Graphene was prepared and used as an adsorbent for removal of cationic red X-GRL from aqueous solutions. The physico-chemical properties of graphene were characterized by the transmission electron microscope (TEM), th...
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Graphene was prepared and used as an adsorbent for removal of cationic red X-GRL from aqueous solutions. The physico-chemical properties of graphene were characterized by the transmission electron microscope (TEM), the Brunauer-Emmett-Teller (BET) specific surface area measurement, atomic force microscope (AFM), and Raman microscope. The adsorption properties of cationic red X-GRL onto graphene were studied as a function of pH, adsorbent dosage, contact time, and temperature. Kinetic data were well fitted by a pseudo second-order model. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. Thermodynamic studies showed that the adsorption was a spontaneous and endothermic process.
The Fe2O3 nanoparticles activated V2O5 nanotubes were achieved via a hydrolysis method. The TEM and SEM images of the nanotubes indicated that the Fe2O3 nanoparticles with the particle size of about 15 nm were dispers...
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作者:
Kaijie LinGuangze TangYujiang WangXinxin MaKen YukimuraSchool of Materials Science and Engineering
Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Science and Technology on Precision Hot Processing of MetalsHarbin Institute of TechnologyHarbin 150001China National Key Laboratory for RemanufacturingAcademy of Armored Forces EngineeringBeijing 100072China State Key Lab of Advanced Welding Production TechnologyHarbin Institute of TechnologyHarbin 150001China
Lead free textured K_(0.5)Na_(0.5)NbO_(3) piezoelectric ceramics have been prepared by reactive-templated grain growth method by using NaNbO_(3) with different morphologies as templates. The NaNbO_(3) template particl...
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ISBN:
(纸本)9781457711626
Lead free textured K_(0.5)Na_(0.5)NbO_(3) piezoelectric ceramics have been prepared by reactive-templated grain growth method by using NaNbO_(3) with different morphologies as templates. The NaNbO_(3) template particles with different edge length (10-20 (mu)m) and thickness (0.5-2.5 (mu)m) was synthesized through controlling Bi_(1.5)Na_(x-1.5)Nb_(x)O_(3x+3) precursor's layer numbers x from 2 to 6 by two-step molten salt methods. The crystalline phases and microstructure of textured K_(0.5)Na_(0.5)NbO_(3) were characterized by X-ray diffraction and scanning electron microscopy, respectively. It shows that all the K_(0.5)Na_(0.5)NbO_(3) ceramics are orthorhombic perovskite structure with {001} orientation. By using the template particles with a ratio of edge length to thickness (l/h)(velence)approx10, the textured ceramics with optimized piezoelectric properties was prepared. The results indicate that the enhanced properties of textured ceramics are concerned with the template morphology.
To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and *** we...
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To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and *** wear and corrosion behaviours of the coatings were *** wear resistance of the coatings was evaluated under dry sliding wear condition at room *** corrosion resistance of the coatings was tested in 3.5%(mass fraction) NaCl *** coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic *** main wear mechanisms of the coatings and the AZ91D sample are *** former is abrasive wear and the latter is adhesive *** coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.
The gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC) plays a prominent effect on the water balance inside the fuel cell. A two-dimensional, steady-state, two-phase model for a PEMFC is devel...
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ISBN:
(纸本)9781424480364
The gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC) plays a prominent effect on the water balance inside the fuel cell. A two-dimensional, steady-state, two-phase model for a PEMFC is developed to investigate the effects of GDL characteristics on the water-protect performance of the fuel cell. Analysis of the water-protect performance of low humidity PEMFC indicates that in the condition of saturated anode inlet humidification and 25% of the cathode inlet humidification, the smaller the porosity, the better the water-protect performance of the fuel cell. The thicker the GDL, the better the water protect capability. The fuel cell with smaller mean aperture has higher water content in the membrane. The stronger hydrophilicity in the GDL plays a certain role of holding the water.
A novel way was used to prepare dense B4C ceramics at a lower temperature by reactive sintering from carbon and boron elemental powders. Spark Plasma Sintering (SPS) technique, a rapid and non-conventional powder cons...
