Xingwen YU
,
Chunan CAO
,
Chuanwei YAN
,
Zhiming YAO
材料科学技术（英文）
A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.
关键词:
Xingwen YU
,
Chuanwei YAN
,
Chunan CAO
材料科学技术（英文）
Technological process of rare earth sealing anodized LY12 (2024) alloy is introduced. Corrosion behavior of the film was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the coating remained passivity at the potential range from the open circuit potential (-780 mV) to –250 mV in NaCl solution. When the potential exceeded -200 mV, corrosion reaction happened on the coating. the results of EIS analysis was consistent with the results of polarization curves.
关键词:
LY12 alloy
,
null
,
null
,
null
Xingwen YU
,
Chuanwei YAN
,
Chunan CAO
材料科学技术（英文）
The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the field emission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show that RE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning of sealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrier to the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with the spherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of the coating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2acts as the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carries electrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure of the film is beneficial to the precipitation of the cerium hydroxides.
关键词:
Rare earth sealing
,
null
,
null
