In this study, porous Mo-5 wt% Cu with unidirectionally aligned pores is prepared by freeze drying of camphene slurry with MoO3-CuO powders. Unidirectional freezing of camphene slurry with dispersion stability is conducted at -25℃, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The green bodies are hydrogen-reduced at 750℃ and sintered at 1000℃ for 1 h. X-ray diffraction analysis reveals that MoO3- CuO composite powders are completely converted to a Mo-and-Cu phase without any reaction phases by hydrogen reduction. The sintered bodies with the Mo-Cu phase show large and aligned parallel pores to the camphene growth direction as well as small pores in the internal walls of large pores. The pore size and porosity decrease with increasing composite powder content from 5 to 10 vol%. The change of pore characteristics is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature (600–850°C) on the CO2 adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of 1488 m2 g–1 was achieved at an activation temperature of 800°C (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to 850°C. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, CO2 adsorption isotherms showed that AC-800 exhibited the best CO2 adsorption capacity of 110 mg g–1 at 298 K and 1 bar.

High surface carbon aerogels with hierarchical and tunable pore structure were prepared using ionic liquid as carbon precursor via a simple salt templating method. The as-prepared carbon aerogels were characterized by nitrogen sorption measurement and scanning electron microscopy. Through instant visual observation experiments, it was found that salt eutectics not only serve as solvents, porogens, and templates, but also play an important role of foaming agents in the preparation of carbon aerogels. When the pyrolyzing temperature rises from 800 to 1000°C, the higher temperature deepens the carbonization reaction further to form a nanoporous interconnected fractal structure and increase the contribution of super-micropores and small mesopores and improve the specific surface area and pore volume, while having few effects on the macropores. As the mass ratio of ionic liquid to salt eutectics drops from 55% to 15%, that is, the content of salt eutectics increases, the salt eutectics gradually aggregate from ion pairs, to clusters with minimal free energy, and finally to a continuous salt phase, leading to the formation of micropores, uniform mesopores, and macropores, respectively; these processes cause BET specific surface area initially to increase but subsequently to decrease. With the mass ratio of ionic liquids to salts at 35% and carbonization temperature at 900°C, the specific surface area of the resultant carbon aerogels reached 2309 m2 g–1. By controlling the carbonization temperature and mass ratio of the raw materials, the hierarchically porous architecture of carbon aerogels can be tuned; this advantage will promote their use in the fields of electrodes and adsorption.

During a long-term operation of polymer electrolyte membrane fuel cells(PEMFCs), the fuel cell performance may degrade due to severe agglomeration and dissolution of metal nanoparticles in the cathode. To enhance the electrochemical durability of metal catalysts and to prevent the particle agglomeration in PEMFC operation, this paper proposes a hybrid catalyst structure composed of PtCo alloy nanoparticles encapsulated by porous carbon layers. In the hybrid catalyst structure, the dissolution and migration of PtCo nanoparticles can be effectively prevented by protective carbon shells. In addition, O2 can properly penetrate the porous carbon layers and react on the active Pt surface, which ensures high catalytic activity for the oxygen reduction reaction. Although the hybrid catalyst has a much smaller active surface area due to the carbon encapsulation compared to a commercial Pt catalyst without a carbon layer, it has a much higher specific activity and significantly improved durability than the Pt catalyst. Therefore, it is expected that the designed hybrid catalyst concept will provide an interesting strategy for development of high-performance fuel cell catalysts.

Porous metals demonstrate not only excessively low densities, but also novel physical, thermal, mechanical, electrical, and acoustic properties. Thus, porous metals exhibit exceptional performance, which are useful for diesel particulate filters, heat exchangers, and noise absorbers. In this study, SUS316L foam with 90% porosity and 3,000 μm pore size is successfully manufactured using the electrostatic powder coating (ESPC) process. The mean size of SUS316L powders is approximately 12.33 μm. The pore properties are evaluated using SEM and Archimedes. As the quantity of powder coating increases, pore size decreases from 2,881 to 1,356 μm. Moreover, the strut thickness and apparent density increase from 423.7 to 898.3 μm and from 0.278 to 0.840 g/cm3, respectively. It demonstrates that pore properties of SUS316L powder porous metal are controllable by template type and quantity of powder coating.

The stereotype of flexible MOFs(Amino-MIL-53) and carbonized porous carbon prepared from renewable resources is successfully synthesized for CO2 reduction application. The textural properties of these microporous materials are investigated, and their CO2 storage capacity and separation performance are evaluated. Owing to the combined effects of CO2-Amino interaction and its flexibility, a CO2 uptake of 2.5 mmol g−1 is observed in Amino-MIL-53 at 20 bar 298 K. In contrast, CH4 uptake in Amino-MIL-53 is very low up to 20 bar, implying potential sorbent for CO2/CH4 separation. Carbonized samples contain a small quantity of metal residues(K, Ca, Mg, S), resulting in naturally doped porous carbon. Due to the trace metal, even higher CO2 uptake of 4.7 mmol g−1 is also observed at 20 bar 298 K. Furthermore, the CH4 storage capacity is 2.9 mmol g−1 at 298 K and 20 bar. To evaluate the CO2 separation performance, the selectivity based on ideal adsorption solution theory for CO2/CH4 binary mixtures on the presented porous materials is investigated.

