添加尖晶石、方镁石和白云石的高铝耐火浇注料的常温机械性能

耐火浇注料的常温机械性能是耐火成分结构设计中选择合适的施工方法考虑的关键参数。本文通过添加合成尖晶石、方镁石和白云石三种途径制备的位于Al2O3-MgO—CaO三元相平衡图中富铝区域的高铝浇注料．研究了浇注料与其基质的两种机械性能,即分析了在不同热处理温度下的常温抗折强度和弹性模量。从室温到1000℃。耐火材料在单轴拉力和压力方式下,因为微裂纹网络的破坏显示出复杂的非线性应力-应变性能,大干1000℃时,由于短暂的液相出现,铝酸钙水泥相（如CA2、CA6）和自形成尖晶石相（含方镁石或白云石）结晶,耐火浇注料开始烧结,在更高的烧成温度下,烧结过程使得机械性能增强。     

Influence of Cold Low Pressure Lamination Parameters on the Joining of Low Temperature Co‐Fired Ceramics Green Tapes and Sintered Alumina Substrates

In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co‐fired Ceramics (LTCC) tapes have been produced via Cold Low Pressure Lamination which is based on adhesive tapes for joining of layers at room temperature and pressures <5 MPa. The influences of lamination parameters such as temperature, pressure, and time on the quality of the green and sintered multilayer stack have been determined. If the bottom LTCC layer of an alumina–LTCC–LTCC laminate is metallized by screen printing defects such as crack formation can occur due to stress formation caused by constrained sintering. By adapting the lamination parameters, these stresses can be avoided. Another defect observed is cavities which form along the printed circuit lines. This type of defect is caused by the shrinkage of the circuit line width during firing; by reducing the height of the conductor line during screen printing, the cavity size can be reduced. In addition, different screen‐printed metallization layouts have been tested to determine the influence of line and spaces on the quality of sintered laminates.     

Novel Monocyclam Derivatives as HIV Entry Inhibitors: Design,Synthesis, Anti‐HIV Evaluation,and Their Interaction with the CXCR4 Co‐receptor

The CXCR4 receptor has been shown to interact with the human immunodeficiency virus (HIV) envelope glycoprotein gp120, leading to fusion of viral and cell membranes. Therefore, ligands that can attach to this receptor represent an important class of therapeutic agents against HIV, thus inhibiting the first step in the cycle of viral infection: the virus–cell entry/fusion. Herein we describe the in silico design, synthesis, and biological evaluation of novel monocyclam derivatives as HIV entry inhibitors. In vitro activity testing of these compounds in cell cultures against HIV strains revealed EC₅₀ values in the low micromolar range without cytotoxicity at the concentrations tested. Docking and molecular dynamics simulations were performed to predict the binding interactions between CXCR4 and the novel monocyclam derivatives. A binding mode of these compounds is proposed which is consistent with the main existing site‐directed mutagenesis data on the CXCR4 co‐receptor. Moreover, molecular modeling comparisons were performed between these novel monocyclams, previously reported non‐cyclam compounds from which the monocyclams are derived, and the well‐known AMD3100 bicyclam CXCR4 inhibitors. Our results suggest that these three structurally diverse CXCR4 inhibitors bind to overlapping but not identical amino acid residues in the transmembrane regions of the receptor.     

Low‐Temperature Synthesis of Aluminum Nitride from Transition Alumina by Microwave Processing

Aluminum nitride (AlN) was synthesized by carbothermal reduction and nitridation method from a mixture of various transition alumina powders and carbon black using 2.45 GHz microwave irradiation in N₂ atmosphere. We achieved the synthesis of AlN at 1300–1400°C using 2.45 GHz microwave irradiation for 60 min. Our results suggest that θ‐Al₂O₃ is more easily nitrided than γ‐, δ‐, and α‐Al₂O₃. On the other hand, nitridation ratio of samples synthesized in a conventional furnace under nitrogen atmosphere were zero or very low. These results show that 2.45 GHz microwave irradiation enhanced the reduction and nitridation reaction of alumina.     

Manufacturing and Characterization of a Deformable Membrane with Integrated Temperature Sensors and Heating Structures in Low Temperature Co‐fired Ceramics

In this article, the challenging manufacturing process of a deformable mirror for the wave front correction of a high energy laser is described. During this process, the low temperature co‐fired ceramic (LTCC) membrane as the base component with integrated sensors must endure several postfire processes at temperatures of up to 900°C without any degradation of the sensors' characteristics. To optimize the sensors, various combinations of resistor and conductor pastes and different geometries are characterized. The usability and the performance of the sensor elements after temperature treatment are investigated by measuring the resistance and its resistance temperature characteristic.     

