Creep behavior of SnAgCu solders with rare earth Ce doping

Extensive testing was carried out to study the effects of rare earth Ce doping on the properties of SnAgCu solder alloys.The addition of 0.03%(mass fraction) rare earth Ce into SnAgCu solder may improve its mechanical properties,but slightly lower its melting temperature.The tensile creep behavior of bulk SnAgCuCe solders was reported and compared with SnAgCu solders.It is found that SnAgCuCe solders show higher creep resistance than SnAgCu alloys.Moreover,Dorn model and Garofalo model are successfully used to describe the creep behavior of SnAgCu and SnAgCuCe alloys.The parameters of the two creep constitutive equations for SnAgCu and SnAgCuCe solders are determined from separated constitutive relations and experimental results.Nonlinear least-squares fitting is selected to determine the model constants.The experimental data of the stress-creep strain rate curves are in good agreement with the theoretical ones.

Rare earth Ce-modified (Ti,Ce)/a-C:H carbon-based film on WC cemented carbide substrate

WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified（Ti,Ce）/a-C：H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties,and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO2 that exists with the amorphous phase in the co-doped（Ti,Ce）/a-C：H carbon-based film. The mechanical properties of this（Ti,Ce）/a-C：H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C：H film. In particular, the as-prepared（Ti,Ce）/a-C：H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water,indicating that（Ti,Ce）/a-C：H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.

La-Ce稀土对Q345D钢夹杂物和冲击性能的影响

通过现场试验,分析了La-Ce稀土处理对Q345D结构钢夹杂物、连铸可浇性和钢种性能的影响。结果表明,RE在Q345D结构钢中的合金收得率为21.5%;与未添加RE的炉次相比,脱硫率提高了37.5%,单位夹杂物密度从80.16个/mm^(2),降低至60.78个/mm^(2);La-Ce稀土处理前钢液中夹杂物主要是MgO-Al_(2)O_(3)-CaO复合夹杂,La-Ce稀土处理对小尺寸(D≤5μm)夹杂物的改性作用较为明显,小尺寸夹杂物改性为(La-Ce-S)和(La-Ce-Al-S-O)稀土类夹杂物;La-Ce稀土处理可以明显降低钢中MnS类夹杂物的纵横比,使MnS类夹杂物在轧制后的形貌更接近椭圆形,而没有长线形,这是Q345D结构钢横向冲击功提高20%的主要原因。

稀土Ce对DH36船板钢显微组织及耐腐蚀性能的影响研究

针对稀土对钢耐腐蚀性的影响规律及稀土夹杂对船板钢的局部腐蚀机理的研究不足,采用金相显微镜、扫描电子显微镜、激光共聚焦显微镜、电化学工作站研究了在3.5%NaCl溶液中稀土Ce含量对DH36船板钢显微组织和耐腐蚀性能的影响。结果表明,稀土Ce可以细化试验钢的晶粒尺寸,同时降低试验钢的珠光体片层间距。稀土Ce的加入将试验钢中的MnS和Al_(2)O_(3)+MnS夹杂转变为MnS+CeAlO_(3)、Mn-Al-O-Ce、Mn-S-Al-O-Ce夹杂。相比于未添加Ce和添加0.001 0%Ce的试验钢而言,Ce含量为0.009 2%时试验钢的腐蚀速率最低,团絮状腐蚀产物最少,腐蚀坑的尺寸与数量最小,表面粗糙程度较小,且初期仍具有金属光泽;稀土Ce的加入使得试验钢的腐蚀电位升高,腐蚀电流密度降低。腐蚀时间为5 d时,Ce含量为0.009 2%时试验钢的腐蚀电流密度最低(2.225×10^(-5 )A/cm^(2)),腐蚀电压最高(-1.057 V),耐腐蚀性能最佳。