Bird screen meshes are installed at the air inlet and outlet ducts of spent fuel storage casks to inhibit the intrusion of debris from the external environment. The presence of these screens introduces an additional resistance to air flow through the ducts. In this study, a porous media model was developed to simplify the bird screen meshes. CFD analyses were used to derive and verify the flow resistance factors for the porous media model. Thermal analyses were carried out for concrete storage cask using the porous media model. Thermal tests were performed for concrete casks with bird screen meshes. The measured temperatures were compared with the analysis results for the porous model. The analysis results agreed well with the test results. The analysis temperatures were slightly higher than the test temperatures. Therefore, the reliability and conservatism of the analysis results for the porous model have been verified.

PURPOSES: The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS: The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS: The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

In order to improve the durability of the asphalt pavement, the glass fiber reinforced asphalt which reinforces the aggregate and the binder in three - dimensional form by adding glass fiber to the asphalt mixture has been studied and the durability improvement effect of the asphalt pavement has been confirmed. Porous pavement has been increasingly applied due to reduced traffic accidents and noise reduction, but durability problems such as aggregate stripping and pot-hole are emerging. This study evaluated the durability enhancement effect by adding glass fiber to the porous mixture. The cantabro loss ratio and the indirect tensile strength test were performed to evaluate the performance of the glass fiber reinforced porous mixture. The glass fibers were added to the mixture using PG76-22 and PG64-22 binder and not to the mixture using PG82-22 binder. The mixture using the PG76-22 binder was added 1.4% (PEGS 0.6%, Micro PPGF 0.2%, Macro PPGF 0.6%) glass fiber based on the weight of the mixture. The mixture using the PG64-22 binder was added 1.4% (PEGS 0.6%, Micro PPGF 0.2%, Macro PPGF 0.6%) and 2.1% %(PEGS 0.9%, Micro PPGF 0.3%, Macro PPGF 0.9%)glass fibers by weight of the mixture. The glass fibers were used at the same ratio as that applied to the conventional asphalt mixture test. As a result of the cantabro loss rate test, the mixture using the PG82-22 binder showed a loss rate of 10.7% at 20 ℃ and 22.4% at -20 ℃. The mixture using PG76-22 binder and 1.4% glass fiber showed a loss ratio of 13.2% at 20 ℃ and 26.7% at -20 ℃. The mixture using PG64-22 binder and 1.4% glass fiber showed a loss rate of 12.5% at 20 ℃ and 35.9% at -20 ℃. The mixture using PG64-22 binder and 2.1% glass fiber showed a loss rate of 11.9% at 20 ℃ and 26.6% at -20 ℃. The three mixtures (using of PG82-22 binder, PG76-22 binder + 1.4% glass fiber and PG64-22 binder + 2.1% glass fiber) satisfied quality standard of Ministry of Land, Infrastructure and Transport. As a result of the indirect tensile strength test, the mixture using the PG82-22 binder showed 0.73 N/㎟. The mixture using PG76-22 binder and 1.4% glass fiber showed 0.88 N/㎟. The mixture using PG64-22 binder and 1.4% glass fiber showed 0.62 N/㎟. The mixture using PG64-22 binder and 2.1% glass fiber showed 0.74 N/㎟. In this study, the durability enhancement effect was confirmed by adding glass fiber to the drainage mixture. We will do further research to confirm the optimal combination of glass fibers.

The current construction and maintenance guidelines applied to airport pavement in Korea are those of the International Civil Aviation Organization (ICAO), the International Air Transport Association (IATA), and the Federal Aviation Administration (FAA). In order to consider local conditions of airports in Korea, more specific details should be addressed in those guidelines. For example, the design and construction for pavements at airports in Korea follow the specifications of materials for general roads or foreign airport pavement guidelines, as there is no design manual or guideline for the granular base and subbase materials for airport pavement in Korea. In such circumstances, the likelihood of premature failure or accelerated damage increases, as the loading from airplanes is not fully taken into account or the local environmental characteristics are not considered. In addition, concerns in public facility drainage systems have been rising recently in line with the increase in the frequency and scale, caused by the global abnormal-temperature phenomenon, of localized torrential rain and snow. For airport runways, measures to maintain swift drainage systems are especially necessary to ensure safety and prevent flight delays. In this study, the appropriate moisture content and pavement method are analyzed by applying porous concrete developed for a cement-treated base course for securing permeability of airport pavement at an actual construction site. In addition, on-site construction testing was performed to determine the appropriate compaction method and the curing method to minimize cracking by using a compaction facility. To determine the optimal moisture content, a quality-control was performed by measuring the moisture content of porous concrete produced at a batch plant. For this purpose, a speed moisture test (ASTM D 4944) was performed on site because the unit-water content of the porous concrete affects its compaction and finishing. Before compaction, a grader was used to remove fragments on the subbase and then a tandem roller was used to level and compact. After compaction, the porous cement-treated base course, called porous concrete, was placed using an asphalt finisher. The mechanical properties and durability of the porous cement-treated base course with a variation of a degree of compaction: noncompaction, tandem roller moved back and forth once, three times, and five times. The pavement was covered with vinyl according to the curing guidelines suggested by the Korea Expressway Corporation’s highway construction specifications, to prevent evaporation from porous concrete that has relatively low moisture content. After curing, the core was collected to analyze the compressive strength, permeability coefficient, porosity, and freeze–thaw resistance characteristics.

