Modifying Behaviors of Ultrasonic Irradiation and Rare Earth Metal Cerium on Electroless Co-Ni-B Alloy Coating

By plasma transmitting spectrograph,electron energy spectrometry,X-ray diffractometry,transmission electron microscopy and micro-hardometry,the effects of ultrasonic irradiation and rare earth metal cerium on the depositing speed,chemical composition,crystal structure and microhardness of electroless Co-Ni-B alloy coating were inspected and analyzed. The results show that cerium and ultrasonic irradiation can evidently raise the depositing speed of electroless Co-Ni-B alloy. The cerium content of electroless Co-Ni-B-Ce alloy coating also increases after ultrasonic irradiation applied to electroless Co-Ni-B plating process. Under the action of ultrasonic irradiation and rare metal cerium,the chemical composition of electroless Co-Ni-B alloy coating is changed. Electroless Co-Ni-B alloy with amorphous structure is transformed to electroless Co-Ni-B-Ce alloy with microcrystalline in general state and electroless Co-Ni-B-Ce alloy with crystalline structure in ultrasonic irradiation. In this way microhardness of the coatings increases remarkably.

Addition of cerium and yttrium to ferritic steel weld metal to improve hydrogen trapping efficiency

The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.

二氧化铈对熔敷金属氢致塑性损失的影响及其机理研究

针对X80管线钢,设计了金属粉型药芯焊丝的药粉成分,在金属粉中加入了二氧化铈,进行熔敷金属堆焊试验和电化学充氢后的拉伸试验,研究焊材中加入二氧化铈对熔敷金属抗氢脆性能的影响,同时通过氢渗透试验研究了二氧化铈的添加对氢在熔敷金属中扩散的影响.结果表明,熔敷金属的显微组织主要由针状铁素体和晶界铁素体构成.二氧化铈的添加对熔敷金属的夹杂物有显著影响,导致其平均尺寸减小、数量密度增加.加入2%的二氧化铈后,夹杂物的平均尺寸由0.349μm减小至0.258μm,夹杂物数量密度由21429mm^(-2)增加至32254mm^(-2).氢渗透试验结果表明,添加二氧化铈可增加熔敷金属的氢陷阱数目,阻碍氢在熔敷金属中的扩散,这导致熔敷金属抗氢脆性能的提升.因此,熔敷金属的氢致塑性损失率由72%降低至50%.对于充氢拉伸断口形貌,未加入二氧化铈的断口为河流花样的准解理断裂样貌,属于典型的脆性断裂特征.加入二氧化铈的断口有大量韧窝,具有韧性断口特征,但出现明显的鱼眼区.鱼眼区内的源区存在夹杂物或气孔,放射区则呈现准解理断裂.

含铈纳米防腐涂层在金属防护中的研究进展

为了提高常规防腐涂层的防护效果与使用寿命,研究人员致力于开发新型纳米复合材料涂层。含铈化合物是一种高效的金属及合金缓蚀剂,将含铈化合物与常规涂层结合构建含铈纳米防腐涂层越来越受到研究人员的重视。目前,将含铈纳米防腐涂层分为含铈纳米防腐涂层、含铈纳米容器涂层和含铈自愈合纳米防腐涂层3大类,针对具体的制备方法及材料,又将其分为7个小类。介绍了每类代表性涂层的主要制备方法、结构及应用效果,阐明了铈在防护过程中的主要作用过程及机理,总结了其中的共性特点。面对当前含铈纳米涂层大规模应用存在的困难及挑战,提出相应的解决方法及思路,并对未来发展方向进行了展望。

磷酸改性CeO_(2)纳米棒负载Pt催化剂催化丙烷燃烧性能的研究

机动车和石油化工等污染源排放造成的环境污染日益严重,其中以丙烷为代表的低碳烷烃结构稳定,难以实现低温完全氧化,亟需开发高效低碳烷烃低温催化氧化催化剂。以氧化铈纳米棒为载体,通过酸改性合成不同量磷酸改性的1%Pt/CeO_(2)-y POx催化剂,发现磷酸改性之后丙烷催化燃烧T_(50)降低了60℃。通过XRD、TEM、EDS mapping等表征发现Pt和P均匀分布在氧化铈表面,且在磷酸改性和Pt负载过程后,氧化铈结构保持稳定。XPS和原位CO-DRIFTs表征结果表明磷酸改性之后,Pt在催化剂表面颗粒大小随磷酸改性程度增加而逐渐变大,并存在最优的Pt^(2+)和Pt^(4+)比,有利于丙烷在催化剂表面吸附和反应。H_(2)-TPR和NH_(3)-TPD表征结果表明,磷酸改性之后,催化剂表面产生了大量的酸性位,而磷酸改性并未大幅降低催化剂的氧化还原能力,从而提高了铈基催化剂的丙烷燃烧活性。

