喷丸处理对锆合金微动磨损及抗腐蚀性能的影响

目的探索喷丸处理工艺对锆合金包壳管的微动磨损及抗腐蚀性能的影响。方法对锆合金包壳管进行喷丸处理,对原始试样及喷丸处理试样进行微动磨损试验,并测量磨损深度和磨损体积、表征微动磨损后的表面粗糙度和表面形貌。此外,对原始试样及喷丸处理试样进行腐蚀试验,测量喷丸前后锆合金的腐蚀增重。结果喷丸处理使ZIRLO锆合金的磨损体积相对于未处理试样减少了5.7%。喷丸处理能够提高ZIRLO锆合金包壳管的硬度,但是高硬度区域较薄,约为4～8μm。腐蚀介质为去离子水和Li OH溶液时,喷丸试样的腐蚀增重分别经过140 d和220 d后低于原始试样。Li OH溶液条件下,未喷丸的ZIRLO合金管氧化膜的厚度约为15μm,喷丸后ZIRLO合金管氧化膜的厚度约为1.21μm。结论喷丸处理在一定程度上可以提高ZIRLO锆合金抗微动磨损性能和抗腐蚀性能,其中抗微动磨损性能有提高,但幅度不大,这与硬化层较薄有关。喷丸后试样经过腐蚀试验,腐蚀增重减少,氧化膜厚度减小,说明抗腐蚀性能增强,但喷丸试样的抗腐蚀性能在腐蚀进行到一定阶段时才开始体现。     

压水堆条件下锌对690合金表面氧化膜的影响

模拟压水堆一回路加锌水环境,对镍基690合金在加锌浓度为10μg/kg的320℃,15.20 MPa溶液中进行了1000 h的腐蚀试验。采用XPS深度分析法对试样氧化膜进行分析。结果表明,锌能有效地降低690合金的均匀腐蚀速率,加锌后氧化膜形貌和成分都有了明显改变,氧化膜厚度变薄。     

锆合金在LiOH水溶液中腐蚀的各向异性研究

选用了具有相同织构的Zr-4,N18和ZIRLO锆合金片状样品,利用高压釜在360℃,18.6 MPa的0.01 mol/LLiOH水溶液中进行了280 d腐蚀实验,采用EBSD和SEM研究了织构及合金成分对锆合金耐腐蚀性能的影响.结果表明,腐蚀280 d后,Zr-4样品表现出明显的腐蚀各向异性特征,在织构因子较大的轧面(S_N面)上氧化膜较厚,耐腐蚀性能差,而在织构因子较小的垂直于轧向的截面(S_R面)和垂直于横向的截面(S_T面)上氧化膜较薄,耐腐蚀性能好.添加合金元素Nb的N18和ZIRLO样品氧化模生长的各向异性受到抑制,在S_N,S_R和S_T 3个不同面上氧化膜的厚度相同,耐腐蚀性能比Zr-4样品的S_N面优良.但是,如果只以样品的S_R和S_T面进行比较,氧化膜的生长速率会随Nb含量的增加而增大,耐腐蚀性能变差.从改善合金的耐腐蚀性能考虑,Nb的添加量不应该高于0.3%(质量分数).     

微弧氧化对ZIRLO合金耐腐蚀性能的影响

采用磷酸盐、硅酸盐电解液体系对ZIRLO合金进行微弧氧化处理。利用XRD、SEM、TEM等研究陶瓷层的相组成、表面形貌、截面组织。结果表明：在磷酸盐电解液体系、硅酸盐电解液体系中制备的陶瓷层主要由m-ZrO₂组成,磷酸盐电解液体系制备的陶瓷层内表面较硅酸盐电解液体系制备的陶瓷层更致密。在硅酸盐电解液体系中微弧氧化的样品靠近陶瓷层/金属界面基体一侧存在少量β-Zr。采用静态高压釜腐蚀实验研究了ZIRLO合金及D(磷酸盐电解液体系微弧氧化)样品和E(硅酸盐电解液体系微弧氧化)样品在360 ℃/18.6 MPa去离子水中及360 ℃/18.6 MPa 0.01 M LiOH水溶液中的耐腐蚀性能。在360 ℃/18.6 MPa去离子水中腐蚀至250 d时,D和E样品耐腐蚀性能相接近,均优于未经微弧氧化处理的ZIRLO合金样品;在360 ℃/18.6 MPa 0.01 M LiOH水溶液中腐蚀至246 d时,D和E样品的耐腐蚀性能与未经微弧氧化处理的ZIRLO合金样品耐腐蚀性能接近甚至有有害的影响。随着腐蚀时间的延长,微弧氧化对ZIRLO合金耐腐蚀性能提升有限。     

