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Preparing conductive composite bipolar plates for fuel cells by compression molding or injection molding is a promising research direction. The very key point is how to meet the requirement of conductivity and mechanical properties. Conductive composites containing either one kind of the same size conductive fillers or two kinds of the different size conductive fillers were prepared and their conductivity and flexural strength were also investigated. The results show that the conductivity of composites containing one kind of the same size conductive fillers improves but the flexural strength of composites decreases with the increase of the filler size. The conductivity and flexural strength of composites containing two kinds of the different size conductive fillers are higher than that of composites containing only one kind of the large size conductive filler (>90μm) in the appropriate proportion to the small size filler in the conductive fillers. However, the flexural strength of conductive composites containing two kinds of the different size conductive fillers is always lower than that of composites using only one kind of the small size conductive fillers (

Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate (TEOS) in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR,TG-DSC and tensile strength. The results show that the silicon oxide is compatible with the Nafion membrane and the thermo stability of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. Furthermore, the tensile strength of Nafion/Silicon oxide composite membrane is similar to that of the Nafion membrane. The proton conductivity of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. When the Nafion/Silicon oxide composite membrane was employed as an electrolyte in H2/O2 PEMFC, a higher current density value (1 000 mA/cm2 at 0.38 V) than that of the Nafion1135 membrane (100 mA/cm2 at 0.04 V) was obtained at 110 °C.

A new composite bipolar plate was fabricated by compression molding technique using polyvinylidene fluoride (PVDF) as binder and titanium silicon carbide (Ti 3 SiC 2 ) as conductive filler. The effects of Ti 3 SiC 2 content, the particle size of Ti 3 SiC 2 , the mould pressure and mould pressing time on the electrical conductivity and the flexural strength of the conductive composite are discussed. The electrical conductivity and flexural strength of the composite bipolar plate with 80 wt.% Ti 3 SiC 2 content, prepared with a mould pressure of 10 MPa for 10 min, was 28.83 S cm −1 and 24.92 MPa, respectively, and can be improved by optimizing the Ti 3 SiC 2 content and Ti 3 SiC 2 particle size. The electrical conductivity of the composite can also be improved by improving the mould pressure and prolonging the mould pressing time.

Aluminate cement/graphite conductive composite bipolar plates were prepared by mould pressing at room temperature. The effects of the graphite content, the mould pressing pressure and mould pressing time on the electrical conductivity and the flexural strength of composite are discussed. The electrical conductivity and the flexural strength of the composite bipolar plates with 60 wt.% graphite content, prepared with a mould pressing pressure of 5 MPa for 10 min, is >100 S cm −1 and 20 MPa, respectively and can be improved by optimizing the mould pressing conditions, especially mould pressing time. The water content of the composite bipolar plate with different graphite contents was also investigated. The water content of the composite bipolar plate is about 6 wt.% with a graphite content of 60 wt.%. This composite bipolar plate contains capillary pores and has hydrophilicity, which is different from other composite bipolar plates. Therefore, it possesses an inner humidifying function and can use the water produced at the cathode for humidifying the proton exchange membrane during the operation of a PEMFC. In addition, the H 2 permeability of the composite bipolar plate is low.

A group of liquid catalysts composed of nicotinic amide functioning on the anode of DMFC were investigated at a Pt electrode, which were nicotinic amide, nicotinamide adenine dinucleotide (NAD+) and its phosphate (NAD(P)+). The kinetics of methanol anode oxidation in the three reaction systems was compared by measuring potentiodynamic current-potential curves and AC impedances. The experimental results show that the dynamic behavior of methanol oxidation at a Pt electrode has been changed with adding the three substances. The influence of temperature on the catalysis of these coenzymes and nicotinic amide was discussed by comparing the AC impedances spectra of methanol oxidation at different temperatures.

