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.

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.

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.

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.

纳米γ-AlOOH水热生长基元模型及结晶生长机理

-γA lOOH是水热法制备纳米A l2O3的中间产物。要制备出具有理想形貌的纳米A l2O3,必须要实现中间产物-γA lOOH的可控制备与定向生长。文中采用水热方法通过控制pH值,成功实现了须状、棒状、类球型及片状纳米-γA lOOH的可控制备,并在分析了大量实验数据的基础上,建立了-γA lOOH在水热过程中的生长基元模型,提出pH值决定生长基元,而生长基元决定生长方向的新观点。得出在酸性条件下,单体A l3+或由羟基联结而成的三聚体,按一维定向成长为晶须或棒条状纳米-γA lOOH;中性条件下,形成类球状纳米-γA lOOH;碱性条件下,单体A l3+由羟基联结而成的"双聚体",以此为生长基元按面扩张机制进行结晶生成片状纳米-γA lOOH。

水热法制备一维纳米γ-AlOOH的形态结构

通过水热法制备了前驱体γ-AlOOH的一维纳米结构,考察了工艺参数对结构的影响.研究结果表明,当AlCl3溶液浓度小于0.2mol/L,反应溶液pH〈7,反应温度控制在160~180℃时,可以得到γ-AlOOH纳米棒,而当pH〉7时,样品呈片状;当AlCl3浓度大于0.2mol/L,pH控制在5~6,反应温度控制在200℃左右,并加入表面活性剂SDBS,可以制备大长径比γ-AlOOH纳米纤维.

水热法制备花状γ-AlOOH

以十八水合硫酸铝和尿素为原料,十六烷基三甲基溴化铵(CTAB)和酒石酸钠为表面活性剂,在165℃水热条件下反应3h,制备花状γ-AlOOH结构。采用扫描电镜(SEM)、热重分析和X射线衍射(XRD)对样品进行表征。实验结果表明,采用水热法可以得到长度、厚度均匀的γ-AlOOH纳米片组装成的花状γ-AlOOH。

微波水热合成γ-AlOOH和γ-Al_2O_3纳米片

以九水合硝酸铝和尿素为原料,聚乙烯吡咯烷酮为表面活性剂,在180℃微波水热条件下反应30min,制备了γ-AlOOH片状结构产物。此前驱物经600℃热分解2h,得到γ-Al2O3纳米片。采用SEM、TEM、SAED和XRD等方法对样品进行表征,并测试了γ-Al2O3纳米片对刚果红染料的吸附性能。实验结果表明,采用微波水热法可以得到长度约为1μm,厚度为30nm的γ-AlOOH纳米片,该产物经煅烧处理后可以得到微观形貌保持不变的γ-Al2O3纳米片,且片状结构表面存在介孔结构。γ-Al2O3纳米片状结构表现出对废水中刚果红污染物的强吸附性能。

勃姆石(γ-AlOOH)溶胶的制备及表征(英文)

以异丙醇铝为先驱体，采用Yoldas方法成功地制备了勃姆石（γ—AlOOH）溶胶；并采用XRD、FTIR、UV—Vis分光光度计和TEM测试技术对勃姆石溶胶进行表征。研究结果表明，制备所得的勃姆石溶胶稳定、透明，溶胶粒子结晶性好，形貌呈纤维状，长度大约为60～100nm。

微波水热合成γ-AlOOH和γ-Al_2O_3片状自组装微球

以六水合氯化铝和氢氧化钠为原料,十六烷基三甲基溴化铵为表面活性剂,在160℃微波水热反应30min的条件下,制备了γ-AlOOH片状自组装微球前驱物。此前驱物经500℃热分解2h,得到γ-Al2O3片状自组装微球。通过SEM、TEM、SAED和XRD等分析手段对产物进行了表征,采用TG-DTA分析γ-AlOOH微球前驱物受热分解时的热力学行为,并测试了γ-AlOOH和γ-Al2O3片状自组装微球对刚果红染料的吸附性能。实验结果表明,采用微波水热法可以得到由厚度约30nm的片状结构单元自组装而成的直径约1μm的γ-AlOOH微球前驱物,经煅烧处理后可以得到微观形貌保持不变的γ-Al2O3片状自组装微球,且片状结构单元表面有孔状结构。同时发现微波水热前驱液的溶剂组成对片状结构单元的厚度有很大影响。γ-AlOOH和γ-Al2O3片状自组装微球均表现出对废水中刚果红污染物的强吸附性能。

γ-AlOOH溶胶的制备和表征

以SB粉为原料、HNO3为解胶剂成功地制备了稳定的γ AlOOH溶胶。考察了酸度、浓度、胶解温度和添加剂等因素对γ AlOOH溶胶的质点大小、粒径分布、稳定性及粘度等胶体性能的影响。实验结果表明,稳定γ AlOOH溶胶适宜的制备条件为:n(H+)/n(AlOOH)=0 08～0 1,SB质量分数小于7%,胶解温度大于80℃,制得γ AlOOH溶胶胶粒的平均粒径在18nm左右。