Low‐Temperature Rapid Synthesis of Rod‐Like ZrB2 Powders by Molten‐Salt and Microwave Co‐Assisted Carbothermal Reduction

A novel molten‐salt and microwave coassisted carbothermal reduction (termed as MSM‐CTR) method was developed to prepare ZrB₂ powders from raw materials of ZrO₂, B₄C, and amorphous carbon. The results indicated that the carbothermal reduction reaction for synthesizing ZrB₂ was initiated at the temperature as low as 1150°C, and phase pure ZrB₂ powders were obtained after only 20 min at 1200°C, which were significantly milder than that of the conventional CTR method as well as the modified CTR method even using active metal as additional reducing agents. More interestingly, the as‐obtained ZrB₂ powders consisted of well‐defined single‐crystalline nanorods, which had diameters of 40–80 nm and high aspect ratios of >10. These results demonstrated that the MSM‐CTR is a simple and efficient route for preparation of high‐quality ZrB₂ powders.     

Simulation Study of a Novel Process Co‐Producing Synthesis Gas and Light Olefins

There are abundant resources of heavy hydrocarbons worldwide, and their utilization is becoming more widespread as time progresses. The present paper proposes a process that combines coke gasification and heavy hydrocarbon pyrolysis, producing synthesis gas and light olefins. Simulation studies on the process are carried out by using Aspen Plus. The results show that the temperature of the gasification‐pyrolysis can be controlled by changing the feed rate of O₂ and steam. In addition, the coke jam problem can be solved by increasing the gasification‐pyrolysis temperature or residence time. The maximum amount of light olefins can be acquired by controlling the gasification‐pyrolysis residence time. More than 37 wt % heavy hydrocarbons are changed to synthesis gas with more than 15 wt % changed to light olefins in the case studied.     

High Stiffness Cellulose Fibers from Low Molecular Weight Microcrystalline Cellulose Solutions Using DMSO as Co‐Solvent with Ionic Liquid

There is a need to develop high‐performance cellulose fibers as sustainable replacements for glass fibers, and as alternative precursors for carbon filaments. Traditional fiber spinning uses toxic solvents, but in this study, by using dimethyl sulfoxide (DMSO) as a co‐solvent with an ionic liquid, a novel high‐performance fiber with exceptional mechanical properties is produced. This involves a one‐step dissolution, and cost‐effective route to convert high concentrations of low molecular weight microcrystalline cellulose into high stiffness cellulose fibers. As the cellulose concentration increases from 20.8 to 23.6 wt%, strong optically anisotropic patterns appear for cellulose solutions, and the clearing temperature (T _c) increases from ≈100 °C to above 105 °C. Highly aligned, stiff cellulose fibers are dry‐jet wet spun from 20.8 and 23.6 wt% cellulose/1‐ethyl‐3‐methylimidazolium diethyl phosphate/DMSO solutions, with a Young's modulus of up to ≈41 GPa. The significant alignment of cellulose chains along the fiber axis is confirmed by scanning electron microscopy, wide‐angle X‐ray diffraction, and powder X‐ray diffraction. This process presents a new route to convert high concentrations of low molecular weight cellulose into high stiffness fibers, while significantly reducing the processing time and cost.     

Synthesis of Alkyl‐Functionalized Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization of Epoxy Resins

Summary: An alkyl‐functionalized hyperbranched polymer, HBP(OH)–C16, was synthesized by partial modification with fatty acid of an aromatic‐aliphatic OH‐terminated hyperbranched polyester HBP? OH. This product was used as additive in the cationic photopolymerization of an epoxy resin. The alkyl‐modified polyester takes part in the photopolymerization process thanks to the residual OH groups by means of chain‐transfer reactions. An increase of the epoxy conversion is observed by increasing the amount of the HBP additive in the photocurable resin with a modification of the bulk properties of the final ultraviolet‐cured films. The presence of HBP(OH)–C16 induces an increase in glass transition temperature, thermal stability, and solvent resistance. Moreover the surface properties of the films are modified achieving highly hydrophobic surfaces in the presence of even very low amounts of HBP(OH)–C16.

Structure of HBP–C16.     