The aim of this study is to show how fractal analysis can be effectively used to characterize the texture of porous solids. The materials under study were carbon papers, the backing material of the gas diffusion layer (GDL) in Proton Exchange Membrane Fuel Cell (PEMFC). The fractal dimensions were calculated by analyzing data from mercury porosimetry. The polytotrafluoroethylene (PTFE) treated carbon paper shows a significantly high fractal dimension value than pure sample, and the high fractal dimension signifies that the physical complexity of the pore surface is enhanced. The fractal dimension can be used as a valid parameter to monitor the textural evolution of the samples as the treatment progresses, as this behaves in a similar way to other textural parameters. The use of fractal analysis in conjunction with the results of classical characterization methods leads to a better understanding of textural modifications in the processing of materiah.

Sodium silicate/graphite conductive composites are prepared by mold pressing at room temperature. The effects of graphite content, size of graphite particles, mold pressing pressure, and mold pressing time on the electrical conductivity of composites are discussed. The density and the water content are composites with different graphite content and are also investigated. The optimized preparation conditions are determined. The results show that the electrical conductivity, the density, and the water content of sodium silicate/graphite composite bipolar plate for proton exchange membrane fuel cell (PEMFC) is >100 s/cm, 1.8g/cm3, and 9 wt%, respectively. The density of this composite bipolar plate material is smaller than that of another bipolar plate. This composite bipolar plate material contains gel capillary pores and has sufficient hydrophilicity, which can humidify the proton exchange membrane during the operating process of PEMFC.

The purpose of this research is to investigate the feasibility of the synthesis of platinum/multi-wall carbon nanotube (Pt/MWNT) catalysts and such catalysts' application in fuel cells. The as-received MWNTs were purified and decorated by pretreatment. Infrared-spectrum indicates the carboxylic (-COOH) and carbonyl (-C=O) groups were introduced on the surface of the MWNTs after pretreatment. These functional groups will act as anchor sites for the Pt deposition. Then the Pt particles in nano scale were deposited on the surface of MWNTs by reduction of a solution of hexachloroplatinic acid. Transmission electron microscopy examination reveals that Pt particles are attached to the surface of MWNTs. If as-received MWNTs are not pretreated in the proper way, the Pt particle aggregates are mostly found on the open end of MWNTs. Occasionally Pt penetrated inside the tube of MWNTs. The relationship between the Pt particle morphology and the conditions of pretreatment and reduction reaction is discussed. After heat treatment, Pt particles recrystallized to form the Pt/MWNT catalysts. The Pt/MWNT catalysts were applied to a single cell and the test result shows a promising future of these catalysts with low Pt loading when applied in proton exchange membrane fuel cells (PEMFCs).

By using an LKB2277, BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Escherichia coli growth at 37°C inhibited by four kinds of heavy metal ions are determined, and parameters such as growth rate constants, inhibitory ratio, half-inhibitory concentration etc. were obtained. The experimental results show that heavy metal ions can inhibit Escherichia coli growth obviously, but low concentration of Cu2+ has a promoting action. The half inhibitory concentrations of Zn2+, Cd2+, Hg2+ and Cu2+ are 28.3, 10.9, 3.19 and 69.6 μg. mL−1, respectively. Judged from the rate constant, the half-inhibitory concentration and the molecular mass, the inhibitory sequence is Hg2+>Cd2+>Zn2+>Cu2+. This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest.

Effects of Ba filling fraction on the thermoelectric properties of p-type filled skutterudite compounds BayFe1.6Co2.4Sb12 (y=0−0.63) were investigated. BayFe1.6Co2.4Sb12 showed p-type conduction. The hall coefficient (Rh) and seebeck coefficient (α) increased with increasing Ba filling fraction. But hole concentration (p) and electrical conductivity (σ) decreased. While Ba filling fraction was about 0.4, the lattice thermal conductivity (kL) reached the minimum value. The results show that effect of Ba rattling on phonon scattering is the strongest as Sb-icosahedron partial voids are filled by Ba. A maximum dimensionless thermoelectric figure of merit (ZT) value of 0.7 was obtained for Ba0.38Fe1.6Co2.4Sb12 at 750 K.

