Cyclic Corrosion Behavior of Ni-Based Superalloys in Hot Lithium Molten Salt

In this study, the cyclic corrosion behavior of N06230, N07263, and N06625 in a LiCl–Li₂O molten salt was investigated at 650?°C in argon atmosphere. The cyclic corrosion behavior was observed through measurements of the oxide morphology and thickness, the extent of internal corrosion, and compositional changes in the oxide scale and the substrate. The corrosion products in the surface corrosion layers of N07263 were (Ni,Co)O, (Ni,Co)Cr₂O₄, Cr₂O₃, and TiO₂ and those in the surface corrosion layers of N06230 were NiO, NiCr₂O₄, and Cr₂O₃, while NiO, NiCr₂O₄, CrNbO₄, and Cr₂O₃ were identified as the corrosion products of N06625. The internal corrosion behavior of N07263 was localized, while N06230 and N06625 showed uniform corrosion. N07263 exhibited superior corrosion resistance as its corrosion layer was more continuous, dense, and adherent as compared to those of N06230 and N06625.     

熔盐堆用结构材料的热腐蚀及防护

本文综述了结构材料在熔融氟化盐中的热腐蚀及其影响因素,以及表面防护涂层研究现状.     

建筑用钎焊合金的热腐蚀行为研究

研究了建筑用钎焊合金BCo46、DZ468和BNi-2在热腐蚀条件下的腐蚀行为。结果表明,在热腐蚀条件下,合金BCo46的抗腐蚀能力强于合金DZ468和BNi-2。3种合金在热腐蚀环境中都出现了硫化物析出和氧化薄膜溶解现象。     

3A21铝合金在乙二醇水溶液中的腐蚀行为

采用电化学方法研究了3A21铝合金在乙二醇水溶液中在不同浓度、温度和浸泡时间条件下的腐蚀电化学行为。采用扫描电子显微镜研究了腐蚀前后3A21铝合金的形貌及表面腐蚀产物。结果表明,随着乙二醇水溶液浓度的增加,铝合金腐蚀速率下降;随着溶液温度升高,铝合金腐蚀速率增大;随着铝合金浸泡时间的延长,一方面,氧化膜的生成和溶解达到动态平衡,另一方面氧化膜薄弱区出现点蚀,点蚀的发展伴随着点蚀的自愈合,并向点蚀加剧方向发展。     

新型Te-Ni-Cr合金在Na2SO4-25％NaCl熔盐中的腐蚀行为

利用粉末冶金技术制备了新型Te-Ni-Cr合金材料.通过静态质量损失试验,X射线物相分析,扫描电镜形貌观察及微区成分分析等手段,研究了合金在750℃Na2SO4-25wt％NaCl熔盐中的热腐蚀行为及热腐蚀动力学规律.研究表明:稀有元素碲的加入,使合金的腐蚀速率较Ni-Cr合金有比较明显的下降;随时间的延长,合金表面的腐蚀程度不断增加;腐蚀产物主要为铁的氧化物、镍及铬的硫化物和氧化物;热腐蚀层主要由铁的氧化物和CrO3组成.     

Hot Corrosion Behavior of Inconel 625 Superalloy in Eutectic Molten Nitrate Salts

Corrosion resistance of Inconel 625 Ni-based superalloy was studied in a molten nitrate salt consisting of 40 KNO₃–60 NaNO₃ (wt%) at 500 and 600 °C. Open-circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy and gravimetric tests were used to evaluate the degradation mechanism and corrosion behavior of the alloy. Surface morphology and chemical analysis of corrosion products were characterized by means of scanning electron microscopy and energy-dispersive X-ray spectrometry. The weight-loss curves showed that with the increase in temperature, the oxidation rate and mass gain increased; the relationship between the mass gain and time was close to the parabolic oxidation law. The electrochemical corrosion results confirmed that during the exposure of Inconel 625 alloy to the molten salts, nickel dissolves as a result of non-protective NiO layer formed. The formation of a non-protective oxide layer with low barrier property was responsible for observing the weak corrosion resistance of the alloy at high temperatures (500 and 600 °C). Cyclic polarization tests showed a positive hysteresis confirming the nucleation and growth of stable pits on the surface of Inconel 625 at high anodic overpotentials. Sodium nitrite acts as an efficient pitting inhibitor for this case. In this way, the sodium nitrite with the concentration of 0.1 molal was found to have an optimum inhibition effect on pit nucleation at 600 °C.     

