Nano-scale Reinforcements and Properties of Al-Si-Cu Alloy Processed by High-Pressure Torsion

To improve the comprehensive mechanical properties of Al-Si-Cu alloy,it was treated by a high-pressure torsion process,and the effect of the deformation degree on the microstructure and properties of the Al-Si-Cu alloy was studied.The results show that the reinforcements(β-Si andθ-CuAl_(2)phases)of the Al-Si-Cu alloy are dispersed in theα-Al matrix phase with finer phase size after the treatment.The processed samples exhibit grain sizes in the submicron or even nanometer range,which effectively improves the mechanical properties of the material.The hardness and strength of the deformed alloy are both significantly raised to 268 HV and 390.04 MPa by 10 turns HPT process,and the fracture morphology shows that the material gradually transits from brittle to plastic before and after deformation.The elements interdiffusion at the interface between the phases has also been effectively enhanced.In addition,it is found that the severe plastic deformation at room temperature induces a ternary eutectic reaction,resulting in the formation of ternary Al+Si+CuAl_(2)eutectic.

In-situ hydrocarbon formation and accumulation mechanisms of micro- and nano-scale pore-fracture in Gulong shale, Songliao Basin, NE China

By conducting experimental analyses, including thermal pyrolysis, micro-/nano-CT, argon-ion polishing field emission scanning electron microscopy (FE-SEM), confocal laser scanning microscopy (CLSM), and two-dimensional nuclear magnetic resonance (2D NMR), the Gulong shale oil in the Songliao Basin was investigated with respect to formation model, pore structure and accumulation mechanism. First, in the Gulong shale, there are a large number of pico-algae, nano-algae and dinoflagellates, which were formed in brackish water environment and constituted the hydrogen-rich oil source materials of shale. Second, most of the oil-generating materials of the Qingshankou Formation shale exist in the form of organo-clay complex. During organic matter thermal evolution, clay minerals had double effects of suppression and catalytic hydrogenation, which expanded shale oil window and increased light hydrocarbon yield. Third, the formation of storage space in the Gulong Shale was related to dissolution and hydrocarbon generation. With the diagenesis, micro-/nano-pores increased, pore diameter decreased and more bedding fractures appeared, which jointly gave rise to the unique reservoir with dual media (i.e. nano-scale pores and micro-scale bedding fractures) in the Gulong shale. Fourth, the micro-/nano-scale oil storage unit in the Gulong shale exhibits independent oil/gas occurrence phase, and shows that all-size pores contain oils, which occur in condensate state in micropores or in oil-gas two phase (or liquid) state in macropores/mesopores. The understanding about Gulong shale oil formation and accumulation mechanism has theoretical and practical significance for advancing continental shale oil exploration in China.

Antibacterial Effect of Nano-scale TiO_2 on Parasitic Bacterium of Nanfeng Citrus in Storage Period

[Objective] The aim was to observe the antibacterial effect of nano-scale Titanium dioxide on parasitic bacterium of Nanfeng Citrus in storage period.[Method] Nano-scale Titanium dioxide was prepared by dibutyl phthalate through sol-gel method under anhydrous conditions,and orthogonal experiment was used to determine optimum conditions for nano-scale Titanium dioxide preparation,and structure characterization of nano-scale Titanium dioxide was carried out by X-Ray diffractometer.Oxford cup method was used to explore inhibition effect of nano-scale Titanium dioxide suspension on the activity of normal parasitic bacterium of Nanfeng Citrus.Simultaneously,the empirical preservation test was carried out.[Result] The average diameter of nano-scale Titanium dioxide powder attained to 14.6 nm,actual average yield could reach 90.83% with RSD（Relative Standard Deviation）of 0.86%.[Conclusion] Nano-scale Titanium dioxide had good antibacterial effect on the parasitic bacterium of Nanfeng Citrus in storage period.

