Advanced Materials Research Vol. 625

Abstract: Effects of surfactant, PTFE concentration in plating bath on surface morphology and the microstructure of electroless Ni-P-PTFE composite coatings were investigated in this study. The dependence of microstructure and distribution of PTFE particles in composite coatings upon surfactant agent and PTFE content in the plating bath were reported. Also, effects of ultrasonic frequencies on PTFE content in the coatings were discussed. The surface morphology and microstructure of the composite coatings were analyzed using scanning electron microscope (SEM) and X-ray dialysis (XRD), respectively. The results obtained are indicating that surfactant and PTFE concentration in the plating bath have a great impact on PTFE content in the coatings, the population of PTFE in the coatings proved to increase with increasing surfactant concentration properly. In addition, ultrasonic frequency could change the PTFE content in the coating. The composite coating shows different surface morphology and microstructure in various surfactant concentrations, PTFE concentrations and ultrasonic frequencies.

Abstract: This article is about the methods and equipment being used in the first step of slime water system, which is called fine particle classification. With the development of automation in coal mining and preparation, fine particles in the raw coal increases substantially. The fine coal preparation is mainly completed in water, which makes the slime water system face to a heavier load. Accurate classification is necessary to large-grained gravity separation and small-grained flotation.

Abstract: Calcium polyacrylate/alginate (CPA/A) hybrid polymer microspheres with the imprinting of bovine serum albumin (BSA) were prepared via Ca2+ crosslinking of sodium polyacrylate (SPA), BSA and sodium alginate (SA) in inverse suspension. The specific rebinding properties of BSA imprinted hydrogel microspheres (CPA/A MIPMs) were investigated by controlling pH value from the viewpoint of adjusting the process of gelling, removing template and rebinding. The optimized pH values in gelling, removing template and rebinding process was 4.1, 8.3 and 4.2, respectively.

Abstract: In this paper, we show that compared with the conventional transformation elastodynamics, the method based on physical interpretation of form-invariance can provide more flexibility in material design. As a result of this flexibility, the impedance-matched condition for both S and P waves in perpendicularly incident cases exists, thus the isotropic homogeneous elastic wave concentrator can be designed. Samples are conceived and validated by numerical simulations.

Abstract: In this paper Proban CC-treated high-wet-modulus (HWM), viscose and Lyocell celluloses were prepared and their properties, such as IR analysis, flammability and mechanical properties were studied. IR showed that in three Proban CC-treated celluloses the new absorption peak around 1560 cm-1 appeared. After combustion, Proban CC-treated HWM celluloses almost completely remained the fiber profile, then the Proban CC-treated Lyocell celluloses, finally the Proban CC-treated viscose celluloses. Though three Proban CC-treated celluloses showed the good thermal stability, their mechanical properties were declined. The strength of the Proban CC-treated HWM celluloses declined most, then the Proban CC-treated Lyocell celluloses, finally the Proban CC-treated viscose celluloses. These indicated that Proban CC treatment influenced the mechanical properties of the celluloses badly.

Abstract: Two kinds of carbon sources and their mixtures with different proportions were employed to prepare the LiFePO4/C composite material by high temperature solid state method. Precursor materials with different carbon sources were prepared by planetary ball-milling without dispersant. Results showed that the various precursors had different effect on the uniformity of the mixing and the crystallinity of the LiFePO4/C positive material. The mixed carbon sources had better effects on the performance of positive material. When the ratio of sucrose and citric acid was 1:3 (75% citric acid), the discharge capacity of LiFePO4/C composite material was 144.1 mAh/g at the discharge rate of 0.2C. Its high-rate performance was also better.

Abstract: The nano-crystalline (Fe,Cr)N was prepared as a single phase by milling Fe80Cr20 in a nitrogen atmosphere. Its crystal structure is determined to be the cubic rock salt-type CrN by X-ray diffraction measurements. The nano-crystalline is stable up to above 773 K and decomposes into (Fe,Cr)N and Fe-Cr solid solution. Due to the combination of Fe atoms and N ones, the intrinsic magnetic moment of Fe atoms is reduced, which is confirmed by our measurements.

Abstract: High temperature proton exchange membrane fuel cells (HT-PEMFCs) have been drawing much attention due to their easy water management and other advantages. A three-dimensional non-isothermal transient model of HT-PEMFCs with phosphoric acid doped polybenzimidazole (PBI) membrane is developed in this study. The inlet relative humidity (RH) is considered for the membrane conductivity in the model. The effect of inlet RH on the transient response of the cell is discussed and the results show that the increase of inlet RH had positive effect on cell performance but negative effect on transient response.

Abstract: Based on first-principle calculations, electronic structure and optical properties of a single-walled zigzag SiC nanotube with silicon antisite defect have been investigated. This defect results in the formation of a bump in the surface of the nanotube. No defect energy level is formed in its band gap, which is originated from the resonance between the defect level and conduction band resulting in the defect level entering its conduction band. The most primary dielectric peak in dielectric function parallel to the axis of the nanotube is depressed, while the first peak perpendicular to its axis is enhanced. These results are meaningful for investigations on SiCNT electronic and optical devices.

Abstract: The mass and charge transport significantly affect the performance of fuel cells. A numerical model of high temperature proton exchange membrane fuel cells is developed. Ohmic losses and activation losses of both anode and cathode are analyzed at different design and operating condition. The polarization curve predicted by the model is in a reasonable agreement with published experimental data. The results of the model indicate that increasing the phosphoric acid doping level or operating temperature is helpful to decrease ohmic losses. The operating temperature has negligible impact on activation losses. Increasing the operating pressure can decrease activation losses.