An Al-50wt% TiC composite was directly synthesized by self-propagating high-temperature synthesis (SHS) technology, and then was used as a grain refining master alloy for commercially pure aluminum. the microstructure and grain refining performance of the synthesized master alloy were emphatically investigated. The SHS master alloy only contained submicron TiC particles except for Al matrix. Moreover, TiC particles were relatively free of agglomeration. Grain refining tests show that adding only 0.1 wt% of the master alloys to the aluminum melt could transform the structure of the solidified samples from coarse columnar grains to fine equiaxed grains (average grain size 120 μm), and that this grain refining effectiveness could be maintained for almost 1. 5h at 1003 K. Therefore, it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys, and that it is highly resistant to the grain refining fading encountered with most grain refiners.

The smart properties of homogeneous electrorheological fluid (HERF) containing side—chain type liquid crystalline polymer were studied and an actual HERF damper with an adjustable viscosity was produced. A mechanical model of the HERF smart damper was established on the basis of experiment and theoretical analysis. Then a controlled equation of SDOF structure by HERF damper was derived and a semi-active control strategy based on optimal sliding displacement of damper was presented. The simulation results for a single story frame structure indicate that HERF, which may avoid some defects of common particles-suspended ER fluids, is an excellent smart material with better stability. Using the semi-active control strategy presented, HERF smart damper controlled could effectively reduce seismic responses of structures and keeps the control stable at all times.

One of the main disadvantages of combustion synthesis of ceramic/metal composite materials is the relatively high level of porosity present in the products. To synthesize TiC/Al composites with a dense structure, this paper proposes a novel application of an elevated-temperature Al-melt to directly ignite and simultaneously infiltrate Al−Ti−C preform dipped in the melt. The emphasis was placed on the combustion synthesis process and microstructural evaluation of the preform in the melt, by a liquid quenching test combined with the measurement of the temperature history of the dipped preform. The results show that the combustion synthesis process of the preform in the elevated-temperature melt involves a series of reactions, and that higher temperature of the melt is favourable for the formation of TiC. The synthesized TiC/Al composites exhibit a dense structure, which is attributed to the infiltration of the melt into the preform.

New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2Nb3O10·1.2H2O and HSr2Nb3O10, were synthesized by solid state reaction and ion-exchange reaction. These new compounds were characterized by EPMA, AAS, XRD, IR, DTA and so on. The structure may be described as treble perovskite sheets [Sr2Nb3O10]− interleaved with K+, H3O+ or H+. These new compounds are new members of the Dion-Jacobsonseries with n=3 for the general formula M[An−1NbnO3n+1], and their indexed X-ray powder diffraction data were first reported in the paper.

The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation, based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear. It is concluded from non-linear dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.

A suitable combustion synthesis and densification process was designed to fabricate dense NiAl/TiB2 composites from Ni−Al−Ti−B system. Combustion synthesis processing and microstructure characteristics of products were studied in detail. The results show that the amount of TiB2 ceramics has a great influence on the combustion synthesis processing and microstructure; with the increase of the amount of TiB2 ceramics, the combustion temperature and combustion velocity increase rapidly. The volume of synthesized products and the grain size of ceramics particle size are also affected by the amount of TiB2 ceramics. TiB2 ceramics fiber can be produced in this synthesis system. The dense NiAl/TiB2 composites with residual porosity of no more than 1% are fabricated by the combustion synthesis and hot pressing, the mechanical properties of the dense NiAl/TiB2 composites increase with increase of the amount of TiB2 ceramics.

Coal’s volatile component, ash and fixed carbon content have different functions in different stages of a combustion process, but the traditional coal classification can precisely show its combustion property. In this experiment coal’s evaluation indexes (ignition index Di), (burn off index Df) were used to qualitatively show the ignition property and combustion ending property of coal samples. Meanwhile, considering actual heating circumstances in calciner (in cement plants), this thesis established the relationship among the ignition index, burn off index and coal’s industrial analysis value, which makes it possible for the user to predict the quality of coal before using it and is very valuable in practice.

