This article studies the effects of the CeCl3 concentrations in conversion solutions with and without addition of NaCl, pH-values of conversion solution, drying temperature, time and temperature of immersion on the Ce...This article studies the effects of the CeCl3 concentrations in conversion solutions with and without addition of NaCl, pH-values of conversion solution, drying temperature, time and temperature of immersion on the Ce-conversion coatings for corrosion protection of the SiCp/5A06 Al-MMC and 5A06 Al-alloy in the 3.5% NaCl aqueous solution at room temperature. Potentiodynamic polarization tests reveal that the Ce-conversion treatment could markedly improve the pitting corrosion resistance of the composite and the matrix alloy in chloride containing environment. The best corrosion resistance effects are obtained for the samples treatment in 1% CeCl3.7H2O/3.5% NaCl solution at 45℃ for 60 min, followed by drying at 100 ℃ for 30 min. Examinations by means of scanning electron microscopy （SEM）, energy dispersion spectroscopy （EDS） and X-ray photoelectron spectroscopy （XPS） indicate that this behavior is due to the precipitation of Ce-oxides/hydroxides on the cathodic intermetallics and the Al-oxide film on the rest of the metal matrix.展开更多
To improve the wettability of common fiUer metals on Al metal matrix composites （ AI-MMCs ） , three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-Al-Ti systems, were prepared by the addition of Ti...To improve the wettability of common fiUer metals on Al metal matrix composites （ AI-MMCs ） , three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-Al-Ti systems, were prepared by the addition of Ti. Excessive melting temperature made the gravity segregation of Ti remarkable in ingot. The effect of Ti content on the melting point for AI-Si-Ti ternary system was not as sensitive as that for Al-Ti binary system. The Al-12Si-1Ti filler metal showed good ability to form brazing foil during rapid cooling, ductile fracture surface and similar shear strength to conventional Al-12Si filler metal. Moreover, the Al2 03 reinforcements on initial surface could be covered by the Al-12Si-1Ti filler metal without interfacial gaps after sessile drop test. For Zn-9.5Al-0. 5 Ti braze alloy, severe vaporization of Zn and severe segregation of Ti Occurred. During wettability test for traditional Al-12Si and Zn-9.5Al-0. 5Ti, although some Si or Zn could penetrate into the composite, interfacial gap still remained. The prepared Cu-19Al-1 Ti interlayer consisted of primary phase of Al4Cu9 and network Cu-Al-Ti ternary intermetaUic compound, showing poor ability to form foil and very brittle nature. These results demonstrated that Al-Si-Ti system should be promising for Al-MMCs.展开更多
文摘This article studies the effects of the CeCl3 concentrations in conversion solutions with and without addition of NaCl, pH-values of conversion solution, drying temperature, time and temperature of immersion on the Ce-conversion coatings for corrosion protection of the SiCp/5A06 Al-MMC and 5A06 Al-alloy in the 3.5% NaCl aqueous solution at room temperature. Potentiodynamic polarization tests reveal that the Ce-conversion treatment could markedly improve the pitting corrosion resistance of the composite and the matrix alloy in chloride containing environment. The best corrosion resistance effects are obtained for the samples treatment in 1% CeCl3.7H2O/3.5% NaCl solution at 45℃ for 60 min, followed by drying at 100 ℃ for 30 min. Examinations by means of scanning electron microscopy （SEM）, energy dispersion spectroscopy （EDS） and X-ray photoelectron spectroscopy （XPS） indicate that this behavior is due to the precipitation of Ce-oxides/hydroxides on the cathodic intermetallics and the Al-oxide film on the rest of the metal matrix.
基金The present research was sponsored by the National Natural Science Foundation of China （ No. 50875199）, and by State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, China.
文摘To improve the wettability of common fiUer metals on Al metal matrix composites （ AI-MMCs ） , three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-Al-Ti systems, were prepared by the addition of Ti. Excessive melting temperature made the gravity segregation of Ti remarkable in ingot. The effect of Ti content on the melting point for AI-Si-Ti ternary system was not as sensitive as that for Al-Ti binary system. The Al-12Si-1Ti filler metal showed good ability to form brazing foil during rapid cooling, ductile fracture surface and similar shear strength to conventional Al-12Si filler metal. Moreover, the Al2 03 reinforcements on initial surface could be covered by the Al-12Si-1Ti filler metal without interfacial gaps after sessile drop test. For Zn-9.5Al-0. 5 Ti braze alloy, severe vaporization of Zn and severe segregation of Ti Occurred. During wettability test for traditional Al-12Si and Zn-9.5Al-0. 5Ti, although some Si or Zn could penetrate into the composite, interfacial gap still remained. The prepared Cu-19Al-1 Ti interlayer consisted of primary phase of Al4Cu9 and network Cu-Al-Ti ternary intermetaUic compound, showing poor ability to form foil and very brittle nature. These results demonstrated that Al-Si-Ti system should be promising for Al-MMCs.
