흡음을 위한 다공성 물질의 최적형상설계에서 물성치의 영향

이중석(Joong Seok Lee),김윤영(Yoon Young Kim),강연준(Yeon June Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

This investigation studies the effects of material properties and corresponding propagation wave types on optimal configurations of sound absorbing porous materials in maximizing the absorption performance by topology optimization. The acoustic behavior of porous materials is characterized by their material properties which determine motions of the frame and the air. When the frame has a motion, two types of compressional wave propagate in the porous material. Because each wave in the material make different influence on the absorption performance, it is important to understand the relative contribution of each wave to the sound absorption. The relative contribution of the propagating waves in a porous material is determined by the material properties, therefore, an optimal configuration of a porous material to maximize the absorption performance is apparently affected by the material properties. In fact, virtually different optimal configurations were obtained for absorption coefficient maximization when the topology optimization method developed by the authors was applied to porous materials having different material properties. In this investigation, some preliminary results to explain the findings are presented. Although several factors should be considered, the present investigation is focused on the effects of the material properties and corresponding propagation waves on the optimized configurations.

Preparation and characterization of a porous silicate material from silica fume

Yinmin Zhang,Haiping Qi,Yaqiong Li,Yongfeng Zhang,Junmin Sun 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.12

A porous silicate material derived from silica fume was successfully prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectroscopy, Thermogravimetry and Differential thermal gravity (TG-DTG), N2 adsorption and desorption isotherms, and scanning electron microscopy (SEM). Raw silica fume was analyzed by XRD, FT-IR and SEM. The analysis results of silica fume indicated that SiO2 in silica fume is mainly determined as amorphous state, and that the particles of raw silica fume exhibited characteristic spherical structure with a diameter of from 50 nm to 200 nm. The preparation of the porous silicate material involved two steps. The first step was the extraction of the SiO3 2− leachate from raw silica fume. The maximum value of SiO3 2− extraction yield was obtained under the following conditions: reaction temperature of 120 oC, reaction time of 120 min, NaOH concentration of 15%, and alkali to SiO2 molar ratio of 2. The second step was the preparation of the porous silicate material though the reaction of SiO3 2− leachate and Ca(OH)2 suspension liquid. The optimum preparation conditions were as follows: preparation temperature of 90 oC, preparation time of 1.5 h, Si/Ca molar ratio of 1 : 1, and stirring rate of 100 r/min. The BET surface area and pore size of the porous silicate material were 220.7m2·g−1 and 8.55 cm3/g, respectively. The porous silicate material presented an amorphous and unordered structure. The spectroscopic results indicated that the porous silicate material was mainly composed of Si, Ca, O, C, and Na, in the form of Ca2+, SiO3 2−, CO3 2− and Na+ ions, respectively, which agreed with the XRD, TG-DSC, and FT-IR data. The N2 adsorption-desorption isotherm mode indicates that the porous silicate material belonged to a typical mesoporous material. The porous silicate material presented efficiency for the removal of formaldehyde: it showed a formaldehyde adsorption capacity of 8.01mg/g for 140 min at 25 oC.

Prediction of Material Properties of Ceramic Composite Material by Porous Structure and Porosity Using the Finite Element Method

이동규,김수현,김세영,유지행,조성욱 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.5

Recently, the use of ceramic composite materials in various areas has been increasing. However, since detailed structures have various porous structures according to the characteristics of the ceramic composite material, it is difficult to predict material properties through simple material experiments. If the detailed structure of ceramic composite materials were metal or other simple and regular forms, it would be possible to predict material properties through experiments or analysis. However, as porous ceramic materials have an irregular structure and random form, it is very difficult to predict their material properties through simple methods and actual material experiments must be conducted several or even dozens of times to predict the material properties with statistical analysis techniques. Therefore, this study uses FEM to predict the porous type or pore ratio of ceramic composite materials and the changes in material properties according to their detailed structure. It attempt to predict the maximum and minimum values of actual material properties. Through the results of this study, it is possible to more easily predict the material properties of ceramic composite materials by porosity and pore dispersity or adjacency. The results can be applied to the manufacturing of parts and structural analysis of models made from ceramic composite materials.