Infrared radiant powder was synthesized by conventional ceramic processing techniques by using Fe2O3, MnO2, CuO, Co2O3 and kaolin as raw materials. A novel infrared radiant glaze was developed by introducing the infrared radiant powder into glazing as a functional additive. Infrared radiant characteristics of the powder and the glaze were investigated. The optimum content of infrared radiant powder in glazing was ascertained to be 5%. The infrared radiant glaze exhibits significant antibacterial and antifungal functions due to the thermal effect of infrared radiation. Antibacterial percentages of the glaze reach 91%–100% when Escherichia coli, Staphylococcus aureus and Bacillus subtilis are used as model bacterium respectively, while antifungal percentage of the glaze exceeds 95% when Penicillum citrinum is used as model fungus.

A new niobate Sr 6 CrNb 9 O 30 was found in the ternary system SrOCr 2 O 3 Nb 2 O 5 . The transparent crystal which has a green color and a need-like shape can be grown by the flux method. The crystal structure was determined by x-ray diffraction analysis and dielectric measurement, and it belongs to the orthorhombic tungsten bronze structure at room temperature with space group Cmm2, and unit cell parameters a=1.7505(4) nm, b=1.7510(1) nm, c=7.768(4)nm, Z=4. Dielectric constant measurement show that Sr 6 CrNb 9 O 30 has two phase transitions, paraelectric to ferroelectric at 110°C and ferroelectric to ferroelastic at 205°C.

The effect of starting Al2O3 materials on synthesis of γ-aluminum oxynitride spinel (γ-AlON) powder by carbothermal reduction has been investigated. Whether using Al(OH)3, boehmite, dried gel, or calcined alumina as an alumina source, the reaction rate is faster than that using α-Al2O3. That is because the oxygen distribution in γ-Al2O3 is cubic close packed as the non-metal arrangement in AlON spinel is whereas that in α-Al2O3 is hexagonal close packed. When hydrated aluminas used lose structural water and transform into γ-Al2O3 in heating cycle, γ-Al2O3 is easily reduced and nitrided into AlON spinel after a slight adjustment in the cation positions and proportions is made in the reduction process of alumina. The particle morphology of the product after carbothermal reduction was strongly influenced by the type of alumina source employed, which suggests the mechanism of Al2O3/C powder mixtures in a flowing N2 stream is the absorption of aluminum-containing gas, such as Al(g), Al2O(g), etc., on the surface of aluminum oxide in the initial stages, followed by reaction with N2 gas to form AlON and AlN phases with nucleation, and growth on Al2O3 particle surfaces.

This paper deals with the crystallization of MgO during sintering of Si3N4-MgO-CeO2 ceramics. At the initial stage of sintering (1450–1550°C), MgO-CeO2 reacts with free silica to form sufficient liquid phase to densify Si3N4 into nearly full density ceramics; at final stage (1600–1800°C), the crystallization of MgO reduces the amount of glassy phase which is harmful to the high-temperature properties. MgO-CeO2 is found to be an excellent sintering aid for Si3N4.

The rods that were shaped from nanocrystalline WC-10.21 Co-0.42 VCI Cr3 C2(wt%) composite powders by using powder extrusion molding (PEM) were investigated. The nanocrystalline WC-10.21 Co-0.42 VC/Cr3 C2 (wt%) composite powders were prepared by the spray thermal decomposition-continuous reduction and carburization technology. In order to improve the properties of rods shaped by using powder extrusion molding, the cold isostatic pressing (CIP) technology was used before or after debinding. Specimens were sintered by vacuum sintering and hot isostatic pressing (HIP). The density, Rockwell A hardness, magnetic coercivity, and magnetic saturation induction of sintered specimen were measured. The microstructure of the green bodies and the sintered specimens was studied by scanning electron microscopy (SEM). Results show that the rod formed by using powder extrusion molding after debinding and followed by cold isostatic pressing can be sintered to 99.5% density of composite cemented carbide rods with an average grain size of about 200–300 nm, magnetic coercivity of 30.4 KA/m, Rockwell A hardness of 92.6 and magnetic saturation induction of 85%. Superfine WC-10Co cemented carbide rods with excellent properties were obtained.

