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.     

The Effects of Ce on Hot Corrosion of Iron-based Alloys

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Corrosion protection of magnesium alloys anode by cerium-based anodization coating in magnesium-ait battery

CeN₃O₉·6H₂O(0.5,1.0,1.5,and 2.0 g/L) was added into an 8.0% NaCl electrolyte solution to investigate this electrolyte for use in a Mg-air battery.The effects of the amount of CeN₃O₉-6H₂O on the corrosion resistance of an AZ31 Mg alloy anode and battery performance were investigated using microstructure,electrochemical(dynamic potential polarization method and electrochemical impedance spectroscopy),and battery measurements.The re ...     

稀土Y、Ce对钼合金力学性能的影响

实验以MoO2和Ce(NO3)3.6H2O、Y(NO3)3.6H2O为原料,通过固-液掺杂、还原、烧结、拉伸制备钼合金丝。通过XRD、扫描电镜以及力学性能试验,研究了稀土元素Y、Ce在粉末及钼合金中的存在形式以及对钼合金力学性能的影响。结果表明:Y、Ce元素分别以CeO2和Y2O3形式存在于钼粉中,Y对钼粉颗粒长大的抑制效果高于Ce;钼合金中,稀土Y和Ce作用不同,Y抑制晶粒的长大,延迟烧结;而Ce促进烧结,使烧结完全致密化;钼合金丝中,CeO2质点以纤维状存在,有利于提高钼丝的塑性,而Y2O3质点以球状颗粒存在,钼合金丝的室温和高温抗拉强度较高。Y、Ce的共同作用,MYCe合金丝综合力学性能好。     

Temperature Programmed Reduction Studies on CeO2-Containing Catalysts

Temperature programmed reduction (TPR) study was carried out for CeO2/A12O3 and CeO2/ZrO2 catalysts to evaluate oxygen storage property induced by a facile redox cycling of Ce ion. The CeO2/ZrO2 catalyst possesses excellent oxygen storage activity at 373 K after reduction above 1173 K although the oxygen storage of CeO2/Al2O3 catalyst after reduction above 1173 K is poor because of the formation of CeAlO3. Consequently, the oxygen storage on the CeO2/ZrO2 catalyst smoothly occurs from low temperatures when the catalyst is reduced even at high temperatures.     

Ce对2.9%Si-0.8%Al无取向硅钢夹杂物变质的影响

研究了添加单一稀土元素Ce后2.9%Si-0.8%Al无取向硅钢中夹杂物的变质机理。依据冶金热力学理论计算了Ce添加后,钢液中可能生成的夹杂物种类,分析了各种夹杂物存在的稳定性和相互转化的条件。在此基础上,利用SEM、EDS研究了Ce对无取向硅钢中夹杂物数量、尺寸、形貌及类型的影响。结果表明:适量的Ce显著降低了无取向硅钢中微细夹夹杂物(小于1μm)的数量,增加了粗大夹杂物(2~5μm)数量;Ce使AlN、Al_2O_3等夹杂物变性为球状的CeO_2S_2+AlN、CeS+CeAlO_3和CeS+Al_2O_3等复合夹杂物,有效抑制了钢中MnS的析出。     

Combined influence of Ce(Ⅲ) and iodide ions for corrosion protection of AA 2024-T3 in acidic to neutral chloride-rich environments:Electrochemical and surface characterization studies

It has been reported that trivalent cerium salts are effective inhibitors for corrosion of AA2024-T3 in neutral to alkaline co rrosive enviro nments,but poor in acidic environments.In this study,work was done for extending corrosion resistance provided by Ce(NO₃)₃ to acidic pHs as low as 2.5 through the addition of iodide ions.To this end,potentiodynamic polarization was used to ascertain the optimum Ce(Ⅲ)concentration for the inhibition of AA2024-T3 corrosion in 3.5%NaCl s...     

