Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

退火处理对Nano-SiC-Al_2O_3/TiC纳米陶瓷复合材料性能的影响

研究了退火工艺对纳米陶瓷复合材料力学性能的影响。研究表明，纳米陶瓷复合材料在适当退火工艺下，其抗弯强度和硬度可以提高４０％ ～５０ ％ ，但断裂韧度略有下降。

SiCp/Al复合材料纳米压痕/划痕下的脆塑性行为研究

为探究SiCp/Al复合材料中两相材料相互作用引起的力学性能差异,研究微观尺度下法向载荷变化对SiCp/Al复合材料形变和去除的影响。采用纳米压痕实验,基于Oliver-Pharr法测得其硬度和弹性模量,并对其压痕表面进行观察,结合有限元仿真分析产生力学性能差异的原因;同时,根据纳米压痕实验所得力学参数进行变载荷纳米划痕仿真,并配合实验后划痕表面观察结果分析材料的形变和脆塑性行为。结果表明:当金刚石压头作用于SiC颗粒时,颗粒出现破碎和二次压入现象,所测硬度与弹性模量小于单晶SiC的理论值;当金刚石压头作用于基体相时,由于SiC颗粒阻碍基体压入,复合材料的硬度与弹性模量测量结果偏大。在纳米划痕过程中,复合材料的去除形式随载荷变化体现为划擦、耕犁和切削阶段,其中的基体相通过塑性流动产生塑性脊堆积并伴随有涂覆现象,SiC颗粒则以脱黏、断裂破碎和拔出等脆性机制而去除,且SiC颗粒的二次压入、断裂、破碎和拔出是导致复合材料力学性能与单晶SiC的力学性能产生巨大差异的主要原因。随着划痕载荷增加,SiC体积分数为45%的SiCp/Al复合材料的去除机制更多取决于以塑性去除为主的基体相,而SiC颗粒则主要表现为脆性去除。

Nano-Al_(2)O_(3)改性石蜡相变微胶囊的热性能及作用机理

以石蜡为芯材,Nano-Al_(2)O_(3)改性三聚氰胺脲醛树脂为壁材,利用原位聚合法制备导热增强型石蜡相变微胶囊。采用ESEM、HotDisk、DSC、TG、FT-IR、EDS测试表征其微观形貌、导热系数、储热性能、热稳定性及化学结构。结果表明:石蜡相变微胶囊呈球状颗粒且分散均匀,相变温度30℃~31℃,热稳定性能良好。掺10%的Nano-Al_(2)O_(3)时,导热系数提高了56.8%。Nano-Al_(2)O_(3)均匀分布在壁材中,形成网状结构,使微胶囊内部与表面形成传热通道,从而赋予石蜡相变微胶囊的高导热性能和高热传输效率。

Preparation of micro/nano-structured ceramic coatings on Ti6Al4V alloy by plasma electrolytic oxidation process

In order to improve the osseointegration and antibacterial activity of titanium alloys,micro/nano-structured ceramic coatings doped with antibacterial element F were prepared by plasma electrolytic oxidation(PEO)process on Ti6Al4V alloy in NaF electrolyte.The influence of NaF concentration(0.15-0.50 mol/L)on the PEO process,microstructure,phase composition,corrosion resistance and thickness of the coatings was investigated using scanning/transmission electron microscopy,energy dispersive spectroscopy,atomic force microscopy,X-ray diffractometer,and potentiodynamic polarization.The results demonstrated that Ti6Al4V alloy had low PEO voltage(less than 200 V)in NaF electrolyte,which decreased further as the NaF concentration increased.A micro/nano-structured coating with 10-15μm pits and 200-800 nm pores was formed in NaF electrolyte;the morphology was different from the typical pancake structure obtained with other electrolytes.The coating formed in NaF electrolyte had low surface roughness and was thin(<4μm).The NaF concentration had a small effect on the phase transition from metastable anatase phase to stable rutile phase,but greatly affected the corrosion resistance.In general,as the NaF concentration increased,the surface roughness,phase(anatase and rutile)contents,corrosion resistance,and thickness of the coating first increased and then decreased,reaching the maximum values at 0.25 mol/L NaF.