With interconnecting voids, porous asphalt provides drainage of rainwater in vertical and lateral direction during rainfall. In addtition, it also offers remarkable advantages compare to traditional asphalt: reduce vehicle splash and spray behind, reduce night time surface glare in wet season and increase tire-pavement friction...On the other hand, the following aspects are recognized as disavantages: reduced performance, winter maintenance issues and high construction cost. For flexible pavement, dynamic modulus master curve is an important parameter in the mechanistic-empirical pavement design guide. In this study, the results of experiment of dynamic modulus test of porous asphalt are discussed for understanding well about the viscoelastic characteristics of porous asphalt.

The straight nanopores in cellulose acetate (CA) polymers for battery gel separators were generated by utilizing both hydrated metal salts and water pressure. When polymer film was exposed to water pressure, the continuous nanopores were generated after complexing with hydrated metal salts. These results could be explained by that polymer chains were weakened because of the plasticization effect of the hydrated regions incorporated into the CA. Pore size could also be easily controlled by adjusting the water pressure. The generated pores in CA polymers were confirmed by scanning electron microscopy (SEM) images. The coordinate interactions between CA polymer and metal salts, and ionic states of metal salts were investigated by FT-IR and Raman spectroscopy, respectively.

Porous graphites were synthesized by removing the template in HF after cabothermal conversion for 3 h at 900 ℃, accompanied by intercalations of pyrolyzed fuel oil (PFO) in the interlayer of Co or Ni loaded magadiite. The X-ray powder diffraction pattern of the porous graphites exhibited 00l reflections corresponding to a basal spacing of 0.7 nm. The particle morphology of the porous graphites was composed of carbon plates intergrown to form spherical nodules resembling rosettes like a magadiite template. TEM shows that the cross section of the porous graphites is composed of layers with very regular spaces. In particular, crystallization of the porous graphite was dependent on the content of Co or Ni loaded in the interlayer. The porous graphite had a surface area of 328-477 m2/g. This indicates that metals such as Co and Ni act as catalysts that accelerate graphite formation.

The present study demonstrates the effect of raw powder on the pore structure of porous W-Ni prepared by freeze drying of camphene-based slurries and sintering process. The reduction behavior of WO3 and WO3-NiO powders is analyzed by a temperature programmed reduction method in Ar-10% H2 atmosphere. After heat treatment in hydrogen atmosphere, WO3- NiO powder mixture is completely converted to metallic W without any reaction phases. Camphene slurries with oxide powders are frozen at −30 oC, and pores in the frozen specimens are generated by sublimation of the camphene during drying in air. The green bodies are hydrogen-reduced at 800 oC and sintered at 1000 oC for 1 h. The sintered samples show large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The strut between large pores, prepared from pure WO3 powder, consists of very fine particles with partially necking between the particles. In contrast, the strut densification is clearly observed in the Ni-added W sample due to the enhanced mass transport in activation sintering.

Porous Cu with a dispersion of nanoscale Al2O3 particles is fabricated by freeze-drying CuO-Al2O3/camphene slurry and sintering. Camphene slurries with CuO-Al2O3 contents of 5 and 10 vol% are unidirectionally frozen at -30oC, and pores are generated in the frozen specimens by camphene sublimation during air drying. The green bodies are sintered for 1 h at 700oC and 800oC in H2 atmosphere. The sintered samples show large pores of 100 μm in average size aligned parallel to the camphene growth direction. The internal walls of the large pores feature relatively small pores of ~10 μm in size. The size of the large pores decreases with increasing CuO-Al2O3 content by the changing degree of powder rearrangement in the slurry. The size of the small pores decreases with increasing sintering temperature. Microstructural analysis reveals that 100-nm Al2O3 particles are homogeneously dispersed in the Cu matrix. These results suggest that a porous composite body with aligned large pores could be fabricated by a freeze-drying and H2 reducing process.

In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.