高性能聚丙烯腈基碳纤维工程化研制及应用进展

概述了西安康本材料公司高性能聚丙烯腈(PAN)基碳纤维工程化研制及应用进展情况。结果表明:在碳纤维方面,该公司在国产碳纤维原丝制造技术及碳纤维韧性提高方面都具有专有技术和独到之处;碳纤维主要性能指标达到了T300级水平,实现了1k和3k军工用小丝束碳纤维的连续稳定化生产和批量供货。在碳纤维复合材料应用方面,采用该公司碳纤维研制的碳/碳复合材料喉衬和碳纤维/酚醛树脂基扩张段,已成功地通过了固体火箭发动机(SRM)热试车试验考核,奠定了耐烧蚀材料方面的军工应用基础。目前3k碳纤维抗拉强度已达到4 500 MPa以上,实现了T400级的技术突破,正在以SRM壳体结构复合材料应用为目标,进行T700级高性能6k和12k碳纤维的攻关研制及应用试验。

Determination of Structure and Polarity of Si C Single Crystal by X-Ray Diffraction Technique

Structure and polarity of the Si C single crystal have been analyzed with the four- circle X- ray diffraction method by a double- crystal diffractom eter.The hexagonal{ 10 15 } pole figure shows that this Si C sam ple has a6 H modification.The difference between the integrated intensities m easured byω scan in the triple- axis diffraction set- up finds some convincing evidence that the surface is either a Si- terminated face or C- terminated face.The experi- mental ratios of| F( 0 0 0 L) | 2 / | F( 0 0 0 L) | 2 are in good agreem entwith the calculated ones after the dispersion cor- rections to the atomic scattering factors( L=6 ,12 and18,respectively) .Thus,this m easurem ent technique is con- venient for the application of the materials with remarkable surface polarity.

Support effect of zinc tin oxide on gold catalyst for CO oxidation reaction

Nanostructured gold catalyst supported on metal oxide is highly active for the CO oxidation reac‐tion. In this work, a new type of oxide support, zinc tin oxide, has been used to deposit 0.7 wt%Au via a deposition‐precipitation method. The textural properties of Zn2SnO4 support have been tuned by varying the molar ratio between base （N2H4＆#183;H2O） and metal ion （Zn2＋） to be 4/1, 8/1 and 16/1. The catalytic tests for CO oxidation reaction revealed that the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ = 8/1 was the highest, while the reactivity on Au‐Zn2SnO4 with N2H4＆#183;H2O/Zn2＋ =16/1 was almost identical to that of the pure support. Both fresh and used catalysts have been characterized by multiple techniques including nitrogen adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, high‐angle annular dark‐field scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray adsorption fine structure, and tempera‐ture‐programmed reduction by hydrogen. These demonstrated that the textural properties, espe‐cially pore volume and pore size distribution, of Zn2SnO4 play crucial roles in the averaged size of gold nanoparticles, and thus determine the catalytic activity of Au‐Zn2SnO4 for CO oxidation.

An efficient strategy for photocatalytic hydrogen peroxide production over oxygen-enriched graphitic carbon nitride with sodium phosphate

Photocatalytic hydrogen peroxide(H_(2)O_(2))production is a promising strategy to replace the traditional production processes;however,the inefficient H_(2)O_(2) productivity limits its application.In this study,oxygen-rich g-C_(3)N_(4) with abundant nitrogen vacancies(OCN)was synthesized for photocatalytic H_(2)O_(2) production.X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that oxygen-containing functional groups(–COOH and C–O–C)were obtained.Electron paramagnetic resonance confirmed the successful introduction of nitrogen vacancies.OCN exhibited efficient photocatalytic H_(2)O_(2) production performance of 1965μmol L^(−1) h^(−1) in air under visible-light irradiation.The high H_(2)O_(2) production was attributed to the enhanced adsorption of oxygen,enlarged specific surface area,and promoted carrier separation.An increased H_(2)O_(2) production rate(5781μmol L^(−1) h^(−1))was achieved in a Na_(3)PO_(4) solution.The improved performance was attributed to the changed reactive oxygen species.Specifically,the adsorbed PO_(4)^(3−) on the surface of the OCN promoted the transfer of holes to the catalyst surface.•O_(2)−obtained by O_(2) reduction reacted with adjacent holes to generate 1O_(2),which could efficiently generate H_(2)O_(2) with isopropanol.Additionally,PO_(4)^(3−),as a stabilizer,inhibited the decomposition of H_(2)O_(2).