Influence of volume percentage of NanoTiB2 particles on tribological&mechanical behaviour of 6061-T6 Al alloy nano-surface composite layer prepared via friction stir process

The aim of present study is to analyze the influence of volume percentage(vol.%) of nano-sized particles(TiB_2: average size is 35 nm) on microstructure, mechanical and tribological behavior of 6061-T6 Al alloy surface nano composite prepared via Friction stir process(FSP). The microstructure of the fabricated surface nanocomposites is examined using optical microscopy(OM) and scanning electron microscope(SEM) for distribution of TiB_2 nano reinforcement particles, thickness of nano composite layer formed on the Aluminum alloy substrate and fracture features. The depth of surface nano composite layer is measured as 3683.82 m m along the cross section of stir zone of nano composite perpendicular to FSP. It was observed that increase in volume percentage of TiB_2 particles, the microhardness is increased up to132 Hv and it is greater than as-received Al alloy's microhardness(104 Hv). It is also observed that at 4volume percentage higher tensile properties exhibited as compared with the 2 and 8 vol. %. It is found that high wear resistance exhibited at 4 volume percentage as-compared with the 2 and 8 vol. %. The observed wear and mechanical properties are interrelated with microstructure, fractography and worn morphology.

Effect of Nano Al Pigment on the Anticorrosive Performance of Waterborne Epoxy Coatings

This paper presents the results regarding the effect of nano aluminum powder pigment concentration on the protective properties of waterborne epoxy films in 3.5 wt pct NaCl solution. The anticorrosive performance of the coatings with 0.5, 1, and 3 wt pct pigments and none pigment were investigated using electrochemical impedance spectroscopy （EIS）, scanning electron microscopy （SEM） and Raman spectroscopy techniques. The results show that adding appropriate amount of nano-aluminium powder pigment can enhance the barrier properties of the epoxy coating, which is attributed to the surface effect of nanoparticles and the compatibility of the pigment with the waterborne epoxy coatings.

Effect of nano-silver on microstructure, mechanical and tribological properties of cast 6061 aluminum alloy

Al6061matrix with different amounts of nano-silver(1%and2%)was produced by stir-casting method.Producedsamples were characterized by hardness,tensile,compression and wear tests.The hardness of the specimens at room temperature wasmeasured by Brinnell hardness testing machine.The magnitude of hardness increased evidently with the function of the mass fractionof the nano-Ag particle.The polished specimens were examined with an optical microscope.The fracture surfaces of tensile andcompressive specimens were further examined by scanning electron microscopy.Wear mechanisms were discussed based on thescanning electron microscopy observations of worn surface and wear debris morphology.There is an increase in compressivestrength,ultimate tensile strength,elongation and wear resistance of the Al?Ag composites compared with base alloy.The executionof stir-casting technique is relatively homogenous and fine microstructure which improves the addition of reinforcement material inthe molten metal.The results show that Al6061?nano-silver which is the best combination of hardness can replace the conventionalmaterial for better performance and longer life.

铝基核壳材料AP/Al的制备及性能研究

以AP和铝粉为原料,采用“AP预处理+表面沉积”两步法工艺制备了以铝粉为“壳”的铝基核壳材料AP/Al;采用SEM-EDS、粒度分析、密度测试等方法表征了AP/Al的表面形貌、元素分布、粒度分布和密度等物理特性,对比测试了铝基核壳材料AP/Al的感度性能、热分解性能、爆热及残渣活性铝含量并与AP/Al物理混合物进行了对比;运用Flynn-Wall-Ozawa方程计算了AP/Al物理混合物及铝基核壳材料AP/Al的分解活化能,并通过高速摄像机记录了铝基核壳材料AP/Al的燃烧特性。结果表明,铝基核壳材料AP/Al是以AP为“核芯”、铝粉为“壳”,密度为2.0485 g/cm^(3)的类球形颗粒;相比于物理混合物,铝基核壳材料AP/Al静电火光感度由27.94 mJ提高至102.88 mJ,AP低温分解和高温分解活化能分别提升10.9和9.0 kJ/mol,爆热值未出现明显降低(物理混合物为9298.4 J/g,铝基核壳材料AP/Al为9260.6 J/g),但铝基核壳材料AP/Al残渣中活性铝质量分数降低90%以上;有别于传统铝粉燃烧的拖拽火焰,铝基核壳材料AP/Al燃烧时,铝液滴溅射大量细颗粒铝珠,且燃烧火焰更加均匀、明亮。

An Al0.25Ga0.75N/GaN Lateral Field Emission Device with a Nano Void Channel

We report an Al0.25Ga0.75N/GaN based lateral field emission device with a nanometer scale void channel. A -45 nm void channel is obtained by etching out the SiO2 sacrificial dielectric layer between the semiconductor emitter and the metal collector. Under an atmospheric environment instead of vacuum conditions, the OaN- based field emission device shows a low turn-on voltage of 2.3 V, a high emission current of -40 μA （line current density 2.3mA/cm） at a collector bias Vc = 3 V, and a low reverse leakage of 3nA at Vc = -3 V. These characteristics are attributed to the nanometer scale void channel as well as the high density of two-dimensional electron gas in the AlGaN/GaN heterojunction. This type of device may have potential applications in high frequency mieroelectronics or nanoelectronics.