水热条件下水合氧化铝(γ-AlOOH)的可控生长研究

以Al片为原料,采用水热法快速制备纳米水合氧化铝(γ-AlOOH).主要讨论了不同溶剂、不同表面活性剂和不同pH值对Al片的作用,制备出不同形貌的纳米水合氧化铝(γ-AlOOH),有纳米砖块(S1),纳米颗粒(S8),纳米线(S11),纳米片(S4、S6、S12),纳米盘(S7、S13),纳米花,S4、S14产物可以观察到是多层的结构,S2、S3、S5、S6、S9、S10、S12、S14产物可以观察到分层次的纳米建筑,初步实现了水合氧化铝的可控生长,并探讨了各种不同形貌γ-AlOOH的形成机理.

特殊结构纳米γ-AlOOH的溶剂热法制备与机理

选用有机铝盐(异丙醇铝和醋酸铝)为原料,分别以氨水和尿素为沉淀剂,在200℃的乙醇溶剂热条件下,制备出白色前驱物粉末。通过SEM,XRD和BET等分析手段对产物进行了表征,考察原料与沉淀剂对产物的影响。结果表明:不同原料得到不同形貌的纳米γ-AlOOH,微观形貌分别为纳米级棒状和片状物;溶剂和沉淀剂种类会影响产物的比表面,采用尿素可使比表面积达到218.64m2/g。同时进一步从结晶机理方面分析了这一结果的成因。

水热合成大长径比的γ-AlOOH纳米线及表征

以NaOH和NH3·H2O的混合溶液为沉淀剂,在水热条件下制备了大长径比的γ-AlOOH纳米线;并采用X射线衍射仪和透射电子显微镜对制备的产物进行了表征。结果表明：调节混合沉淀剂中NaOH和NH3·H2O的比例,可得到不同形貌的γ-AlOOH纳米结构;大长径比γ-AlOOH纳米线是由水热反应初期形成的尺寸较大的层状γ-AlOOH通过卷曲而形成的;以体积比1∶1的NaOH和NH3·H2O混合溶液为沉淀剂,在保温时间24h条件下,制备的γ-AlOOH纳米线形态最好,其直径为10-30nm,长度为1-2μm,长径比为60-100,并具有明显的晶面择优取向。

水热温度和pH对合成纳米结构γ-AlOOH形态的影响

1 mol/L的Al Cl3溶液为铝源,1 mol/L的Na OH溶液为沉淀剂,在水热法反应体系中研究了温度和p H值对合成纳米结构γ-Al OOH形态的影响。利用X射线衍射仪(XRD)和热场发射透射电子显微镜(FETEM)对合成的样品进行表征。XRD分析表明不同水热条件下获得样品的物相为γ-Al OOH。FETEM分析显示在时间为48 h和p H为5时水热法合成γ-Al OOH,在120℃下合成了径向分布不均匀的棒状γ-Al OOH;在150℃下获得了径向尺寸趋于均匀的棒状γ-Al OOH;在180℃下制备出了径向分布较均匀的约20 nm的γ-Al OOH。但是,在210℃下合成的薄片状的γ-Al OOH。在温度为180℃、48 h时水热法合成γ-Al OOH时,当p H由5增加到7时,合成γ-Al OOH的径向尺寸变小得不太明显;当p H由7增加到9时,获得γ-Al OOH的径向尺寸显著的变小,其径向尺寸约为10 nm。但是,当p H为11时,制备出了细小薄片状的γ-Al OOH。最后,对水热法体系中温度和p H对合成γ-Al OOH形态影响的机理进行了讨论。

γ-AlOOH纳米棒的水热合成与形貌调控

γ-AlOOH作为液相法合成γ-Al_2O_3的前驱体,其形貌与最终产物的性能密切相关。本文采用水热法合成γ-AlOOH纳米棒,通过改变Al3+浓度和沉淀剂的种类调控γ-AlOOH纳米棒的长径比,利用X射线衍射仪(XRD)和透射电子显微镜(TEM)表征产物的晶体结构和形貌。结果表明,随Al3+浓度增大可得到长径比在5.9~8.0的γ-AlOOH纳米棒,而改变沉淀剂的种类可进一步将长径比增大到8.0~10.0。通过对产物结晶过程的分析,发现增大Al3+浓度和增强沉淀剂碱性均可以促进铝离子与羟基的配合。提高反应体系中Al(OH)3浓度,有利于γ-AlOOH晶粒的成核,促进了晶核之间的定向接触,从而提高了纳米棒的长径比。长径比为10.0的γ-AlOOH纳米棒烧结所得纳米γ-Al_2O_3改性变压器油(体积分数为0.1%)的正冲击击穿强度较纯油提高9.9%.