Inconel690在ETA/NH_3水化学环境中的均匀腐蚀行为研究

本文在模拟压水堆二回路的高温高压水化学环境下,研究了蒸汽发生器传热管材料镍基合金Inconel690试样在乙醇胺(ETA)和氨(NH3)水化学环境中的均匀腐蚀行为。结果显示:在5 000h均匀腐蚀试验后,ETA水化学环境下试样的均匀腐蚀速率为0.21mg/(m2·h),NH3水化学环境下试样的均匀腐蚀速率为0.50mg/(m2·h);在ETA水化学环境下试样表面形成的氧化膜中铬含量更高,氧化膜的保护性更好。以上结果表明,Inconel690在ETA水化学环境下的耐蚀性强于NH3水化学环境。     

HR3C在超临界水中的腐蚀性能研究

通过高压釜浸泡实验研究了超级奥氏体不锈钢HR3C在循环的超临界水（SCW）中的均匀腐蚀性能,实验温度分别为550、600、650 ℃,压力为25 MPa,并对实验后试样生成的氧化膜进行了SEM、EDS和XRD分析。实验结果显示,HR3C在SCW环境中的氧化腐蚀速率随着温度的升高而增大,1 500 h后650 ℃ SCW环境下材料的腐蚀增重约为550 ℃时的2倍。材料表面生成的氧化膜主要成分为FeCr₂O₃、Fe₃O₄和Fe₂O₃,内层氧化膜富Cr而外层氧化膜富Fe。     

候选材料在650 ℃超临界水中的腐蚀行为研究

研究了3种候选材料（347、HR3C和In-718）在650 ℃、25 MPa去离子水中的均匀腐蚀行为,使用场发射扫描电镜（FEG-SEM）和能谱（EDS）观察了不同腐蚀时间的表面氧化膜形貌与合金元素分布,使用掠入射X射线衍射（GIXRD）分析了氧化膜相结构。结果表明,3种材料腐蚀失重均符合抛物线规律,347的失重为HR3C和In 718的40倍以上;3种材料氧化膜均以Ni(Cr, Fe) ₂O₄为主,In-718点蚀严重,347氧化膜明显脱落,HR3C氧化膜较均匀致密;高温超临界水中,提高合金的Cr含量有助于增强均匀腐蚀性能,添加Nb有损合金的点蚀抗力。     

不锈钢及高温合金在拟临界区的腐蚀行为研究

研究3种高温合金和4种奥氏体不锈钢在380℃、25 MPa去离子水中的均匀腐蚀行为,使用场发射扫描电镜(FEG-SEM)和X射线能谱仪(EDS)分析不同腐蚀时间的表面氧化膜形貌与合金元素分布。结果表明,实验工况下合金腐蚀增重无明显规律,腐蚀失重均为对数规律;HR3C合金腐蚀失重最小,347合金最大,二者相差一个数量级。所有材料表面均能生成较为完整致密的双层氧化膜,外层相对贫Cr、Ni,缺Mo而富O。316Ti、718、825、800H、HR3C等多种合金出现点蚀,依照成分不同,点蚀区域呈现富Nb、Ti,贫Cr、Ni,缺Mn、Mo等现象。     

C-276合金在650℃/25MPa超临界水中的腐蚀行为

研究了HastelloyC-276（C-276）镍基合金在650℃/25MPa超临界水中的腐蚀特性。采用扫描电镜、X射线能谱仪、X射线衍射和X射线光电子能谱分析了氧化膜的腐蚀形貌、组织结构和合金元素分布。研究结果表明,C-276合金在650℃/25MPa的超临界水中的腐蚀过程主要是Ni的溶解,由于不能形成均匀、完整的氧化膜,合金在超临界水中并不具备优越的耐腐蚀性能,其双层结构的氧化膜富Cr而贫Ni、Mo,外层疏松的大颗粒（Ni(OH)₂和NiO）为金属溶解和氧化物沉淀形成,内层（Cr₂O₃）的生长则是水穿过氧化物微孔作用的结果。     

