Density Functional Theory Study Of The Adsorption And Insertion Of Br/Cl On Ni(100)and NiO(111)surface

Ni is widely used in petroleum equipment,medical equipment,aerospace,electronics and other fields,because of its excellent physical,chemical and mechanical properties.It's easily to form a layer of oxide film on Ni surface and the oxide film can isolate Ni surface from the corrosive medium,so the corrosive resistance can be improved.Corrosive resistance can be improved.However,pitting corrosion can be formed in the metal surface in the environment of halogen element.Currently,we can only surmise the mechanism and process of corrosion by the morphology and component.Most researchers are restricted to study the adsorption behavior and never to describe the process of corrosion.So periodic DFT calculations have been performed on Ni(100)and NiO(111)surface model the adsorption and sub-surface insertion of Br and Cl and the corrosion process is also studied in the thesis.From the study of adsorption and insertion of Br and Cl on Ni(100)surface and the description of the process of corrosion,I can get some conclusions.Br and Cl tend to be adsorbed on hollow site of Ni(100)surface,and Br is more stable on the surface,which indicate that the tendency of corrosion of Ni is larger with Br.There are common electrons between Br/Cl and Ni atom on Ni(100)surface after adsorption.Because of the hybridization phenomenon of electronic orbits,there is strong interaction between Br/Cl and Ni atom.On the vacancy defect of Ni(100)surface,Br/Cl can insert into the inside of Ni metal.The insertion of Br/Cl may cause serious damage of metal structure.What's more,the structure change becomes more obvious with the increasing atoms insertion.And Br atom has greater destructive power.Compare the adsorption property between O and Br/Cl on Ni(100)surface,I find that O is more easily to combine with Ni surface forming a layer of oxide film.Through the simulation and analysis of the adsorption and insertion of Br/Cl on NiO(111)surface,I find that the configuration of Br/Cl on top site of Ni O(111)surface is most stable.In the process of adsorption,the system could adsorb energy from the outside world.It indicates that NiO has rejection to corrosive particles.However,under a certain conditions,Br/Cl can substitute the O atom of NiO surface and insert into passive film.The structure of NiO will be destroyed by the inserted atoms.The structure change becomes more obvious with the increasing atoms insertion.And Br atom has greater destructive power.After the above content were studied,I got the adsorption properties of Br/Cl on Ni(100)and NiO(111)surfaces and described the process of Br/Cl inserting into Ni and NiO matrix,which are contribute to corrosion mechanism research.