灰铸铁在熔融富铅渣中腐蚀行为的研究

研究分析了灰铸铁在1150℃熔融富铅渣中的热腐蚀行为,并对灰铸铁的腐蚀形貌和腐蚀产物进行了观察和分析。结果表明,石墨及石墨的分布形态对灰铸铁的抗热腐蚀性能有重要影响,PbO和PbO.SiO2是富铅渣中参与腐蚀反应的主要物质。从电化学腐蚀模型讨论了富铅渣对灰铸铁的热腐蚀机理。     

Corrosion Behavior of IN-800 Superalloy in Waste-Incineration Environments: Hot Corrosion by Molten Chlorides

The corrosion resistance of the IN-800superalloy in contact with a molten mixture of (52-48)mol.% PbCl₂-KCl, similar to that found inwaste-incineration plants, has been studied. Thecorrosion kinetics have been analyzed using continuous-currentelectrochemical techniques and electrochemical-impedancespectroscopy (EIS). Studies were performed to determinethe influence of temperature and of the presence of carbon in the salt on the corrosion rate.Scanning electron microscopy (SEM) and electron probemicroanalysis (EPMA) were used as additional techniquesto analyze the corrosion products in order to elucidate the corrosion mechanism.     

新型镁合金在生理体液环境下腐蚀行为评价

研究了2种新型医用植入镁合金材料(Mg-6%Zn和Mg-6%Zn-2%Y合金)在生理盐水和林格试液(人体模拟体液)中的腐蚀行为,来评价其作为医用植入材料的服役情况.实验结果表明:在中性介质环境下,镁合金很快被腐蚀.随着介质溶液pH值的提高,镁合金表面能够形成厚的Mg(OH)2沉淀膜,阻止腐蚀的深入.镁合金在林格试液中的...     

Corrosion Behavior of 12CrMoV Steel in Waste Incineration Environments: Hot Corrosion by Molten Chlorides

The corrosion resistance of a 12CrMoV alloy incontact with a molten mixture of (52-48)mol.%PbCl₂-KCl, similar to that found inwaste incineration plants, has been studied. Thecorrosion kinetics have been analyzed using continuous-currentelectrochemical techniques and electrochemical impedancespectroscopy (EIS). Studies were performed to determinethe influence that temperature and the presence of carbon in the salt have on the corrosion rate.Scanning electron microscopy (SEM) and electron-probemicroanalysis (EPMA) were used as additional analyticaltechniques to analyze the corrosion products in order to elucidate the corrosionmechanism.     

Corrosion of Ni in Molten Alkali Sulphates

The corrosion of Ni base alloys under molten ash deposits containing considerable quantities of alkali sulphates can take place as a sulphidation or oxidation. The former is very dangerous with respect to gas turbine operation since it gives rise to a decrease in strength of the materials; this type of corrosion is also predominant under thick layers of molten deposits at higher oxygen pressures, the effect being then increased by the poorer transport properties of the melt respect to oxygen diffusion. When cobalt sulphate is found in the ash the accelerated oxidation of Ni base alloys is due to the stable redox system Co⁺²/Co⁺² in the melt Increasing the acidity of the flue gases (increasing SO₃ content) enhances the corrosion rate and the solubility of corrosion products in the melt.     

Molten Salt Electrodeposition of Praseodymium-iron Alloy

ＭｏｌｔｅｎＳａｌｔＥｌｅｃｔｒｏｄｅｐｏｓｉｔｉｏｎｏｆＰｒａｓｅｏｄｙｍｉｕｍ－ｉｒｏｎＡｌｌｏｙＬｉｕＧｕａｎｋｕｎ，ＹａｎｇＱｉｑｉｎ，ＴｏｎｇＹｅｘｉａｎｇ，ＺｈｏｕＸｉａｎｚｈｉａｎｄＣｈｅｎＱｉｎｇｓｏｎｇ（刘冠昆）（杨绮琴）（童叶翔）...     

铜铝层状复合板中性盐雾腐蚀行为研究

采取模拟大气环境的室内中性盐雾腐蚀实验,探讨了铜铝层状复合材料的腐蚀行为.通过扫描电镜(SEM)观察腐蚀后铜铝界面形貌,结合X射线衍射仪(XRD)和能谱仪(EDS)分析腐蚀产物成分,并通过电化学检测分析试样经过不同时间盐雾腐蚀后的表面腐蚀状态,探讨铜铝复合板在服役环境下的腐蚀机制.结果 表明:铜铝复合板在盐雾环境下铜铝...     