Several methods of manufacturing γ-aluminium oxynitride spinel (ALON) powder are discussed in this paper. In the carbothermal reduction process, ALON is an intermediate compound, and powders with a high ALON content may be produced in flowing nitrogen below 1650 °C if process parameters are carefully controlled. In addition, ALON may be produced when Al2O3/C mixtures are heated in a coke powder bed above 1650 °C. In the reaction sintering process, ALON is unlikely to form below 1600 °C in a flowing nitrogen atmosphere or in a coke powder bed, owing to the instability of ALON and the fact that the solid–solid reaction does not readily occur unless additives, e.g. MgO, MgAl2O4, are employed.

The PAn-PEO-PAn triblock copolymer with the PEG chain length of 400 was synthesized by chemical oxidation copolymerization of aniline and α, ω-bis(p-aminophenyl) poly(ethylene glycol) and characterized by FT-IR and TEM. The experimental results show that the copolymer particles are of a typical core-shell structure after the self-assembly process in water. Its conductivity is much lower than that of the pure PAn. The suspension containing 20 vol% PAn-PEO-PAn triblock copolymer in silicone oil exhibits a typical electrorheological (ER) effect in DC electric field, while it shows a lower leakage current density than that of the pure PAn-based ER fluids. Therefore, the PEO shell hinders the electric hop among PANI chains and decreases the current density of ER fluids in an external electric field, at the same time the interface polarity imprones the ER effects.

Nafion modified Pt nano-particles with size about 4nm were synthesized. The modified particles were absorbed on the surface of carbon nanotubes and used as electro- catalysts for proton exchange membrane fuel cell. Due to the plentiful proton channels provided by the modifying Nafion ionomers, the single fuel cell with the modified Pt catalyst has a promised performance. The output was 0.282W/cm^2 with Pt loading of 0.1 mg/cm^2, better than that of unmodified one, which was 0.273W/cm^2 with Pt loading of 0.11mg/cm^2.

Sr5LaTi3Nb1O30 ceramic was prepared by the conventional high temperature solid-state reaction route. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), differential thermal calorimetry (DSC) and dielectric measurements. The results show Sr5LaTi3Nb7O30 belongs to paraelectric phase of filled tetragonal TB structure at room temperature, and undergoes a diffuse phase transition in the temperature range of−54-34°C. And Sr5LaTi3Nb7O30 ceramic shows a high dielectric constant of 479 with a low dielectric loss of 0.005 at 1 MHz. In comparison with Ba-based ceramics with TB structure, the temperature coefficients of the dielectric constant (τe) is significantly reduced.

The hydration and pore structure of sulphoaluminate MDF cement were studied by X-ray diffractometer (XRD), scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP) etc. The experimental results indicate that hydration products of the materials are entringites (AFt), aluminium hydroxide and CSH (I) gel etc. Due to its very low water-cement ratio, hydration function is only confined to the surfaces of cement grains, and there is a lot of sulphoaluminate cement in the hardenite which is unhydrated yet. Hydration reaction was rapidly carried under the condition of the heat-pressing. Therefore cement hydrates AFt, CSH (I) and aluminium hydroxide gel fill in pores. The expansibility of AFt makes the porosity of MDF cement lower (less than 1 percent) and the size of pore smaller (80 percent pore was less than 250A), and enhances its strength.

By means of chemical reduction, nanoparticles of platinum were deposited on the surface of multi-walled carbon nanotubes (MWCNTs). The performance of hydrogen storage of as-prepared MWCNTs decorated with platinum was investigated. The results indicate that: (1) Hydrogen uptake is more quick and intense for decorated MWCNTs than that for not decorated ones at 10.931 MPa and room temperature. The saturation of hydrogen uptake of the former only lasts about 30 min, while the latter needs about 150 min; (2) The amount of hydrogen uptake of decorated MWCNTs is about 1.13wt%, which is larger than that of not decorated ones (about 0.54wt%); (3) However, more than 37% hydrogen absorbed by decorated MWCNTs is chemisorbed.

