自反应性材料

英国Dugdale塑料公司开发出一系列负温度系数(NTC)PVC挤出型混合物,与普通的PVC材料相比,可生产出更薄、成本更低的电缆护套。此外,Dugdale塑料公司开发的CT99/127品级材料,制成电缆护套热感点系统的一部分,当它检测到有危险情况时能帮助关闭电力系统。

毁伤增强型破片探索研究

为提高破片式防空武器的毁伤效能,对毁伤增强型材料进行了探索研究,并设计制备了一种Φ10mm×10mm的铝/聚四氟乙烯毁伤增强型破片。毁伤性试验表明该破片除具有对目标的动能打击外,还具有爆炸、冲击超压、高温作用、纵火等复合毁伤打击,其毁伤性明显优于同尺寸的钢破片,其化学潜能是动能的12.4倍。

炸药发展中的新技术

介绍了炸药科学在高能量密度化合物、金属化炸药、复合炸药、新型高分子粘结剂应用、反应性材料和纳米技术应用等方面的新技术和新进展 ,总结了目前炸药研究和应用中采用的一些新思路 ,并对我国炸药技术的发展提出了建议。

Microstructure and interface thermal stability of C/Mo double-coated SiC fiber reinforced γ-TiAl matrix composites

C/Mo duplex coating interfacially modified SiC fiber-reinforced γ-TiAl matrix composite （SiCf/C/Mo/γ-TiA1） was prepared by foil-fiber-foil method to investigate its interfacial modification effect. SiCf/C/TiAl composites were also prepared under the same processing condition for comparision. Both kinds of the composites were thermally exposed in vacuum at 800 and 900℃ for different durations in order to study thermal stability of the interfacial zone. With the aids of scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）, the interracial microstructures of the composites were investigated. The results reveal that, although adding the Mo coating, the interfacial reaction product of the SiCf/C/Mo/TiAl composite is the same with that of the SiCf/C/TiA1 composite, which is TiC/Ti2AlC between the coating and the matrix. However, C/Mo duplex coating is more efficient in hindering interfacial reaction than C single coating at 900 ℃ and below. In addition, a new layer of interfacial reaction product was found between Ti2AlC and the matrix after 900 ℃, 200 h thermal exposure, which is rich in V and close to the chemical composition of B2 phase.

Unusual Charge Transport and Spin Response of Doped Bilayer Triangular Antiferromagnets

Within the t-J model, the charge transport and spin response of the doped bilayer triangular antiferromagnetare studied by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in theelectronic structure, the qualitative behaviors of the physical properties are the same as in the single layer case. Theconductivity spectrum shows the low-energy peak and unusual midinfrared band, the temperature-dependent resistivityis characterized by the nonlinearity metallic-like behavior in the higher temperature range and the deviation from themetallic-like behavior in the lower temperature range and the commensurate neutron scattering peak near the half-fillingis split into six incommensurate peaks in the underdoped regime, with the incommensurability increasing with the holeconcentration at lower dopings, and saturating at higher dopings.

Hydrogenation reaction characteristics and properties of its hydrides for magnetic regenerative material HoCu_2

The hydrogenation reaction characteristics and the properties of its hydrides for the magnetic regenerative material HoCu_2(CeCu_2-type) of a cryocooler were investigated. The XRD testing reveals that the hydrides of HoCu_2 were a mixture of Cu, unknown hydride Ⅰ, and unknown hydride Ⅱ. Based on the PCT(pressure-concentration-temperature) curves under different reaction temperatures, the relationships among reaction temperature, equilibrium pressure, and maximum hydrogen absorption capacity were analyzed and discussed. The enthalpy change ΔH and entropy change ΔS as a result of the whole hydrogenation process were also calculated from the PCT curves. The magnetization and volumetric specific heat capacity of the hydride were also measured by SQUID magnetometer and PPMS, respectively.