Visual Object Tracking and Servoing Control of a Nano-Scale Quadrotor:System,Algorithms,and Experiments

There are two main trends in the development of unmanned aerial vehicle(UAV)technologies:miniaturization and intellectualization,in which realizing object tracking capabilities for a nano-scale UAV is one of the most challenging problems.In this paper,we present a visual object tracking and servoing control system utilizing a tailor-made 38 g nano-scale quadrotor.A lightweight visual module is integrated to enable object tracking capabilities,and a micro positioning deck is mounted to provide accurate pose estimation.In order to be robust against object appearance variations,a novel object tracking algorithm,denoted by RMCTer,is proposed,which integrates a powerful short-term tracking module and an efficient long-term processing module.In particular,the long-term processing module can provide additional object information and modify the short-term tracking model in a timely manner.Furthermore,a positionbased visual servoing control method is proposed for the quadrotor,where an adaptive tracking controller is designed by leveraging backstepping and adaptive techniques.Stable and accurate object tracking is achieved even under disturbances.Experimental results are presented to demonstrate the high accuracy and stability of the whole tracking system.

Numerical Analysis of the Adhesive Forces in Nano-Scale Structure

Nanohairs, which can be found on the epidermis of Tokay gecko＇s toes, contribute to the adhesion by means of van der Waals force, capillary force, etc. This structure has inspired many researchers to fabricate the attachable nano-scale structures. However, the efficiency of artificial nano-scale structures is not reliable sufficiently. Moreover, the mechanical parameters related to the nano-hair attachment are not yet revealed qualitatively. The mechanical parameters which have influence on the ability of adhesive nano-hairs were investigated through numerical simulation in which only van der Waals force was considered. For the numerical analysis, finite element method was utilized and van der Waals force, assumed as 12-6 Lennard-Jones potential, was implemented as the body force term in the finite element formulation.

Nano-scale Interfacial Friction Behavior between Two Kinds of Materials in MEMS Based on Molecular Dynamics Simulations

The aim of this article was to provide a systematic method to perform molecular dynamics simulotion or evaluation for nano-scale interfacial friction behavior between two kinds of materials in MEMS design. Friction is an important factor affecting the performance and reliability of MEMS. The model of the nano-scale interracial friction behavior between two kinds of materials was presented based on the Newton＇ s equations of motion. The Morse potential function was selected for the model. The improved Verlet algorithm was employed to resolve the model, the atom trajectories and the law of the interfacial friction behavior. Comparisons with experimental data in other paper confirm the validity of the model. Using the model it is possible to simulate or evaluate the importance of different factors for designing of the nano-scale interfacial friction behavior between two kinds of materials in MEMS.

Influence of the finite size effect of Si（001）/SiO2 interface on the gate leakage current in nano-scale transistors

With the device size gradually approaching the physical limit, the small changes of the Si(001)/SiO 2 interface in silicon-based devices may have a great impact on the device characteristics. Based on this, the bridge-oxygen model is used to construct the interface of different sizes, and the finite size effect of the interface between fine electronic structure silicon and silicon dioxide is studied. Then, the influence of the finite size effect on the electrical properties of nanotransistors is calculated by using the first principle. Theoretical calculation results demonstrate that the bond length of Si-Si and Si-O shows a saturate tendency when the size increases, while the absorption capacity of visible light and the barrier of the interface increase with the decrease of size. Finally, the results of two tunneling current models show that the finite size effect of Si(001)/SiO 2 interface can lead to a larger change in the gate leakage current of nano-scale devices, and the transition region and image potential, which play an important role in the calculation of interface characteristics of large-scale devices, show different sensitivities to the finite size effect. Therefore, the finite size effect of the interface on the gate leakage current cannot be ignored in nano-scale devices.

Novel Nano-scale Overlay Alignment Method for Room-temperature Imprint Lithography

A novel nano-scale alignment technique based on Moiré signal for room-temperature imprint lithography in the submicron realm is proposed. The Moiré signals generated by a pair of quadruple gratings on two templates respectively are optically projected onto a photodetector array, then the detected Moiré signals are used to estimate the alignment errors in x and y directions. The experiment result indicates that complex differential Moiré signal is sensitive to relative displacement of the pair of marks than each single Moiré signal, and the alignment resolutions obtained in x and y directions are ±20nm(3σ) and ±24nm(3σ). They can meet the requirement of alignment accuracy for submicron imprint lithography.