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ISBN:
(纸本)9780470927151
A novel way was used to prepare dense B4C ceramics at a lower temperature by reactive sintering from carbon and boron elemental powders. Spark Plasma Sintering (SPS) technique, a rapid and non-conventional powder consolidation method, was employed. The densification, microstructure and mechanical property of the as-prepared B4C ceramics were investigated. The reactive sintering process could be divided into two stages, corresponding to synthesis (1300∼1700°C) and densification (1700∼1900°C), respectively. At those stages, boron first reacted with carbon to form B4C, and then the in-situ densification of the as-synthesized B4C occurred and was enhanced by increasing sintering temperature. B4C ceramics with grain size of several hundred nanometers and high densification (98%) were obtained at 1800°C, a lower sintering temperature as compared with general hot press. Due to the high densification and purity as well as fine texture, the SPS-sintered B4C ceramics had high Vickers hardness (48.8GPa), Young's modulus (264.5GPa), fracture toughness (3.9MPa·m1/2) and flexure strength (450MPa).
One interesting and challenging BGA solder ball cracked issue occurred at certain electronic production line. This paper is expected to carry out a detail investigation and improvement plan on failure mechanism, by co...
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One interesting and challenging BGA solder ball cracked issue occurred at certain electronic production line. This paper is expected to carry out a detail investigation and improvement plan on failure mechanism, by combining some experiment methods, such as SEM/EDX, pin pull test, cross section, dye & pry etc. And also environment test thermal cycling is involved in to qualify the improved products. Thermal stress, mechanical stress and strength of BGA solder ball will be studied as critical factors. The result revealed the crack tracing is along with IMC layer smoothly, and the IMC layer with poor mechanical strength is damaged easily during undergoing process mechanical stress, even through process strain level is within design specification. Meanwhile, the poor strength is shown by pin pull test on BGA solder balls, which means the solder ball strength can be tested by the pin pull test that is designed primarily for PCB pad to laminate strength. To solve the crack phenomenon on current PCBA without changing any BGA produced process, underfill and edge bonding process are suggested to protect the solder balls from mechanical and thermal stress shock. Reliability qualification plan is also conducted and confirmed that both processes solved the failure mechanism successfully. It is believed the history of the investigation and improvement on mentioned solder crack issue will be meaningful for electronic product manufacturing, especially for similar solder ball failure mode.
In the present work, tetragonal BaTiO3 particles down to 20 nm have been synthesized by low temperature aqueous co-precipitation method through composition control. Field emission scanning electron microscopy (FE-SEM)...
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In the present work, tetragonal BaTiO3 particles down to 20 nm have been synthesized by low temperature aqueous co-precipitation method through composition control. Field emission scanning electron microscopy (FE-SEM) images indicated that the precipitates contained fine (about 20-30 nm) faceted particles. The Raman spectra revealed that tetragonal phase appeared with the increase in Ba/Ti ratio in the precursor solution. The appearance of tetragonal phase in BaTiO3 nanoparticle was related with the lattice defect revealed by lattice parameter and lattice strain calculated by XRD results. The lattice defect can be modified through composition control.
Dense SnO2-based electrode ceramics have extensive application prospect in glass electric-melting industry due to the excellent electrically-conductive and chemical property in high temperatures and oxidation environm...
Dense SnO2-based electrode ceramics have extensive application prospect in glass electric-melting industry due to the excellent electrically-conductive and chemical property in high temperatures and oxidation environment. In this paper, dense SnO2-based electrode ceramics doped with MnO2 and Sb2O3 were prepared by pressureless sintering method and the corrosion rate in soda-lime glass liquid as well as the microstructure evolution was mainly investigated. The results suggested that SnO2-based ceramics had good corrosion resistance, and the minimum value was only 2.54×10−4 mm/h when MnO2 content is 1.0% and Sb2O3 content is 0.1%. Composition Elements of Glass liquid were detected in the grain boundary and some intergranular pores. It was found that SnO2 grains remained unchanged, whereas MnO2 was easily dissolved into molten glass liquid. SnO2-based electrode ceramics with dense structure and few amounts of additives had excellent corrosion resistance to the molten glass.
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