锌和镀锌钢的稀土表面改性

通过在Ce(NO_3)_3水溶液中对锌和电镀锌钢进行化学转化(钝化)处理,在试样表面形成了铈转化膜。利用电子探针显微分析(EPMA)、X射线光电子能谱(XPS)和X射线衍射(XRD)等研究了转化膜的形貌、成分和结构,探讨了锌表面铈转化膜的形成机理。在氯化钠溶液中测定了试样的腐蚀率、极化曲线和电化学交流阻抗谱(EIS)等腐蚀性能参量,并与未钝化和普通铬酸盐钝化试样的情况作了对比。结果表明,本实验得到的锌表面稀土转化膜主要是由CeO_2、Ce_2O_3和ZnO组成的复合氧化物膜,铈转化膜的存在阻碍了锌在电化学腐蚀过程中的阴极反应和阳极反应,导致电荷传递电阻增大,腐蚀率降低。在一定条件下,铈转化膜对锌和镀锌钢的肪蚀效果优于铬酸盐转化膜。     

5083铝镁合金在不同浓度NaCl溶液中的腐蚀研究

采用扫描电化学显微镜（SECM）中的极化曲线法和交流阻抗图谱法研究5083铝镁合金在不同浓度NaCl溶液中的腐蚀行为,结果表明:合金在中性NaCl溶液中的腐蚀为钝化材料体系,随着盐度的增加,Cl-对合金基体的破坏加剧,腐蚀电位正移,点蚀电位减小,其电化学阻抗谱中仅有1个容抗弧且呈现收缩趋势.同时,阻抗减小,相位角增加,弥散指数降低,合金的耐腐蚀性能下降.溶液中存在强活化作用的Cl-,会损坏合金表面的氧化膜,逐渐取代腐蚀产物Al（OH）₃中的OH-,生成新的腐蚀产物AlCl₃.      

CeO_2对Mo/Al_2O_3复合材料微观结构的影响

采用无压烧结法制备含CeO2的Mo/Al2O3材料,用MM-200型环-块式摩擦磨损试验机测试该材料在滑动干摩擦条件下的磨损行为,通过X射线衍射(XRD)和电子探针对其微观结构和磨损后的形貌进行研究和分析。结果表明,添加CeO2的烧结样品中出现CeAl11O18相,且随CeO2含量(体积分数)增加,CeAl11O18逐渐增多,Al2O3相应减少。当CeO2的体积分数为6%时Al2O3全部由CeAl11O18取代;CeO2的添加使Al2O3和CeAl11O18相边界处均呈现圆钝形貌,并且存在Mo、Al、O的相互扩散区域。磨损形貌表明,1 730℃烧结的样品中出现摩擦转移层,当CeO2含量达到4%时,该摩擦转移层大量出现,从而改善材料的耐磨性。     

Oxidation Resistance of Fe-13Cr Alloy with Micro-Laminated （ZrO2-Y2O3 ） / （Al2O3-Y2O3 ） Films

Oxidationofmetalsoralloysathightemperatures canbetreatedasaspecialcaseofmetalliccorrosion,inwhichsolidphasesinteracteitherwithaliquid agentoragaseousagent.Toimprovetheresistance againsthigh temperatureoxidationandelectrochemical corrosionofmetals,thesurfa…     

Study on Anticorrosive Cerium Conversion Coating of Cf/6061Al Composite Surface

The optimum chemical passivation process of the rare earth metal (REM) conversion coating on the Cf/6061Al composite surface was introduced in this paper and its polarization curves properties were investigated. Ridge-like coatings were found by scanning electro microscope (SEM) observations, and the Al matrix and carbon fibre reinforcement were both coated with Ce conversion coatings, with some minor cracks. The energy dispersive spectroscopy (EDS) plane scan analysis indicates that the major elements in the coating are Ce, O, Si, Al and the Ce content reaches 47.48%(mass fraction). The Ce conversion coatings increase the corrosion resisting properties of Cf/6061Al composite, with a higher free corrosion potential (Ecorr) and a lower free corrosion current density (icorr) for the coated composite than those of the bare composite. And the Boehmite-treatment would enhance the corrosion resistance of the REM conversion coating. The cathodic polarization and anodic polarization were retarded by REM conversion coating, resulting in an improved corrosion resistance.     

