Materials Science Forum Vols. 610-613

Abstract: O'-SiAlON/SiC ecomaterials were synthesized by using the Yangtze River sand that containing abundant Si and Al elements as the major raw material with minor additives through the carbothermal reduction nitridation route combined with colloidal process. This study realized the conversion of ecomaterials from non-traditional resources, Yangtze River sand. Orthogonal design was adopted to optimize the colloidal process parameters. The green compact with the largest bulk density was obtained when the solid volume loading is 50%, the addition mass fraction of SL is 0.8%, the addition mass fraction of CMC is 0.05%, the ball milling time is 10 h, the pH value is 9 and particle size distribution is multi-peak in the colloidal process. The effects of reduction agent, flowing rate of N2, sintering temperature during carbothermal reduction nitridation process on the microstructure of as-fabricated SiAlON materials were explored. The XRD results indicated that when sintering temperature is 1450°C, maintaining time is 6 h, flowing rate of N2 is 1.0 L/min and carbon black is selected as reduction agent, O-SiAlON/SiC composites was successfully synthesized. The SEM images showed the densificated microstructure and uniform grains with the short column shape.

Abstract: The Ce-V/TiO2 catalysts with the selective catalytic reduction (SCR) were prepared by method of Sol-gel and insuccation. The phase compositions, microstructures and specific surface area of the catalysts were analyzed by XRD, SEM and BET, respectively. The effect of CeO2 and V2O5 loading and reaction temperature on the catalytic performances of the as-prepared catalysts was investigated by using the selective reduction of NOx with NH3. The results showed all the as-prepared Ce-V/TiO2 catalysts were made up of nanometer grains. Compared to conventional TiO2 catalysts, the as-prepared Ce-V/TiO2 catalysts possessed better catalytic performance, higher adsorbability and larger area of contact with reactant, which is due to large quantity surface micropores. The NOx conversion of SCR over 5wt%Ce-10wt%V/TiO2 catalysts reached 96.2% at the reaction temperature of 500 oC.

Abstract: In this paper, the research mainly focused on utilization of iron ore tailing of Panzhihua region. Based on the analysis of its components, Carbothermal Reduction Nitridation (CRN) method was selected to synthesize eco-friendly composite material. Different additives were tried to improve the property of the samples. The influence of different sintering temperature, holding time and contents of additives were taken into account, and orthogonal design was employed to obtain the optimal parameters. It indicated that only when the temperature was 1450°C and the holding time was 5 hours, the samples with the bulk density of 3.42g/cm3 was obtained. The phase and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Experimental results showed that the phases of the product were Fe3Si and TiC0.3N0.7. The research provided a novel recycling process for ore tailings.

Abstract: The brookite-phase TiO2 was prepared by a hydrothermal synthesis of titanium chloride solution. The thermolysis time and the pH value of the solution were controlled during the synthesis. X-ray diffraction experiments showed that TiO2 powders partially containing the brookite-phase were successfully obtained. A higher amount of OH- in the reaction solution was found to be important to obtain the brookite phase because the intermediate complex leading to the brookite phase consumes more amount of OH- than other phases like the rutile.

Abstract: Combined with sol-gel method, ultrasonic impregnation approach was employed to prepare TiO2/ Al2O3 surface composite on aluminum. The results showed that with the effect of ultrasonic, the TiO2 colloid fabricated by sol-gel method can enter the inner of the ordered AAO film to form anatase TiO2 nano wires after being heated at 500°C for 2h. The diameters and lengths of TiO2 nano wires were controlled by the diameter and thickness of AAO film. Close to the bottom of aluminum substrate, the TiO2 nano wires became nano pipes, plates and particles.

Abstract: The direct current (DC) reactive magnetron sputtering of a metal copper target in oxygen-argon mixed atmospheres to produce thin films of crystalline copper oxides was described. The sputtering pressure, sputtering power and oxygen flow rate were established in order to control the structures and properties of Cu2O films. The as-deposited Cu2O films with various crystal structures have high visible absorption and photo-catalytic activity under visible light irradiation. The photo-catalytic properties of Cu2O films are affected by not only the crystal structure but also the surface morphology.

