Galvanic corrosion of AZ31B joined with bare or Zn-coated DP590 steel by ultrasonic spot welding or linear friction stir welding was quantitatively studied by pre-defining anode and cathode in the lap joint samples. C...Galvanic corrosion of AZ31B joined with bare or Zn-coated DP590 steel by ultrasonic spot welding or linear friction stir welding was quantitatively studied by pre-defining anode and cathode in the lap joint samples. Corrosion volume and depth from Mg anode surfaces exposed to 0.1 M sodium chloride solution was analyzed as functions of cathode surface type and welding method. Characterization of as-welded joints was performed to identify any microstructural feature of the bonding zone that could impact galvanic corrosion behavior.COMSOL modeling with modified user subroutine was conducted to simulate the progression of Mg corrosion in the same joint and electrode configurations used for the corrosion experiments. The experimental results indicated that Zn-coated cathode surface can reduce Mg galvanic corrosion significantly as galvanic polarization and cathodic current on Zn-coated surface remained relatively low for Mg in the weld joints.COMSOL modeling described the growth of Mg galvanic corrosion in a reasonable manner but showed limitation by underestimating the corrosion volume as it did not capture self-corrosion.展开更多
A Cu/Al galvanic couple was established to study the influence of the oxidantKMnO_4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminumalloy. It is found that the galvanic couple ...A Cu/Al galvanic couple was established to study the influence of the oxidantKMnO_4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminumalloy. It is found that the galvanic couple simulative experiment accords with the actual immersion,and it can be substantially used to simulate the behavior of LY12 aluminum alloy in thefilm-forming process. It is showed that the formation of the coating is quickened in CeCl_3 solutioncontaining KMnO_4 compared with that not containing KMnO_4. XPS results reveal that the coatingformed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation ofREM conversion coating changes when KMnO4 is added.展开更多
A number of industrial and biomedical fields,such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials,require Mg alloys with rapid dissolution.An iron-bearing phosphate chemical conv...A number of industrial and biomedical fields,such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials,require Mg alloys with rapid dissolution.An iron-bearing phosphate chemical conversion(PCC)coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31.Surface morphologies,chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM,XPS,XRD,FTIR,electrochemical and hydrogen evolution tests.Results indicated that the PCC coating was characterized by iron,its phosphates and hydroxides,amorphous Mg(OH)2 and Mg3-n(HnPO4)2.The self-catalytic degradation effects were predominately concerned with the Fe concentration,chemical composition and microstructure of the PCC coating,which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate.The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate,while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.展开更多
基金funded by the U.S. Department Energy’s Vehicle Technology Offices as a part of the Joining Core Program。
文摘Galvanic corrosion of AZ31B joined with bare or Zn-coated DP590 steel by ultrasonic spot welding or linear friction stir welding was quantitatively studied by pre-defining anode and cathode in the lap joint samples. Corrosion volume and depth from Mg anode surfaces exposed to 0.1 M sodium chloride solution was analyzed as functions of cathode surface type and welding method. Characterization of as-welded joints was performed to identify any microstructural feature of the bonding zone that could impact galvanic corrosion behavior.COMSOL modeling with modified user subroutine was conducted to simulate the progression of Mg corrosion in the same joint and electrode configurations used for the corrosion experiments. The experimental results indicated that Zn-coated cathode surface can reduce Mg galvanic corrosion significantly as galvanic polarization and cathodic current on Zn-coated surface remained relatively low for Mg in the weld joints.COMSOL modeling described the growth of Mg galvanic corrosion in a reasonable manner but showed limitation by underestimating the corrosion volume as it did not capture self-corrosion.
基金[This work was financially supported by the National Natural Science Fund of China (No.59771067).]
文摘A Cu/Al galvanic couple was established to study the influence of the oxidantKMnO_4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminumalloy. It is found that the galvanic couple simulative experiment accords with the actual immersion,and it can be substantially used to simulate the behavior of LY12 aluminum alloy in thefilm-forming process. It is showed that the formation of the coating is quickened in CeCl_3 solutioncontaining KMnO_4 compared with that not containing KMnO_4. XPS results reveal that the coatingformed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation ofREM conversion coating changes when KMnO4 is added.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51571134)the Scientific Research Foundation of Shandong University of Science and Technology Research Fund(2014TDJH104).
文摘A number of industrial and biomedical fields,such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials,require Mg alloys with rapid dissolution.An iron-bearing phosphate chemical conversion(PCC)coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31.Surface morphologies,chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM,XPS,XRD,FTIR,electrochemical and hydrogen evolution tests.Results indicated that the PCC coating was characterized by iron,its phosphates and hydroxides,amorphous Mg(OH)2 and Mg3-n(HnPO4)2.The self-catalytic degradation effects were predominately concerned with the Fe concentration,chemical composition and microstructure of the PCC coating,which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate.The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate,while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.