Corrosion Behavior of AZ31 Magnesium Alloy in Highly Alkaline Environment

Industrial components made with a magnesium-aluminum alloy AZ31 are often used in diverse engineering applications where component weight,strength,and durability are critical.Similarly as other Mg alloys,however,the AZ31 is susceptible to corrosion in alkaline environments.In this work,corrosion of commercial grade AZ31 alloy plate was examined in potassium hydroxide(KOH) using immersion and potentiodynamic studies.The results suggest that the concentration of Al and Mn in the alloy may govern the kinetics of micro-galvanic corrosion and the initiation of corrosion pits.Further,trace amounts of Ni in the AZ31 alloy were seen to enable formation of Ni(OH)2 surface layer,which may have further accelerated alloy corrosion due to its cracking and void coalescence.The effect of pH on the corrosion behavior of AZ31 was studied with reference to Pourbaix diagrams.     

HastelloyB3合金在盐酸中的腐蚀行为

通过浸泡试验、电化学试验研究了HastelloyB3合金在不同条件盐酸中的腐蚀行为。结果表明:合金在不同HCl含量与温度的纯盐酸中均具有良好的耐蚀性,随着温度与HCl含量的提高,合金腐蚀速率虽有所增长,但仍然处于钝化态;盐酸中添加氧化性离子Fe~(3+)后,腐蚀速率急剧增大并伴随着点蚀,随着Fe~(3+)含量的提高,腐蚀速率快速增大;在纯盐酸中,HastelloyB3表面生成Mo~(4+)钝化膜,对基体起到保护作用,但添加氧化性Fe~(3+)后,钝化膜中的Mo~(4+)极易被氧化成Mo~(6+),发生溶解,使合金由钝态向过钝化态转变,导致耐蚀性急剧下降;HastelloyB3合金适用于不同HCl含量与温度的纯盐酸中,但不适用于含氧化性离子或溶解氧高的盐酸中。     

氮化处理的贫铀表面在盐雾环境中的腐蚀行为

利用激光共聚焦显微镜(CLSM)、扫描电子显微镜(SEM)和激光拉曼光谱(Raman Spectroscopy)等技术研究了氮化处理的贫铀表面在盐雾环境中的腐蚀行为。结果表明:盐雾环境对氮化处理的贫铀表面具有较强的腐蚀破坏作用;在含夹杂缺陷位置最先发生点蚀,随着在盐雾环境中暴露时间的延长,腐蚀加剧,氮化改性层被破坏,直接导致基体发生严重的腐蚀;盐雾环境中贫铀的腐蚀产物中含有U3O8。     

Hot Salt Corrosion of titanium aluminides

There is considerable interest in the use of γ-TiAl within advanced gas turbines where they offer greater high temperature capability over conventional titanium at reduced weight. These factors would enable engines with greater thrust to weight ratio to be developed. Thus γ-TiAl offers the potential of replacing nickel based alloys within the high pressure compressor and potentially the fourth stage turbine. Service in both of these locations would require that the γ-TiAl be resistant, not only to oxidation, but hot salt corrosion. This paper presents a study of the hot salt corrosion resistance of γ-TiAl over the temperature range 500–700°C. At 700°C, laboratory tests have shown that corrosion rates in a salt ladened environment are some 20X that of equivalent oxidation for exposures out to 100 h. The morphology of attack is consistent with a corrosion mechanism involving the vapour phase transport of aluminium from within the alloy and formation of a non protective oxide scale. A model for the corrosion mechanisms is presented, involving intermediate chloride phases. The mechanism is believed to be self sustaining, requires little chloride present, and leads to the observed accelerated oxidation rates.     

Morphology and Corrosion Properties of Electroplated Ni–Cr Alloy Coatings in Salt Solutions

The relationship between the morphologic and corrosion properties of electroplated binary Ni–Cr alloys is examined. Codeposition of chromium with nickel changes the morphology of the coating, through the microcracks of which the corrosion of copper starts and accelerates by forming corrosion cells (between the substrate and coating) in an acidic 5% NaCl solution (pH 3.1). In neutral media, the substrate is protected from corrosion not only by the passive Ni–Cr coating, but also by insoluble copper compounds that block the coating microcracks, which manifests itself in inhibiting the corrosion. Upon a long exposure to acidic NaCl solutions, uniform corrosion of the Ni coating gives way to pitting corrosion.     

熔盐电解还原制备TiFe合金

在CaCl2熔盐中采用熔盐电解法由阴极的混合氧化物制备组分可控的TiFe合金。初步探讨了TiFe合金的形成机制,研究了电解时间对电解产物的影响。结果表明,混合氧化物的还原经历了从优先生成铁到逐步形成TiFe2、TiFe的合金化历程,中间产物包括CaTiO3、Fe：TiO4、TiO,电解过程中没有金属钛出现。扩散是混合氧化物熔盐电解反应的控制步骤。