Influence of rare earth elements on corrosion resistance of BFe10-1-1 alloys in flowing marine water

The corrosion behavior of BFe10-1-1 alloy with different rare earth (RE) contents in simulated flowing marine water was investi-gated by X-ray diffractometer and scanning electron microscope (SEM). It was demonstrated that the corrosion rate of BFe10-1-1 alloy with the same chemical compositions in faster flow velocity of marine water was higher than that in a lower flow velocity of marine water. Fixing the flow velocity, BFe10-1-1 alloy had the best flushing corrosion resistance when the RE content was 0.04wt.%. The consequence of such good corrosion resistance was attributed to the formation of compact protective film on alloy surface containing RE phase such as CeNi5- The RE-contained film combines with other corrosion products firmly, which was difficult to fall off from the alloy surface in the flowing marine water. Additionally, SEM analysis confirmed that pitting mechanism, which would be transformed to spalling mechanism gradually with further increasing RE content, was the prevalent mechanism when the alloy contained 0.04wt.%RE.     

Effect of Zn addition on corrosion resistance of Cu-10Ni alloy in clean and sulphide contaminated seawater

Cu-10Ni alloy has an outstanding resistance to corrosion in seawater due to formation of protective Cu₂O film. However, in presence of S^2? ions, it suffers accelerated corrosion. The present paper investigates the corrosion behaviour of Cu-10Ni, Cu-10Ni-6Zn and Cu-10Ni-12Zn alloys using weight loss, electrochemical impedance spectroscopy and potentiodynamic polarisation technique. The experiments were performed in clean seawater and sulphide contaminated seawater. The Cu-10Ni-6Zn and Cu-10Ni-12Zn alloys were found to exhibit lower corrosion rate than Cu-10Ni alloy in clean and sulphide contaminated seawater. Lower corrosion rate of Zn containing alloys in clean seawater is attributed to the incorporation of Zn²⁺ ions in Cu₂O lattice. Lower corrosion rate of Zn containing alloys sulphide contaminated seawater is attributed to formation of ZnS in the film.     

6005A铝合金的表面损伤对其耐海水腐蚀性能的影响

以6005A铝合金商品实际产生的表面少缺陷、多缺陷试样,以及作为比较的完全去除商品表面膜的人工磨制的三种不同表面状态试样为研究对象,研究铝合金商品表面的实际损伤对其耐海水腐蚀性能的影响及其腐蚀电化学行为.通过场发射扫描电镜和激光共聚焦扫描显微镜对具有不同表面状态的6005A铝合金表面形貌和粗糙度进行了表征,表明铝合金商品实际产生的表面缺陷主要为划伤,体现在随着表面缺陷的增多,表面粗糙度Ra明显增大,表面粗糙度Ra大小可以定量描述表面损伤的严重程度. 6005A铝合金在NaCl质量分数3.5%的模拟海水溶液中发生全面腐蚀和点蚀,表面缺陷越多,粗糙度越大,耐蚀性越差;电化学测试结果表明,表面缺陷越多,粗糙度越大,腐蚀电位越低,腐蚀电流密度越大,耐蚀性越差. 6005A铝合金表面损伤对其耐海水腐蚀性能产生影响的原因为：表面损伤造成铝合金商品原表面膜被破坏,表面缺陷越多,粗糙度越大,表面膜的破坏和表面塑性变形越严重,铝元素会因为被活化而迅速溶解,有着更高的腐蚀速率,而缺陷较少表面有较为均匀致密的氧化膜,对基体有着较好的保护性.     

Effect of rare earths on oxidation resistance of heat resistant steel

The application of rare earths(RE) in the Ni saving heat resistant steel was studied by metalloscopy,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray difference(XRD).Because the diffusion of chromium was promoted by RE,a dense and adhesive Cr2O3 layer could form rapidly at the early oxidation stage,which played a effective protection role;the pinning effect of silicon dioxide was enhanced by RE in the internal oxidation layer,which had a block effect on the diffusion of metal ions and oxygen ions at later stage of oxidation and resulted in that the high temperature oxidation rate of RE heat resistant steel was decreased.     

Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Influence of adding various rare earths on microstructures and corrosion resistance of chromizing coatings prepared via pack cementation on P110 steel

In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation,four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementation process.The surface morphologies and microstructures of the chromizing coatings were observed using scanning electron microscopy(SEM),and the phase constitutions were investigated by X-ray diffraction(XRD).Electrochemical corrosion behavior of the chromizing coatings in simulated oilfield ...     

微量稀土对铸态Cu-3.0Si-2.0Ni合金组织及性能的影响

加入适量的稀土元素能有效改善铜合金的组织和性能.铸态Cu-3.0Si-2.0Ni合金中添加稀土Ce后,进行熔炼及热处理试验,再通过室温拉伸、导电率试验和金相观察,研究了微量Ce对铸态Cu-3.0Si-2.0Ni合金组织与性能的影响.结果表明:铸态合金晶粒随着Ce含量的升高呈现先减小后递增的趋势;铸态合金的抗拉强度和导电性随着Ce的增加分别先升高后减低;当Ce的质量分数为0.06%时,铸态合金的抗拉强度最高、导电性最强.     

Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy

The effects of samarium（Sm） on microstructure and corrosion resistance of AZ92 magnesium alloy were characterized and analyzed by scanning electronic microscopy, X-ray diffraction, mass loss test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and potentio-dynamic polarization test. The results showed that the added Sm could promote continuous precipitation of β-Mg17Al12 phase in grains, and meanwhile restrain discontinuous precipitation of the same phase along the grain boundaries. Thus, the precipitations distributed more uniformly in the aged AZ92 magnesium alloys. When the content of Sm was 0.5 wt.%, the corrosion resistance of aged AZ92 alloy tended to be the best, which was due to the β-phase distributes more homogeneous reducing the galvanic corrosion. The corrosion product film had more integrality and compactness than AZ92 alloys without Sm. However, it resulted in worse corrosion resistance of AZ92 alloy because of the formation of mass cathodic Al2 Sm phase coming from excess Sm in AZ92 alloy.     

Influence of rare earth elements on corrosion behavior of Al-brass in marine water

The corrosion behaviors of Al-brass in stagnant and flowing marine water as a function of combinative rare earths (Ce and La) ad-dition were investigated by electrochemical techniques, X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was demon-strated that RE elements could make the corrosion product layer more protective and strengthen the cohesion between the film and matrix in stagnant seawater. The electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) anal...     

Composition and corrosion resistance of cerium conversion films on 2195Al-Li alloy

The Ce conversion films on 2195Al-Li alloy without and with post-treatment were studied and the corrosion resistance was evalu-ated as well. The surface morphology was observed by scanning electron microscopy (SEM), and the chemical composition was characterized by X-ray photoelectron spectroscopy (XPS). The corrosion behaviors of 2195Al-Li alloy and conversion coating were assessed by means of potentiodynamic polarization curves. The experimental results indicated that after post-treatment the surface quality was improved signifi-cantly. According to XPS, the conversion coating after post-treatment was mainly composed of CeO2, Ce2O3, Ce-OH and a little MoO3 and MoO2. The results of potentiodynamic polarization curves revealed that the conversion coating with post-treatment possessed better corrosion resistance than bare alloy and Ce conversion coating without post-treatment.     

注射成形和模压成形Cu-10Ni合金的烧结行为

分别采用模压成形和注射成形技术制备Cu-10Ni合金,研究该合金不同成形方式下的烧结行为.结果表明:合金的致密化过程和力学性能均受烧结温度的显著影响,烧结过程均包括合金化、均匀化和致密化3个阶段.模压成形坯在1000℃、注射成形坯在1050℃烧结后,致密化程度均较高、显微组织较好、力学性能较佳.其中,注射成形制备的Cu-Ni合金表现出致密化过程较长、滞后于模压成形合金的烧结行为,完成烧结所需的温度较高.     

The effect of rare earths on the solidification structure of Fe-36Ni invar alloy

The effect of Ce,La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated.The results show that great amounts of high-melting point compounds (Ce2O3,La2O2S and (Ce,La)2O2S) respectively formed in the alloy with the addition of Ce,La or mischmetal.Based on the theory of lattice misfit,the lattice misfit between the (0001) surfaces of Ce2O3,Ce2O2S and La2O2S and (100) surface of Fe-36Ni invar alloy were 6.21%,5.77% and 5.42%,respectively,which are relatively low.Therefore,Ce2O3 ,La2O2S and (Ce,La)2O2S could serve as the core of heterogeneous nucleation,improve the equiaxed grain ratio,reduce the equiaxed grain size and refine the solidification structure of alloy.     

Corrosion resistance of new copper alloy containing 29Zn, 10Ni and up to 5Mn vis-a-vis Cu-10Ni in sulphide polluted synthetic seawater

Cu-10 Ni alloy suffers from accelerated corrosion in sulphide-polluted seawater. New copper alloys containing 29% Zn, 10Ni and 3 or 5% Mn have been found to be more corrosion resistant than Cu-10Ni alloys in sulphide polluted synthetic seawater. The studies were carried out in synthetic seawater (ASTM D 114–75) and sulphide was added through Na₂S (1 gpl ≈ 41ppm S²⁻). Testing was carried out using cathodic and anodic potentiodynamic polarization methods. Corrosion product film formed on the Cu-29Zn-10Ni-5Mn alloy in sulphide polluted synthetic seawater was characterized using SEM and XRD. The film was found to contain Cu₂O, Cu₂S, NiS and ZnS. Better corrosion resistance of new alloys as compared to that of Cu-10Ni alloy is attributed to formation of ZnS, a bad conductor, in the film and incorporation of Mn³⁺ cations in Cu₂O and Cu₂S lattice.     

Mechanical and corrosion resistant properties of martensitic stainless steel plasma nitrocarburized with rare earths addition

In order to improve surface hardness and corrosion resistant property of 17-4PH martensitic stainless steel, the steel was plasma nitrocarburized at 560 °C for 2-24 h in a gas mixture of nitrogen, hydrogen and ethanol with rare earths (RE) addition. The experimental results showed that the modified layer was characterized by a compound layer containing two distinct zones (i.e. out ’dark zone’ and inner ’white zone’). The inner ’white zone’ was almost a precipitation free zone and had high hardness as well as good corrosion resistance. Anodic polarization test results showed that the specimens plasma nitrocarburized with RE addition had good corrosion resistance resulted mainly from their higher corrosion potentials, lower corrosion current densities and larger passive regions as compared with those of the untreated one.     

