Anze Shui

Template-free sonochemical synthesis of hierarchically porous NiO microsphere

A novel template-free sonochemical synthesis technique was used to prepare NiO microspheres combined with calcination of NiO2.45C0.74N0.25H2.90 precursor at 500 °C. The NiO microspheres samples were systematically investigated by the thermograviometric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier-transformed infrared spectroscopy (FT-IR), Brunnauer-Emmett-Teller (BET) nitrogen adsorption-desorption isotherms, laser particle size analyzer, and ultraviolet-visible spectroscopy (UV-Vis). The morphology of the precursor was retained even after the calcination process, and exhibited hierarchically porous sphericity. The morphology changed over the ultrasonic radiation time, and the shortest reaction time was 70 min, which was much less than 4h for the mechanical stirring process. The mechanical stirring was difficult to form the complete hierarchically porous microsphere structure. The BET specific surface area and the median diameter of the hierarchically porous NiO microspheres were 103.20 m(2)/g and 3.436 μm, respectively. The synthesized NiO microspheres were mesoporous materials with a high fraction of macropores. The pores were resulted from the intergranular accumulation. The ultraviolet absorption spectrum showed a broad emission at the center of 475 nm, and the band gap energy was estimated to be 3.63 eV.

Alumina Ceramic Texturing Induced by High Magnetic Field and its Microstructure

Various textured alumina ceramics were prepared by colloidal processing in high magnetic field and heating from alumina powder as raw material in this study. The effects of the magnetic field strength, heating time and heating temperature on the particle orientation were systematically examined for these samples with scanning electron microscope (SEM) and X-ray diffraction (XRD) etc. The experimental results showed that alumina grains are polyhedral ball shape of, no textured structure exists in the sintered bodies without magnetic field treatment; the alumina grains align with the c-axis parallel the magnetic field direction under high magnetic field, the grains present strip shape in the sintered alumina bodies with the magnetic field treatment; the particle orientation degree increases with increasing the heating time and heating temperature; when the sintering temperature achieves about 1823K, the textured microstructure can be obviously observed in the sintered alumina bodies.

Photocatalytic Degradation of Methyl Orange on ZnO in Aqueous

The photocatalyst of nanometer ZnO powder was prepared by precipitation method with ZnSO4⋅7H2O and Na2CO3 as raw materials. Laboratory experiments with methyl orange (MO) as the model pollutant have been carried out to evaluate the photocatalytic activity of nanometer ZnO photocatalyst. A high-pressure mercury lamp was used as the energy source for the photocatalytic experiments. The effects of process parameters such as catalyst loading, initial methyl orange concentration, pH and electrolyte on the photodegradation have been investigated.

Microwave Synthesis of Nano-Titanium Carbide

A new synthesis technology of titanium carbide with microwave is introduced in this article. Microwave synthesis technology is a fast and relatively low temperature of synthesis method. Nano-titanium carbide powders were synthesized by carbothermal reduction of titanium dioxide and carbon black with the microwave synthesis method at 1100°C-1400°C in argon gas atmosphere. Nano-TiO2 powder and carbon black were used as raw materials. The TiC powders were characterized with the XRD and TEM. The experimental results show that the synthesis rate is quick, even at relatively low synthesis temperature. The average particle size of the TiC powders synthesized by the microwave synthesis technology under low temperature (<1300°C) is less than 50nm, and the average particle size augments with increasing the microwave synthesis temperature and time.

Sintering Shrinkage Anisotropy of Spherical Alumina Powder Compacts with Particle Orientation

Spherical alumina powder and dispersant were mixed with distilled and deionized water, and ball milled to make alumina slurry. The slurry was dried in a high magnetic field to make a compact. Subsequently, the compact was cold-isostatic-pressed (CIP) to enhance the homogeneity in particle packing density. Anisotropy of shrinkage during sintering was examined for the alumina compacts in detail. Particle orientation existed in the spherical alumina powder compacts prepared in 10T, and made them shrink anisotropically during sintering. Sintering shrinkage was larger in the direction parallel to magnetic field direction (i.e., the c-axis direction of alumina crystal) than that in its perpendicular direction. The particle orientation structure in the compacts was confirmed with the immersion liquid method of polarized light microscope, and the grain alignment structure in the sintered bodies was also observed with X-ray diffraction, the c-plane was perpendicular to the magnetic field direction. On the other hand, isotropic sintering shrinkage occurred in the spherical alumina powder compacts prepared in 0T, which did not hold the particle orientation. The experimental results indicate that sintering shrinkage of spherical alumina powder compact depends on alumina crystal axis direction. Origin of the sintering shrinkage anisotropy for the spherical alumina powder compacts can be attributed to the particle orientation caused by high magnetic field.

Preparation and Microstructure of Bauxite Ceramic Microsphere

In this paper, microspheres were prepared by using Chinese bauxite as raw materials through centrifugal spray drying method. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction, scanning electron microscope and X-ray energy spectrum. The particle size was 10~100#m. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere were α-Al2O3 and mullite (3Al2O3•2SiO2). The Al2O3 content (chemical composition) of the microspheres was little more than 70%, and the molar ratio of Al2O3/SiO2 was near to the molar ratio of alumina and silica of mullite.

Control of Ceramic Material Microstructure with Super High Magnetic Field

A new control method of the particle orientation structure with super high magnetic field is studied for Al2O3 ceramics. Al2O3 slurry was made with two types of Al2O3 particles, which one was spherical shape of, and the other one was elongated shape of. The Al2O3 ceramics of orientation structure was fabricated by drying the Al2O3 slurry under the super high magnetic field, cold isostatic pressing (CIP) and sintering. Effects of particle shape, particle size, the solid loading, slurry viscosity, dispersant content and the magnetic field strength on the particle orientation structure were examined in detail. The experimental results indicate that even the spherical Al2O3 particles can align under the magnetic field; the particle orientation degree changes with the particle shape and the solid loading under same magnetic field strength conditions, and the elongated particle system is easier to align than the spherical particle system; the particle orientation degree of the Al2O3 ceramics can be controlled by adjusting the particle shape, particle size, solid loading, slurry viscosity, dispersant content and magnetic field strength.