Zn-5Al-xMn(x=0,0.1,0.2,0.3)合金的铸态组织与耐蚀性能
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摘要
采用SEM、EDS、电化学测试等方法研究了热浸镀用Zn-5Al-xMn(x=0,0.1,0.2,0.3)合金的铸态组织与耐蚀性能。结果表明:在Zn-5Al合金中加入少量的Mn显著抑制了粗大初生β-Zn相的生成,当Mn含量为0.2%时,初生β-Zn相最少,共晶组织占比最高。试验合金的自腐蚀电位随着Mn含量的提高而增大,自腐蚀电流密度先减小后增大。Zn-5Al-0.2Mn合金自腐蚀电流最小为1.403μA/cm~2,其高频阻抗和低频扩散阻抗均最大。Zn-5Al合金中初生β-Zn相优先腐蚀,Zn-5Al-0.2Mn合金因初生β-Zn相较少,发生均匀性腐蚀,其腐蚀产物在Zn-5Al-xMn合金中最致密。
The microstructure and corrosion behavior of the as-cast hot-dip Zn-5Al-xMn(x=0,0.1,0.2,0.3) alloys have been investigated by SEM,EDS,electrochemical test techniques,etc. The results indicate that a small addition of Mn in as-cast Zn-5Al alloy can greatly inhibit the formation of primary β-Zn phase. When the Mn addition is 0.2%(in mass),the amount of β-Zn phase is the least and the percentage of eutectic composition reaches the maximum. The corrosion potential of the tested alloy moves positive direction,while the corrosion current density decreases first and then increases as increasing of Mn addition. The corrosion current density of the Zn-5 Al-0.2Mn alloy has the minimum value of 1.403 μ A/cm~2,with which the impedance spectra at both high and low frequencies reach the maximum. The primary β-Zn phase is corroded preferentially in Zn-5Al alloy,but uniform corrosion happens in Zn-5Al-0.2 Mn alloy for little amount of β-Zn phase. The corrosion products of Zn-5Al-0.2Mn is the most compact in the Zn-5Al-xMn alloys.
The microstructure and corrosion behavior of the as-cast hot-dip Zn-5Al-xMn(x=0,0.1,0.2,0.3) alloys have been investigated by SEM,EDS,electrochemical test techniques,etc. The results indicate that a small addition of Mn in as-cast Zn-5Al alloy can greatly inhibit the formation of primary β-Zn phase. When the Mn addition is 0.2%(in mass),the amount of β-Zn phase is the least and the percentage of eutectic composition reaches the maximum. The corrosion potential of the tested alloy moves positive direction,while the corrosion current density decreases first and then increases as increasing of Mn addition. The corrosion current density of the Zn-5 Al-0.2Mn alloy has the minimum value of 1.403 μ A/cm~2,with which the impedance spectra at both high and low frequencies reach the maximum. The primary β-Zn phase is corroded preferentially in Zn-5Al alloy,but uniform corrosion happens in Zn-5Al-0.2 Mn alloy for little amount of β-Zn phase. The corrosion products of Zn-5Al-0.2Mn is the most compact in the Zn-5Al-xMn alloys.
引文
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[4] LI Y Y, LUO J M, LUO Z Q, et al. The microstructure and wear mechanism of a novel high-strength,wear-resistant zinc alloy(ZMJ)[J]. J Mater Process Tech,1995,55(3/4):154-161.
[5] MUNZ R,WOLF G K,GUZMAN L,et al. Zinc/manganese multilayer coatings for corrosion protection[J]. Thin Solid Films,2004,459(1/2):297-302.
[6] ZHANG B,ZHOU H B,HAN E H,et al. Effects of a small addition of Mn on the corrosion behaviour of Zn in a mixed solution[J]. Electrochimica Acta,2009,54(26):6598-6608.
[7] SHI Z,LIU M,ATRENS A. Measurement of the corrosion rate of magnesium alloys using Tafel extrapolation[J]. Corrosion Science,2010,52(2):579-588.
[8]曹楚南.腐蚀电化学原理[M].北京:化学工业出版社,2004.CAO Chunan. Corrosion theory[M]. Beijing:Chemi-cal Industry Press,2004.
[9] SOUTO R M,FERNANDEZ M L,GONZALEZ S,et al. Comparative EIS study of different Zn-based intermediate metallic layers in coil-coated steels[J].Corrosion Science,2006,48(5):1182-1192.
[10]孙敏,肖葵,董超芳,等.带腐蚀产物超强度钢的电化学行为[J].金属学报,2011,47(4):442-448.SUN Min,XIAO Kui,DONG Chaofang,et al. Elec-trochemical behaviors of ultra high strength steels with corrosion products[J]. Acta Metallurgica Sinica,2011,47(4):442-448.
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[13]陈长风,路民旭,赵国仙,等.腐蚀产物膜覆盖条件下油套管钢CO2腐蚀电化学特征[J].中国腐蚀与防护学报,2003,23(3):139-143.CHEN Changfeng,LU Minxu,ZHAO Guoxian,et al. Electrochemical characteristics of CO2corrosion of well tube steels with corrosion scales[J]. Journal of Chinese Society Corrosion Protection,2003,23(3):139-143.