Influence of crystallization on corrosion resistance of Al86Ni6La6Cu2 amorphous alloy

The influence of crystallization on the corrosion behavior of Al86Ni6La6Cu2 amorphous alloy in 0.01 M NaCl solution was investigated by electrochemical techniques. The Al86Ni6La6Cu2 amorphous alloy was prepared by melt spinning method, and the partially and fully crystallized states were obtained by controlled annealing. The evolution of the crystallization process after annealing was characterized by differential scanning calorimeter （DSC） and X-ray diffraction. The polarization curves revealed that all samples exhibited spontaneous passivation. The fully amorphous Al86Ni6La6Cu2 sample exhibited the best corrosion resistance. Partial and full crystallization resulted in deterioration of corrosion resistance in comparison with that of the as-spun amorphous state.     

固溶参数对热轧Cu-3Si-2Ni合金晶粒长大的影响

研究了固溶温度和保温时间对热轧Cu-3Si-2Ni合金晶粒长大的影响。在875℃固溶处理时,合金晶粒长大缓慢,晶粒长大动力学指数很小,只有0.153。n值随固溶温度的提高而增大。Cu-3Si-2Ni合金在850℃到875℃范围内,保温60min,晶粒均匀长大,晶粒粗化不明显。晶粒长大的表现激活能为Q=80.11kJ/mol,晶粒长大是通过晶界空位扩散的晶界迁移机制;当固溶温度超过875℃,晶粒明显粗化。     

稀土对T91耐热钢动态再结晶行为影响

采用Gleeble-1500热/力模拟试验机进行压缩试验,研究了不同变形条件下微量稀土对T91耐热钢动态再结晶行为的影响.分析绘制了稀土加入前后实验钢的真应力-真应变曲线、再结晶-温度-时间图、再结晶图及功率耗散图,并计算了高温下实验钢的再结晶激活能.在变形温度为850~1100℃,变形速率为0.004~10 s^-1变形条件下,变形温度越高和变形速率越低,动态再结晶越容易发生.稀土加入会产生固溶强化,稀土元素与碳原子发生交互作用,且在晶界处或晶界附近偏聚,使变形抗力与峰值应变均增大,再结晶激活能由354.6 kJ·mol^-1提高到397.2 kJ·mol^-1.另外,稀土会显著推迟再结晶发生时间,扩大再结晶的时间间隔,推迟再结晶动力学过程.     

脉冲电镀Ni镀层参数影响及耐腐蚀机理

用脉冲电流在钕铁硼磁体表面制备Ni镀层;并通过单因素试验依次对脉冲参数进行优化.实验发现当占空比为60％、频率为1000 Hz、电流密度为6 A/dm2时,Ni镀层的耐腐蚀倾向和腐蚀速率最小,Ni镀层耐电化学腐蚀性能较优.观察镀层表面的微观结构发现镀层表面Ni颗粒尺寸更加均匀,镀层表面平整度更高,因此镀层的综合质量更高...     

氯化镧对2024铝合金缝隙腐蚀的缓蚀作用

为了降低2024铝合金在海水中的缝隙腐蚀敏感性,采用浸泡和动电位极化、电化学阻抗等研究了氯化镧(LaCl₃)对该铝合金缝隙腐蚀行为的影响,并通过原子力显微镜对缝隙试样内、外腐蚀产物膜的形貌进行了观察.结果表明:当海水中LaCl₃的质量浓度超过2.0 g·L^-1以后,它能有效地减缓2024铝合金在海水中的缝隙腐蚀.这主要是因为LaCl₃减缓了缝隙的阴极反应速率,降低了缝隙内、外的氧浓度差,且缝隙内、外生成的均匀致密的腐蚀产物膜降低了Cl-侵蚀性,这些因素抑制了缝隙的萌生与扩展,提高了2024铝合金在海水中的抗缝隙腐蚀能力.     

Effect of rare earths on viscosity and thermal expansion of soda-lime-silicate glass

Viscosity of soda-lime-silicate glass doped with rare earth oxides(Pr6O11,Eu2O3,Yb2O3) was investigated by the rotating crucible viscometer,the melting temperature and activation energy for viscous flow of the studied melt were derived on the basis of the Arrhenius Equation,the coefficient of thermal expansion,glass transition temperature and dilatometric softening temperature were also determined with dilatometry,in order to reveal the effects of rare earth elements on the behavior of soda-lime-silicate glass.The results showed that introduction of rare earth oxides decreased the viscosity of soda-lime-silicate glass and melting temperature of corresponding melt,increased coefficient of thermal expansion of soda-lime-silicate glass.The glass transition temperature,dilatometric softening temperature,and melting temperature of soda-lime-silicate glass doped with rare earth oxides increased with increasing cationic field strength of corresponding rare earth ions.