Applied Mechanics and Materials Vol. 459

Abstract: Elementary compositions of municipal solid waste incineration (MSWI) fly ash was analyzed. In addition, influence of perchloric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that there are 11 major elements in fly ash, with content over 1%, and content of them follows sequence of O > Ca > Si > Cl > Al > Fe > Na > S > C > Mg. These major elements account for around 97.5~98.7% of the ash. Removal ratio of Zn, Pb, Cd and Cu followed the decreasing sequence of Zn > Pb > Cd >Cu for acid extraction using perchloric acid. The optimal extraction conditions are: perchloric acid 3 M, liquid to solid ratio 30 mL liquid / 1 g ash, resulting in an extraction ratio of 89% for Zn, 85% for Pb, 41% for Cd and 32% for Cu.

Abstract: MSWI (municipal solid waste incineration) fly ash, generated in incineration process of municipal solid waste, contains lots of heavy metals, which will do harm do the environment if extracted. In this work, the ash is stabilized by cement to reduce leaching toxicity of heavy metals. Besides, mineralogical compositions of the product of different cement / ash ratios after conservation for different period were analyzed by means of XRD (X-ray diffraction). It was found that major mineralogical compositions CaCO₃, Ca (0H)₂ and C-H-S hydration products. Content of Ca (0H)₂ and C-H-S rises with increase of conservation period and cement / ash ratio.

Abstract: Carbon nanotubes (CNTs) reinforced copper (Cu) matrix nanocomposites prepared via advanced fabrication method is presented. Functionalization and ultrasonication processes have been applied to enhance the dispersion of purified CNTs and creates sidewalls groups that have the potential to bond CNTs to the metal matrix. The main part of this approach was metal injection molding (MIM) technique, which is a combination of powder metallurgy and plastic injection molding technique. Preparation of MIM feedstock required a melting and mixing process of binder system (polymers) with the solid loading, which has been carried out using a twin screw rotor machine. This machine provides a viscous media of the molten binder with high shear forces that allow the additives (carbon nanotubes/copper powder) to be mixed properly and exfoliate the CNTs clusters with uniformdispersion inside the Cu matrix. Subsequently, to prove our expected results, observation tests of TEM, SEM, FESEM and CNTS were employed and discussed literally.

Abstract: In the current study, the material corrosion behavior and degradation of a closed-loop copper piping systems were investigated taking temperature and flow parameters into consideration. To simulate the practical environment conditions, two identical copper closed-loop piping systems were constructed with three types of joints. Both systems were filled with 3% sodium chloride solution and run for about eleven months period. They were heated to a temperature of 80°C for eight hours a day and for 5 days a week. Outside that heating period, systems were maintained at room temperature (23± 2°C). Within such a heating interval, the contained solution for one system was kept in stagnation condition while it was flowing at input velocity of 0.27 m/s for the other. For both systems, the corrosion was then assessed and quantified using different evaluation techniques: Potentiodynamic test, Pourbaix diagrams, light microscope and scanning electron microscopy (SEM). The experimental results confirmed a diverse significant influence of solution flowing conditions on the damage of copper pipes.

Abstract: Friction on the atomistic scale was simulated using a molecular dynamics model consisting of a slider and substrate. The slider is in contact with the substrate through interatomic forces, while being pulled by a spring connected to a tractor moving parallel to the substrate surface at a constant velocity. The frictional force, which is defined as the force working on the connecting spring, is registered as the slider moves over the substrate, and consequently stick-slip behavior is observed. The static frictional force is higher if the lattice mismatch between slider and substrate is smaller. The sliding velocity affects whether atoms can rapidly settle into a stable site, and hence affects the kinetic friction; at high velocities, the atoms are forcibly moved resulting in a smaller kinetic friction force and a steady force curve.