Superior activity of Rh1/ZnO single-atom catalyst for CO oxidation

CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom catalysts(SACs)can maximize the metal atom efficiency.Herein,ZnO nanowire(ZnO-nw)supported Rh,Au,and Pt SACs were successfully developed to investigate their CO oxidation performance.Interestingly,it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation.In addition,the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons.The high activity and stability make Rh1/ZnO-nw promising for practical applications,especially in the automotive exhaust emission control.Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.

Effect of Mo_2C on electrochemical corrosion behavior of Ti(C,N)-based cermets

The electrochemical corrosion behavior of Ti（C,N）-based cermets with different Mo2C additions was investigated in freely aerated 10% H2SO4 and potentiodynamic polarization of all the materials was conducted from -0.5 to 1.5 V. There are two passive regions for all polarization curves. The first should be attributed to passive film formation due to Ti（C,N）, while the second may be due to the presence of Ni. Corrosion current density increases with M02C content increasing, from 2.06×10^-3 to 6.70×10^-3 mA/cm2. It is indicated that the corrosion resistance of Ti（C,N）-based cermets decreases with the increase of Mo2C addition. A skeleton of Ti（C,N） gains is observed after dissolution of Ni. The inner rim of cermets, rich in Mo2C, is corroded along with Ni binder and is more serious with the increase of Mo2C content. The secondary carbide Mo2C can be oxidized and dissolved in sulphuric acid.

In situ studies on ceria promoted cobalt oxide for CO oxidation

In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.

Measurement and analysis of polarization curves of mild steel in sodium carbonate/bicarbonate solution under erosion-corrosion conditions

The polarization curves of mild steel in de-aerated 0.5 mol NaHCO 3+0.5 mol Na 2CO 3 solution with and without erodent particles of 300 g/L of 100 μm alumina have been measured using a rotating cylinder electrode (RCE) apparatus over the range of rotation speeds from 0 to 4 000 r/min. The results show that the mild steel in the de-aerated slurry exhibits classical active/passive polarization behavior. The speed of cylinder rotation has a great effect in the presence of particles on the active dissolution current density. The erosion-corrosion process is severely erosion-dominated for the mild steel. However, the poor corrosion resistance of the mild steel in such turbulent slurries is also significant, especially at lower than 4 m/s.

Microstructure and hydrogen storage properties of as-cast and rapidly solidified Ti-rich Ti-V alloys

The goal of the present work was to optimize the phase-structural composition and microstructure of binary Ti0.8-0.9V0.2-0.1 alloys with respect to their hydrogen sorption properties. Application of these alloys is for hydrogen absorption from gaseous mixtures containing substantial amounts of carbon monoxide （CO） at high temperatures. Irrespective of alloy composition, both α（HCP） and β（BCC） phases in Ti0.8-0.9V0.2-0.1 formed single phase FCC hydrides upon hydrogenation in pure H2. An in situ synchrotron X-ray diffraction study showed that only the β-phase transformed to the corresponding hydride when the alloy was hydrogenated in a mixture of H2＋10%CO. Rapid solidification （RS） of the alloy resulted in refined grain sizes both in the Ti0.8V0.2 and Ti0.9V0.1 alloys. Furthermore, RS was found to increase the β-phase fraction in Ti0.9V0.1, being twice larger than that of the as-cast alloy. Ti0.9V0.1 had a platelike microstructure as observed by scanning electron microscopy （SEM）, the plates were about 300 nm thick. The microstructure refinement resulted in a faster kinetics of H desorption as observed by temperature desorption spectroscopy （TDS）.

Prediction on adsorption ratio of carbon dioxide to methane on coals with multiple linear regression

The multiple linear regression equations for adsorption ratio of CO2/CH4 and its coal quality indexes were built with SPSS software on basis of existing coal quality data and its adsorption amount of CO2 and OH4. The regression equations built were tested with data collected from some s, and the influences of coal quality indexes on adsorption ratio of CO2/CH4 were studied with investigation of regression equations. The study results show that the regression equation for adsorption ratio of CO2/CH4 and volatile matter, ash and moisture in coal can be obtained with multiple linear regression analysis, that the influence of same coal quality index with the degree of metamorphosis or influence of coal quality indexes for same coal rank on adsorption ratio is not consistent.