The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO3 xerogel via sol-gel route. The electrochromic behavior and the chemical conditions of Li+ ions were investigated by cyclic voltammograms, UV-visible spectral transmittance and XPS. The results show that the cycling efficiency and the reversibility of insertion/extraction of Li+ ions in (PEO)1MoO3·nH2O nanocomposite film were improved. The intercalation of PEO into MoO3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency. Two different chemical conditions of Li+ ions existing in the interlayer and interstitial positions of MoO3 lattice were observed in MoO3 xerogel and (PEO)1MoO3·nH2O nanocomposite films.

Ag−TiO2 thin films were prepared on glasses. The morphology and structure of Ag−TiO2 films were investigated by XRD, SEM and FT-IR. The photocatalytic and hydrophilic properties of Ag−TiO2 thin films were also evaluated by examining photocatalytic degradation dichlorophos under sunlight illumination and the change of contact angle respectively. The research results show that the Ag−TiO2 thin film is mainly composed of 20–100 nm Ag and TiO2 particles. The Ag−TiO2 thin films possess a super-hydrophilic ability and higher photocatalytic activity than that of pure TiO2 thin film.

A new method is introduced to study the action between biomaterials and organism. By using an LKB-2277 bioactivity monitor and ampoule method, the fundamental thermogenesis curves of the metabolic process of pk-15 and the toxic effect of three kinds of selenomorpholine compounds on it were studied at 37°C. From the thermogenesis curves, the heat released by pk-15 metabolism was calculated. The results show that the selenium compounds all have toxic action on the metabolism process of pk-15 at the range of experimental concentrations. The sequence of the toxic action of selenium compounds is: Na2SeO3>β-(N-selenomorpholine)-ethyl phenylketone hydrochloride>selenomorpholine.

The sintering resistance for conductive TiB2 and non-conductive Al2O3 as well as empty die during pulse current sintering were investigated in this paper. Equivalent resistances were measured by current and valtage during sintering the conductive and non-conductive materials in the same conditions. It is found that the current paths for conductive are different from those for non-conductive materials. For non-conductive materials, sintering resistances are influenced by powder sizes and heating rates, which indicates that pulse current has some interaction with non-conductive powders. For conductive TiB2, sintering resistances are influenced by heating rates and ball-milling time, which indicates the effect of powders activated by spark.

Electromagnetorheological (EMR) fluids containing CuPc−Fe3O4 nanopareticles composite were prepared and their properties were studied. The results show that Δτ of this kind of EMR fluids increases with the increments of applied electric field, magnetic field and volume fraction of the nanoparticles composite. Δτ has an approximate linear relationship with γ. When an electric and magnetic field are applied simulateously, the EMR fluids have a synergistic effect. The EMR fluids have a good long-term stability.

Composite particles consisting of polyaniline (PAn) core and barium titanate (BaTiO3) layer shell were synthesized. The PAn-BaTiO3 composites particles were characterized with TEM and XRD. The dielectric behavior of particles was tested and the electrorheological (ER) behavior of the suspensions of PAn/BaTiO3 particles in chlorinated paraffin oil with a 20 vol% was investigated under DC electric field. The results show that the ER effect of composite particle is far stronger than that of pure polyaniline and barium titanate which were synthesized by the same method. pH and thickness of BaTiO3 have an important influence on the ER effects.

Various silicon nitride materials have been prepared by pressureless sintering using MgO/CeO 2 as sintering aids. The weight fractions of MgO+CeO 2 added were 2, 4, 6, 8, 10, 12, and 14%, respectively, corresponding to MgO/CeO 2 weight ratio of 1/1, and constant 10 wt.% of MgO+CeO 2 were added in the ratios 0/10, 2/8, 4/6, 5/5, 6/4, 8/2, and 10/0, respectively. The densification effect of the combination of MgO with CeO 2 is much better than either MgO or CeO 2 alone. The optimum MgO/CeO 2 weight ratio is 1/1 and the optimum MgO+CeO 2 concentration is 8–10 wt.%, resulting in a relative density of 98.5% and a bending strength of 948 MPa for the pressureless sintered Si 3 N 4 –MgO–CeO 2 ceramics.