Effect of ZrO_(2)Addition on Lanthanum Aluminate-based High Emissivity Coating Materials

In order to enhance the sintering resistance of lanthanum aluminate based high emissivity coatings,Ca^(2+)-Fe^(3+)doped LaAlO_(3)/ZrO_(2)specimens were prepared by solid state sintering using La_(2)O_(3),Al_(2)O_(3),CaCO_(3) and Fe_(2)O_(3) as raw materials,extra-adding fused Y_(2)O_(3)-stabilized ZrO_(2)(0,5%,10%,and 15%,by mass),ball milling,pre-calcining,pressing into shapes and sintering at 1600℃for 2 h.The effect of the ZrO_(2)addition on the properties of lanthanum aluminate based high emissivity coatings was explored.It is concluded that ZrO_(2)does not react with LaAlO_(3),which can inhibit the sintering of the specimens.With the increase of the ZrO_(2),addition,the linear shrinkage rate and the thermal conductivity decrease significantly,while the emissivity decreases,but the emissivity of all the specimens is all higher than 0.9.The optimal addition of ZrO_(2),is 10%.

电沉积辅助真空处理制备铝合金超疏水保护膜及其性能研究

铝合金是工业领域经常用到的金属材料,为了使其成为耐污、耐腐蚀的高性能超疏水材料,以铝合金为基底、硝酸镧为电沉积液,采用电沉积辅助真空处理法不经修饰直接制备出超疏水铝合金表面。通过对所制备超疏水铝合金表面的形貌、化学组成、浸润性、自清洁、耐腐蚀等方面进行表征和测试可知,所制备铝合金表面存在一层致密的蛛网状微纳米氧化镧粗糙结构,再加上稀土氧化镧本征超疏水的协同作用,使其表现出超疏水特性,对水的接触角可达到160°,滚动角约为5.0°,且具备良好的自清洁、耐磨和耐腐蚀性能。

锁磷剂与增氧剂联用去除沉积物中砷的效果与机制

为研究锁磷剂(LMB)与增氧剂CaO_(2)联合应用对富营养化湖泊沉积物中砷(As)污染的去除效果,理清联用技术对沉积物水界面As的去除机制,以太湖梅梁湾底泥为研究对象开展模拟试验。结果表明:LMB与CaO_(2)联用对沉积物中的As的去除效果优于LMB、CaO_(2)单独使用;在试验第45天,LMB与CaO_(2)联用对沉积物溶解态As去除率最大,为39.31%,在试验第90天,LMB与CaO_(2)联用对As的去除效果较差;为实现沉积物中As的高效去除,可在加入LMB和CaO_(2)45 d后对LMB和CaO_(2)进行回收;LMB与CaO_(2)联用去除As的主要机制为LMB和CaO_(2)中的La^(3+)、Ca^(2+)与砷酸根离子络合形成LaAsO_(4)和Ca_(3)(AsO_(4))2沉淀以及Fe(Ⅲ)、Mn(Ⅳ)氧化物的协同吸附作用;Fe和Mn氧化还原在控制沉积物As的释放中起着关键作用。

GECAM卫星溴化镧晶体性能研究

GECAM卫星伽马射线探测器(GRD)设计使用3 in(1 in=25.4 mm)直径的溴化镧晶体(LaBr3晶体)作为伽马射线探测灵敏材料,后端耦合硅光电倍增管(SiPM)进行读出。对引力波最高能电磁对应体全天监测器(GECAM)卫星所用的LaBr_(3)晶体进行了本底测试,并根据晶体的掺杂类型进行了分类,使用放射源对所有晶体的性能进行了测试。为了研究LaBr_(3)晶体的辐照损伤情况,使用^(60)Co放射源对晶体进行了辐照损伤性能测试。测试结果表明,LaBr_(3)晶体的本底可分为单掺杂和双掺杂两个类型。GECAM卫星的LaBr_(3)晶体的能量分辨<18%@59.5 keV,满足设计使用要求。在1.65 kGy剂量的累积辐照后,经过较长时间的退激发,LaBr_(3)晶体试验前后662 keV的峰值变化小于15%,满足空间环境条件下(GECAM卫星在轨3年)的使用要求。