Zr-4合金表面氧化膜的电化学阻抗谱特征

电化学阻抗谱是分析锆合金表面氧化膜结构及其演化行为的有效方法。利用10%HCl溶液研究了锆合金在400 ℃, 10.3 MPa过热蒸汽中腐蚀后的表面氧化膜电化学阻抗行为。结果表明：锆合金过热蒸汽腐蚀初期表面氧化膜的阻抗谱为单一容抗弧,随着腐蚀进行而演变为双容抗弧。氧化膜表现为双层膜结构特征。氧化膜阻挡作用的降低是锆合金过热蒸汽腐蚀发生转折的一个原因。锆合金中第二相粒子对氧化膜阻抗谱及合金耐蚀性有较大影响     

水化学及合金成分对锆合金腐蚀时氧化膜显微组织演化的影响

将Zr-4和成分接近ZIRLO的3#合金样品置于高压釜中,经过360℃,18.6 MPa的0.01 mol/L LiOH水溶液腐蚀1 50 d后,增重分别达到310 mg/dm^2和82 mg/dm^2,3#合金的耐腐蚀性能明显优于Zr-4.用透射电镜、扫描电镜和扫描探针显微镜研究了两种样品经过70 d和150 d腐蚀后,氧化膜不同深度处的显微组织和晶体结构;研究了氧化膜的断口形貌和氧化膜的表面形貌.结果表明：Zr-4氧化膜中的空位比3#合金氧化膜中的更容易通过扩散凝聚形成孔洞簇和晶界微裂纹,也容易发展成平行于氧化膜/金属界面的裂纹,导致腐蚀转折提早发生,这与Li^＋和OH^-渗入氧化膜后降低氧化锆表面自由能的程度有关.从氧化膜表面晶粒形貌判断,Zr-4样品形成氧化锆后的表面自由能比3#合金样品形成氧化锆后的低,这是合金成分不同引起的一种差异,也可能是Zr-4样品在LiOH水溶液中的耐腐蚀性能比3#样品差的一个重要原因.     

2024-T3铝合金在不同酸性水溶液中的电化学行为

采用动电位极化和交流阻抗两种电化学测量技术,结合表面微观形貌观察,研究了2024-T3铝合金在不同种酸（包括乙酸、硫酸和盐酸）以及不同pH值水溶液中的电化学行为。结果表明:随pH值降低,合金自腐蚀电位负移,自腐蚀电流密度和腐蚀速率增大,合金表面钝化膜越易遭到破坏,溶液的腐蚀作用越强,且在不同pH值下,阴极极化过程的控制反应有所不同;在相同pH值下,以盐酸水溶液的腐蚀作用最强,硫酸水溶液相近但次之,乙酸水溶液最弱,这是酸的不同水解能力和氯离子的存在共同导致的;铝合金表面钝化膜的存在使得其在不同环境中的电化学行为表现不同,酸性条件下钝化膜失稳溶解,合金基体裸露并与溶液直接接触发生反应,而弱酸性条件下,钝化膜则能够保持相对完整性,对合金基体起到一定保护作用。     

NH3��CuBiAl�Ͻ���3��5%NaCl��Һ�еĸ�ʴ���ܵ�Ӱ��

 通过金相、X射线衍射（XRD）及扫描电镜(SEM/EDX),结合电化学测试手段研究了CuBiAl合金在35% NaCl +NH3溶液中的腐蚀行为,并探讨了NH3对CuBiAl合金在3.5%NaCl溶液中腐蚀性能的影响。结果表明：NH3能使合金的腐蚀电位负移,腐蚀电流增加,加速了合金的腐蚀,且合金的腐蚀速率随NH3浓度的增加而增大。     