Mechanism of Clay Mineral Affect on Strength of Solidification Sludge

To solve the problem of vast cement and low strength in the treated sludge, clay mineral used for accessorial solidification material was applied to advance strength. The principle of solidification sludge strength because of clay mineral is not clear and has not supported the choice of clay mineral. The mineral and pore water is analyzed in order to contrast clay mineral added or not based on the XRD and pore water chemical character. The result shows that the absorbed quantity of Ca2~ was reduced by sludge because of clay mineral added, the hydrated reaction was advanced and integrated solidified materials was formed.

新型膜胶一体化太阳能电池背板与氟碳涂料

以羟基反应性功能氟材料为主要原料并辅以等离子体表面修饰技术和流延切线涂覆技术得到了一种新型膜胶一体化太阳能电池背板。与传统的多层复膜型背板不同,膜胶一体化背板完全整合了氟膜层和胶层,使之不再有分界面,从而大大降低了背板在应用中出现自身分层(层间剥离)的几率。等离子体表面修饰技术的应用不仅可以显著改进氟层(膜胶整合层)与基材之间的界面情况,增加它们之间的相容性,使膜胶整合层与基材的结合更趋完美、粘接更为牢固,而且还能赋予背板特殊的表面性能,使背板与EVA之间具有长期的绝佳粘接性能。

Effect of graphene on mechanical properties of cement mortars

Functionalized graphene nano-sheets(FGN) of 0.01%-0.05%(mass fraction) were added to produce FGN-cement composites in the form of mortars. Flow properties, mechanical properties and microstructure of the cementitious material were then investigated. The results indicate that the addition of FGN decreases the fluidity slightly and improves mechanical properties of cement-based composites significantly. The highest strength is obtained with FGN content of 0.02% where the flexural strength and compressive strength at 28 days are 12.917 MPa and 52.42 MPa, respectively. Besides, scanning electron micrographs show that FGN can regulate formation of massive compact cross-linking structures and thermo gravimetric analysis indicates that FGN can accelerate the hydration reaction to increase the function of the composite effectively.

High-temperature thermal stability of C/C−ZrC−SiC composites via region labeling method

To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method,the high-temperature thermal stability of the composites was systematically studied by changing the temperature and holding time of thermal treatment.Results show that the mass loss rate of low Si composites has a growth trend with increasing temperature,and a crystal transformation from β-SiC toα-SiC occurs in the composites.In the calibrated area,SiC phase experiences Ostwald ripening and volume change with location migration,while ZrC phase experiences a re-sintering process with diffusion.Moreover,it is found that increasing temperature has a more obvious effect on the thermal stability than extending holding time,which is mainly attributed to the faster diffusion rate of atoms.

Effects of homogeneous-heterogeneous reactions in flow of Powell-Eyring fluid

The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced to the ordinary differential equations by similarity transformations. The analytic solutions are presented in series forms by homotopy analysis method(HAM). Convergence of the obtained series solutions is explicitly discussed. The physical significance of different parameters on the velocity and concentration profiles is discussed through graphical illustrations. It is noticed that the boundary layer thickness increases by increasing the Powell-Eyring fluid material parameter(ε) whereas it decreases by increasing the fluid material parameter(δ). Further, the concentration profile increases when Powell-Eyring fluid material parameters increase. The concentration is also an increasing function of Schmidt number and decreasing function of strength of homogeneous reaction. Also mass transfer rate increases for larger rate of heterogeneous reaction.

Preparation and Characterization of Polyimide Attached with Azo-dye Chromophore Side Chain

In order to improve the nonlinear optical property and stability of azo-dye chromophore, the nonlinear optical polyimide (NLOPI) attached with azo chromophore side chain is synthesized by diazo coupling reaction of 4-nitrobenzenediazonium tetrafloroborate. The designed chemical structure of production can be proved in the infrared spectrum and ultraviolet-visible absorption spectrum. The NLOPI exhibited UV-Vis absorption of the azobenzene chromophore in the vicinity of the wavelengths of 330 and 490 nm. The broad amorphous peak proved that the NLOPI was amorphous with a little periodical structure along the side chain. According to transmission electron microscope, the NLOPI film was homogeneous. NLOPI only displayed a decrease in mass of about 5% at the temperature of 400 ℃ through thermogravimetric analysis.

