Advanced Materials Research Vol. 412

Abstract: The Ge doped Mn₃CuN powder was synthesized using gas-solid reaction method with manganese, copper, germanium powders and N₂ gas as raw material. The phase constitute of the as-prepared powder was characterized using X-ray diffraction (XRD). The intrinsic and macro thermal expansion coefficients of the powder were measured by in-situ X-ray diffraction at different temperatures and TMA, respectively. The crystal structure of the powders was analyzed using Rietveld refinement method. The results show that the pure Mn₃(Cu_0.5Ge_0.5)N powder can be prepared via the gas-solid method at 850 °C. The crystal structures of Mn₃(Cu_0.5Ge_0.5)N and Mn₃CuN both have the antiperovskite structures. The intrinsic and macro thermal expansion coefficient of Mn₃(Cu_0.5Ge_0.5)N powder is-16.8×10^-6K^-1 and-17×10^-6K^-1, respectively. The temperature range with negative thermal expansion is from-80 °C to 50 °C.

Abstract: The optical properties of the Mg (OH)₂ crystalline powder samples, which were prepared by us, were investigated by first-principles method. The calculated results show that the static state dielectric function ε₁(0) for Mg (OH)₂ is 2.8673. The peak value range for the Mg (OH)₂ absorption coefficient is mainly in the energy range from 45.521 eV to 66.0213 eV. Moreover, absorption coefficient researches its maximum, which is 1490460cm^-1, at the energy of 63.7988eV. Besides, when energy is greater than 66.3901eV, the reflectivity rate is one. And the average static state refractive rate n (0) for Mg (OH)₂ is 1.6292. While the maximum peak of energy loss function for Mg (OH)₂ is in 20.4755eV.

Abstract: According to the conditions of preparation of mullite composites by open-system hydrothermal crystallization method, surface energies of mullite crystal were calculated by the first principle plane pseudo-potential. Growth habit plane of mullite composites was also discussed and analyzed. The calculation results demonstrate that surface energies of (001), (010), (100), (210) and (120) of mullite crystal are 0.337KeV•nm^-2, 0.029KeV•nm^-2, 0.027KeV•nm^-2, 0.032KeV•nm^-2, 0.037KeV•nm^-2, respectively. That is to say, the surface energies of mullite crystal follow the order of (001) >> (210) > (120) > (100) > (010). It is also found that E₍₀₀₁₎ is much larger than others. According to Curie-Wulff principle, growth rate of crystal face is directly proportional to its surface energy, which shows that growth rate of mullite crystal in (001) direction is the fastest and mullite crystal is favorable for one-dimensional growth to columnar.

Abstract: Preparation of hydrophobic and oleophobic ABS laminates by a template method or additives added method and hydrophobic and oleophobic mechanism of ABS were investigated. ABS laminates with micro/nanopores were fabricated by adding additives and dissolving the micro/nanomaterial on surface for forming pores, and with low surface energy were prepared by adding nanometer titanium dioxide (TiO₂) and silicon dioxide (SiO₂). The contact angle of ABS laminates with oil and water were tested by the contact angle meter. Surface microstructure of the ABS laminates were observed by SEM. The results show that the contact angle of the Al-ABS laminates treated by diluted hydrochloric acid with water is 117° increase 67°than the contact angle of ABS laminates without any treatment, which was since aluminum particles on the surface of ABS laminates are dissolved by diluted hydrochloric acid and form rough surface morphology with the surface micro/nanostructure.

Abstract: Determination of particle size and shape factors of the corundum powders by SEM image analysis has been reported in our preceding work. However, the effect of sample preparation and image processing has not been investigated. In order to obtain appropriate images, samples was well-dispersed by vibrating particles manually up and down, and then thicker Pt coating was well sputter coated on the surface of samples; compared with the magnifications of 100 and 32, magnification of 50 was more reasonable; for distinguishing particles from image background properly, the gray threshold value of 70 was set to transform gray image to binary image; to decrease image noises, three image filters, i.e. Erosion Filter, Dilation Filter and Median Filter were investigated and the last one was the most effective. This method of sample preparation and image processing can be used in regular and irregular particles determination.

Abstract: Two observation techniques of internal microstructure, including hole and second particle, of micron scale powders have been established and applied to frangible and tough powders. One is that powders were embedded in epoxy resin, sectioned by an ultramicrotome, then observed by using the transmission electron microscopy (TEM) in turn; another is that the fracture of powders were observed by using the scanning electron microscopy (SEM).

Abstract: Here we studied in vivo stability and biodistribution of quantum dots. Their distribution in vivo at various time points were determined by measuring the amount of cadmium ions and selenium ions in various organs by inductively coupled plasma-atomic emission spectrometry. The amount of cadmium ions was higher in liver than in other organs at all times. The amount of cadmium ions in kidney and spleen were increased gradually in time-dependent. There are also obviously increased cadmium ions in lung and heart at all times compared to the control. However the amount of selenium ions was high in all organs except for brain before the 3rd day.

Abstract: The basic structure, classification principle and low efficiency of the traditional spiral classifier were analyzed. The trial industrial comparative experiment was carried out by using φ300×4500 spiral classifier with the two-sided overflow and the port side overflow at the same parameter. The experimental results showed that, the qualified fine materials could overflow with the shortest distance by using two-sided overflow method, which avoided circulation circuit of fine materials and reduced the content of-200 mesh fine materials in the sinking sand down lower 2-5 percentage points compared with the port side overflow. At the same time, adjusting the overflow emissions height of two-sided overflow could delay the settling time of coarse mineral which reduced the content of +200 mesh materials of the overflow discharge lower 5-8 percentage points than the port side overflow. Compared with the port side overflow, the classification efficiency was improved about from 40% to 60%, and the average increase rate was up to 17%. The improvement of overflow discharge can be used not only for the adjusting of present spiral classifiers but also for making new machines, which is of a significant application prospect.

Abstract: Drying is one of the most important methods for industrial processing since moisture content is an extremely relevant parameter affecting the crucial properties of final products. Nowadays, fluidized bed drying technology is widely employed in various industries. Comparing to other drying methods, fluidized beds generate high efficient thermal conditions. In the current study, drying kinetics of cornstarch granules was investigated in a fluidized bed dryer. The drying experiments were performed at different temperatures and velocities of the inlet drying air and in different granule sizes. The results showed that air temperature had the most significant effect on the drying rate among the three variables. Five drying empirical models were fitted to the experimental moisture data and were evaluated using the determination coefficient and chi-square. Four of the models were found to be suitable for describing the drying behavior of cornstarch granules. Therefore, it is possible for them to be applied to estimate the drying end-point of cornstarch granules as well as to design and scale up of the drying process for the similar products in the fluidized bed dryer.

Abstract: The mechanism of drying paste materials was investigated in a fluidized bed with inert particles and inner heats. A mathematical model is proposed to predict the specific water evaporation. The drying properties of dryer can be predicted based on the correlation equations. The drying of paste CaCO₃ materials was industrial-mode experimentally carried out in a fluidized bed with inert particles and immersed heating tubes. The paste material was spray droplet in sizes range of 200~400μm with pressure nozzles or air-blast nozzles, and spray to the surface of inert particles, and the feasible drying conditions were researched. The feasible drying parameters, operation parameters and equipment parameters were researched. The results show that this drying technology can be enhanced the heat transfer and the paste materials of high viscosity can be effectively distributed into the fluidized bed, well distributed temperature in beds, large elasticity of operation, the low energy consumption. The new drying equipment has high drying capacity, small equipment size. The results can provide important meaning on theory and instructing practice for developing the new drying technology with high drying efficiency and low dissipation of energy.