Influence of silane coupling agent on the conversion film forming of galvanized steel treated with cerium salt

The influence of silane coupling agent on the film forming of galvanized steel treated with cerium salt was studied by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）, and the corrosion resistance of conversion films was analyzed by electro interstitial scanning （EIS）. The results show that silane coupling agent KH-570 has significant influence on the compactness and homogeneity of cerium conversion films, and the process of film forming is promoted by increasing the content of tervalent and tetravalent cerium oxide. The impedance value of the cerium conversion film, especially modified with KH-570, is greater than that of the base metal, which reveals that it is necessary to add silane coupling agent to the film-forming solution in order to improve the corrosion resistance of the conversion film.

Study on Ignition Proof AZ91D Magnesium Alloy Chips with Cerium Addition

The effect of Ce on ignition point of AZ91D magnesium alloy chips was studied. For the AZ91D and the AZ91D-xCe magnesium alloys, changing the sizes of the chips in the range of 58 - 270 μm has a limited influence on ignition point, however, the shift of the content of Ce has much effect on ignition point. Increasing the Ce content, x from 0.15 to 0.25, the ignition point increases with increasing of Ce; however, x from 0.25 to 0.45, the ignition point decreases with increasing of Ce. By the addition of Ce of 0.25 %. the ignition point is raised by 43℃.

Saturation phenomenon of Ce and Ti in the modification of Al–Zn–Si filler metal

Cerium and titanium were added to an A1-42Zn-5.5Si brazing alloy, and the subsequent microstructures of the brazing alloy and the 6061 AI alloy brazing seam were investigated. The microstructures of filler metals and brazed joints were characterized by scanning elec- tron microscopy and X-ray energy dispersion spectrometry. A new Ce-Ti phase formed around the silicon phase in the modified filler metal and this saturation phenomenon was analyzed. Interestingly, following brazing of the 6061 alloy, there is no evidence of the Ce--Ti phase in the brazing seam. Because of the mutual solubility of the brazing alloy and base metal, the quantity of the solvent increases, and the solute Ce and Ti atoms assume an undersaturated state.

Effect of Ce-rich misch metal addition on squeeze cast microstructure and mechanical properties of AZ81 alloy

The effect of cerium-rich misch metal addition on the microstructure and properties of squeeze cast magnesium alloys AZ81 was empirically investigated.The results indicate that the addition of cerium-rich misch metal modifies the microstructure gradually.With the increase of the RE addition,the amount of Mg_(17)Al_(12) decreases while that of Al_(11)(RE)_3 increases,accompanied by grain refinement.When the addition reaches 1.5%,the grain refinement becomes obvious.However,when the addition exceeds 2.0%, Al_(11)(RE)_3 phase coarsens into rod shape and the grain size increases.The tensile properties of the AZ81 at both room temperature and 150℃increase with the addition,and reach their optimal values with the addition of 1.5%.Further increase of the addition to above 2.0%decreases the tensile properties considerably.The tensile fracture of the alloy is characterized by the cleavage of the brittle second phases and ductile dimples of the matrix.

Structural Characterizations for Glass Ionomer Cement Doped with Transition Metal Phthalocyanines

Glass and Glass iomomer cement (GICs) based on a specific composition of cerium phosphate glass (40 CeO2-60P2O5) have been prepared. Effect of the doping type at a fixed doping concentration from metal-phthalocyanines (M-PCs) on material structure and morphologies has been carefully studied. The corresponding changes in the material structure were widely followed up by?31P MAS NMR, X-Ray diffraction and FTIR spectroscopy. The network structure of both base glass and GIC which all free from metal phthalocyanines has been confirmed to be amorphous. GIC doped with M-PCs has shown a more ordered structure. There were clear changes in the position and intensities of?31P NMR spectral peaks of glasses upon changing the dopant type. In all cases, a little concentration from M-Phthalocyanine (0.8 mol%) leads to changing the network structure from amorphous to a more ordered structure. Phosphate structural phases are evidenced to be formed upon addition of a fixed amount of M-PCs (Ga, Co, Fe). The morphologies of some selected samples were characterized by SEM. The micrographs have revealed that formulating of cerium phosphate powder of the amorphous glass with a polymeric acid successfully led to the formation of CePO4-H2O bundles phases. But formulation with GIC containing Co or Fe or Ga Phthalocyanine can simply form co-aligned linear slaps and elongated nanofibers which are consisted of hydrated and carbonated CePO4?a GaPO4, FePO4?or CoPO4?crystals. The structure of all doped materials has a lower crack length than that of base glass. This was discussed on bases of formation of more aligned and elongated tough-fibers in matrix of all doped materials. Such tough fibers have ability to withstand breaking stress via suppressing crack propagation.

