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The purpose of this paper is to investigate the effect of water content of assembly solution on the adsorption behavior and corrosion protection performance of 1–tetradecylphosphonic acid [TDPA, CH3(CH2)13P(O)(OH)2] films on aluminum alloy surface in NaCl solution.

Self-assembled monolayers (SAMs) of TDPA were prepared on the 2024 aluminum alloy surface in TDPA containing ethanol-water solutions with different water contents. The adsorption behavior of the SAMs on the alloy surface and their corrosion protection properties in a 3.5 per cent NaCl solution were characterized by potentiodynamic polarization scan, Fourier-transformed infrared spectroscopy (FTIR) and atomic force microscopy (AFM).

The FTIR results demonstrated that the TDPA molecules were successfully adsorbed on the 2024 aluminum alloy surface, and the density of the SAMs increased with the increasing water content in the assembly solution. The electrochemical studies and corrosion morphologies observed by AFM showed that the optimal condition is 2 h of assembling in solution B or solution C. The corrosion inhibition efficiency values follow the order solution B ≈ solution C > solution A at the first 2 h assembly and solution B > solution C > solution A while the assembly time exceeded 2 h. The dependence of corrosion inhibition performance of the SAM on the water content and on the assembly time is related to the balancing of competition between TDPA adsorption and dissolution of the alloy oxidation film.

It illustrates potential application prospects of TDPA for surface treatment of aluminum alloy. Via the comparison with our previous work, this paper provides useful information regarding the difference of corrosion inhibition properties of organic phosphonic acid for aluminum alloy between in neutral and in acid solution.

A kind of novel heterocyclic bisquaternary ammonium salt (MBQA) was successfully synthesised with metronidazole as matrix and dichloroethyl ether as the link agent. Weight loss measurement, potentiodynamic polarisation curves, electrochemical impedance spectroscopy and atomic force microscopy were used to evaluate the corrosion inhibiting performance of MBQA in simulated oilfield water. Experimental data revealed that MBQA acted as an inhibitor in the acidic environment and, furthermore, the compound was a mixed‐type inhibitor. It was found that inhibition efficiency increased with an increase in MBQA concentration at different temperatures. The process of inhibition was attributed to the formation of an adsorbed film on the metal surface, which protected the metal against corrosive agents.

To investigate the influence of an organic corrosion inhibitor on the enhanced dissolution of metal, initiated by AFM tip scratching in corrosive media.

The test solutions were 1.5 M NaCl and 0.01 M HCl. AFM tip scratching experiments were performed for Cu‐Ni alloys in solutions with or without 0.005 M dodecylamine. AFM frictional loop tests were also performed to investigate the effect of dodecylamine on the tip‐surface frictional interaction.

Enhanced dissolution of Cu‐Ni alloy was observed as a result of AFM tip scratching both in NaCl and HCl solutions, and in HCl the effect was more severe than was the case in NaCl. Enhanced dissolution was inhibited markedly by adding 0.005 M dodecylamine to the corrosive media. The results of frictional loop tests indicated that frictional interaction between the tip and the alloy surface was diminished by the adsorption of dodecylamine on the sample surface. The weakening of tip‐surface frictional interaction and the elevation of the ionization energy of metal atoms were responsible for the notable inhibition effect of dodecylamine on the accelerated dissolution.

In this paper, the influence of an organic corrosion inhibitor on the corrosion of metal induced by outside forces was investigated. This was carried out initially by AFM scratching skill and the inhibition mechanism of dodecylamine on the enhanced dissolution of Cu‐Ni alloy initiated by AFM tip scratching.