二氧化硫复合盐雾环境下2024-T351铝合金应力腐蚀开裂

通过SO₂复合盐雾试验模拟工业污染海洋大气环境,结合有限元模拟分析、扫描电镜/能谱仪、光电子能谱分析等技术研究2024-T351铝合金在弹性应力区间的应力腐蚀开裂行为.结果表明:应力腐蚀开裂行为优先发生在2024-T351铝合金C型环的顶部应力集中区域;疏松的腐蚀产物层的形貌经历了由细棒状、团絮状到板块状的变化;试验6 h就可以监测到裂纹,进行到480 h的时候有贯穿裂纹形成,720 h的时候试样完全断裂;裂纹为穿晶和沿晶混合机制,主裂纹以穿晶机制沿C型环法线扩展,二次裂纹沿晶界扩展.      

Ultraviolet-shielding and conductive double functional films coated on glass substrates by sol-gel process

Ultraviolet-shielding and conductive double functional films were composed of CeO2-TiO2 film and SnO2:Sb film deposited on glass substrates using sol-gel process.Ce(NO3)3·6H2O and Ti(C4H9O4),SnCl4 and SbCl3 were used as precursors of the two different functional films respectively.The CeO2-TiO2 films were deposited on glass substrates by sol-gel dip coating method,and then the SnO2:Sb films with different thickness were deposited on the pre-coated CeO2-TiO2 thin film glass substrates,finally,the substrates coated with double functional films were annealed at different temperatures.The optical and electrical properties of the CeO2-TiO2 films and the double films were measured by UV-Vis spectrometer and four probe resistance measuring instrument.The crystal structures and surface morphology of the films were characterized using XRD and optical microscope,respectively.The obtained results show that the ultraviolet-shielding rate of the glass substrates with CeO2-TiO2 films is not less than 90%,and transmittance in visible lights can reach 65%.With the thickness of the SnO2:Sb film increasing,its conductivity became better,and the surface resistance is about 260 Ω/ when the SnO2:Sb films were deposited 11 cycles of the dip on the pre-coated CeO2-TiO2 glass.The ultraviolet-shielding rate of the glass substrates with double functional films is higher than 97%,and the peak transmittance in the visible lights is 72%.Additionally,with increasing the heat treatment time,the Na+ of the glass substrates diffuses into the films,resulting in the particle size of SnO2 crystal smaller.     

Preparation of Well Dispersed and Ultra-Fine Ce （Zr）O2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.     

SiC_P/2024Al铝基复合材料的腐蚀及防护

用电化学方法研究了 2 0 2 4Al和SiCP/2 0 2 4Al基复合材料在 3 5NaCl水溶液中的耐蚀性 ,用电化学阻抗技术对它们的硫酸阳极氧化膜的耐蚀性进行了研究 .结果表明 ,SiCP/2 0 2 4Al复合材料在3 5 %NaCl水溶液中比相应的基体金属有较大的腐蚀敏感性 .SiCP/2 0 2 4Al的阳极氧化膜具有良好的耐NaCl溶液腐蚀能力 ,但其耐蚀性不如 2 0 2 4Al合金的阳极氧化膜 ,这是由于氧化膜中SiC颗粒的存在破坏了氧化膜的完整性和均匀性所致     

Preparation and characterization of Ce1-xFexO2 complex oxides and its catalytic activity for methane selective oxidation

A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.402 exhibited the best activity, which converted 94.52% of CH4 at 900 ℃.     

