Study On Properties Of Nanocrystalline Industrial Pure Iron And Ni Coating

With the development of science and technology,nano-material is widely used in all sectors of society because of its excellent physical and chemical properties.At the same time,people pay attention to the corrosion of nano-material.There are many kinds of protection methods for materials.Coating protection technology because of the simple process and easy to operate has become an important method of protection.At present,most people use ordinary block material as the matrix for the preparation and protection of the coating,but fewer scholars studied the bulk nano-materials as the matrix to prepare coating.In experience,study on nickel plating anticorrosion process on the surface of nanocrystalline industrial pure iron prepared by deep rolling technology,and the corrosion behavior of matrix and coating under different heat treatment conditions is discussed,and it lays a foundation for the application of nanomaterials in corrosion protection.Therefore,the research of the subject has certain research significance and use value.In this paper,the substrates were bulk nanocrystalline industrial pure iron(NI)and conventional polycrystalline pure iron(CP)formed by heat treatment at 500℃(CP-500)and 800℃(CP-800)for 1h.Fe-Ni coatings with plating times of 30 s,60s,120 s and 240 s and thicknesses of 5μm,10μm,15μm and 20μm were prepared.The surface morphology and microstructure of the coatings were observed and analyzed by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The electrochemical tests were used to test the effects of the matrix and different coatings in 0.1mol/L HCl and NaCl solution.The corrosion behavior of 5μm and 15μm coatings in 0.5mol/L HCl solution was studied by immersion method.The corrosion behavior of matrix and coating was further studied,and the corrosion mechanism was discussed.At the same time,the hardness and adhesion of various coatings were tested.SEM and XRD results showed that the average grain sizes of NI,CP-500 and CP-800 were 63 nm,33μm and 65μm,respectively.In the initial stage of electrodeposition,the deposition amount of Ni on CP-500 was larger than that of NI.After deposition for 240 s,the deposition of Ni tended to be consistent,and as the thickness of the coating increased,the grain size decreased.At the same time,it was found that the Ni grain size of NI was smaller than that of CP under the same thickness.The electrochemical test results showed that the corrosion resistance of NI matrix and its Ni coating was better than that of CP matrix and Ni coating at the same thickness,respectively.And the corrosion resistance was enhanced as the thickness of the coating increased.The corrosion resistance of matrix and coating in 0.1mol/L NaCl solution was better than that in 0.1mol/L HCl solution.The results of the soaking test showed that the corrosion rate of the coating with thickness of 15μm was less than that of the coating with the thickness of 5μm at the same etching time.And with the same thickness of the coating,corrosion rate of Ni coating on NI was smaller.Microhardness and binding strength test results showed that the hardness of NI and its coating was greater than that of CP-500 and its coating,and the binding strength of CP-500 in Ni coating was better.With the thickness of the coating increased,hardness and binding force gradually increased.