Abstract: Silver / CNTs was prepared by ball milling method and was used as filler to reinforce epoxide resin based conductive adhesive. The effect of content and dispersion state of the filler on tensile strength, tensile modulus, fracture extensibility and electrical resistance of the composites were studied. The results indicated that the filler could be dispersed well in epoxide resin matrix by ultrasonic method and the mechanical and electrical properties was improved greatly. The best content of the silver / CNTs was 0.75 wt% (considering of CNTs weight percentage), when the tensile strength, tensile modulus and fracture extensibility increased 42.6%, 18.8% and 115.3% respectively. With the increase of silver/CNTs, the conductivity of the matrix increased significantly. The micro structure analyses showed that the silver-covered CNTs worked as conductive channel and the electrons were easy to transfer through silver powder by CNTs network.

Abstract: . The Ce3+/TiO2 complex membrane made from Ce3+on the TiO2 framework with the activity of photocatalysis were prepared. The degradation behavior of the best mass ratio of Ce3+/TiO2 complex membrane , and the influences of the diameters of particles of Ce3+/TiO2 complex membrane on the degradation of the harmful gases under 254nm and 365nm ultraviolet light or natural light in room were investigated. AFM result showed that the Ce3+/TiO2 complex membrane were composed of nanoparticles with 10nm~50nm diameters of particles. The experimental results revealed that the smaller the nanoparticles in Ce3+/TiO2 complex membrane, the greater the degradation degree was. The best mole ratio of Ce3+ and TiO2 was 5% and the best mass ratio of Ce3+/TiO2 and formaldehyde were 7.06 under 254nm and 365nm ultraviolet and 23.55 under the natural light in room after 24h when the degradation percents of formaldehyde were more than 90%. Same as above conditions ammonia were 8.76 and 25.79 and benzene were 15.65 and 35.32. The degradation percents of Ce3+/TiO2 complex membrane to harmful gases were higher about 3 times under 254nm and 365nm ultraviolet than under the natural light in room.

Abstract: TiO2-C composites of high photocatalytic activity were in-situ fabricated with nano-TiO2 powders and resins. The composites were characterized by differential scanning calorimetry and thermal gravimetric analysis (DSC-TG), X-ray diffraction (XRD), UV-Vis diffuse reflection spectrum (DRS), transmission electron microscope (TEM) and scan electronic microscopy (SEM). XRD results indicated that the composites consist of carbon and anatase phases. UV-Vis DRS showed that composites not only have a good performance in the ultraviolet region, but also have a very good performance in the visible light region. Photocatalysis degradations of methyl orange with purity nano-TiO2 and TiO2-C composite were tested by lighting of visible light. After methyl orange liquid was lighted by visible light for 1 hour, the decolorization ratio of methyl orange can be up to 96.3%( reactive brilliant red X-3B:98.7%) with TiO2-C powders, while it was only 34.7% (reactive brilliant red X-3B:66.9%) with purity nano-TiO2 powders. In-situ fabricated carbon can change the width of energy band of TiO2 and adsorb methyl orange and reactive brilliant red X-3B molecules. The former accelerate the absorption of visible light, and the later raise the decomposition rate of methyl orange and reactive brilliant red X-3B. All of these can improve photocatalytic activity of TiO2-C composites under the visible light.

Abstract: The role of both nano-sized of plasma treated Nano Titanium Dioxide particles and strain rate on the tensile properties of plasma treated Nano Titanium Dioxide particles/PP/PLA nano-composites filaments (PTNTOPPCF) was studied. Filaments tensile samples of PTNTOPPCF were prepared by a twin screw mixer- twin screw extruder with a particle content of 0.3~1%. The influence of surface treatment of the particles, with and without low-temperature oxygen plasma treatment, on the physico-mechanical properties was studied. The tensile tests were carried out, differential scanning calorimetry (DSC) and SEM were used in this investigation. Tensile tests were done at different strain rates. The addition of plasma treated Nano Titanium Dioxide particles to PP/PLA caused a change in Young's modulus and yield stress of its composites. The experimental results also showed that the strain-rate sensitivity of PTNTOPPCF changed as plasma with and without oxygen treated Nano Titanium Dioxide particles was added to it with different o.w.f.. We found that the models lead to estimates of activation volumes in the range 4−40nm3 for truly nanocrystalline material. Activation volumes were found to changing un-monotonically with oxygen plasma treatment. The findings were found to be in accord with available experimental evidence in both a quantitative and qualitative manner. Deficiencies in the available experimental evidence were noted, specifically in the context of explaining some of the difficulties in comparing theoretical predictions to experimental observation.