NH3对CuBiAI合金在3．5％NaCI溶液中的腐蚀性能的影响

通过金相、X射线衍射(XRD)及扫描电镜(SEM/EDX),结合电化学测试手段研究了CuBiAl合金在3.5%NaCl NH3溶液中的腐蚀行为,并探讨了NH3对CuBiAl合金在3.5%NaCl溶液中腐蚀性能的影响.结果表明:NH3能使合金的腐蚀电位负移,腐蚀电流增加,加速了合金的腐蚀,且合金的腐蚀速率随NH3浓度的增加而增大.     

锆合金在HCl和H2SO4溶液中的耐蚀性能研究

采用化学浸泡、电化学测试和物理检测技术,研究了HCl和H2SO4溶液中锆合金的腐蚀行为.结果表明,锆合金在还原性的HCl和低浓度H2SO4溶液中,具有优异的耐蚀性,而在高浓度的氧化性H2SO4溶液中腐蚀速率显著增大.物理检测结果显示,腐蚀的锆合金表面均匀地覆盖着弥散分布的微小颗粒状ZrO2.还原性的HCl和低浓度H2SO4溶液中ZrO2膜保持了原有的致密性,增强了锆合金的耐蚀性能.而高浓度H2SO4溶液中,在其强氧化作用下,锆合金基体/膜界面处不断生成ZrO2.当膜增加到一定厚度时,氧化膜的晶格参数与金属的晶格参数不一致,产生内应力,降低了氧化膜的附着力,直至氧化膜破裂,露出新鲜的锆合金表面.继之,新鲜的锆合金再次被氧化,以此循环往复,导致锆合金在浓H2SO4溶液中腐蚀加剧.     

The effect of Sn on autoclave corrosion performance and corrosion mechanisms in Zr–Sn–Nb alloys

The desire to improve the corrosion resistance of Zr cladding material for high burn-up has resulted in a general trend among fuel manufacturers to develop alloys with reduced levels of Sn. While commonly accepted, the reason for the improved corrosion performance observed for low-tin zirconium alloys in high-temperature aqueous environments remains unclear. High-energy synchrotron X-ray diffraction was used to characterize the oxides formed by autoclave exposure on Zr–Sn–Nb alloys with tin concentration ranging from 0.01 to 0.92 wt.%. The alloys studied included the commercial alloy ZIRLO® (ZIRLO® is a registered trademark of Westinghouse Electric Company LLC in the USA and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.) and two variants of ZIRLO with significantly lower tin levels, referred to here as A-0.6Sn and A-0.0Sn. The nature of the oxide grown on tube samples from each alloy was investigated via cross-sectional scanning electron microscopy. Atom probe analysis of ZIRLO demonstrated that the tin present in the alloy passes into the oxide as it forms, with no significant difference in the Sn/Zr ratio between the two. Synchrotron X-ray diffraction measurements on the oxides formed on each alloy revealed that the monoclinic and tetragonal oxide phases display highly compressive in-plane residual stresses with the magnitudes dependent on the phase and alloy. The amount of tetragonal phase present and, more importantly, the level of tetragonal-to-monoclinic phase transformation both decrease with decreasing tin levels, suggesting that tin is a tetragonal oxide phase stabilizing element. It is proposed that in Zr–Nb–Sn alloys with low Sn, the tetragonal phase is mainly stabilized by very small grain size and therefore remains stable throughout the corrosion process. In contrast, alloys with higher tin levels can in addition grow larger, stress stabilized, tetragonal grains that become unstable as the corrosion front continues to grow further inwards and stresses in the existing oxide relax.     