Abstract: This study investigates the resulting nanocomposite material formed by hot-forming and molding epoxy resin containing diluent, nanosilica powder, and hardener. The effects of different processing conditions on the composite material, such as post-processing, nanopowder content, thinner amount, etc. The optimal processing conditions can be discovered by analyzing samples with a differential scanning calorimeter (DSC) to discern the glass transition temperature (Tg). Experimental results show that without post-processing, the composite material would not have enough reaction time, and that without thinner, the sample containing 1 wt% nanopowder had the highest Tg. The addition of thinner lowers the Tg of a sample, leading to reduced thermal properties.

Abstract: In this study, the Taguchi experimental design methodology is used to optimize the composition of a nanopowder/epoxy resin material comprising Al₂O₃, SiO₂, carbon black nanopowders, epoxy resin and diluent. A Taguchi orthogonal array is employed in planning the configuration of the samples for the experiment. The signal-to-noise (S/N) ratios, and the variances are analyzed. The thermal decomposition temperature of the nanocomposite with optimum composition increased 37.16°C (increased by 12.5%) compared to pure epoxy. The experimental data generated in the Taguchi trials are processed using a regression analysis technique in order to derive an analytical formula relating the composition of the composite samples to their thermal properties. It is shown that the results obtained using the analytical formula are in good agreement with the experimental observations with only 1.95% error.

Abstract: Zr/TiAlN coatings as well as single TiAlN coatings were deposited on high-speed steel and cemented carbide substrates by medium frequency magnetron sputtering. The crystal structure and cross-sectional morphology of coatings were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The adhesion of coatings to substrate was measured by Rockwell indention tests. These investigations show that the main diffraction peak of Zr/TiAlN and TiAlN coatings are corresponding to the TiN phase. The preferred orientation of out TiAlN coatings is obviously affected by Zr interlayer and substrate materials. The TiAlN coatings both on HSS and cemented carbide substrates exhibit a columnar structure. But, the columnar morphology of Zr/TiAlN on cemented carbide substrate becomes ambiguous and this structure of Zr/TiAlN coatings on HSS substrate even changes to isometric. The Rockwell indention results indicate that the adhesion of TiAlN coatings is significantly improved by adding Zr interlayer both on HSS substrate and cemented carbide substrate.

Abstract: In the aspect of biomedical diagnosis, magnetic nanoparticle can be used as drug carrier and MRI/ SPECT/ PET contrast agents. Magnetic fluid hyperthermia is one of the most important cancer therapies. Magnetic nanoparticles display their unique features as heating mediators for hyperthermia. In this study, Fe₃O₄ magnetic nanoparticle was prepared by using chemical co-precipitation method. Tc-99m pertechnetate with Fe₃O₄ magnetic nanoparticles is prepared by using magnet adsorption method. An attempt was also made to evaluate the application in the field of magnetic targeted drug delivery and radioactive targeted cancer treatment in the future. In this work, preparation and characterization of non-polymer and polymer (dextran) coated Fe₃O₄ magnetic nanoparticles labeled with technetium-99m pertectnetate were evaluated and served as precursors study. The Tc-99m labeling efficiency of in-house Fe₃O₄ magnetic nanoparticles (MNP) and commercial kit were ca.98.4 % and 85% (n=5), under the same conc. of 6mM, 0.1 ml of SnCl₂·2H₂O, respectively. The Tc-99m labeling efficiency of magnetic nanoparticles with its dextran-coated was ca. 58.2% (n=5) at the same conc. and volume of SnCl₂·2H₂O. The in-vitro stabilities of the 3 kinds of magnetite magnetic fluids were higher than 96.0% (n=5) during 2 hours. The reducing agent of SnCl₂·2H₂O plays a key role due to its reducing ability for Tc-99m pertechnetate. The optimal reaction time of SnCl₂·2H₂O with Tc-99m is better under 1 hour. In conclusion, the Fe₃O₄ magnetic nanoparticle labeled with Tc-99m pertechnetate has shown good qualities for its labeling efficiency and stability. It may be feasible preliminary to utilize in the application of magnetic targeted drug delivery of bio-medicine.