Preparation of Cerium Doped Cu/MIL-53(A1) Catalyst and Its Catalytic Activity in CO Oxidation Reaction

Metal-organic framework（MOF） material MIL-53（A1） with high thermal stability was prepared by a solvothermal method,serving as a support material of cerium doped copper catalyst（Ce-Cu）/MIL-53（A1） material for CO oxidation with high catalytic activity.The catalytic performance between the（CuCe）/MIL-53（A1） and the Cu/MIL-53（A1） catalytic material was compared to understand the catalytic behavior of the catalysts.The catalysts were characterized by thermogravimetric-differential scanning calorimetry（TGDSC）,N2 adsorption- desorption,X-ray diffraction（XRD）,and transmission electron microscopy（TEM）.The characterization results showed that MIL-53（A1） had good stability and high surface areas,the（Ce-Cu）nanoparticles on the MIL-53（A1） support was uniform.Therefore,the heterogeneous catalytic composite materials（Ce-Cu）/MIL-53（A1） catalyst exhibited much higher activity than that of the Cu/MIL- 53（A1） catalyst in CO oxidation test,with 100%conversion at 80 ℃.The results reveal that（Cu-Ce）/MIL-53（A1） is the suitable candidate for achieving low temperature and higher activity CO oxidation catalyst of MOFs.

阳离子树脂基铁锰铈吸附剂的制备及其去除水中铅、铬的性能研究

为了获得去除重金属离子Pb^(2+)和Cr^(6+)的特异性强、易回收的高性能吸附剂,通过将铁锰铈金属氧化物(Fe-Mn-Ce)负载到强酸性阳离子树脂(D001)上,成功制备了树脂基铁锰铈吸附剂(Fe-Mn-Ce@D001)。研究了吸附剂对水中Pb^(2+)、Cr^(6+)的去除性能,考察了不同因素对Pb^(2+)、Cr^(6+)去除率的影响,同时进行吸附动力学以及吸附热力学实验,探讨其吸附规律。实验结果表明:在温度为298K、pH=5、投加量为0.01g时,Fe-Mn-Ce@D001对Pb^(2+)和Cr^(6+)的饱和吸附容量分别为528.06mg/g和218.33mg/g,优于原树脂D001。Fe-Mn-Ce@D001树脂比D001对Pb^(2+)和Cr^(6+)具有更高的吸附选择性,在高浓度Ca^(2+)、Mg^(2+)、NO_(3)^(-)、SO_(4)^(2-)等离子共存的条件下仍保持较高的去除率;在Pb^(2+)和Cr^(6+)混合溶液中比D001具有更好的同步吸附性能;相对于D001具备更好地重复利用性。Fe-Mn-Ce@D001对Pb^(2+)和Cr^(6+)的吸附等温模型均符合Langmuir模型,吸附动力学行为与准一级动力学和准二级动力学均能很好的相符。

基于多金属掺杂的氧化铈阳极的甲烷协助电解水制氢研究

采用甲烷协助电解水制氢可以显著降低固体氧化物电解池制氢电耗。从甲烷氧化活性和氧离子传导性的角度出发,采用一锅水解法制备了氧化锆和氧化钐掺杂的氧化铈阳极材料(Sm_(0.1)Zr_(0.1)Ce_(0.8)O_(2-x)),并同时一锅负载Ni、Co和Fe活性金属。结果表明钐和锆的掺杂显著提高氧化铈的氧化活性,而Ni金属负载可以使甲烷完全转化温度降低75℃,良好的甲烷氧化活性可以实现甲烷气氛下更低的电解电压。不同负载金属的结果表明,具有良好甲烷氧化活性的Ni、Co负载Sm_(0.1)Zr_(0.1)Ce_(0.8)O_(2-x)在不同电流密度下均体现出甲烷协助电解水性能,低的欧姆阻抗和高频极化阻抗使Co负载的阳极具有更高的性能,电解电压低至0.37 V@250 mA/cm^(2);缺乏甲烷氧化活性的Fe负载Sm_(0.1)Zr_(0.1)Ce_(0.8)O_(2-x)具有良好的析氧性能,但缺乏甲烷辅助性能。具有甲烷氧化活性性能是实现甲烷协助电解水制氢的关键。