Ce对DH36船板钢显微组织和力学性能的影响

为探究稀土Ce对DH36船板钢显微组织和力学性能的影响,采用真空感应炉熔炼不同Ce含量的DH36船板钢,利用场发射扫描电镜、显微硬度计、冲击试验机、电子万能试验机等设备研究了Ce对DH36船板钢组织、硬度、冲击性能、拉伸性能的影响。结果显示:在DH36船板钢中加入Ce使铁素体和珠光体组织细化。含0.009%Ce的试验钢综合力学性能最好,硬度增幅最大,相比未加Ce的试验钢提升15.6%;抗拉强度由未添加Ce的581.97 MPa提升到643.80 MPa,提升10.6%;冲击功由未添加Ce的162.8 J提升到174.5 J,提升7.2%。加入稀土Ce后,试验钢的拉伸断口和冲击断口形貌得到改善,韧窝数量增多,断口表面的夹杂物类型发生改变,由大尺寸不规则夹杂物变成了小尺寸类球状稀土夹杂物,降低了有害夹杂物引起的应力集中,使断口表面的裂纹源明显减少。

稀土Ce变质对ADC12铝合金组织及力学性能的影响

采用光学显微镜、扫描电镜、拉伸试验机及布氏硬度计研究了稀土Ce改性处理对ADC12铝合金微观组织及力学性能的影响。结果表明:当加入质量分数为0.6%的稀土Ce时,组织中粗大的初生α-Al相变得圆整、细小且分布均匀,共晶Si相由针片状变为颗粒状。稀土Ce与合金中的Al元素发生共晶反应生成Al11Ce3等金属间化合物,在扫描电镜下化合物形状为长条针状,并呈亮白色。添加质量分数为0.6%Ce有效提高了合金的屈服强度、抗拉强度和伸长率,分别达到171.72、260.37 MPa和4.1%,与未添加Ce元素的合金相比分别提升了33.83%、48.69%和155%,与此同时,合金的布氏硬度也达到峰值,为88 HB。

富Ce稀土对多元Al-Si活塞合金凝固组织的影响

采用DSC以及光学显微镜与扫描电镜研究了富Ce稀土(0.1wt%,0.3wt%,0.5wt%)对多元近共晶Al-11.5Si-4Cu-2Ni-1Mg-0.5Fe(wt%)活塞合金凝固组织的影响。发现富Ce稀土加入对该合金的共晶硅和多种第二相的凝固温度、形态与体积分数均有明显影响。富Ce稀土的加入,使Al-Si共晶温度降低,T-Al_(9)FeNi相和δ-Al_(3)CuNi相析出温度升高。富Ce稀土加入量0.3wt%时,共晶硅变质效果最佳,T-Al_(9)FeNi相由初始的板条状转变为小块状,体积分数减小到3.22vol%,δ-Al_(3)CuNi相由初始的片状转化为鱼骨状,体积分数增加到6.47vol%。富Ce稀土中La、Ce原子在凝固过程中富集在固液界面前沿,增大了成分过冷,细化共晶组织。当富Ce稀土含量为0.5wt%时,合金中出现长针状富稀土相。

稀土Ce变质ZK60变形镁合金的微观组织及其机制研究

在ZK60变形镁合金基体中加入了不同质量分数的稀土元素Ce。借助金相、SEM、EDS、XRD研究稀土Ce变质ZK60变形镁合金微观组织演变,探讨变质机理。结果表明,当Ce从0%增加到0.9wt%时,合金晶粒尺寸逐渐减小,尺寸由88μm减小到51μm,抗拉强度由104 MPa增加到160 MPa,伸长率从6%增加到7%;当Ce增加到1.2wt%时,晶粒尺寸反而增大到61μm,出现过变质现象;MgZn2可作为α-Mg的异质形核核心;Ce、Mg与Zn结合成Mg42Zn53Ce5化合物钉扎在晶界处,有利于减小晶粒尺寸。

