Materials Science Forum Vols. 610-613

Abstract: To prepare the renewable carrier materials for immobilization of nitrifying bacteria, polylactic acid (PLA) dichloromethane solution was added to chitosan aqueous solution, mixed by agitation at a speed of 150 rpm / min. The resultant PLA microspheres were fund to have diameter of 100 ~ 300 μm, thus underwent ammonolysis by a 6 % hexamethylenediamine / n-propanol solution for 8 min, hydroformylation by a 1% glutaraldehyde solution for 3 h, and grafted with 1% chitosan for 24 h, to improve the surface hydrophilic property. The static adsorption was applied for adhesion of nitrifying bacteria to the surface of the carrier, i.e. immobilization of nitrifying bacteria. The removal efficiency of ammonia by the immobilized nitrifying bacteria in wastewater treatment was tested. The results showed that the surface of the microsphere carrier was rough and osteoporosis, therefore it can adhere more nitrifying bacteria. When it was immersed in the suspension of nitrifying bacteria for 8 h, the rate of nitrification by the immobilized nitrifying bacteria reached the highest level and tended to be stable afterwards.

Abstract: In the present work, the effect of electromagnetic field on the microstructure and the alloying agent distribution was investigated. Tin element was shown to have the tendency to be inversely segregated on the surface of tin bronze. The microstructures of the continuous cast tin bronze plates are coarse and inhomogeneous. The factory test parameters were determined according the simulated data. The flow behavior of the mercury to be stirred as well as the relations between the microstructure of plate blanks and the current parameters were analyzed. With an appropriate electromagnetic stirring, the inverse segregation of tin for C51900 alloy plant blank was improved by 80%, and the microstructure was refined from about 10mm to 1~3mm in grain size.

Abstract: Silt from the Yellow River was mixed with a certain amount of SiO2 powder to fabricate eco-friendly silica bricks and different amounts of TiO2 were added to ameliorate the thermal conductivity of the bricks. Results showed that the phases of as-fabricated silica bricks are cristobalite and tridymite with cristobalite predominating. With increasing amounts of TiO2, the bulk density and thermal conductivity of the samples increase. Although the bulk density (1.65~1.76 g/cm3 ) than the ideal density 1.85 g/cm3, the thermal conductivity is significantly ameliorated. The thermal conductivity of the sample with 1.5% TiO2 addition is 2.11 W/m.°C, which is nearly three times higher than that of commercial silica bricks (0.8 W/m.°C).

Abstract: A biomorphic porous carbon coated with gradient SiC coating (SiC/BPC) was prepared by controlled carbonizing native pine under Ar atmosphere and then processed with precursor infiltration-pyrolysis (PIP) of organosilan. Microstructure and component of SiC/BPC were performed by SEM, EDS (attached with line scanning program) and XRD. The non-isothermal oxidation properties and mechanism of SiC/BPC were studied by TGA. The kinetic parameters were calculated through model-functions methods. Experimental results showed that SiC/BPC has a topologically uniform interconnected porous network microstructure, the SiC coating was amorphous and combines well with the carbon surface, which improved the oxidation resistance of BPC material about 150K. The non-isothermal oxidation reaction of SiC/BPC exhibited the characteristic of self-catalytic, the oxidation mechanism of SiC/BPC was 2-D diffusion, decelerator -t curve, the kinetic parameters are lgA/min-1= 15.483；E/kJ•mol-1 = 287.49.

Abstract: Titania cloth was successfully prepared by the process comprising the steps of (1) immersing a cellulose fabric into titanium compound solution and (2) heating the impregnated fabric under controlled conditions. Several methods such as TG-DTA measurement， X-ray power diffraction (XRD), scanning electron microscope (SEM) were used to characterize the structure and properties of TiO2 cloth. And the TiO2 cloth sintered at 500°C exhibited the highest photodegradation efficiency of MB relative to the other samples.