Papers by Keyword: Porous Material

Abstract: Porous membranes made of Ti – 48 at. % Al intermetallic compound was obtained by elemental powder synthesis. These disks can be used as microfiltration membranes due to their low pores size and interconnected porosity. During this study titanium (purity 99.5%) and aluminum (purity 99 %) with low particle size range were mixed in corresponding ratios. The powder mixture was pressed at 500 MPa and the samples were heat treated in two stages. In the first step is the forming of Al₃Ti compound by a solid state reaction at a temperature of 640 °C, slightly below the melting point of aluminum. In the second step the Ti-Al compound was formed at the temperature of 1300 °C and the sintering the porous structure was accomplished too. The obtained membranes were characterized by X-ray diffraction and scanning electron microscopy (SEM).

Abstract: We have established a processing method to fabricate three - dimensional porous carbonate apatite (CO₃Ap) with interconnected porous structure and improved mechanical strength. Briefly, porous CO₃Ap materials were produced via phosphorization of porous calcite precursor in hydrothermal condition. In order to make porous calcite precursor, negative replication of modified polyurethane foam template was conducted. In this study, an in vivo behavior of that porous CO₃Ap was evaluated. The interconnected porous CO₃Ap material was implanted in the tibia of Japanese male rabbits and removed after a period of 6 months. Micro-computed tomography (μ-CT) scanner and histological analysis were used to characterize the bone formation response of the porous CO₃Ap. The results suggest that porous CO₃Ap with enhanced mechanical strength was not only osteoconductive but also bioresorbable therefore it could be used as bone substitute material.

Abstract: A single-slope solar still with the basin area of 1m x1m and slope of 13^○ was fabricated and tested in Anna University, Chennai. Both the inner and outer walls were coated with black paint in order to improve the heat transfer rate. The bottom and side losses of the still are considerably reduced, due to the porous material beneath the basin liner. Effect of solar pond coupled with the still are experimentally investigated on a clear, partially cloudy and cloudy days and found that clear day has the maximum productivity. A model economic analysis calculation for single basin solar still coupled with pond is also done and the results are reported in this paper.

Abstract: Porous materials, such as filters made of sintered metals, lagging materials, and fireproof materials, are utilized in various fields. The porosity changes the characteristics of the materials. For example, with heat-insulating foam, the higher the porosity, the greater is the insulation factor. However, increased porosity leads to a decline in mechanical properties. Thus, when using porous materials, analyzing the mechanical strength is necessary. We modeled a porous structure of sintered metal sample and estimated the Young's modulus using the numerical analysis software “ADVENTURE” and compared the estimated value with the experimental value. Also, we modeled the effect of porosity and pore diameter on the mechanical property of the material. From the results, the Young's modulus decreases with increases in porosity and pore diameter, as expected.

Abstract: For the need of high speed and load capacity of precision industry, a bearing used in a high speed spindle is studied. The hydrodynamic bearing composed a hydrodynamic bearing made of porous material and several hydrostatic chambers with an external oil system. The hydrodynamic bearing is pressurized with oil chamber and supports the spindle shaft both at rest and at rotation state. Because of the external pressure and the property of porous material, the load capacity of hydraulic bearing can be promoted without decreasing precision. To consider the relationship of parameters, we applied the Reynolds equation and Darcy’s law to describe the flow of the oil film between bearing and spindle shaft.

Abstract: Titanium (Ti) foams used in biomedical application has been attracted scientific and technological interest because of their excellent mechanical properties, superior corrosion resistance and good biocompability. In this article, Ti foam with semi-open cell was prepared using the acicular carbamide as a space holder without any adhesives. The pore structure was characterized by SEM and the mechanical properties were determined by compressive tests. The results show that the porosity is 56.8%, the compressive strength and Young’s modulus are 104.6 MPa and 2.9 GPa, respectively. These results demonstrated that the obtained foam has a great potential as a substitute biomaterial for cortical bone.

Abstract: To explore the isolation mechanism and optimize the performance of the porous material in a dynamic viewpoint, a nonlinear porous material vibration isolator is modeled in this work. The stiffness of the isolator is regarded to be a piecewise linear, according to the stress–strain characteristics of porous material. Averaging method is employed to analyze the amplitude-frequency characteristics when the system excited by harmonic excitation. It is found that the vibration system represents linear, bilinear and tri-linear characteristics, when the porous material isolator works in linear-elastic phase, plateau phase and densification phase, respectively. The result shows that the amplitude response of the system in the plateau stage is much less than the linear isolator.

Abstract: The work explores feasibility of 3D finite element modeling (FEM) to study the effective linear properties of porous brittle material microstructures represented by a uniform cubic mesh. Both artificial virtually generated and real 3D tomography specimens are considered in this work. A method for assessment of the critical value of tomography resolution is proposed. A method to build approximations of the linear effective structure properties of interest at virtually zero FE size is developed. The methods do not have to be associated with mechanical modeling only but can be applied in some other cases, e.g. effective thermal conductivity or effective permeability calculations.

Abstract: Porous poly (1-naphthylamine) were synthesized by interfacial polymerization method. The effects of several reaction conditions including oxidant/monomer molar ratio, polymerization temperature and reaction time on the polymerization yield have been investigated. The highest yield of poly (1-naphthylamine) was up to 73% at oxidant/monomer molar ratio of 3 and polymerization temperature of 25 °C for over 20h. Using FT-IR and XRD to analyze the structure of the obtained polymer, the results show that the main mode of connection for 1-naphthylamine units was linking N to para-C and it formed amorphous polymer with some ordered strutures. The micro-morphology of the polymer observed by SEM was found to have irregular porous structure with pore size less than 5μm, which may be related to the “self-emulsion effect” during polymerization.

Abstract: The paper presents the results of strength and fatigue life of porous sintered 316L stainless steel. Samples with different porosity ( 26%, 33% and 41%) were tested. Graphs of fatigue life were obtained. Both areas of crack initiation propagation and destructions of the samples were determined.