稀土Ce对2A12铝合金耐蚀性的影响

通过室内周期浸润腐蚀实验方法,研究了稀土Ce对2A12铝合金在含Cl-海洋大气模拟环境中的腐蚀行为。采用蔡司显微镜观察了铸态金相组织,用能量色散谱仪(EDS)分析了腐蚀产物元素组成。采用失重法分析了2A12铝合金腐蚀动力学规律,采用电化学极化曲线分析了2A12铝合金腐蚀后的电化学行为。结果表明,稀土的加入使得2A12铝合金的均匀性得到改善,腐蚀速率明显减小,腐蚀电流密度降低,腐蚀电压增加。稀土Ce的加入使得2A12铝合金锈层更致密而导致铝合金基体表面的电化学反应缓慢。

微量Ce添加对Al-Si-Fe铝合金微观组织及导热性能的影响

随着汽车零部件、通讯和电子产品的发展,其对铝合金的导热性能提出更高的需求,因此急需开发新型高强韧高导热铝合金材料。通过金相显微镜、扫描电镜、涡流电导率仪和万能力学性能测试仪等研究了微量Ce添加对Al-Si-Fe铝合金的微观组织、导电导热性能以及力学性能的影响。结果表明,稀土Ce添加量少于0.05%时对组织没有明显细化,0.07%Ce可以细化铝合金的微观组织,减少二次枝晶臂间距,初生α-Al相由粗大的枝状晶转化成胞状晶。当Ce含量为0.07%时,合金中出现亮白色的块状Al11Ce3相和灰白色针片状β-Al5FeSi相。稀土Ce元素的添加能提高合金的导电和导热性能,当添加0.07%Ce时,合金的导电率和导热率达到最佳值,导电率为36.6%IACS,导热率为153.97 W/(m·K)。随着微量稀土Ce元素的添加,合金的抗拉强度与屈服强度整体变化不大,抗拉强度为144.5 MPa,屈服强度为89.7 MPa,但伸长率有所提升。当添加0.07%Ce时,合金伸长率为4.54%,比未添加Ce时提升26.1%,这是由于微量Ce没有对组织产生足够的细化效果来提高强度,而使共晶Si和富铁相变质与细化,故提高了合金的伸长率。

Effect of Ce-rich rare earth on microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy

To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy,different amount of Ce-rich rare earth(RE)was added to the alloy,and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy(SEM),energy dispersive spectroscope(EDS)and X-ray diffraction(XRD).The results show that an appropriate amount of Ce-rich rare earth addition can make the Al4Ce phase particles and CeSb phase disperse more evenly in the alloy.These phases refine the alloy's matrix and make the secondary phases[?-Mg 32 (Al,Zn)49 phase and?-Al 2 Mg5Zn2 phase]finer and more dispersive,therefore significantly improve the mechanical properties of the Mg-10Zn-5Al-0.1Sb alloy.When the RE addition is 1.0 wt.%,the tensile strengths of the alloy both at room temperature and 150oC reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy.The hardness increases with the increase of RE addition.

铜结晶器表面双脉冲共沉积制备Co-Ni-Ce防护镀层

为了提高铜结晶器的防护能力,延长其使用寿命,本文利用双脉冲在氨基磺酸体系下共沉积制备Co-Ni-Ce防护镀层,研究Co(SO_(3)NH_(2))2·4H_(2)O质量浓度、脉冲电流密度、电信号控制以及CeCl_(3)·7H_(2)O质量浓度等工艺参数对镀层硬度的影响。实验结果表明,最优工艺参数为Co(SO_(3)NH_(2))2·4H_(2)O质量浓度33.3 g/L,脉冲电流密度4 A/dm^(2),占空比40%,脉冲频率20 kHz,CeCl_(3)·7H_(2)O质量浓度2 g/L;硬度达到559.01 HV;Co-Ni-Ce镀层形貌致密,晶粒分布均匀。添加Ce以后,合金衍射峰择优取向由(111)向(200)转变,无金属单质相生成。

Distribution of rare earth elements of granitic regolith under the influence of climate

The distribution and anomalies of rare earth elements(REEs) of granitic regolith were studied in Inner Mongolia and Hainan Island, China. One profile showed slight REE enrichment of an upper layer and no obvious light REE/heavy REE(LREE/HREE) fractionation(La_N/Yb_N of 0.9). The second profile was significantly enriched in REEs and enriched in LREEs in the upper portion(La_N/Yb_N>1.8). Eu, Ce, and Gd anomalies of the two profiles are different. Slightly negative Eu, Ce, and Gd anomalies in NMG-3-1 indicate slow dissolution of primary minerals and little secondary products; in contrast, a positive Eu anomaly in HN-2 suggests the vegetation cycle may contribute to soil. The Ce anomaly of HN-2 reflects oxidation of Ce and coprecipitation by Fe-and Mn-oxides and organic matter. Correlation between Ce and Gd anomalies in HN-2 suggests Ce and Gd are both influenced by redoxreduction.