压水堆二回路工况下碱化剂对结构材料腐蚀的影响

利用长期浸泡的方法分析研究了压水堆二回路工况下A508Ⅲ和A106Gr.B低合金钢在乙醇胺（ETA）+二甲胺（DMA）、ETA、氨（NH₃·H₂O） 3种碱化剂中的均匀腐蚀行为,并利用扫描电镜、X射线光电子能谱和AES等技术分析了氧化膜的结构和组分。结果表明,在2 000 h试验后,A508Ⅲ试样在NH₃·H₂O中的腐蚀速率为0.15 mg/(dm²·h),而在ETA+DMA条件下的腐蚀速率为0.087 mg/(dm²·h),较在NH₃·H₂O中降低约42%。对于A106Gr.B材料,ETA+DMA环境的腐蚀速率相对于NH₃·H₂O环境下降约29.01%,说明复合碱化剂条件下,试样更耐蚀。氧化膜结构分析表明,氧化膜主要以Fe和O为主,ETA+DMA环境下的氧化膜厚度较薄,结构更加致密,氧化膜内含有N元素,说明胺分子参与了氧化膜的生成。复合碱化剂下材料耐蚀性提高的主要原因是由于复合碱化剂中的胺挥发性小于NH₃·H₂O,液相冷却剂pH值升高,减缓了Fe的氧化反应,另外胺分子易通过吸附作用吸附于氧化膜表面,降低了金属氧化反应的活化能,提高了材料的耐蚀性能。复合碱化剂与二回路设备材料具有较好的相容性,能有效降低设备材料的腐蚀速率,对于二回路水化学处理方法的改进有积极意义。     

Inconel-690合金在核电厂水质环境中的均匀腐蚀性能研究

模拟核电厂水质环境,采用动水腐蚀回路研究3种蒸汽发生器传热管商用690材料的均匀腐蚀性能以及氧化膜的特性,并分别采用国家标准和美国标准对材料均匀腐蚀速率和腐蚀产物释放速率进行评价。结果表明:690合金管在核电厂水质环境中具有极低的腐蚀速率和腐蚀产物释放速率,日本住友管的腐蚀性能略优于宝钢管。     

压水堆二回路工况下碱化剂对结构材料腐蚀的影响

利用长期浸泡的方法分析研究了压水堆二回路工况下A508Ⅲ和A106Gr.B低合金钢在乙醇胺(ETA)+二甲胺(DMA)、ETA、氨(NH_3·H_2O) 3种碱化剂中的均匀腐蚀行为,并利用扫描电镜、X射线光电子能谱和AES等技术分析了氧化膜的结构和组分。结果表明,在2 000 h试验后,A508Ⅲ试样在NH_3·H_2O中的腐蚀速率为0.15 mg/(dm~2·h),而在ETA+DMA条件下的腐蚀速率为0.087 mg/(dm~2·h),较在NH_3·H_2O中降低约42%。对于A106Gr.B材料,ETA+DMA环境的腐蚀速率相对于NH_3·H_2O环境下降约29.01%,说明复合碱化剂条件下,试样更耐蚀。氧化膜结构分析表明,氧化膜主要以Fe和O为主,ETA+DMA环境下的氧化膜厚度较薄,结构更加致密,氧化膜内含有N元素,说明胺分子参与了氧化膜的生成。复合碱化剂下材料耐蚀性提高的主要原因是由于复合碱化剂中的胺挥发性小于NH_3·H_2O,液相冷却剂pH值升高,减缓了Fe的氧化反应,另外胺分子易通过吸附作用吸附于氧化膜表面,降低了金属氧化反应的活化能,提高了材料的耐蚀性能。复合碱化剂与二回路设备材料具有较好的相容性,能有效降低设备材料的腐蚀速率,对于二回路水化学处理方法的改进有积极意义。     

奥氏体304NG不锈钢在550℃/25MPa超临界水中的腐蚀行为

研究了304NG不锈钢在550℃/25MPa超临界水中的腐蚀特性。采用扫描电镜、X射线能谱仪和X射线衍射分析了氧化膜的腐蚀形貌、组织结构和元素成分分布。实验结果表明,在550℃/25MPa的超临界水中腐蚀1000h后,304NG不锈钢显示出优越的耐腐蚀性能,其均匀腐蚀增重速率仅为0.01299mg•dm^-2•h^-1。304NG不锈钢在超临界水中形成均匀致密、但带有疖状腐蚀的双层氧化膜,厚度约为2.0μm,内层氧化膜致密而富Cr和Ni,外层氧化膜疏松而富Fe。     

