海水中小球藻对Mg-3Y-1.5Nd镁合金腐蚀行为的影响

Effect of chlorella vulgaris on corrosion behavior of Mg-3Y-1.5Nd alloy in natural seawater

采用X射线衍射、扫描电子显微镜、X射线能谱仪等表面分析技术以及电化学技术,以稀土镁合金Mg-3Y-1.5Nd为基体,研究小球藻对其腐蚀行为的影响。结果表明:含小球藻培养液和不含小球藻培养液的镁合金表面主要腐蚀产物均为Mg(OH)2,Mg 3(PO4)2以及Mg 2(OH)3 Cl;含小球藻培养液的镁合金表面腐蚀产物中镁元素的占比较未含小球藻要小(29.6%vs 39.8%);腐蚀产物存在疏松的结构有利于腐蚀性离子侵入,促进镁合金的进一步腐蚀;小球藻的光合作用导致生物膜保护层下出现高浓度的溶解氧,使氧还原阴极电流变大,从而增大Mg-3Y-1.5Nd合金的腐蚀速率。综上所述,当小球藻存在时,Mg-3Y-1.5Nd合金受到的腐蚀更为严重。

The effect of chlorella vulgaris on corrosion behavior of Mg-3Y-1.5Nd alloy in f/2 culture medium was studied by means of X-ray diffraction,scanning electron microscope,energy dispersive analysis system of X-ray and other electrochemistry test.Results show that the main corrosion products on the surface of alloy with and without chlorella vulgaris are Mg(OH)2,Mg 3(PO 4)2 and Mg 2(OH)3 Cl;Mg and O are present on the specimen surface,and the content of Mg in culture medium with chlorella vulgaris(29.6%)is lower than that without chlorella vulgaris(39.8%);and corrosive ions invade the loose corrosion product structure and promote further corrosion of the alloy;the high O 2 concentration produced by the photosynthesis of chlorella vulgaris results in the increase of local O 2 concentration underneath the biofilm,which adds oxygen reduction cathodic currents and enhances corrosion.It is conduded that the average corrosion rate in the presence of chlorella vulgaris is more serious than that in the absence of chlorella vulgaris.