A multi‐particle 2D plane strain model was used to investigate the dynamic compressive properties of ceramic particle reinforced metal matrix composites (MMCs) in this paper. Ceramic particles were simulated as circl...
A multi‐particle 2D plane strain model was used to investigate the dynamic compressive properties of ceramic particle reinforced metal matrix composites (MMCs) in this paper. Ceramic particles were simulated as circles with different diameters, which were randomly and discretely embedded in the matrix. The constitutive relationship of ceramic material was characterized by Johnson‐Holmquist (JH‐2) damage model. The matrix was assumed to be power‐law strain hardening material, coupled with power‐law strain rate hardening. The ceramic/metal interface was assumed to be perfect. The predicted stress‐strain curves by the numerical models agreed well with those of experiments and unit cell analysis formulae developed by Bao and Lin [3]. The effects of overall strain rates and ceramic volume fraction on the dynamic behavior of the composites had been investigated by this numerical model. The effect of particles' distribution on the particles' damage was also discussed. The results show that the distribution and volume fraction of the particles have obvious effect on the particles' damage.
A new micromechanical method, called the Weighted Residual Self‐Consistent Scheme (WRSCS), is developed to study the effective thermal conductivity of particulate composites. WRSCS provides us with a new approach to ...
A new micromechanical method, called the Weighted Residual Self‐Consistent Scheme (WRSCS), is developed to study the effective thermal conductivity of particulate composites. WRSCS provides us with a new approach to the approximation of effective thermal conductivity of particulate composites with arbitrary phase geometry based on the thermal conduction theory of two‐phase materials within the framework of SCS. FE analyses of a generalized multi‐inclusion model and GSCS model are also carried out in the prediction of the effective thermal conductivity at different inclusion volume fractions. Results show that the effective thermal conductivity depends not only on the properties and volume fractions of its constituents, but also on the geometric shape of the particulate.
Two phosphonic acids: dodecylamine-N, N-dimethylenephosphonic acid (DDPA) and dodecylphosphonic acid (DPA), were used to modify zirconia stationary phase in this paper. The result of FTIR and element analysis indicate...
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Two phosphonic acids: dodecylamine-N, N-dimethylenephosphonic acid (DDPA) and dodecylphosphonic acid (DPA), were used to modify zirconia stationary phase in this paper. The result of FTIR and element analysis indicated that DPA adsorbed on zirconia with Lewis acid-base interaction;however, DDPA adsorbed mainly with chelating effect. Apart from the hydrophobicity, DDPA-ZrO2 had cation-exchange and anion-repellent interaction which was useful for the separation of polar compounds.
A coupled and uncoupled non-linear thermomechanical finite element analysis using ANSYS have been carried out to analyze the heat transfer and associated thermal stresses during different simulated thermal shock proce...
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A coupled and uncoupled non-linear thermomechanical finite element analysis using ANSYS have been carried out to analyze the heat transfer and associated thermal stresses during different simulated thermal shock processes, and the results of two analyses are discussed. It indicates that piezocaloric effect can be neglect when thermal shock intensity is mild and piezocaloric effect should be taken into account when thermal shock intensity is severe.
Extrusion gelation freeform fabrication process is an extrusion-based freeforming technique capable of fabricating complex shaped monolithic ceramic prototypes by the sequential deposition and solidification of cerami...
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Extrusion gelation freeform fabrication process is an extrusion-based freeforming technique capable of fabricating complex shaped monolithic ceramic prototypes by the sequential deposition and solidification of ceramic suspensions from a computer aided design model. In this process, ceramic parts are produced using an extrusion nozzle suitable for extruding ceramic suspensions. In this study, the processing parameters influencing on manufacturing Al2O3 parts were discussed. Air pressure on top of suspensions, rotating speed of screw, nozzle diameter and scan speed are the main factors to influence the dimensional precision of ceramic bodies. By optimizing these processing parameters, the green bodies were fabricated with high precision. The sintered samples with homogenous microstructure and ∼97.6% relative density could be prepared by sintering of these green bodies at 1600°C for 2 hours.