非皂化P507体系萃取分离镧和锕元素

由于稀土生产过程中锕元素未被有效分离去除,导致我国部分稀土产品的放射性超出豁免值(α和β总放射性小于1 Bq/g)。本工作以非皂化的2-乙基己基磷酸单-2-乙基己基酯(P507)为萃取剂,二乙基三胺五乙酸(DTPA)或N-(2-羟乙基)乙二胺-N,N',N'-三乙酸(HEDTA)为水相掩蔽剂,乳酸为酸度缓冲剂,分别在盐酸和硝酸体系中研究了对镧和锕两种元素的萃取分离。结果显示,弱酸试剂可有效缓冲稀土料液的酸度,使萃取反应向有利于生成有机配合物的方向进行。在pH为3.0、初始La^(3+)浓度为0.2 mol/L的盐酸溶液中,该体系对La^(3+)的萃取效果较单一的皂化P507有显著提高,D(La)可达5.0。在pH为2.0~2.5的硝酸体系中,恒定DTPA/HEDTA和乳酸的浓度分别为0.02 mol/L和1.0 mol/L,此时Ac^(3+)被有效掩蔽,D(Ac)的最大值仅有0.46,SF(La/Ac)值较盐酸体系的3~4可提高至5~7。此外,该非皂化P507体系也可以优先去除稀土低酸废水中的放射性Ac^(3+),其SF(Ac/La)值随乳酸浓度的增加可提高至14,这一现象能够用于实现有效控制稀土工业废水中放射性物质的目标。

添加氧化镧对钼铼合金组织性能的影响

采用粉末冶金技术在钼铼合金中添加氧化镧制备了ODS-Mo-14Re,通过EBSD、XRD、维氏硬度计、电子万能试验机对氧化镧添加前后钼合金管材的显微结构、室温与高温力学性能进行了分析。结果表明,适量氧化镧的添加可以对钼铼合金起到很好的细晶强化与弥散强化作用;添加0.3%(质量分数)氧化镧使得钼铼合金的平均晶粒尺寸由22.6μm降低至7μm;氧化镧作为细小弥散的第二相添加在钼铼合金中,使晶粒内部位错密度增多,位错相互缠结,运动被阻碍,从而使钼铼合金的强度及塑性明显提升,弥散强化效果显著。室温和高温(1 300℃)拉伸时,Mo-14Re的抗拉强度为725.8、195.3 MPa,而ODS-Mo-14Re的抗拉强度达780.9、226.4 MPa,分别提升了7.6%和15.9%,表明氧化镧的添加使钼铼合金的室温以及高温力学性能得到明显提高。

硝酸镧含量对锌铝涂层组织结构和耐蚀性的影响

以稀土硝酸镧为添加剂,用硅烷钝化液代替铬酐,通过添加不量的硝酸镧制备了水性无铬锌铝涂层。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)分析、中性盐雾试验和极化曲线等对含硝酸镧涂层试样的结构和性能进行了评价。结果表明:含5g/L硝酸镧(指其在B组分中的质量浓度)涂层试样的耐蚀性最好,适量的镧盐可以改善涂层结构,使涂层均匀致密;硝酸镧钝化处理可以显著降低涂层试样的腐蚀电流,提高腐蚀电位,抑制腐蚀速率,提高涂层的耐蚀性。硝酸镧也可以作为物理屏障,阻止腐蚀介质渗透到涂层中,但它不改变极化曲线的形状。水性无铬锌铝涂层中硝酸镧的最佳用量为5g/L。

