Advanced Materials Research Vols. 383-390

Abstract: The study of physicochemical properties such as surface area, particle size and basicity of heterogeneous catalysts is in great interest nowadays. CaO yield a number of surface defects centers and these were important especially for heterogeneous catalyst. In this study, nano structured CaO was synthesized via hydration-dehydration method. The basic strength of the prepared CaO was also studied using simple back titration method with respect to the activation temperature. This result revealed that, the basic strength increases with the increasing of activation temperature. As the nano structured CaO were prepared, more surface cavity and defect were expected to be present and thus, exposing more O^2- sites, which influences the basic strength. Finally it was found that nano structured CaO was successfully prepared, while compared to the commercial CaO have a better chemical properties for catalytic chemical reactions.

Abstract: The non-local formulation of elasticity has been introduced as a correction to the local theory in order to account for long ranged inter-atomic forces. This elasticity theory is useful to estimate the in-plane stiffness of Single Wall Carbon Nanotube. The non- local effect is present in Single Wall Carbon Nanotube through the introduction of a non-local nanoscale which depends of the material and a molecular internal characteristics length. This non-local nanoscale goes to zero at macro scale and hence the non-local effect vanishes with reference to classical mechanics. The resulting from the non-local elasticity theory is verified through molecular simulations results. For this study of non-local theory in analysis of Carbon Nanotube, the value of scale coefficient is about 0.7nm.

Abstract: Based on Zwick/Roell,this paper had carried on flexural experiments of epoxy resin filled with nano-silica particles, obtaining related mechanical properties.Microstructures of nanocomposites were analyzed by scanning electron microscopy (SEM) in the meanwhile. The flexural experiments revealed that nano- silica particles strengthened epoxy resin very well, and flexural modulus of modified matrices rised due to rigid silica particles, compared with pure epoxy matrices. Flexural strengths of epoxies modified by silica nanoparticles improved significantly.

Abstract: This paper presents the study of rheological and thermal behaviour of high impact polystyrene/multiwall carbon nanotubes (HIPS/MWCNTs) nanocomposite. The nanocomposite was prepared via melt mixing method. The influence of different loadings of MWCNTs on the HIPS viscosity and other rheological characteristics were analyzed experimentally. Other rheological characteristics were studied using dynamic analysis of viscosity through rotational rehometer. Glass transition temperature (Tg) were also investigated using non-isothermal differential scanning calorimeter analysis. The viscosity was found to be directly proportional to MWCNTs’ loading, up to five times the value of pure HIPS at loading level of 7.5wt% of MWCNTs. The MWCNTs loading demonstrated a marginal effect (1-2%) on the Tg.

Abstract: In this work, nanocomposite hydrogels on the basis of Polyvinyl alcohol (PVA) and kaolinite nanoclay were prepared by the repeatedly freezing-thawing method. The structure and morphology of nanocomposite hydrogels were studied by the XRD, TEM and SEM techniques. The function of nanoclay in the nanocomposite hydrogels was investigated using the FTIR and DSC tests. It was found that the prepared nanocomposite hydrogels have the intercalated morphology with good dispersion of nanoclay layers in hydrogel matrix. DSC results showed some shifting in the glass transition temperature of PVA hydrogel in presence of nanoclay. The FTIR results also showed that some interactions have been developed between the hydroxyl groups of PVA chains and kaolinite layers in nanocomposite hydrogels.

Abstract: Nano- crystallization of Fe₅₅Cr₁₈Mo₇B₁₆C₄ bulk amorphous alloy has been analyzed by X- ray diffraction, differential scanning calorimetric test, and TEM observations in this research. In practice, crystallization and growth mechanism were evaluated using DSC tests in four different heating rates (10, 20, 30, 40 K/min) and kinetic models. A two -step crystallization process was observed in the alloy in which α – Fe, Fe23B6, and Fe3C phases were crystallized in the structure after annealing process. In addition, activation energy for the first step of crystallization process (i.e. α – Fe phase) was measured to be 276 (kj/mol) and 290 (kj/mol) according to Kissinger and Ozawa models respectively. Avrami exponent calculated from DSC curves was 2 and a three -dimensional diffusion controlled mechanism with decreasing nucleation rate was observed in the alloy. Further, it is known from the TEM observations that crystalline α – Fe phase nucleated in structure of the alloy in an average size of 10 nm and completely mottled morphology.

Abstract: The anodization of aluminum templates created nanoporous alumina tubes arranged parallel to each other and electrodeposition using gold solution (AuHCl₄) resulted in arrays of gold nanowires (GNWs) inside the pores. For investigation of Au-nano-neuronal interactions, we have cultured embryonic day 18 rat hippocampal neurons on the surface of nanowires. For preliminary understanding of the neuronal growth and connectivity, we studied the images of nano-neuronal interactions by using optical, fluorescence and scanning electron microscopy (SEM). For adhesion of neurons to nanoarrays surfaces, we used bioconjugating protein coating Poly-D-Lysine (PDL). The embryonic hippocampal tissues were dissociated mechanically and cultured on Au-nano templates. We demonstrated well-defined neuronal networks on Au-nanowire (GNW) arrays and on standard glass coverslips. The neurons attached with the nanowires surfaces by an interface of PDL, which is a positively charged poly-peptide and plays a vital role in neurites growth on the nanowire arrays. The pre- and post-synaptic affects of neuronal interactions on the surfaces of nanowires were measured by Ca+ imaging in Keck microscope.

Abstract: In metal processing, lubricant penetration process can be explained by the capillary model theory. Observed through microscope, cylindrical capillary model was chosen and was analyzed on the basis of hydrokinetics. Moreover, it was indicated of the basis for dividing the entire penetration process. Based on kinetic theory of gases, the penetration of gas-liquid two-phase flow in minimum quantity lubrication (MQL) machining was simply analyzed and it was pointed out that there was only gaseous phase filling process.

Abstract: Some terrible disasters of aircrafts were caused by inadequate lubrication or interruption of lubricant delivery of the gas turbine engine mainshaft bearings. This paper introduces the design of the test equipment, performs the experiments of failure performance for 51306 coated bearings to respond to oil interruption under the actual situation. The main failure performance of test coated bearings has been demonstrated to be the cage damage of the test coated bearing. The failure mechanism model of the damaged cage of test coated bearings under oil interruption condition is established for the failure analysis of damage cages. The failure mechanism of the damaged cages is revealed. The main reason for the damages of test coated bearing cages under lubricant interruption condition is that the perpendicular component force acted on the cage increases continually to go with the increase of the friction force between the balls and the cage due to inadequate lubrication until the cage is broken.

Abstract: Stable evaluation of coal strength is needed in coal well-bore stability analysis. The regular analysis method of wellbore stability adopts Mohr-Coulomb strength criteria to judge the collapse pressure. Coal is dual porosity structure and contains joint fissures richly. Hoek-Brown criterion is much more reasonable to estimate the strength of jointed and fractured rock. So Hoek-Brown criterion is used to analyze the stability of multi-lateral horizontal coal bed methane well. Considering the GSI (geological strength index), structural and surface conditions of coal, the coal and rock mass strength parameters are converted into the underground coal mechanical parameters based on the triaxial test of intact coal. According to the stress state of multi-lateral horizontal well, the borehole collapse formulas are established based on Hoek-Brown Criterion. The effects on the wellbore stability, due to the joint fissures of coal, borehole size, drilling disturbance, are also discussed in this paper.