Discussion on the Mode of China's Low-carbon Society and Construction Routes

In responding to global climate change,the idea of low-carbon economy emerges as the times require.Developing low-carbon economy is based on the construction of low-carbon society.The so called "two-orientation society"(resources conservation orientated society and environmental friendly orientated society) is the concrete representation of low-carbon society with Chinese characteristics,and an actual action for China in developing low-carbon economy.Based on urban agglomeration,the paper discusses the meaning of and the route to low-carbon society which would better reflect the intrinsic requirements of such a society.

A Fully Flexible Potential Model for Carbon Dioxide

A fully flexible potential model for carbon dioxide has been developed to predict the vapor-liquid coexistence properties using the NVT-Gibbs ensemble Monte Carlo technique(GEMC).The average absolute deviation between our simulation and the literature experimental data for saturated liquid and vapor densities is 0.3% and 2.0%,respectively.Compared with the experimental data,our calculated results of critical properties(7.39 MPa,304.04 K,and 0.4679 g?cm-3) are acceptable and are better than those from the rescaling the potential parameters of elementary physical model(EPM2).The agreement of our simulated densities of supercritical carbon dioxide with the experimental data is acceptable in a wide range of pressure and temperature.The radial distribution function estimated at the supercritical conditions suggests that the carbon dioxide is a nonlinear molecule with the C O bond length of 0.117 nm and the O C O bond angle of 176.4°,which are consistent with Car-Parrinello molecular-dynamics(CPMD),whereas the EPM2 model shows large deviation at supercritical state.The predicted self-diffusion coefficients are in agreement with the experiments.

Artificial Neural Network Model of Hydrocarbon Migration and Accumulation

Based on the dynamic simulation of the 3 D structure the sedimentary modeling, the unit entity model has been adopted to transfer the heterogeneous complex passage system into limited simple homogeneous entity, and then the traditional dynamic simulation has been used to calculate the phase and the drive forces of the hydrocarbon , and the artificial neural network(ANN) technology has been applied to resolve such problems as the direction, velocity and quantity of the hydrocarbon migration among the unit entities. Through simulating of petroleum migration and accumulation in Zhu Ⅲ depression, the complex mechanism of hydrocarbon migration and accumulation has been opened out.

Photoluminescence origin of nanocrystalline SiC films

The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes （111） substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared （FIR） absorption spectra and the X-ray diffraction （XRD） analysis. Measurement of photoluminescence （PL） of the nanocrystalline SiC （nc-SiC） films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap. The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.

Conservation of Leaves of a Medicinal Plant of Western Algeria （Pistacia atlantica）

In our context, and in the goal to valorize the Pistacia atlantica species Desfthat grows spontaneously in Algeria occidental except the coastline, and that is used by the nomadic populations in their daily consumptions, we are thinking about drying its leaves. Here, the biochemical analysis of dried leaves ofPistacia atlantica is determined, the sorption is other ms are of great importance in the food industry, especially in the drying; the sorption isotherms of pistachio leaves were measured by the gravimetric method at three temperatures 40, 50 and 60 ℃. The equilibrium was achieved after eight days for desorption and seven days for adsorption with water activity ranging from 5% to 90%. Only the GAB and Peleg models were found to be the most suitable for describing the sorption curves. The isosteric heat of sorption of Pistacia atlantica leaves decreases with an increase in moisture content and was found to be an exponential function of moisture content for adsorption and desorption. The pistachio leaves could be considered as a rich natural source of valuable nutriments （carbohydrates, proteins and lipids）; lipid fraction is equal to 2.25%; proteins are the second macronutriment that predominates in these sheets： 4.35%; accordingly carbohydrates content was about 25.77%.

Wet friction performance of C/C-SiC composites prepared by new processing route

C/C-SiC composites with SiC island distribution Were prepared via a new processing route. The fabrication process mainly included silicon infiltration by ultrasonic vibration, chemical vapor deposition （CVD）, siliconizing, liquid phase impregnation and carbonization. The wear and friction properties were tested by an MM-1000 wet friction machine. The results show that SiC phases are mainly distributed between carbon fibers and pyrocarbons as well as among the pryoearbons. The dynamic friction coefficient of the composites decreases gradually from 0.126 to 0.088 with the increase of the surface pressure from 0.5 to 2.5 MPa at the same rotary speed. Furthermore, under the constant surface pressure, the dynamic friction coefficient increases from 0.114 to 0.126 with the increase of the rotary speed from 1 500 to 2 500 r/min. However, the coefficient decreases to 0.104 when the rotary speed exceeds 4 500 r/min. During the friction process, the friction coefficient of C/C-SiC composite is between 0.088 and 0.126, and the wear value is zero after 300 times brake testing.

