Advanced Materials Research Vols. 284-286

Abstract: Earthquake damage of MMCs simulated by computer is a very valuable area. It can do large, prototype, repeated and destructive simulation. The failure process of the material and structural can be analyzed .The process of numerical simulation of Fe / Zn MMCs is first described in this paper.

Abstract: Cementitious material can be considered consisting of particulate elements on the levels of the microstructure and mesostructure. HADES is a concurrent algorithm-based program, designed to simulate the mixing or flow of granular material encompassed arbitrary particle shapes. In this paper, a specific technology is employed to generate the single aggregate particle of arbitrary shape in HADES. Then with the HADES toolbox materials structure can be formed. Based on these work, concrete is taken as an example of a typical cementitious material. With the simulated meso-structure of concrete from HADES, interfacial transition zone (ITZ) is enriched and a special tool is employed for the meshing of aggregates, cement paste and ITZ. After that finite element method is used for the analysis of stress and strain within the meso-structure. The calculation results show that the approach to simulate cementitious material, of HADES packing, then meshing and finally finite elements analysis, is feasible and effective and the numerical prediction of elastic modulus of concrete consisting of three-phase material is in agreement with effective.

Abstract: This paper is concerned in semi-infinite interface crack of orthotropic and isotropic bi-materials and using the composite material fracture complex function method. By means of constructing special stress functions with two real singularity index and solving the problem of a class of generalized bi-harmonic equations , the stress and displacement fields of two dissimilar materials are obtained .Results demonstrate that the stress and displacement fields near the crack tip show mixed crack characteristics without oscillation.

Abstract: Ti₆₆V₁₃Cu₈Ni_6.8Al6.2 bulk composites with high strength were fabricated by spark plasma sintering of amorphous Ti₆₆V₁₃Cu₈Ni_6.8Al_6.2 powder synthesized by mechanical alloying. X-ray diffraction (XRD), differential scanning calorimeter (DSC), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to investigate the synthesized amorphous powder and the fabricated composites. Results show that the supercooled liquid region ΔT_x and the crystallization enthalpy DH_x of the synthesized amorphous powder decrease, in relative with amorphous Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 powder, indicating that the thermal stability and glass forming ability of the synthesized amorphous powders decreases with vanadium element substituted for niobium element. And particle size of the synthesized amorphous powder also decreases. In addition, the fabricated alloys also consist of body-centered cubic β-Ti (V) and face-centered cubic (Cu, Ni)-Ti₂ regions, similar to Ti₆₆Nb₁₃Cu₈Ni_6.8Al_6.2 bulk alloys. The alloys exhibit a high fracture strength around 1966 MPa but limited plasticity.

Abstract: The hydration kinetics of carbonized spinel carbon bricks with different proportions of Mg / A1 additive has been studied in water steam of super thermostatic bath between 25°C and 85°C.The kinetic equations for hydration of the brick have been derived according to the experimental data and the theory of kinetics. Methods of various protections against hydration have been discussed. It shows that chemical reaction control occurs in the carbonized spinel carbon brick with Al and Mg at 44.3°C-84°C. The cracking time reduces from 40h to 4h with the rising of temperature verifies from 44°C to 84°C, the hydration is controlled by diffusion between 24.7°C and 33°C. And cracking does not appear after 50-day-and-night hydration at 24.7°C.

Abstract: Particles reinforced Al-xwt.%Si-Al₂O₃ (x=10,20) composites are fabricated through in situ reaction sintering of Al and SiO₂ powder by hot isostatic pressing. Outgassing process and the microstructure of composites under different sintering processes are studied.XRD analysis confirms that the best hot outgassing temperature is 500°C,in situ reaction achieves completely and samples A2 and B2 have better microstructure at 550°C then heating-up to 700°C only for 1h.The microstructure analysis indicates that the reinforcement particulates distribute uniformly in the aluminum matrix.The mechanical properties test results show that the tensile strength of A2 is higher than B2. when x=10,the Al-Si-Al₂O₃ composites have better performance.

Abstract: Based on ceramic laser gelling process, the purpose of this research is to obtain a proper slurry, which can be employed to cast layer with a thickness smaller than 100 μm to improve the staircase effect occurred in layer manufacturing, by optimization of the water content to fabricate ceramic part with better surface. The slurry was composed of alumina particles with average size of 0.5 μm as the structure element, silica sol as an inorganic binder and ammonium polymethacrylate as a dispersant. The slurry was dispersed uniformly by a ball mill. The results revealed the variation of water content will significantly influence the viscosity of the slurry and the formability of the ceramic green part. High water content led to poor binding of the particles and induced the delamination of the consolidated layers. On the contrary, low water content led to high shear force between scraper and slurry surface; such force damaged the previous layer during the casting process. As a result, the water content of 34 wt% was the most favorable to casting thin layers. The capability of casting 40 μm layer, which is smaller than that obtained by previous studies, was achieved. Because of the thinner layer, the staircase effect was improved.

Abstract: SiO_x barrier films were deposited on poly (ethylene terephthalate) (PET) by radio frequency (RF) magnetron co-sputtering with double targets. The films deposited by co-sputtering were denser and smoother because different energy particles sputtering from double targets grew small islands to weaken shadowing effect which greatly reduce the interval gaps. The water vapor and oxygen transmission of SiO_x films deposited by co-sputtering decreased to 0.31 cc/m²/day, 0.27 g/m²/24h respectively.

Abstract: In order to study the effects of laminated structure on acoustic insulation property of composites, the frequently-used flexible polyvinyl chloride (EPVC) sheets and non-woven fabric were selected as the substrate materials to prepare for ten types of nonwoven fabric/EPVC composites with different laminated structures in this study. Their acoustic insulation properties were tested and analyzed by the double channel acoustic instrument. The results showed that the different laminated order of composites has significant influence on its acoustic insulation property under the same conditions; and the acoustic insulation property of composites can be improved by the change of laminated order only.