In625合金和316L不锈钢在NaCl-CaCl_2-MgCl_2熔盐中的腐蚀机理  

Corrosion behavior of In625 alloy and 316L stainless steel in NaCl-CaCl_2-MgCl_2 ternary eutectic molten salt

作　　者：刘波[1] 魏小兰[1] 王维龙[2] 宋明[1] 丁静[2] 

机构地区：[1]华南理工大学化学与化工学院,广东广州510640 [2]中山大学工学院,广东广州510006

出　　处：《化工学报》2017年第8期3202-3210,共9页CIESC Journal

基　　金：NSFC-盐湖集团联合基金项目(U1507121);国家自然科学基金重点项目(51436009)~~

摘　　要：为了解Cr元素对含铬合金在三元NaCl-CaCl_2-MgCl_2氯化物熔盐中腐蚀的影响机理,选择两种含铬合金镍基Inconel 625(In625)和铁基奥氏体316L型不锈钢,采用全浸没法分别研究它们在500~700℃下于三元氯化物NaCl-CaCl_2-MgCl_2低共熔盐中的腐蚀行为,以及接触空气程度与温度对腐蚀的影响。绘制了In625合金和316L不锈钢在熔盐中600℃下浸没21 d的腐蚀速率曲线。采用XRD(X射线衍射仪)、SEM(扫描电镜)和EDX(X射线能谱仪)对In625合金和316L不锈钢的腐蚀产物和截面形貌进行分析。结果表明:两种金属的腐蚀程度随着接触空气的量和腐蚀温度的增加而加大;600℃下腐蚀21 d后金属表面和截面的元素及形貌分析表明,Cr具有优先脱溶性;600℃下腐蚀21 d后在合金截面形成了贫Cr区域;致密的腐蚀层可以降低金属的腐蚀速率;在NaCl-CaCl_2-MgCl_2三元氯化物熔盐中镍基合金In625拥有比奥氏体不锈钢更好的耐腐蚀性能。Isothermal corrosion of 316L stainless steel and nickel based Inconel 625 alloy was evaluated by total immersion in eutectic NaCI-CaC12-MgC12 molten salt at 500--700 ℃.The effect of chromium （Cr）, air contact, and temperature on corrosion was studied. Corrosion dynamic and velocity curves of 316L and Inconel 625 alloy at 600℃ molten salt for 21 d were obtained. X-Ray diffraction （XRD）, scanning electron microscope （SEM） and X-ray energy spectrometer （EDX） were used to analyze corrosion products and cross section morphologies. The results show that mass loss of the steel and alloy increases with the increase of air contact and corrosion temperature. Element and morphology of metal surface and cross section after 21 d immersion at 600℃ indicate that Cr has a preferential solubility to other elements, which Cr depletion region was observed across cross-section. The dense layer of corrosion products can reduce corrosion rate. Inconel 625 exhibits better corrosion resistance than austenitic stainless steel in NaC1-CaC12-MgC12 eutectic molten salt.

关 键 词：氯化物熔盐 腐蚀 不锈钢 INCONEL 625镍基合金 

分 类 号：TQ050.91[化学工程]