时效温度对Ni-P-Nano-Al_2O_3复合镀层性能的影响

研究了时效温度对Ni-P -Nano -Al2 O3 的复合镀层的组织、显微硬度和耐磨性能的影响。结果表明Ni-P -Nano -Al2 O3 复合镀可有效地提高镀层的硬度 ,并显著减缓镀层在较高温度下的软化趋势而使镀层保持较高的硬度 ;经4 0 0℃时效处理后 ,复合镀层相对于Ni-P镀层的相对耐磨性能提高了 2倍。

Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD, TEM, IR and DSC. Moreover, based on the DSC test results, the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

Fluoride-mediated nano-sized high-silica ZSM-5 as an ultrastable catalyst for methanol conversion to propylene

Fluoride mediated nano-sized ZSM-5 （ZSM-5-F） with a high Si/AI ratio of 181 was fabricated using a seed-induction method and evaluated the catalysis of the methanol to propylene （MTP） reaction. High propylene selectivity （45%） was similar to ZSM-5-OH synthesized via a hydroxide route. However, ZSM- 5-F showed much longer lifetime （305 h） compared with ZSM-5-OH （157 h） in spite of similar crystal size and aluminum content. Characterization by NH3-TPD. Py-IR, OH-IR, SEM, TG-DTA, XRD and 1H MAS NMR techniques indicated that the enhanced catalytic performance of ZSM-S-F is attributed to the fewer structural defects in the form of internal silanol groups and silanol nests.

One-dimensional nano-structure of Cu-Zn-Al alloy

Cu-Zn-Al alloy of one dimensional nano-structure was prepared and thestructure of obtained nano-material was characterized by transmission electron microscope (TEM). Itwas shown that there are non-linear oscillations on the surface of Cu-Zn-Al alloy and theconsanguineous connection exists between non-linear oscillation and the growth process of onedimensional nano-structure. The diameter of one dimensional nano-structure is about 40 nm, and theratio of length to diameter is over 40. Finally, the growth mechanism of one dimensionalnano-structure was also studied.

Al−Cu−Li−Mg合金纳米相之间溶质配分行为的第一性原理研究

采用一性原理计算考察25种合金化元素在大多数商业牌号Al−Cu−Li−Mg合金中主要纳米相(δʹ-Al3Li、θʹ-Al2Cu、T1-Al6Cu4Li3和S-Al2CuMg)之间的溶质配分能和配分行为。计算结果表明,主合金化元素Li不能直接影响θʹ和S相,Cu不能直接影响δʹ相,Mg不能直接影响θʹ和δʹ相,但可以较弱地固溶于T1相。对于微合金化元素,Si是唯一一种可以固溶于4种纳米相的元素。Au能固溶于δʹ、θʹ和S相,Cd能固溶于δʹ、T1和S相,Zr能固溶于δʹ和T1相,Ni仅有微弱的趋势固溶于θʹ和S相。Ti、V、Zn、Ag和Mo只能固溶于δʹ相,而Cr、Mn、Fe和Co对这4种纳米相均没有直接影响。几乎所有的稀土元素均能强烈固溶于T1、δʹ和S相,但无法固溶于θʹ相。仅Sc略显特殊,对S相没有明显的固溶趋势。计算预测的溶质配分能构成了一个原型数据库,有利于指导和加速Al−Li合金及其他相关Al合金的设计。

Tape Casting of Al_2O_3-TiB_2/Al_2O_3-Nano-TiC Multilayer Composites

Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃

Pickering乳液自组装CL-20/n-Al/F2605复合空心微球的制备与性能

高能量、高爆热的六硝基六氮杂异伍兹烷(CL-20)/Al复合物由于自身的高感度而限制了在炸药领域的广泛应用。为制备高能量和高安全性的CL-20/Al含能复合材料,采用Pickering乳液法制备了空心球形CL-20/n-Al/F2605(氟橡胶)复合物,并对Pickering乳液稳定性、复合物表面结构、热分解、燃烧及安全性能进行了分析。结果显示:当2 mL乙酸乙酯中溶解的CL-20固体质量为0.10~0.14 g、油水质量比在1:5~1:7之间、超声时间小于30 min、静置时间小于120 min时,形成的乳液稳定性好。该复合物表面结构粗糙,中位径d_(50)为73.17μm,各组分复合均匀。复合物的热分解峰温和活化能分别为236.7℃、164.6 kJ/mol,n-Al和F2605降低了CL-20分解过程中21.2%的活化能。复合物平均线性燃速为7.14 cm/s;特性落高H_(50)为39.5 cm,和原料CL-20相比提升了26.5 cm,安全性能得到提高。