Pitting corrosion behavior of cerium treated HSLA steel induced by sulfide inclusions in 3.5 wt% NaCl solution

Pitting corrosion behavior of Ce treated HSLA steels induced by sulfide inclusions in 3.5 wt% NaCl solution was investigated with potentiodynamic polarization and immersion corrosion test.The results show that Ce added steels exhibit better pitting corrosion resistance with lower corrosion current density and bigger pitting potential compared with steel without Ce,which is mainly attributed to optimized characteristics of spherical Ce-oxysulfide inclusions with less number density,smaller average size and lower pitting corrosion susceptibility.The spherical Ce₂O₂ S inclusions precipitated on the surface of CeAlO₃ inclusions in the Ce added steels induce pits with bigger opening mouth and shallow depth,reducing their tendency of extension to go deeper due to occlusion corrosion battery in the pitting holes.Furthermore,corrosion inhibitor Ce(OH)₃ generated by Ce₂O₂ S hydration can weaken electrochemical corrosion of the matrix micro-region around the pits.To avoid harmful bigger inclusions,Ce content in steels should be regulated within reasonable range,0.015 wt% Ce in present steels effectively modified inclusions to acquire the best pitting corrosion resistance of the steels.     

含锶钪2099型铝锂合金的晶间腐蚀和剥落腐蚀性能

采用维氏硬度计(HV)、金相显微镜(OM)和扫描电镜(SEM)显微分析技术,研究了一种锶钪复合微合金化2099型铝锂合金(其化学成分为:Al-2.57Cu-1.86Li-1.31Zn-0.420Mg-0.321Mn-0.0735Zr-0.0943Sr-0.0433Sc)的晶间腐蚀性能和剥落腐蚀性能。结果表明,该合金经均匀化退火处理(475℃×24 h)、热锻压变形加工处理(三次变形量均约为100%)、固溶处理(540℃×2 h)、冷水淬火(水温大约5℃)、T8时效处理(121℃×14 h+151℃×48 h)后,合金显微硬度值达到174.6 HV,比2024-T6合金(固溶处理500℃×2 h+时效处理191℃×12 h)高23.1%。合金具有良好的抗晶间腐蚀性能和抗剥落腐蚀性能,其抗腐蚀性能明显优于2024-T6合金。该合金Sr,Zr,Sc的复合微合金化作用(细化粗大第二相、抑制再结晶和晶粒长大),第二相分散、分布不连续,以及Zn的含量高,是合金抗腐蚀性能高的主要原因。研究结果还说明了微量复合添加对铝锂合金具有奇效微合金化作用的过渡族金属元素Sr,Sc,是得到抗腐蚀性能良好的铝锂合金的一种有效途径。     

Corrosion behavior of Ce-doped Ni-10Cu-11Fe-6Al (wt%) inert anode in molten CaCl2 salt

In this research the effect of cerium dopingon corrosion behavior of Ni-10 Cu-11 Fe-6 Al(wt%) alloy as a novel inert anode in titanium electrolytic production was investigated. The samples, including un-doped and Ce-doped nickel-based alloys, were prepared using vacuum induction melting(VIM) process and then exposed to the electrolysis in molten calcium chloride at 900C at à1.6 V versus graphite reference electrode for different immersion time. The surface and cross-section of the samples were characterized using scanning electron microscopy(SEM), and their electrochemical behavior was investigated by electrochemical impedance spectroscopy(EIS). The results show that the un-doped samples have greater number of voids and porosities as compared to that of the 0.0064 wt% Ce-doped samples(as the optimum content of cerium in the alloy). Thus, the nickel-based alloy becomes less sensitive to the pitting by addition of cerium. The corrosion penetration depth reaches about 244 mm after 16 h of electrolysis in the un-doped sample, while was approximately 103 mm for the 0.0064 wt% Ce-doped sample, which is an indication that the corrosion penetration depth decreases by adding small amounts of Ce.