Non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends

The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry(DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature(T onset) and crystallization peak temperature(T p) decrease with the increase of the content of reactive microgel, while ΔT(T onset–T p), the crystallization half-time(t1/2) and the crystallization enthalpy(ΔH c) increase. The required cooling rates of blends are higher than that of neat nylon6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity(X t) reaches the maximum.

Thorium and Its Future Importance for Nuclear Energy Generation

Thorium was discovered in 1828 by the Swedish chemist Jons J. Berzelius. Despite some advantages over uranium for use in nuclear reactors, its main use, in the almost two centuries since its discovery, thorium was restricted to use for gas mantles, especially in the early 20th century. In the beginning of the nuclear era, many countries had interested on thorium, particularly during the 1950-1970 period. There are about 435 nuclear reactors in the world nowadays. They need more than 65,000 tons of uranium yearly. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, there will be a significant increasing in the uranium prices occur, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Thorium is nearly three times more abundant than uranium in the Earth＇s crust. Despite thorium is not a fissile material, ^232Th can be converted to ^233U （fissile） more efficiently than ^238U to ^239pu. Besides this, since it is possible to convert thorium waste into non-radioactive elements, thorium is an environment-friendly alternative energy source. Thorium fuel cycle is also inherently resistant to proliferation. Some papers evaluate the thorium resources in Brazil over 1,200,000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. In this paper a brief history of thorium is presented, besides a review of the world thorium utilization and a discussion about advantages and restrictions of thorium use.

Strengthen Vanadium Alloy by Aging and Its Thermal Stability

V-4Cr-4Ti is the leading candidate vanadium alloy for fusion applications as structural material of first wall and blanket. Due to the interaction between Ti and interstitial solutes of C, N, and O, precipitation occurs at elevated temperature. The behavior has been studied in the past few years by short time annealing and results showed that it may greatly affect its mechanical properties Ti-CON type precipitates, appearing at- 700℃ in the solid-solution annealed alloy in high number density and small size, strengthen the alloy significantly and reduce its ductility. As the ductility reduction is in an acceptable level, the strengthening might be utilized for a light and strong vanadium alloy structure. Before a conclusion, uncertainty of its thermal stability should be studied during the high temperature serves. Besides, seldom has been studied for the effect of long time aging on precipitation behavior and tensile properties of the alloy.

Effective enhancement of electrochemical energy storage of cobalt-based nanocrystals by hybridization with nitrogen-doped carbon nanocages

Cobalt-based oxygenic compounds Co(OH)2,CoO and Co3 O4 are attractive for electrochemical energy storage owing to their high theoretical capacities and pseudocapacitive properties.Despite the great efforts to their compositional and morphological regulations,the performances to date are still quite limited owing to the low active surface area and sluggish charge transfer kinetics.Herein,different Co-based nanocrystals(Co-NCs)were conveniently anchored on the hierarchical nitrogen-doped carbon nanocages(hNCNCs)with high specific surface area and coexisting micro-meso-macropores to decrease the size and facilitate the charge transfer.Accordingly,a high specific capacity of1170 Fg^-1 is achieved at 2 Ag^-1 for the Co(OH)2/hNCNCs hybrid,in which the capacitance of Co(OH)2(2214 F gco(OH)2)is approaching to its theoretical maximum(2595 Fg^-1),demonstrating the high utilization of active materials by the hybridization with N-doped nanocarbons.This study also reveals that these Co-NCs store/release electrical energy via the same reversible redox reaction despite their different pristine compositions.This insight on the energy storage of Co-based nanomaterials suggests that the commonly-employed transformation of the Co-NCs from Co(OH)2 to CoO and Co3 O4 on carbon supports is unnecessary and even could be harmful to the energy storage performance.The result is instructive to develop high-energy-density electrodes from transition metal compounds.

