缓蚀剂对HT700T合金在氯化物熔盐中腐蚀行为的影响

Effect of corrosion inhibitor on corrosion behavor of HT700T alloy in chloride molten salts

采用浸泡法研究了镍铁基高温合金HT700T在800℃下添加不同剂量Al粉缓蚀剂的NaCl/KCl/MgCl_(2)氯化物熔盐中的腐蚀行为,浸泡时间分别为200、300、400 h。采用X射线衍射(XRD)和配备能谱仪的扫描电子显微镜(SEM/EDS)对腐蚀产物的组成、形貌和元素分布进行了研究,分析了缓蚀剂对HT700T合金腐蚀行为的影响。结果表明:HT700T合金在800℃下腐蚀后,添加Al粉缓蚀剂可在样品表面生成具有面心立方结构的Ni_(3)Al相;当Al粉缓蚀剂添加量为2%(质量分数)时,可在合金表面形成致密的Al_(2)O_(3)膜;当Al粉缓蚀剂添加量为10%(质量分数)时,Al向内扩散导致合金内部元素发生变化,形成由Al_(2)O_(3)、Al-Ni-Fe、Ni-Fe、Ni-Al、Ni-Al-Fe+Cr_(2)O_(3)组成的防护层,其深度随时间变化分别为185.8μm(200 h)、145.66μm(300 h)、166.02μm(400 h),可有效降低800℃下氯化物熔盐的腐蚀速率。

By immersion method,the corrosion behavior of HT700T alloy in NaCl-KCl-MgCl_(2) molten salts with different doses of Al powder inhibitor at 800 ℃ was studied,with immersion time of 200 h,300 h and 400 h.The morphologies and phase composition of the HT700T alloy after corrosion tests were determined by X-ray diffraction(XRD) and scanning electron microscopy(SEM) equipped with energy dispersive spectroscopy(EDS),and the effect of corrosion inhibitor on corrosion behavior of the HT700T alloy was analyzed.The results showed that,Ni_(3)Al with face-centred cubic(FCC) structure could be formed on the sample surface by adding Al powder inhibitor after immersion at 800 ℃.When the addition mass fraction of the Al powder inhibitor was 2%,a dense and stable Al_(2)O_(3) film could be formed on the alloy surface.When the addition mass fraction was 10%,the Al diffused inward,resulting in the change of internal elements of the alloy and the formation of protective layer(composed of Al_(2)O_(3),Al-Ni-Fe,Ni-Fe,Ni-Al,Ni-Al-Fe+Cr_(2)O_(3)),of which the depth changed with time(185.8 μm(200 h),145.66 μm (300 h),166.02 μm(400 h)),indicating the inhibitor could effectively reduce the corrosion rate of chloride molten salts at 800 ℃.