Oxidation of Advanced Zirconium Cladding Alloys in Steam at Temperatures in the Range of 600�C1200?��C

The oxidation kinetics of the classical pressurized water reactors (PWR) cladding alloy Zircaloy-4 have been extensively investigated over a wide temperature range from operational conditions to beyond design basis accident (BDBA) temperatures. In recent years, new cladding alloys optimized for longer operation and higher burn-up are used in Western light water reactors (LWR). This paper presents the results of thermo-gravimetric tests with Zircaloy-4 as the reference material, Duplex DX-D4, M5^® (both AREVA), ZIRLO? (Westinghouse), and the Russian E110 alloy. All materials were investigated in isothermal and transient tests in a thermal balance with steam furnace. Post-test analyses were performed by light-microscopy and neutron radiography for investigation of the hydrogen absorbed by the metal. Strong and varying differences (up to 800%) in oxidation kinetics between the alloys were found at up to 1000 °C, where the breakaway effect plays a role. Less but significant differences (ca. 30%) were observed at 1100 and 1200 °C. Generally, the M5^® alloy revealed the lowest oxidation rate over the temperature range investigated whereas the behavior of the other alloys was considerably dependent on temperature. A strong correlation was found between oxide scale structure and amount of absorbed hydrogen.     

New insight into crack formation during corrosion of zirconium-based metal-oxide systems

Zirconium alloys are typically used in nuclear pressurized water reactors (PWR) as fuel cladding tubes due to their chemical stability and their mechanical strength at operating temperatures (≈300 °C). However, the corrosion of Zr-based cladding tubes is one of the factors limiting the burn-off rate in PWRs. It is commonly accepted that the corrosion kinetics involves a periodic succession of growth where the oxide thickness varies parabolically with time. As the oxide thickens, a cracking structure forms. The oxide appears striated with periodic layers of cracks running parallel to the metal/oxide interface. This cracking structure has been experimentally related to the periodicity of the oxide growth. In the present work, a finite-element study is used to investigate the development of stresses in the oxide under the combined influence of molar volume expansion during oxide formation, metal/oxide interface geometry and metallic substrate creep. The generation of tensile stresses capable of initiating the cracks that are observed experimentally is explored.     

Si对Ni-Cr-Mo合金熔覆层高温耐腐蚀性能的影响

为研究Si含量对Ni-Cr-Mo系合金熔覆层耐高温腐蚀性能的影响，利用激光熔覆技术制备了4种不同Si含量的熔覆层。采用失重法测试了4种熔覆层在模拟垃圾发电腐蚀环境中多种温度下的耐腐蚀性能。通过对4种熔覆层在600及650℃下腐蚀产物的特性分析，发现Si的加入有助于腐蚀产物中富Cr氧化皮的稳定性。还可以通过“钉扎”作用提升富Cr氧化皮与基体的粘结性，从而有效提高熔覆层的耐腐蚀性能。但Si含量并非越多越好。当温度提升到600℃以上，含3%(质量分数，下同)Si的合金展现了最佳的耐腐蚀性能。这是由于含3%Si的合金腐蚀层中形成了一层保护性的SiO₂，有助于耐腐蚀性能的提升。而含1%Si的合金由于Si含量较低，含5%Si的合金由于Si的偏析严重，均未能形成有效的SiO₂保护层。     

Cr涂层对Zr-1Nb合金包壳微动磨损行为的影响

采用三维白光干涉仪、扫描电子显微镜、能谱仪等表征技术对比研究Cr涂层Zr-1Nb合金包壳和Zr-1Nb合金包壳与格架在模拟压水堆一回路水环境下的微动磨损行为及损伤机制。结果表明,Cr涂层显著提高Zr-1Nb合金包壳的抗微动磨损性能。此外,对磨副为刚凸时,Zr-1Nb合金包壳微动磨损机制以磨粒磨损和剥层磨损为主,而Cr涂层Zr-1Nb合金包壳由于表面硬度较高,且表面形成具有保护作用的三体层,其损伤机制以黏着磨损和材料单向转移为主。对磨副为弹簧时,Zr-1Nb合金包壳微动磨损机制主要为剥层和黏着磨损,Cr涂层Zr-1Nb合金包壳主要为磨粒磨损。     