两种锆合金显微组织与腐蚀机理研究

根据国产C锆合金与低锡Zr-4合金在纯水以及LiOH水溶液中的高压釜腐蚀试验的结果,采用透射电镜（TEM）观察基体和氧化膜显微组织,通过分析氧化增重数据,对C锆合金的腐蚀机理进行了研究。提出了3种腐蚀机理:即Nb元素有效抑制阴离子空位浓度提高,可减少氧元素扩散速率;缺陷阱的数量影响氧扩散带来的腐蚀,且空位阱数量与第二相颗粒总表面积成正比;第二相粒子氧化膨胀造成氧化膜压应力松弛,降低其稳定性并失去保护能力。      

Corrosion Resistance of Fe-Al-Alloy-Coated Ferritic/Martensitic Steel under Bending Stress in High-Temperature Lead-Bismuth Eutectic

The corrosion test was performed for ferritic/martensitic steel HCM12A with and without Fe-Al alloy coating in LBE at temperatures of 550 and 650°C under loading for an immersion time up to 500 h. After the corrosion test at 550°C for 500 h, both of the uncoated and Fe-Al-coated HCM12A showed a good corrosion resistance without the influence of the tensile stress on the LBE corrosion. On the other hand, after the corrosion test at 650°C, the Fe-Al coating layer on the specimen surface exhibited no LBE dissolution corrosion because of the formation of a stable oxide protection film on the coating layer surface, although the coating layer cracked. The LBE penetrated into the cracks and corroded the base metal and the precoating layer. The uncoated HCM12A exhibited the double oxide layers of FeO and Fe- Cr spinel. The FeO was damaged in the bent zone by the stress, and the Fe-Cr spinel layer was not destroyed by the influence of cracking and the tensile stress. The cracking and stress did not have a large influence on the overall oxidation corrosion rate.     

含铝奥氏体耐热钢在超临界二氧化碳中的腐蚀行为

研究了20Cr-25Ni合金和一种新型结构材料含铝的奥氏体耐热钢(AFA钢)在600℃/20 MPa的超临界二氧化碳(S-CO₂)环境中的腐蚀行为,并对2种合金的氧化膜形貌、成分和结构进行分析。研究发现,20Cr-25Ni合金出现明显的腐蚀增重增长趋势,表现出“抛物线”上升规律;AFA钢腐蚀增重趋势缓慢,腐蚀1000 h后仅为2.11 mg/dm²。20Cr-25Ni合金表面出现粗大的氧化产物,随腐蚀时间延长,AFA钢的氧化膜始终保持致密、连续。通过氧化膜的截面形貌分析发现,20Cr-25Ni合金腐蚀后具有两层氧化膜结构,主要由Fe₃O₄和FeCr₂O4_氧化层以及少量尖晶石组成。而AFA钢中出现了3层氧化膜结构,中间和最内层分别为Cr₂O₃和Al₂O₃氧化膜,最外层分布了一层不连续的FeCr₂O₄尖晶石氧化物。由于形成了致密的...     

Corrosion studies in support of lead-bismuth cooled FBRs

The performance of structural materials in lead or lead-bismuth eutectic (LBE) systems is evaluated. The materials evaluated included several US steels (austenitic steel [316L], carbon steels [F-22, Fe-Si], ferritic/martensitic steels [HT-9 and 410]), and several experimental Fe-Si-Cr alloys that were expected to demonstrate corrosion resistance. The materials were exposed in either a dynamic corrosion cell for periods from 100 to 1,000 h at temperatures of 400, 500, 600 and 700°C, depending on material and exposure location. Weight change and optical SEM or X-ray analysis of the specimen were used to characterize oxide film thickness, corrosion depth, microstructure, and composition changes. The tests conducted with stainless steels (410, 316L and HT-9) produced mass transfer of elements (e.g., Ni and Cr) into the LBE, resulting in degradation of the material. With Fe-Si alloys a Si rich layer (as SiO₂) is formed on the surface during exposure to LBE from the selective dissolution of Fe.     

