample surface, the native oxide film on the ferrite contained more Cr oxide than the austenite. Anodic polarization up to 1000 mV/(Ag/AgCl) in 1M NaCl solution at room temperature resulted in a growth of the Cr- and Fe-oxides, diminish of Cr-hydroxide, and an increased proportion of Fe3+ species. by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.