Ce-O和Fe-Ce-O催化剂的固相合成及其CH_4催化燃烧性能

以(NH4)2Ce(NO3)6为原料,选用葡萄糖为络合剂,采用研磨固相法制备了在不同温度下焙烧的氧化铈(Ce-O)和掺杂铁的氧化铈(Fe-Ce-O)催化剂。用X射线衍射法表征了催化剂的结构;用程序升温还原法测试了催化剂的还原性能;考察了经不同温度焙烧后,掺杂铁对Ce-O催化剂的CH4催化燃烧活性的影响。实验结果表明,掺杂铁后的Fe-Ce-O催化剂的粒径变小、还原性能增强、CH4催化燃烧活性提高。经400℃焙烧的Fe-Ce-O催化剂呈现单一的CeO2物相,属立方晶系;经800℃和 1 200℃焙烧的Fe-Ce-O催化剂以CeO2为主要物相,并有少量Fe2O3物相。与未掺杂铁的Ce-O催化剂相比,Fe-Ce-O催化剂具有较高的CH4催化燃烧活性。

稀土Ce对化学镀Co-Fe-B合金层组织结构的影响

利用等离子发射光谱仪、电子能谱仪、X 射线衍射仪、透射电子显微镜等 ,考察引入稀土金属Ce后化学镀Co Fe B合金镀层的化学成分和晶体结构。结果表明 ,随镀液中稀土金属Ce添加量的增加 ,镀层中Ce的含量先增后降 ,在Ce =1 0g/L时达到最大值。Ce的介入使化学镀Co Fe B Ce合金镀层中B含量减少 ,Co和Fe含量增加 ,并使非晶态结构的合金镀层转化为微晶态结构。

磁场和稀土Ce介入下化学镀Co-Ni-B合金的晶化行为

利用恒电位仪、等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜等研究了在常态和磁场条件下化学镀Co Ni B Ce合金的电化学性质、化学组成和组织结构。结果表明 ,微量稀土和磁场的介入改善了化学镀Co Ni B合金的静止电位和极化度 ;随镀液里稀土金属Ce量的增加 ,化学镀Co Ni B Ce合金镀层中的Ce含量是先增加后下降 ,均在Ce的质量浓度为 0 8g/L时达到最大值。在磁场和稀土铈的作用下 ,化学镀Co Ni B Ce合金镀层中B的含量减少 ,Co和Ni的含量增加 ,因而在常态下非晶态的Co Ni B镀层转变成了微晶结构的Co Ni B Ce镀层 ,在磁场条件下含稀土Ce的镀层则发生了晶化转变。

超声波和稀土铈对化学镀Co-Ni-B合金镀层的改性作用

利用等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜和显微硬度计等考察和分析了引入超声波和稀土金属铈时化学镀Co Ni B合金镀液的沉积速度、Co Ni B合金镀层的化学成分、晶体结构和显微硬度。结果表明 ,超声波和稀土金属铈的介入明显提高了化学镀Co Ni B合金的沉积速度 ,超声波的介入则提高了化学镀Co Ni B Ce合金镀层中稀土铈的含量。在超声波和稀土铈的共同作用下 ,化学镀Co Ni B合金镀层的化学组成发生了改变 ,镀层结构由非晶态向微晶和晶态转化 。

铈对高Cu/Mg比率Al-Cu-Mg合金组织和耐热性能的影响

采用拉伸测试和透射电镜(TEM),研究了微量Ce对高Cu Mg比率的Al Cu Mg合金组织和耐热性能的影响。结果表明,添加0.20%Ce后,在室温到350℃测试范围内,合金的室温拉伸强度和高温耐热性能得到了提高。透射电镜分析表明,合金中的主要强化相为{111}型Ω相和少量的θ′相,添加微量Ce能细化合金中的强化相,提高强化相的高温热稳定性。

脉冲熔融-红外吸收法测定镧铈合金中氧

为满足国内稀土钢研制的需要,与镧、铈及镧铈合金提纯研究同步,逐步建立脉冲熔融-红外吸收法对镧铈合金中杂质氧的测定方法。考察了称样量、分析功率、不同(助熔)浴料对分析结果的影响。找出熔体平滑、峰形好的最佳分析功率4200W,称样范围为0.10~0.20g。从助熔剂法和浴料法中筛选并确定Cu-Sn-Fe-Ni四元浴,自制配方比例为3∶3∶1∶1(质量比);尝试“样品与标样间隔投样校正法”定量评估和抵消仪器(被污染)产生的干扰。实测范例显示:目前国内镧铈合金样品中氧质量分数可低至0.00679%;相对标准偏差(RSD,n=7)为5.5%。以钢中氧标准样品GBW(E)020143进行加标回收试验,回收率为101%~105%;另通过与辉光放电质谱法方法对比,一致性较好。

添加稀土对铜的性能和组织的影响

分别研究在真空和空气条件下熔炼“铈-钢”“混合稀土钢”合金的拉伸强度、硬度、电阻率和显微组织与组成的关系。实验结果表明:添加稀土可去除铜中杂质、细化。在真空熔炼条件下,添加稀土能显著提高铜的导电率。但在空气条件下,当稀土添加量超过0.05％wt后,导电率下降。铈与混合稀土均能提高铜的拉伸强度和硬度。