一步电沉积法制备铜表面稀土镧/石墨烯超疏水复合涂层及其耐腐蚀性能

海洋腐蚀的倾向性是制约铜基材料使用性能和安全性的一个重要因素。因此,提高铜表面耐腐蚀能力成为研究重点。采用一步快速电沉积工艺在铜基表面制备肉豆蔻酸镧/氧化石墨烯(LaM/GO)超疏水复合涂层,采用扫描电镜(SEM)、X射线光电子能谱仪(XPS)、水接触角测量和电化学测试等手段对复合涂层的结构及性能进行了表征。结果表明:电沉积阴极表面产生了低表面能材料和花瓣状微纳粗糙结构,涂层表面静态水接触角为154°±3°,滚动角为5°±3°;电位动态极化曲线测量表明,超疏水复合涂层表面的腐蚀电位增加、腐蚀电流密度降低了2个数量级,缓蚀效率达99.34%,耐腐蚀性能得到显著提升;此外,所获得超疏水复合涂层表面显示出优异的防污性能和机械稳定性。

稀土镧对Q450NQR1铁路车厢用钢中夹杂物生成的影响

文章通过采用感应炉试验和热力学计算研究钢中镧元素含量对钢中夹杂物的影响,得出在Q450NQR1铁路车厢用钢的钢液热力学条件下,首先形成的是稀土硫氧化物,然后是稀土镧的铝酸盐、氧化物、碳化物、硫化物,最后是反应趋势较小的镧-硅和镧-铝金属间化合物以及稀土氢化物。通过Ohnaka偏析模型的计算得出,LaAs和LaP夹杂物可以在凝固过程中产生。

氟化镧对粉煤灰基堇青石陶瓷力学性能的影响

针对粉煤灰基堇青石陶瓷力学强度难以满足高质量应用要求的难题,以氟化镧为烧结助剂,制备了力学性能优异的堇青石陶瓷。当氟化镧添加量为1.0 wt.%、烧结温度为1300℃时,所得陶瓷弹性模量、硬度和压缩强度分别为200.09 GPa、17.63 GPa和118.41 MPa。性能的显著改善主要是因为氟化镧的引入可提高液相流动性,产生致密化效果;同时,镧元素可在晶界处富集促进晶粒细化增韧。此外,少量镧元素可能会进入堇青石晶格内部,亦可对力学性能产生积极影响。

粉煤灰镧改性吸附水中磷的性能研究

将粉煤灰与碳酸钾混合后焙烧,再浸渍硝酸镧,制备出镧改性粉煤灰(La-FA)。通过多种手段对La-FA进行了表征,并研究了其对含磷废水的吸附性能。结果表明:La-FA表面形成许多孔隙,具有更多吸附位点和羟基官能团,硅和铝含量的增加。La-FA零点电位的pH值为5.8。当水中磷的质量浓度为30 mg/L、温度为20℃、pH为4.1时,投加2 g/L的La-FA且吸附时间为20 min时,磷去除率可达98%,吸附量为24.13 mg/g。La-FA对磷的吸附过程可分为三个阶段,符合Langmuir等温吸附模型和拟二级吸附动力学模型。吸附过程是自发进行的,且为吸热反应,吸附机理为离子交换。

Kinetics of thermal decomposition of lanthanum oxalate hydrate

Lanthanum oxalate hydrate La2（C2O4）3·10H2O,the precursor of La2O3 ultrafine powders,was prepared by impinging stream reactor method with PEG 20000 as surfactant.Thermal decomposition of La2（C2O4）3·10H2O from room temperature to 900 °C was investigated and intermediates and final solid products were characterized by FTIR and DSC-TG.Results show that the thermal decomposition process consists of five consecutive stage reactions.Flynn-Wall-Ozawa（FWO） and Kissinger-Akahira-Sunose（KAS） methods were implemented for the calculation of energy of activation（E）,and the results show that E depends on α,demonstrating that the decomposition reaction process of the lanthanum oxalate is of a complex kinetic mechanism.The most probable mechanistic function,G（α）=[1-（1＋α）1/3]2,and the kinetic parameters were obtained by multivariate non-linear regression analysis method.The average E-value that is compatible with the kinetic model is close to value which was obtained by FWO and KAS methods.The fitting curve matches the original TG curve very well.