Sintering Behavior,Properties, and Applications of Co‐Fired Piezoelectric/Low Temperature Co‐Fired Ceramic (PZT‐SKN/LTCC) Multilayer Ceramics

Materials and processing conditions have been developed allowing co‐firing of fluxed PZT‐SKN materials with commercial low temperature co‐fired ceramic (LTCC) tapes. Previously, Pb(Zr_0.53, Ti_0.47)O₃–Sr(K_0.25, Nb_0.75)O₃ (PZT‐SKN) ceramics fluxed with 1 wt% LiBiO₂ and 1 wt% CuO addition were shown to sinter to high density at 900°C for 1 h, with a large d₃₃ piezoelectric coefficient of ~415 pm/V. Currently, the master sintering curve (MSC) approach has been used to study the densification behaviors of fluxed PZT‐SKN and LTCC tapes. Different sintering mechanisms for fluxed PZT‐SKN ceramics and LTCC materials are confirmed by analyzing the apparent activation energy (Q_a). Using knowledge gained from MSC results, an optimized sintering profile was developed. Multilayer PZT‐SKN/HL2000 (HeraLock^? Tape, Heraeus) stacks co‐fired at 900°C for 0.5 h maintain large piezoelectric coefficient (high field d₃₃ > 340 pm/V). EDS analysis reveal limited interdiffusion of Pb from PZT‐SKN layers in LTCC and the appearance of Al, Ca, and Si in the PZT‐SKN near the PZT‐SKN/LTCC interface. Further, elemental interdiffusion was not detected at the center of piezoelectric layer in PZT‐SKN/LTCC multilayer ceramics and no subsequent reduction in piezoelectric coefficient d₃₃ was observed. Finally, a piezoelectric microbalance with mass sensitivity of 150 kHz/mg was fabricated using the materials and methods developed.     

Productions of Ultra‐Fine Powders and Their Use in High Energetic Compositions

Fine and ultra‐fine powders are actively studied in pyrotechnics, explosives and propellants. The important questions are how to produce a powder with specified characteristics and how to use the powder produced.     

Synthesis and Characterization of Amorphous Nano‐Alumina Powders with High Surface Area for Biodiesel Production

Nano‐alumina powders containing yttrium oxide were synthesized via the sol‐gel method using aluminum chloride hexahydrate as catalyst precursor. Fourier transform infrared analysis showed the presence of Al‐O and Al‐O‐Al bands in the powder structure and X‐ray diffraction spectra proved that the alumina was in the amorphous phase. The amorphous nano‐alumina powders were shown to be mesoporous with a high surface area, and both spherical and slit‐shaped particles were found in the calcined powder. A high percentage of conversion of oil to biodiesel was obtained in the transesterification reaction and the synthesized nano‐alumina powders could be easily regenerated for further use. The amorphous nano‐alumina powder can thus be recommended for use as active catalyst in the transesterification reaction for biodiesel production on the industrial scale.     

Preliminary Model and Technology of Piezoelectric Low Temperature Co‐fired Ceramic (LTCC) Uniaxial Accelerometer

Design procedure, technology and basic properties of a piezoelectric Low Temperature Co‐fired Ceramics (LTCC) accelerometer are presented in this paper. The sensor consists of a LTCC membrane with a seismic mass. Meggitt InSensor^® PZT thick film has been applied as the sensing material. Finite element method (FEM) has been used to analyze the impact of the sensor geometry (membrane thickness, membrane and seismic mass radii) and PZT thick film placement on basic properties (sensitivity and bandwidth) of the device. The LTCC process was optimized in order to create thin and planar ceramic membrane with relatively huge seismic mass. Selected properties of the sensor have been measured and compared with the simulated ones.     

145 dtex/144 f高强低缩细旦熔体直纺涤纶FDY的研发

对影响生产145 dtex/144 f高强低缩细旦涤纶全拉伸丝(FDY)纤维的工艺条件进行了探讨和研究,当聚酯熔体特性黏度为0.65 dL/g、熔体输送温度为283~285℃、熔体冷却器温度为276~278℃、纺丝箱体温度为293℃、卷绕速度为4 200 m/min、热辊拉伸比为3.0、热定形温度为180℃时,能够稳定生产出断裂强度为4.8 cN/dtex、断裂伸长率为22%、沸水收缩率为3.1%的涤纶高强低缩细旦FDY,满足细分市场不同客户特定产品的需求。     

Rapid Densification of Nano-Grained Alumina by High Temperature and Pressure with a Very High Heating Rate

A novel method for producing full-dense nano-grained alumina was reported. The heat generated by the combustion reaction (or self-propagating high-temperature synthesis (SHS)) was applied to act as a heating source. An alumina compact was loaded inside the combustion reactants. After reaction, the temperature of the alumina compact was increased at a heating rate of 1600°C/min. A large mechanical pressure was applied, when the temperature reached the maximum. Two kinds of α-Al₂O₃ powders (200 and 600 nm) were used as the raw materials. The rapid densification process was performed within 2 min. Microstructure analysis indicated that the grains had no significant growth.     