Using the development tool C++ Builder and adopting object oriented programming method, the ceramic/metal gradient thermal barrier coating design software (CCDS) is developed according to software engineering criterio...
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Using the development tool C++ Builder and adopting object oriented programming method, the ceramic/metal gradient thermal barrier coating design software (CCDS) is developed according to software engineering criterion. The CCDS, which has user-friendly interface, is composed of three functional modules: preprocess module, analysis module and post process module. In addition, this software is attached with an optimal design module and an expert module. The calculation and design of the ceramic/metal gradient thermal barrier coating can be carried out by the CCDS, and the numerical results show good agreement with the analytical results.
e effect of sintering temperature on the microstructure, nonlinear electrical behavior, and dielectric properties of the Y2O3-doped WO3 ceramics was studied. The decrease in breakdown voltage directly relates to the g...
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e effect of sintering temperature on the microstructure, nonlinear electrical behavior, and dielectric properties of the Y2O3-doped WO3 ceramics was studied. The decrease in breakdown voltage directly relates to the grain growth of WO3 grains when increasing the sintering temperatures from 1050 to 1200 'C. The capacitor-varistor of WO3- 0.8 mol％ Y2O3 composite sintered at 1150 °C exhibits the maximal nonlinear coefficient of 3.5 and the highest dielectric constant of 1.13 x 104. However, higher sintering temperature than 1150 °C is not favorable for the nonlinear electrical behavior of the WO3 ceramics. The best nonlinear properties of the samples sintered at 1150 'C can be explained by the most efficient boundary barrier layer with can be formed sintered at the proper temperature.
Potassium lithium niobate (KLN:K3Li2Nb5O15) thin films have been deposited on quartz glass by pulsed laser deposition (PLD) technique using a stoichiometric KLN target, which was prepared by solid reaction with K2CO3,...
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Potassium lithium niobate (KLN:K3Li2Nb5O15) thin films have been deposited on quartz glass by pulsed laser deposition (PLD) technique using a stoichiometric KLN target, which was prepared by solid reaction with K2CO3, Li2CO3, and Nb2O5 powders as starting materials. X-ray diffraction (XRD) and Raman studies have revealed that tetragonal tungsten-bronze-type structure of KLN films with (310) preferred orientation could be achieved at the substrate temperature of 700°C and the oxygen partial pressure of 10 Pa. The average transmittance of as-deposited thin films in the visible range was nearly 90%.
In this paper the inflaming retarding effects of epoxy resins blended with basic magnesium carbonate [Mg(OH)2·4MgCO3·5H2O] were synthesized. When the add-on of basic magnesium carbonate reached 56.5%, the LO...
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In this paper the inflaming retarding effects of epoxy resins blended with basic magnesium carbonate [Mg(OH)2·4MgCO3·5H2O] were synthesized. When the add-on of basic magnesium carbonate reached 56.5%, the LOI of the epoxy resins increased to 29.7%. The flame retardant mechanisms of basic magnesium carbonate for epoxy resins was investigated by XRD, TG-DSC and SEM. Results showed that through the ways of diluting, cooling, isolating and their synergies, basic magnesium carbonate achieves the flame retarding target.
This paper used amino-terminated polyether, and amino-terminated polyurethane mixture as curing agent to cure the epoxy resin. A series of epoxy elastmors was gotten. The curing products of epoxy elastomers were chara...
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This paper used amino-terminated polyether, and amino-terminated polyurethane mixture as curing agent to cure the epoxy resin. A series of epoxy elastmors was gotten. The curing products of epoxy elastomers were characterized by DSC and FT-IR respectively. The fracture surface morphologies of the cured products were observed by scanning and transmission electron microscopy analysis. The results showed that the impact toughness of the cured products reaches 52.1 kJ/m2 and the elongation of fraction reaches 160% as well as good mechanical properties.
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