Nano Particles and Nano Composites for Preservation of Historic Marble Minbars with Application on the Minber of Soliman Pasha Al-Khadim Mosque in Salah El-Din Citadel in Cairo, Egypt

Minbar, in Islam, the pulpit from which the sermon (khutbah) is delivered. In its simplest form, the minbar is a platform with three steps. Often it is constructed as a domed box at the top of a staircase and is reached through a doorway that can be closed. Soliman pasha Al-Khadim mosque in Salah El-Din citadel in Cairo is considered the first mosque with ottoman architectural style. This Minbar exposed to aggressive human intervention by mosque workers and archaeological crafts unity-ministry of antiquities in Egypt, to lose more of its historical and architectural values. Now this Minbar undergoes restoration process, they are removing all modern pigments and remains of last reconstruction in 2014 so we proposed some Nano particles and Nano composites for Preservation of it. The study started with the characteristics of the historic architectural elements of Mibars and their joining structural mortars in order to risk assessment and to define the necessary characteristics of the intervention retrofitting new materials, which will be used in the ongoing preservation work of these stucco architectural elements. To achieve such, several analyses and laboratory tests like ultra-sonic pulse method testing and uniaxial compression test were carried out to determine their basic, physical and mechanical properties, along with the microstructural properties determination using Mercury porosimeter. On the other hand, the morphological description, petrography, mineralogical and microstructural properties were determined using scanning electron microscope equipped by EDS, transmission electron microscopy TEM, polarizing light microscopy, XRD and XRF. The results proved the superiority of the samples that have been strengthened by nano lime concentration of 2% with Wacker OH 100 concentration in 5%.

A Comparative Study on the Milling Speed for the Synthesis of Nano-Structured Al 6063 Alloy Powder by Mechanical Alloying

The present article reports on characterization studies performed on amorphized nanostructured Al 6063 alloy powder synthesized by mechanical alloying (MA). The as-milled powder was characterized by X-ray diffraction (XRD) for investigating the development of crystallite nature and determining the different phases of the materials present, scanning electron microscope (SEM) was used for in depth morphological study and High Resolution-transmission electron microscope (HR-TEM) was employed to ensure the development of a nano-structured nature of the Al 6063 matrix. In the present work alloyed powder was milled for 20 h and 40 h at 300 rpm;and 20 h at 700 rpm in a hardened stainless steel medium. Using Williamson-Hall equation;crystallite size, lattice strain and lattice parameter of Al 6063 nanostructure alloy powder was estimated with broadening of XRD peaks. XRD results showed that the crystallite size of Al 6063 alloy powder reached 32 and 53 nm after 20 h at 700 rpm and 40 h at 300 rpm respectively.

CL-20-NBC/Al球形复合物的制备及性能表征

针对六硝基六氮杂异伍兹烷(CL-20)安全性能差的问题,基于Pickering乳液法,将CL-20、Al两种高能组分进行复合,引入含能黏结剂硝化细菌纤维素(NBC)降低体系感度,制备了CL-20-NBC/Al球形复合物;研究了油水比、物料比、表面活性剂用量对乳液稳定性的影响;采用X-射线衍射(XRD)、扫描电镜(SEM)、差示扫描量热(DSC)对CL-20-NBC/Al复合物的结构、形貌、热性能等进行了表征。结果表明,Pickering乳液法制备的CL-20-NBC/Al复合物,控制油水体积比为4∶6、CL-20与NBC质量比为6∶4、表面活性剂用量为原料用量的10%时,能形成稳定的乳液体系;CL-20-NBC/Al复合物为规则的球形,表面光滑,粒径分布(D_(50))为27.4μm;与原料CL-20相比,CL-20-NBC/Al复合物的放热量提高了42%;特性落高由原料的13 cm升高到40 cm,摩擦感度爆炸概率由原料的100%降至88%,其机械安全性能得到较大幅度的提升。