摘要
The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation(PEO) process for AZ91 Mg alloy was investigated.The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis.The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%-18%(mass fraction) of phosphorous.The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer,which strongly implied that the phosphorous ion might be concentrated at the barrier layer.Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate.The polarization resistance(Rp) of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65×107 Ω/cm2,which was higher than that(Rp=3.56×104 Ω/cm2) of the sample coated from electrolyte without potassium pyrophosphate.The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance.
The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation （PEO） process for AZ91 Mg alloy was investigated. The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis. The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%-18% （mass fraction） of phosphorous. The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer, which strongly implied that the phosphorous ion might be concentrated at the barrier layer. Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate. The polarization resistance （Rp） of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65× 10^7 Ω/cm^2, which was higher than that （Rp=3.56 × 10^4 Ω/cm^2） of the sample coated from electrolyte without potassium pyrophosphate. The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance.
出处
《中国有色金属学会会刊：英文版》
EI
CSCD
2009年第4期824-828,共5页
Transactions of Nonferrous Metals Society of China
基金
supported by a grant from the Center for Advanced Materials Processing (CAMP) of the 21st Century Frontier R&D Program funded by the Ministry of Knowledge Economy (MKE),Korea
supported by the Korea Science and Engineering Foundation (No.2009-0079807)
