【摘要】 铝硅合金用作烟气冷凝器基材具有良好的前景,目前对其在烟气冷凝液中的腐蚀行为研究不多。通过扫描电镜、电子能谱、金相显微镜、极化曲线、交流阻抗和全浸腐蚀试验考察了不同硅含量的铝硅合金在60℃烟气冷凝液中的腐蚀行为。结果表明:铝硅合金在60℃的烟气冷凝液中主要发生点蚀,硅含量较低(小于共晶点12.5%)时,铝硅合金容易在晶间发生局部腐蚀;硅含量较高(大于共晶点12.5%)时,共晶体逐渐减少,块状初晶硅大量析出,加剧了铝硅合金的局部腐蚀;Si含量为13%时,铝硅合金中形成较多的纤维状共晶体(α+Si)并均匀分布在铝基中,其耐孔蚀性能最强,这种铝硅合金可用作烟气冷凝换热器基材。更多还原

【Abstract】 Overall immersion corrosion tests were conducted to examine the corrosion behavior of Al-Si alloys with different content of Si in flue gas condensate.The polarization curves and electrochemical impedance spectra of the alloy samples in the corrosive medium were measured.The morphology and elemental composition of corroded alloy surfaces were analyzed by means of scanning electron microscopy,energy dispersive spectrometry,and metallurgical microscopy.Results show that Al-Si alloy samples are dominated by pitting in the flue gas condensate at 60 ℃,and they are liable to local intergranular corrosion when their Si content is low(mass fraction below eutectic point of 12.5%).As to Al-Si alloy samples with high Si content(above eutectic point of 12.5%),the local corrosion is accelerated owing to the precipitation of a large amount of block-like primary Si crystal,though the content of eutectics gradually declines.Moreover,a large amount of fibrous eutectics(α+Si) is formed in the Al-Si alloy containing 13.0% Si,and the fibrous eutectics possess excellent corrosion resistance and are evenly distributed in Al matrix.This makes it feasible for Al-Si alloy with 13.0% Si to be used as a candidate corrosion resistant material for fabricating flue gas condenser.更多还原