Papers by Keyword: Porous Material

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Authors: Jan Škramlík, Miloslav Novotný, Ondřej Fuciman, Karel Šuhajda
Abstract: The moisture in building construction material affects the physical properties of buildings and he may lead to their degradation. With few exceptions, building materials are almost never dry. For the expected negative effect of moisture on building materials of structures is needed accurate method of determining the characteristics of their moisture as possible. The capillary conductivity coefficient characterizes transfer of liquid moisture in porous material. The method for its determination is experimentally arranged in such a way that it is possible to apply diffusion equation derived from the Luikov equation that is a phenomenological description of liquid moisture transport in porous materials as well as from the continuity equation, which expresses the classic conservation of matter principle. To records of the moisture distribution has been developed the methodology for measuring of moisture in the porous material, using microwave radiation. The calculation of the capillary conductivity coefficient and its dependence is based on the moisture curves in 3 D in non-stationary state of wetting, determined by non-destructive method.
180
Authors: Christian N. Della, Dong Wei Shu
Abstract: In this research, a comparative study of the hydrostatic performances of 1-3 piezoelectric composites with a porous matrix is presented. The piezoelectric fibers PZT-5H and PZT-7A are considered in the present study. The micromechanics based Mori-Tanaka model is used. Results of the study show that PZT-5H/Aradite D composite have better hydrostatic performance than PZT- 7A/Aradite D composite, and this advantage of PZT-5H/Aradite D composite over PZT-7A/Aradite D composite increases with the increase of porosity in the matrix.
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Authors: Feng Li Cao, Hong Bai Bai, Zhong Bo He, Guo Quan Ren
Abstract: Dynamic load experiments of the disc-shaped metal rubber isolation component are performed. Through analyzing variation law of the parameters with amplitude and frequency, which are stiffness coefficient, damping coefficient and damping component factor, the hysteresis restoring force model which is able to fully reveal the dynamic characteristics of the component is established. The experimental verification results show that the theoretic calculations are consistent with the experimental data, which verifies the practicability and effectiveness of mathematical model and parameter identification. It has important practical significance for design of vibration isolation component with different requirements.
186
Authors: Mao Deng, Zong Ming Wang, Chun Xue Zhang
Abstract: We present an easy approach to obtain the dynamic flow field with a moving body inside. Instead of popular interface boundaries, the interior boundaries were applied as moving parts, which made separated computation volumes a default-continuum meanwhile. With the combination use of UDF and dynamic mesh model, the numerical technique was tested and validated by simulating flow through moving screen, a kind of porous material. The pressure and velocity contours obtained clearly showed the changing behaviors of the flow while passing through a moving porous material, and clarified the influence posed by the movement of its frame. The method is used for the simulation of the flow with a moving body inside.
319
Authors: K.E. Belyavin, D.V. Minko, N.V. Reshnetikov
Abstract: A technology of hardening porous materials of titan powders has been elaborated. The technology is based on passing alternating current with duration of ~10-1…101 s through porous (35…40%) blanks made by method of Sintering by Electric Discharge (SED) by passing a pulse of current with duration of ~10-5…10-3 s. The influence of technological regimes of porous blanks treatment on their structure and properties is investigated. Geometry and dimension of contact necks between powder particles of obtained samples are evaluated. Variations of porosity and strengths as well as microstructure of porous samples materials before and after treatment are investigated. Optimum range of treatment technological regimes is determined within which porosity of 30…35% with maximum strength values.
613
Authors: Kazushige Ohno
Abstract: The long time of twenty years has passed since Diesel Particulate Filter (DPF) was proposed before the practical use. The main factors that DPF has been put to practical use in this time, are the same time proposal of the evaluation method of SiC porous materials linked to the performance on the vehicle, and that the nature of thermal shock required for the soot regeneration (combustion of soot) in the DPF is different from the conventional requirement for the rather rapid thermal shock. For the requirements, these include demonstrating utmost the characteristic of SiC’s high thermal conductivity, and overcoming the difficulty of thermal expansion of SiC-DPF by dividing the filter into segments binding with the cement of lower Young’s modulus, and the innovation of technology around the diesel exhaust system such as Common-Rail system. As the results of these, the cumulative shipments of SiC-DPF have reached about 5 million, and it goes at no claim in the market.
207
Authors: Shun Jian Xu, Xing Zhong Zhao, Zong Hu Xiao, Yong Ping Luo, Yong Huang, Wei Zhong, Hui Ou
Abstract: A novel approach has been developed to fabricate an oriented flat porous carbon (OFPC) by combining the polymerizationinduced phase separation and pyrolysis (PIPSP) and the directional compressive deformation (DCD). At first, an elastic body in the shape of cylinder is obtained by controlling the polymerization degree of resin, and then the application of symmetrical axial pressures results in the directional deformation of two interconnected phases (of a polymerized resin phase and a poreforming agent phase) in the elastic body. Then the elastic deformed body is transformed to the rigid deformed body by precuring and further to the cured body by curing. At last, the cured body is pyrolyzed to form an OFPC. The pressures are removed after precuring. The pores in the OFPC are survived as the discs in the radial direction. Both flat pores and carbon skeletons in the OFPC are oriented toward a radial direction. The OFPC has comparable pore volume with a normal porous carbon, which is fabricated by the PIPSP with same process except for the application of the DCD.
551
Authors: Yin Zhang, Yoshiyuki Yokogawa, Tetsuya Kameyama
Abstract: There is a clinical need for synthetic scaffolds that will promote bone regeneration. Important factors include obtaining an optimal porosity and size of interconnecting macropores whilst maintaining scaffold mechanical strength, enabling complete penetration of cells and nutrients throughout the scaffold, preventing the formation of necrotic tissue in the centre of the scaffold. To address this we investigated flexural strength of bimodal porous apatite ceramics prepared using apatite slurry and its slurry synthesis was studied. Slips with different contents of HAp (K-HAp and T-HAp) and deflocculant were prepared by milling in a pot mill. The viscosity of slurries made of commercial T-HAp powder showed a drop after 3 hours’ milling, but the viscosity of slurry with high solid content of k-HAp and 2.0 wt% deflocculant increased with an increase of milling time after 2 hours’ milling. The porosity and flexural strength of the porous HAp prepared by heating the foam dipped in K-HAp slip with 2.0 wt% of deflocculant and 0.5wt% of foaming regent heated at 1200°C were 62.4 % and 14.7 MPa, and those in T-HAp were 59.7 % and 15.2 MPa with 1.5 wt% of deflocculant and 0.5wt% of foaming regent heated at 1200°C.
151
Authors: Shou Ren Wang, Pei Quan Guo, Hong Yan Wang, Min Wang
Abstract: Owing to two phases are continuous and penetrated each other, Interpenetrating composites exhibit good abrasive wear properties, can be an attractive candidate for structural and functional materials. Specifically, the abrasive wear model of IPCs is an important topic in the field of tribology. In present work, the model has been proposed according to the mixing rule. Many factors such as special topology structure characteristic of reinforcement, hardness and elastic module are discussed in this model. One kind of Al2O3/Mg composite with different volume content was fabricated and many test data of friction wear were obtained. These data validate the correctness and universality of model.
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