Enhanced visible-light-driven photocatalytic activities of 0D/1D heterojunction carbon quantum dot modified CdS nanowires

Zero‐dimensional carbon dots(0D C‐dots)and one‐dimensional sulfide cadmium nanowires(1D CdS NWs)were prepared by microwave and solvothermal methods,respectively.A series of heterogeneous photocatalysts that consisted of 1D CdS NWs that were modified with 0D C‐dots(C‐dots/CdS NWs)were synthesized using chemical deposition methods.The mass fraction of C‐dots to CdS NWs in these photocatalysts was varied.The photocatalysts were characterized using X‐ray diffraction,scanning electron microscopy,transmission electron microscopy,X‐ray photoelectron spectroscopy,and ultraviolet‐visible spectroscopy.Their photocatalytic performance for the spitting of water and the degradation of rhodamine B(RhB)under visible light irradiation were investigated.The photocatalytic performance of the C‐dots/CdS NWs was enhanced when compared with that of the pure CdS NWs,with the 0.4%C‐dots/CdS NWs exhibiting the highest photocatalytic activity for the splitting of water and the degradation of RhB.The enhanced photocatalytic activity was attributed to a higher carrier density because of the heterojunction between the C‐dots and CdS NWs.This heterojunction improved the electronic transmission capacity and promoted efficient separation of photogenerated electrons and holes.

Study on structural and compositional transitions of coal ash by using NMR

Structural and compositional transitions of Datong coal ash and its CaCO3 additional effects were carefully exam- ined at a temperature range of 300 to 1 600℃ by using XRD and solid state NMR. The quantitative estimation of amorphous structures of ashes can be successfully obtained through the analyses of solid state NMR spectra. Viscosity of molten ash and its changes with CaCO3 addition were also evaluated up to 1 700 ℃ by using a rotary type viscometer. Glasses with poor crystalline and amorphous phase were continuously formed through the eutectic reaction of silica above fusing temperature （FT〉1 500 ℃） that caused broadening and shift of 29Si and 27A1 peaks in NMR results. With the additional amount of CaCO3 increasing, the peaks shifted to downfield obviously; the fraction of Si（OA1）0（OSi）4 decreased, while that of Si（OA1）l（OSi）l at 84.3 x 10-6 increased apparently. These transitions indicated the destruction of large alumina-silicate framework into small segments by the addition of Ca ion.

Porosity Estimation from Compressional Wave Velocity： A Study Based on Egyptian Carbonate Samples

The porosity of a rock is one of the most important reservoir properties. It controls the reservoir storage capacity. In other words, porosity quantifies the amount of fluids that the rock can store. Most of the world＇s giant fields produce hydrocarbons from carbonate reservoirs. Carbonate rocks contain more than 50% of the world＇s hydrocarbon reserves. Porosity and compressional wave velocity of 41 carbonate samples were determined under ambient conditions in laboratory. The samples were collected from seven shallow wells in west Tushka area, south Western Desert, Egypt. This paper evaluates the well known Wyllie and Raymer equations, an empirical linear equation, and a generalized model for porosity estimation from compressional wave velocity of saturated carbonate samples. Based on the comparison of the predicting identified to provide the most reliable porosity estimation. qualities, the Raymer equation and the empirical linear equation were

Near Ambient Pressure Adsorption of Nickel Carbonyl Contaminated CO on Cu(111) Surface

Formation of volatile nickel carbonyls with CO in catalytic reaction is one of the mechanisms of catalyst deactivation. CO is one of the most popular probe molecules to study the surface properties in model catalysis. Under ultra-high vacuum (UHV) conditions, the problem of nickel carbonyl impurity almost does not exist in the case that a high purity of CO is used directly. While in the near ambient pressure (NAP) range, nickel carbonyl is easily found on the surface by passing through the Ni containing tubes. Here, the NAP techniques such as NAP-X-ray photoelectron spectroscopy and NAP-scanning tunneling microscopy are used to study the adsorption of nickel carbonyl contaminated CO gas on Cu(111) surface in UHV and NAP conditions. By controlling the pressure of contaminated CO, the Ni-Cu bimetallic catalyst can form on Cu(111) surface. Furthermore, we investigate the process of CO adsorption and dissociation on the formed Ni-Cu bi-metal surface, and several high-pressure phases of CO structures are reported. This work contributes to understanding the interaction of nickel carbonyl with Cu(111) at room temperature, and reminds the consideration of CO molecules contaminated by nickel carbonyl especially in the NAP range study.