稀土Ce对铝硅合金组织、力学及耐腐蚀性能的影响

研究熔铸工艺条件下制备的不同稀土铈含量(w(Ce)分别为0%、0.3%、0.6%和0.9%)的Al-Si合金微观组织、力学性能及耐腐蚀性能。研究结果表明:稀土Ce的添加极大的优化了Al-Si合金的微观结构,α-Al枝晶明显被细化,枝晶变得十分圆整且规则。共晶Si相也变得非常细小,颗粒状的共晶Si相边缘圆润,且排布有序。随着稀土Ce添加量的逐渐增大,Al-Si合金的拉伸性能及显微硬度均逐渐增大,当稀土Ce的含量为0.6%时,合金的抗拉强度、伸长率及显微硬度达到峰值,分别为228.96 MPa、5.1%和109.5 HV,比未添加稀土Ce的合金分别提高了24.59%、54.55%和40.74%。并且此时合金的抗腐蚀性能达到最佳,通过浸泡测试可知合金的失重腐蚀速率仅为11.36 mg/(cm^(2)·d),相比于未变质的Al-Si合金基体降低了50%。

New Advances in Structural Studies of Barium Rare-Earth Fluor-Carbonate Minerals

This paper summarizes the new developments in the study of barium rare-earth fluor-carbonate mineral structures .The second order superstructure of cebaite -(Ce ) was solved by using high power X-ray single crystal diffractometer . Five kinds of coordination forms were found . All atoms in the cell , including C and F , were properly located . In the process of study in a cordylite-(Ce ), a new mineral was discovered , whose chemical formula is (Ca0.5□0.5) BaCe2 (CO3)4F . It is isostructural with baiyuneboite - (Ce ), but different in composition (Na in baiyuneboite- (Ce ) is substituted by Ca disorderly ) . On the basis of the studies a proposal to re-define cordylite-(Ce )as a mineral group name is put forth by the authors . Finally a new type of twinning of huanghoite-(Ce ) was found on the systematical absence of diffraction data by means of a single crystal diffractometer .

湿法制备Cu基Mn-Ce改性甲醇重整制氢催化剂及其催化性能研究

为了提升Cu基催化剂的高温稳定性和使用寿命,并研究过渡金属Mn及轻稀土金属Ce对Cu基甲醇重整催化剂的影响,本文采用新型湿法制备了Cu基Mn-Ce改性催化剂,并在气-固相固定床催化反应装置上评价了其甲醇重整制氢的性能。甲醇转化实验结果显示,Cu基Mn-Ce改性催化剂的甲醇转化率达到98.77%,产出的(H2+CO)含量达到92.5%。高温碳化性能对比实验结果表明,相比未改性的催化剂,Mn-Ce改性催化剂的高温稳定性更强,使用寿命更长。高温碳化后,205℃下的甲醇转化率均在40%以上,未改性催化剂的转化率仅为20%左右。催化剂性能评价实验结果表明,催化反应温度与其制氢性能呈正相关,高温下催化剂有更优异的制氢表现。Mn、Ce的加入可以有效提高Cu基催化剂甲醇重整制氢的性能。

Improving Corrosion Resistance of C_f/Mg Composites using Rare Earth Conversion Coatings

