Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe...Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe（SKP）.The results showed that galvanic effect on the corrosion of AZ91D magnesium alloy is closely related to the potential difference between the anodic and cathodic materials.In the initial period,corrosion only occurred in a narrow area at the coupling interface because of the limited distance galvanic current.Then,the corrosion rate of 2A12 aluminum alloy was accelerated due to its poor stability in strong alkali environment,which was attributed to the strong alkalization caused by the corrosion of AZ91D magnesium alloy.With the increase of the potential of 2A12 aluminum alloy as a result of the continuous covering of corrosion products,the potential difference between the two materials was enlarged,which enhanced the galvanic corrosion.展开更多
The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments(pH=3.5)are studied by Scanning Electron Microscope(SEM),optical microscope,Fourier Transform Infrare...The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments(pH=3.5)are studied by Scanning Electron Microscope(SEM),optical microscope,Fourier Transform Infrared Spectroscopy(FT-IR),X-Ray Diffraction(XRD),potentiodynamic polarization,Electrochemical Impedance Spectroscopy(EIS),and Scanning Kelvin Probe(SKP).The results show that pitting corrosion occurs at the initial corrosion stage,and the potential difference between the second phase particles is the main cause of pitting.Pitting pits on different locations gradually expand and coalesce with the proceeding of corrosion.The main components of corrosion products are Al_(2)O_(3),Al(OH)_(3),and AlCl_(3),and the generation rate of the corrosion product layer under the salt spray environment is larger than that under acid immersion environment.Under both environments,the Volta potential distribution first disperses and then concentrates,while the charge transfer resistance first decreases and then increases with the corrosion time.The Volta potential gradually shifts in a positive direction,indicating that corrosion products have an inhibitory effect on corrosion.After the same corrosion time,the corrosion product layer resistance and the expectation of the Volta potential of the salt spray sample are higher than those of the immersion sample.Comparatively,the corrosion current density for the salt spray sample is significantly lower than the immersion sample,which indicates that the thicker the corrosion product layer,the stronger the inhibition of corrosion reaction.展开更多
基金Funded by the National Natural Science Foundation of China(No.51271032)
文摘Galvanic corrosion on samples of AZ91D magnesium alloy coupled with 2A12 aluminum alloy during neutral salt spray test was investigated.The variations of the surface potential were measured using scanning kelvin probe（SKP）.The results showed that galvanic effect on the corrosion of AZ91D magnesium alloy is closely related to the potential difference between the anodic and cathodic materials.In the initial period,corrosion only occurred in a narrow area at the coupling interface because of the limited distance galvanic current.Then,the corrosion rate of 2A12 aluminum alloy was accelerated due to its poor stability in strong alkali environment,which was attributed to the strong alkalization caused by the corrosion of AZ91D magnesium alloy.With the increase of the potential of 2A12 aluminum alloy as a result of the continuous covering of corrosion products,the potential difference between the two materials was enlarged,which enhanced the galvanic corrosion.
基金co-supported by the China Postdoctoral Science Foundation(No.2019M653929)the Green Innovation Science+1 种基金Technology Plan of CollegesUniversities in Shandong Province,China(No.2020KJA014).
文摘The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments(pH=3.5)are studied by Scanning Electron Microscope(SEM),optical microscope,Fourier Transform Infrared Spectroscopy(FT-IR),X-Ray Diffraction(XRD),potentiodynamic polarization,Electrochemical Impedance Spectroscopy(EIS),and Scanning Kelvin Probe(SKP).The results show that pitting corrosion occurs at the initial corrosion stage,and the potential difference between the second phase particles is the main cause of pitting.Pitting pits on different locations gradually expand and coalesce with the proceeding of corrosion.The main components of corrosion products are Al_(2)O_(3),Al(OH)_(3),and AlCl_(3),and the generation rate of the corrosion product layer under the salt spray environment is larger than that under acid immersion environment.Under both environments,the Volta potential distribution first disperses and then concentrates,while the charge transfer resistance first decreases and then increases with the corrosion time.The Volta potential gradually shifts in a positive direction,indicating that corrosion products have an inhibitory effect on corrosion.After the same corrosion time,the corrosion product layer resistance and the expectation of the Volta potential of the salt spray sample are higher than those of the immersion sample.Comparatively,the corrosion current density for the salt spray sample is significantly lower than the immersion sample,which indicates that the thicker the corrosion product layer,the stronger the inhibition of corrosion reaction.
