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在pH等于4(6.25×10~(-5)MH_2SO_4)的酸性氯化物溶液[200ppmCl~-(5.5×10~(-3)MNaCl)」中,铝铁中间化合物的腐蚀特征(点蚀和缝隙腐蚀)由合金添加物和热处理方法而定.电化学试验表明:添加铬(Cr)和钼(Mo)可提高耐蚀效果.浸渍试验证明了电化学试验的结果,同时表明了点蚀特征与时间有关.用电化学法和浸渍缝隙试验,研究了铝铁中间化合物的缝隙腐蚀行为.缝隙腐蚀和点蚀的敏感性差异:含Mo的铝铁中间化合物敏感性差异是很小的,不含Mo的铝铁中间化合物则差异较大.用X-射线光电子能谱法(XPS)研究得知,铝铁中间化合物的保护膜主要是由氧化铝(Al_2O_3)组成,同时含有氧化铬(Cr_2O_3)和氧化钼(MoO_3).在含Cr的铝铁中间化合物中,Mo有提高抗局部腐蚀的作用,钼可促使钝化膜中Al含量的增加,阻止表面对Cl~- 的吸附.
In the acidic chloride solution [200ppmCl ~ - (5.5 × 10 ~ (-3) MNaCl) at a pH equal to 4 (6.25 × 10 -5 MH_2SO_4), the corrosion characteristics of the intermediate compounds of aluminum and iron Corrosion) is determined by the addition of alloy and the heat treatment method.The results of electrochemical tests show that adding Cr and Mo can improve the corrosion resistance, Time.The relationship between crevice corrosion and pitting corrosion sensitivity was studied by using electrochemical method and immersion crack test.The crevice corrosion sensitivity of the intermediate compound containing Mo is very small, The results showed that the protective film of Al-Fe intermediate compound mainly consisted of alumina (Al 2 O 3) and contained Cr 2 O 3 (Cr 2 O 3) And molybdenum oxide (MoO_3) .In the Cr-containing aluminum-iron intermediate compounds, Mo can enhance the resistance to localized corrosion, molybdenum can promote the increase of Al content in the passivation film, and prevent the adsorption of Cl ~ - on the surface.