Molecular Dynamics Simulation And Corrosion Inhibition Mechanism Of Mixed Inhibitor

The mixed inhibitor has become one of the main ways to prevent metal corrosion in the research field of inhibitors.It is very important for the design and development of inhibitor to understand the inhibition mechanism of mixed inhibitor.In order to further study the inhibition effect of mixed inhibitor,molecular dynamics simulation is used to study the adsorption behavior,diffusion behavior and interaction between inhibitors on metal surface,the simulation results are as follow.From the perspective of adsorption,two kinds of mixed inhibitors,one is mixing mannich base and sodium tungstate,the other is mixing vanillin and cinnamaldehyde,are subjected to strong van der Waals action to form a inhibitor protective film with high surface coverage on metal surface,which acts as a barrier to isolate the metal surface and corrosive solution.From the perspective of diffusion,the WO₄^2-is easy to form hydrogen bonds with the surrounding H ions after mixed mannich base and sodium tungstate,and the diffusion coefficient of corrosive particles in the mixed inhibitor film is slow down.When mixed vanillin with cinnamaldehyde,due to the interaction between the two inhibitors,although the diffusion coefficient of corrosive particles do not slow down,it improves the stability of inhibition film,also reduce the probability of corrosive particles through inhibition film,improve the inhibition efficiency.In addition,the quantum chemistry calculation shows that the inhibition mechanism mixed cinnamaldehyde and vanillin is not the same as on iron and copper,which is affected by electronic transfer of inhibitor and metal surface,the two kinds of metal surface are easy to lose electrons and is positively charged.On the Cu surface,the vanillin provides charge for metal cation,the cinnamaldehyde receives the free charge on the metal surface,the free charge and the cation on the Cu surface decrease,which improves the stability of metal material.On the Fe surface,two kinds of inhibitors receive the free charge on the metal surface.The inhibitors with negative charges will adsorbed well on the Fe surface with positive charge,and improve the adsorption capacity of inhibitors on Fe surface.Although the inhibition mechanism of the two kinds of mixed inhibitors on various metal surfaces is different,it can form a good inhibition effect on the metal surface.