A mini review of NiFe-based materials as highly active oxygen evolution reaction electrocatalysts

Oxygen evolution reaction （OER） electrolysis, as an important reaction involved in water splitting and rechargeable metal-air batteries, has attracted increasing attention for clean energy generation and efficient energy storage. Nickel/iron （NiFe）-based compounds have been known as active OER catalysts since the last century, and renewed interest has been witnessed in recent years on developing advanced NiFe-based materials for better activity and stability. In this review, we present the early discovery and recent progress on NiFe-based OER electrocatalysts in terms of chemical properties, synthetic methodologies and catalytic performances. The advantages and disadvantages of each class of NiFe-based compounds are summarized, including NiFe alloys, electrodeposited films and layered double hydroxide nanoplates. Some mechanistic studies of the active phase of NiFe-based compounds are introduced and discussed to give insight into the nature of active catalytic sites, which could facilitate further improving NiFe based OER electrocatalysts. Finally, some applications of NiFe- based compounds for OER are described, including the development of an electrolyzer operating with a single AAA battery with voltage below 1.5 V and high performance rechargeable Zn-air batteries.

One-step scalable preparation of N-doped nanoporous carbon as a high-performance electrocatalyst for the oxygen reduction reaction

N-doped porous carbon materials have been prepared by a simple one-step pyrolysis of ethylenediaminetetraacetic acid （EDTA） and melamine in the presence of KOH and Co（NO3）2·6H20. The combination of the high specific area （1,485 m2.g-l）, high nitrogen content （10.8%） and suitable graphitic degree results in catalysts exhibiting high activity （with onset and half-wave potentials of 0.88 and 0.79 V vs the reversible hydrogen electrode （RHE）, respectively） and four-electron selectivity for the oxygen reduction reaction （ORR） in alkaline medium---comparable to a commercial Pt/C catalyst, but far exceeding Pt/C in stability and durability. Owing to their superb ORR performance, low cost and facile preparation, the catalysts have great potential applications in fuel cells, metal-air batteries, and ORR-related electrochemical industries.

Intrinsically inert hyperbranched interlayer for enhanced stability of organic solar cells

Device stability becomes one of the most crucial issues for the commercialization of organic solar cells(OSCs) after high power conversion efficiencies have been achieved. Besides the intrinsic stability of photoactive materials, the chemical/catalytic reaction between interfacial materials and photoactive materials is another critical factor that determines the stability of OSC devices. Herein, we design and synthesize a reaction-inert rylene diimide-embedded hyperbranched polymer named as PDIEIE, which effectively reduces the work function of indium tin oxide electrode from 4.62 to 3.65 eV. Meanwhile, PDIEIE shows negligible chemical reaction with high-performance photoactive materials and no catalytic effect under strong ultraviolet illumination, resulting in much better photo-stability of OSCs with PDIEIE cathode interlayer(CIL), relative to the traditional CILs, including most-widely used metal oxides and polyethyleneimine derivatives.

Application of hierarchically porous metal-organic frameworks in heterogeneous catalysis:A review

Hierarchically porous metal-organic frameworks(H-MOFs)with micro-,meso-and macropores have emerged as a popular class of crystalline porous materials that have attracted extensive interests,and they have been studied in diverse applications,especially in heterogeneous catalysis.The hierarchical structures enable sufficient diffusion and accessibility to the active sites of the molecules and permit the encapsulation of catalytic guest molecules to exploit more possibilities with enhanced catalytic performance.In this review,we have summarized the recent representative developments of H-MOFs in the field of heterogeneous catalysis,which includes oxidation reaction,hydrogenation reaction,and condensation reaction.Emphasis is placed on the multiple functions of hierarchical structures,and the catalytic activity,selectivity,stability,recyclability,etc.of the industrial utility of H-MOFs.Finally,the prospects and challenges of H-MOFs in heterogeneous catalysis and the remaining issues in this field are presented.