Synthesis of Three Novel Laurylamine‐Derived Long‐Chain Alkyl Bonding Agents and Their Interactions with RDX

Three novel long‐chain alkyl bonding agents including 1,1′‐dodecylimino‐bis[3‐[bis(2‐hydroxyethyl)amino]‐2‐propanol (DHAP), 1‐acetyl‐5‐dodecyl‐octahydro‐1,5‐diazocine‐3,7‐diol (ADODD) and 1,3‐bis(dodecylimino)‐5,5‐dimethyl‐2,4‐imidazolidinedione (DDID) were synthesized by modification of laurylamine. Interaction energies between bonding agents and RDX were calculated and compared using the molecular dynamics method. Effects of coating by different bonding agents on characteristic absorption peaks of RDX were analyzed by micro‐infrared spectroscopy. The adhesion degrees of different bonding agents on the surface of RDX solid particles were calculated by XPS methods. The three prepared bonding agents were added to the HTPB/RDX/Al propellant and their effects on σ, ε_m, ε_b and Φ (the adhesion index between filling particles and binder matrix) value of propellant were studied. Simulation and experimental results showed that those three types of long‐chain alkyl bonding agents exhibit a strong interaction with RDX, with highest interaction potencial observed for DHAP, followed by DDID and ADODD. In addition, the current study demonstrated that results obtained by molecular dynamics simulation were in very good agreement with the experimental data.     

Synthesis and Characterization of Ethylene‐Bridged Copolycarbosilazane as Precursors for Silicon Carbonitride Ceramics

An ethylene‐bridged copolycarbosilazane precursor of copolysilylethylenediamine (co‐PSDA) is synthesized by polycondensation of ethylenediamine with the mixture of vinylmethyldichlorosilane and methyldichlorosilane in the presence of triethylamine as acid absorbing agent. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR, ¹H NMR and ¹³C NMR) spectral analysis of the as‐synthesized co‐PSDA suggests a structure of ethylene‐bridged polycarbosilazane having –Si–N–C–C–N– as backbone chain with –CH=CH₂, –H and –CH₃ attached to Si as side groups. Co‐PSDA can be cross‐linked at 80°C using 2, 2‐azobisisobutyronitrile as initiator through the polyaddition of the vinyl group and dehydrogenation/deamination of Si–H and N–H. Then the cross‐linked co‐PSDA precursor is pyrolyzed at 1000°C in argon, giving out amorphous silicon carbon nitride (SiCN) ceramics with a high ceramic yield of 76 wt%. The obtained SiCN ceramics consist of nitrogen‐rich silicon sites of SiN₄ as predominant component and some SiCN₃ sites, which should arise from the breaking of N–C bonds below 600°C and the formation of active N–Si bonds.     

Synthesis of CoFe2O4 Nanoparticles by a Low Temperature Microwave‐Assisted Ball‐Milling Technique

Well‐crystallized Cobalt ferrite nanoparticles with mean size of 20 nm and high saturation magnetization (82.9 emu/g) were synthesized at a low temperature (≤100°C) by microwave‐assisted solid–liquid reaction ball‐milling technique without subsequent calcination. CoC₂O₄·4H₂O and Fe powder were used as raw materials and stainless steel or pure iron milling balls with diameter of 1.5 mm were used. As a contrast, solid–liquid reaction ball milling without microwave assistance was also investigated. The results showed that this is a simple, environmentally friendly, and energy‐saving technique for ferrite nanocrystal synthesis.     

Simulation and Analysis of a Tubular Fixed‐Bed Fischer‐Tropsch Synthesis Reactor with Co‐Based Catalyst

A two‐dimensional pseudohomogeneous reactor model is proposed to simulate the performance of fixed‐bed Fischer‐Tropsch synthesis (FTS) reactors by lumped thought. A CO consumption kinetics equation and a carbon chain growth probability model were incorporated into the reactor model. The model equations discretized by a two‐dimensional orthogonal collocation method were solved by the Broyden method. Concentration and temperature profiles were obtained. The validity of the reactor model against the pilot plant test data was investigated. Satisfactory agreements between model prediction values and experiment results were obtained. Further simulations were carried out to investigate the effect of operating conditions on the reaction behavior of the fixed‐bed FTS reactor.     

First Synthesis of Benzotrifuroxan at Low Temperature: Unexpected Behavior of 5,7‐Dichloro‐4,6‐dinitrobenzo‐furoxan with Sodium Azide

Attempts to prepare 5‐chloro‐6‐nitrobenzodifuroxan from the reaction of 5,7‐dichloro‐4,6‐dinitrobenzofuroxan with sodium azide have failed and, surprisingly, the formation of the powerful hydrogen‐free explosive – benzotrifuroxan (BTF) through spontaneous cyclization at 0 °C was observed (yield: 75 %). Importantly, BTF was synthesized avoiding the isolation and the heating of the hazardous intermediate trinitro‐triazidobenzene. The structure of BTF was confirmed by IR spectroscopy, elemental analysis, and melting point measurement.