PWR 水环境中 Zn 对 Co 在氧化膜中沉积行为的影响

在315 ℃的模拟压水堆一回路水环境下,针对316和304奥氏体不锈钢及690合金等压水堆核电站主设备材料,通过将在含Co的高温溶液中浸泡形成的氧化膜试样再放入含Zn溶液中进行腐蚀实验,研究了Zn对Co在氧化膜中沉积行为的影响。结果表明,Co的沉积使氧化膜形貌发生了变化,Zn对沉积在氧化膜中的Co有置换作用。     

Zn对均匀化态Mg-3Sn-Ca镁合金腐蚀性能的影响

研究了Zn元素对均匀化态Mg-3Sn-Ca合金耐腐蚀性能的影响。通过XRD、金相、SEM、失重、析氢、电化学极化曲线和阻抗谱分析了Mg-3Sn-Ca(TX31)和Mg-3Sn-Ca-Zn(TXZ311)2种合金的耐蚀性能。结果表明,Mg-3Sn-Ca合金中主要由CaMgSn及Mg₂Sn相组成,加入Zn元素后晶粒得到显著细化,第二相体积分数增加并呈弥散分布,并有Mg₂Ca相析出。而Zn的添加可显著提高Mg-3Sn-Ca合金的耐蚀性能,这主要归因于TXZ311合金具有更细小的晶粒尺寸以及均匀密集分布的CaMgSn相,使合金在腐蚀过程中形成的钝化膜更加均匀。因此,TXZ311合金的耐蚀性远高于TX31合金。     

注锌对316L奥氏体不锈钢氧化膜成分的影响

通过模拟压水堆一回路水环境,对316L奥氏体不锈钢在320℃含锌10μg/kg的高温溶液中进行了1000 h的腐蚀实验,对腐蚀后的试样表面进行了XPS分析。结果表明,试样在含锌溶液中形成了化学成分为(Zn,Fe,Ni)(Cr,Fe)2O4的致密氧化膜,随着腐蚀时间的增加,氧化膜中的富Cr区由内层扩展至整个氧化膜。     

High-Temperature Corrosion of Fe3Al in 1% Cl2/Ar

The high-temperature corrosion of iron aluminide (Fe₃Al) in environments containing chlorine has been investigated using the thermogravimetric method. The corrosion experiments were performed in a 1%Cl₂–Ar mixture in the temperature range of 750 to 900°C. Two distinct stages of weight change during corrosion were observed: slow linear weight loss and subsequent fast linear weight-loss stage. Considering corrosion kinetics and products, different corrosion mechanisms are proposed for each stage. The first stage is characterized by localized chlorine attack, repassivation or defect healing by alumina- forming active oxidation and diffusion of volatile aluminum chloride to the gas/scale interface through dense aluminum oxide. The depletion of aluminum in the alloy near the metal–oxide interface after the first stage and the subsequent evaporation of iron chlorides may result in rapid weight loss during the second stage. It was observed that a significant amount of porous nonprotective oxide scale was formed by active oxidation in the second stage. The segregation of sulfur at the metal–oxide interface during the second stage was also observed.     

Ca、Mn元素对Mg-Zn系合金在磷酸盐缓冲液中腐蚀行为的影响

采用XRD、SEM、EDS、三维轮廓仪和失重法等手段研究了Mg-6Zn、Mg-6Zn-1Ca和Mg-6Zn-1Mn合金在磷酸盐缓冲盐溶液(PBS)中的腐蚀行为,并探讨了3种合金的腐蚀机理。结果表明,添加相同含量的Ca和Mn均能使合金的失重率(W_r)降低,但添加Mn元素后(浸泡10d时W_r=3.91%)比添加Ca元素后(W_r=6.78%)合金的失重率更低,说明Mn元素更有抗PBS腐蚀能力,这与Mn的加入在合金表面形成致密的氧化膜有关;同时,Mg-6Zn-1Mn合金在浸泡过程中表面存在点蚀现象,经分析是由第二相与基体构成原电池导致。在420℃不同保温时间(2～20 h)固溶处理后,合金表面的点腐蚀现象随着保温时间的增加而减弱,表明长时间的固溶处理可以减少第二相与镁基体之间的微电偶腐蚀,增加了合金均匀腐蚀的倾向。