Study On The Effect Of Iron And Manganese On The Corrosion Resistance Of B10 Cupronickel Alloy And Its Mechanism

Copper-nickel alloys are widely used in heat exchangers and condensing pipes for coastal power plants and ships due to their excellent corrosion resistance and anti-fouling properties.The reason why copper-nickel alloy has excellent seawater corrosion resistance is attributed to the cuprous oxide film formed on the surface,which effectively prevents further contact between the substrate and the solution.Iron and manganese are the main additive elements of copper-nickel alloy,which have an important influence on improving the corrosion resistance of copper-nickel alloy.However,there is no consensus on the influence mechanism of iron and manganese.In this paper,the effects of iron and manganese on the corrosion resistance of B10 alloy were studied by means of static corrosion weight loss experiment,electrochemical impedance spectroscopy and potentiodynamic polarization curve test.The effects of iron and manganese on the surface morphology,electronic structure and phase composition of B10 alloy corrosion products were investigated by field emission scanning electron microscopy,energy dispersive spectroscopy,Mott-Schottky,X-ray diffractometry and X-ray photoelectron spectroscopy.In addition,based on the above research,this paper further explores the influence mechanism of iron and manganese on the corrosion behavior of B10 alloy.The results show:?1?The addition of different contents of iron and manganese in B10 white copper alloy will have a significant effect on the corrosion resistance of the alloy.Under the same corrosion conditions,the corrosion resistance of the alloy increases first and then decreases with the increase of iron content.The corrosion resistance is optimal when the iron content is1.26%,and the corrosion rate is 2.39?m/a,which is the most corrosion resistant.The corrosion rate of the inferior sample decreased by 72.47%.The corrosion resistance of the alloy increased first and then decreased with the increase of manganese content.The corrosion resistance of the sample with the manganese content of 0.87%was the best,and the corrosion rate was 2.39?m/a.The corrosion rate of the least corrosive sample was reduced by70.96%.?2?After corrosion of B10 white copper alloy in 3.5%NaCl solution for 30 days,the surface corrosion products are mainly composed of Cu₂O and Cu₂?OH?₃Cl.Cu₂O film plays a major role in protecting the alloy,while Cu₂?OH?₃Cl is covered in a block form.On Cu₂O.The Cu₂O film formed on the surface of B10 white copper alloy sample with iron content of1.26%and manganese content of 0.87%is relatively dense and complete.The surface of other components is composed of granular Cu₂O and the structure is loose.After removing the corrosion product film,the surface of the sample with an iron content of 1.26%and a manganese content of 0.87%is smooth and smooth,while other sample substrates have corrosion pits with different amounts and depths.?3?Adding an appropriate amount of iron to the alloy hinders the dissolution of NiO in the corrosion product film,reduces the number of defects in the film,increases the resistance of Cl^-diffusion in the film,improves the protective properties of the alloy,and adds an appropriate amount to the alloy.Manganese,which promotes the filling of cation vacancies in the corrosion product film by nickel.With the increase of nickel loading,the amount of NiO increases,the number of defects in the corrosion product film decreases,the resistance of the aggressive Cl^-diffusion in the film increases,the protection performance of the corrosion product film increases,and the corrosion resistance of the corresponding alloy is better.