铀表面磁控溅射镍镀层的电化学腐蚀行为研究

采用磁控溅射离子镀膜技术在贫铀表面制备金属镍镀层,利用电化学测试技术研究了镍镀层在Cl^-溶液中的电化学腐蚀行为。结果表明：在含50 μg/g Cl^-的KCl溶液中,镍镀层的腐蚀电位-100.8 mV高于贫铀的腐蚀电位-641.2 mV,相对于贫铀是阴极性镀层,对贫铀的保护基于对腐蚀介质的物理屏障;镀镍贫铀样品的极化电阻和电化学阻抗幅值远大于贫铀,其腐蚀电流远小于贫铀;约70 h的连续腐蚀实验中镍镀层未出现镀层破裂、剥落现象,且腐蚀电位、电流保持稳定。说明镍镀层对贫铀基体具有良好的防腐蚀性能。     

Corrosion behavior of heat-treated Fe-Al coated steel in lead-bismuth eutectic under loading

A protective surface alloy coating on steel surfaces can prevent steels from the heavy LBE corrosion in the LBE cooled reactor. Especially, Fe-Al alloy coating on a steel surface is effective for corrosion resistance in LBE due to the self-healing of a thin and stable Al oxide layer on the surface of the coating layer. In order to investigate the utility of the coating layer under the stress due to the hydrodynamic and thermal stress induced in the practical system. The Fe-Al coated 316SS, which was heat-treated after the coating process, was immersed in the stagnant LBE at 650 °C for 250 h with loading to investigate the corrosion behavior of the specimen with the bending stress. The Fe-Al coating layer was not corroded because of the protection by Al oxide scale which was formed on the surface of the coating layer and the interface between the coating and the matrix during the heat treatment process. The coating layer cracked elastically. The LBE penetrated into the cracks and corroded the 316SS matrix and the pre-coating layer. The matrix exhibited the dissolution corrosion caused by the preferential dissolution of Ni and the oxidation forming the Fe oxide and Cr oxide. The coating layer is effective to reduce the surface of the matrix to be corroded by LBE, and can moderate the corrosion of the depth direction.     

Effect of Metallographic Factor on Hydrogen Pick-up Properties of Zircaloy-2

Zirconium alloy sheets were prepared with varying Fe, Cr and Ni systematically. The corrosion and hydrogen pickup property were estimated in steam at 673 K, in water at 633 K and in super critical water at 673 K. The effect of the SPP and the oxide film on the hydrogen pick-up was studied from the hydrogen pick-up route using D₂O and the microstructure of the oxide film and secondary phase particle (SPP) in the oxide film. The hydrogen pick-up ratio decreased with increase of Fe and decrease of Ni. It was affected by Fe/Ni ratio of the matrix. The hydrogen pickup was not related to SPP but was related to the oxide film when the oxide film was relatively thick. The tetragonal ZrO₂ is considered to act as a barrier for hydrogen pick-up.     

The general corrosion behavior of ENiCrFe-7 weld overlay cladding material in deoxygenated high-temperature and high-pressure water

The general corrosion behavior of Alloy ENiCrFe-7 in deoxygenated high-temperature and high-pressure water was investigated. The results showed that the precipitates of Alloy ENiCrFe-7 included niobium carbide and Al-Ti-O compounds, and the weight gain increased fast firstly before 2250 h, then the weight gain slowed down. There were obvious large particles spread on denser oxide film after 3000 h exposure. Ni was present at a single chemical metallic Ni state, Feⁿ⁺ content of the outer layer was close to 60%, which was much higher than that of the matrix. The oxide film consisted of an inner layer and an outer layer, the inner layer was mainly composed of Cr₂O₃ and the outer layer was mainly composed of Fe₃O₄ and FeCr₂O₄. Finally, it is found that the preferential corrosion location of pitting was niobium carbide precipitates by in same site observation, while Al-Ti-O compounds was not dissolved in deoxygenated high-temperature and high-pressure water for 1500 h exposure. The size and number of the pitting was not significantly changed with increasing exposure time.