The surface of carbon fiber reinforced Mg matrix (Cf/Mg) composites was modified by treatment of rare earth conversion coating, and nontoxic, non-pollution Ce conversion coatings were prepared. The effect of the coatings on corrosion behaviors of composites was investigated by electrochemical polarization technology and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The higher Ecorr and lower icorr were obtained by Ce conversion coatings. EIS results showed that the higher values of R2 were obtained by treatment containing CeCl3, the high corrosion resistance occured in treatment containing CeCl3, the low corrosion resistance in uncoating sample, the coating of treatment containing Ce(NO3)3 was medium. The microstructure of Ce conversion coatings was observed by scanning electron microscopy (SEM), and the elements of corresponding for coatings was characterized by energy dispersive spectrometer (EDS). The micro-cracks and Ce-riched spherical particles were characteristics of these coatings.

稀土Ce对SUS444铁素体不锈钢夹杂物及力学性能的影响

通过金相显微镜、扫描电子显微镜、拉伸和冲击试验等分析测试手段,研究了稀土Ce含量对SUS444铁素体不锈钢夹杂物及室温力学性能的影响。结果表明,添加0.008wt%~0.015wt%Ce可改变夹杂物的种类、形态和尺寸,可将大尺寸、不规则形状的SiO_(2)变质为小尺寸球形的Ce_(2)O_(3)夹杂物,添加0.008%Ce不足以使SiO_(2)完全变质,但添加0.015%Ce可实现夹杂物的完全变质。稀土Ce可细化不锈钢的显微组织,随Ce含量增加,不锈钢的抗拉强度提升,拉伸断口由韧-脆结合断裂完全转变成韧性断裂;冲击韧性显著提升,最高可提升至未添加Ce的4.9倍,冲击断口由脆性断裂向韧性断裂转变。综合考虑夹杂物和力学性能,不锈钢中Ce最优含量为0.015wt%。

Ce含量和T6热处理对Al-0.3Fe-0.1Si合金组织与性能的影响

研究了稀土元素Ce和T6热处理工艺对Al-0.3Fe-0.1Si合金组织和性能的影响。结果表明,添加适量的稀土Ce和T6热处理均可抑制晶粒长大,并有效细化Al-0.3Fe-0.1Si合金的晶粒尺寸。当稀土Ce的加入量为0.2%时,铸态合金的抗拉强度为81.7 MPa,比加入量为0.1%时提高了10.7%。稀土Ce的加入量为0.3%时,T6态合金的电导率为58.13%IACS,比铸态合金提高了2.3%。热处理前后的Al-0.3Fe-0.1Si-0.1Ce合金与Al-0.3Fe-0.1Si-0.3Ce合金的电导率接近。当稀土Ce的加入量为0.1%~0.2%时Al-0.3Fe-0.1Si合金获得较好的综合性能。本研究的结果可为导电Al-0.3Fe-0.1Si合金制备提供理论和试验参考。

稀土Ce对X100管线钢组织及耐腐蚀性能的影响

以X100管线钢为研究对象,在实验室条件下采用真空感应炉熔炼不同稀土Ce含量的试验钢,通过扫描电子显微镜、蔡司金相显微镜、电化学工作站以及X射线衍射仪研究了Ce对X100管线钢组织及耐腐蚀性能的影响。结果表明,Ce的加入使X100钢中MnS、Mn-Si-Al-O夹杂变性成Ce_(x)O_(y)、Mn-Si-Al-O-Ce夹杂,尺寸由4μm左右增大到10μm左右。Ce对X100试验钢显微组织具有明显的细化作用,在0~0.0049%范围内,试验钢组织随着Ce含量的提高逐渐细化。Ce的加入能够提高试验钢的腐蚀电位,降低其腐蚀电流密度,在3.5%NaCl溶液浸泡28 d条件下,试验钢腐蚀电流密度由未添加Ce时的4.6347 mA/cm^(2)降低至Ce含量为0.0049%时的3.7784 mA/cm^(2),Ce含量为0.0049%时的试验钢表现出较好的耐腐蚀性能。另外,Ce的加入能够有效提高腐蚀产物中α-FeOOH和Fe_(3)O_(4)的含量,增强对钢基体的保护作用,有利于提高试验钢的耐腐蚀性能。