미립화 및 분무장치 1 : 다공성 물질 표면의 분무 냉각에 관한 연구 동향

김우식 ( Woo Shik Kim ),이상용 ( Sang Yong Lee ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

Recently, several attempts have been made to enhance the spray cooling performance by employing porous layers or constructing micro-structures on the target substrates. The impinged drops permeate easily through the porous surfaces and the heat transfer area between the solid and the liquid becomes much larger compared to the non-porous case. Also, the duration of the liquid-solid contact becomes much longer due to retention of the liquid within the substrate by the capillary force. At the same time, the pores on the surface behave as the nucleation sites when the substrate temperature is maintained higher than the boiling point. A few studies showed that existence of the optimum geometry of the porous later/structure but any reasonable criterion based on the physical explanations has yet been proposed. To find the ideal spraying conditions and the optimum configuration of the porous layers/structures for improvement of the cooling performance, the heat transfer mechanism of a single-drop impact on the porous surface should be investigated in detail. The amount of liquid mass deposited onto the surface, time of contact and the vapor release rates in single-drop impact should be obtained as fundamental information in estimating the surface cooling performance of sprays. According to the previous studies on hydrodynamic behavior and cooling performance of a liquid drop impinging on a porous substrate, suppression of Leidenfrost phenomenon, decrease in total evaporation time, absence of receding process, and suppression of splash phenomena were observed in accordance with the penetration of the drop into the porous structures. However, most of the previous studies are limited to the qualitative comparison between the porous and non-porous substrates based on each specific type of porous material. Thus, there should be a systematic study on the effects of the porous characteristics (e.g. porosity, permeability) on the post-impingement behavior and the cooling performance. In other words, effects of the nucleation site density and cavity size (represented by the number density of the surface pores and the size of them) on the boiling phenomena (bubble growth rate), and the relationship between the spreading and penetrating behavior (represented by permeability) should be investigated in detail as the future work.

Contiguity as a governing parameter to predict the strength of porous materials

Nam, Kyungju,Park, Hyeji,Choi, Hyelim,Choe, Heeman Elsevier 2018 Materials letters Vol.214 No.-

<P><B>Abstract</B></P> <P>With increasing demand for porous materials with their popular use in functional applications, there is a strong need to develop a decent strength prediction method for porous materials. The Gibson-Ashby (G-A) model, which is the most common prediction method, has served this purpose. This model is constructed upon a weakly-structured open-cell porous material, thus providing a ‘lower bound’ of yield strength. This study considers ‘contiguity’ as a governing parameter to predict the strength of porous materials and proposes a modified G-A model by incorporating the concept of contiguity. This paper supports preliminary evidence that the new model better describes the strength of selected porous materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> There is strong need for decent strength prediction method for porous materials. </LI> <LI> We consider contiguity as governing parameter to predict porous material’s strength. </LI> <LI> Our new empirical formula yields outstanding predictions for yield strength. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

다공성 원료를 사용한 수열합성 패널의 물성과 포름알데히드 흡착 특성

임두혁,추용식,송훈,이종규,Im, Du-Hyuk,Chu, Yong-Sik,Song, Hoon,Lee, Jong-Kyu 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6

Formaldehyde emissions from the construct was harmful to human. Diatomite, bentonite and zeolite were used as porous materials for fabricating panels. Formaldehyde adsorption and physical characteristics of porous materials were investigated and hydrothermal method was applied to fabricate panels. Formaldehyde adsorption contents of panels with porous materials were higher than that of panel without porous materials. The panels with Cheolwon diatomite and Pohang zeolite showed excellent characteristics of Formaldehyde adsorption. These characteristics were caused by higher surface area and pore volume of porous materials. Formaldehyde adsorption contents were influenced by surface area and pore volume of panels. Correlation coefficient between surface area and Formaldehyde adsorption content of panels was 0.87. The panels with porous materials had higher strength than that without porous materials because of bridging role particles.

Development of Porous Metal Materials and Applications

Fang Y.,Wang H.,Zhou Y.,Kuang C. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

This paper described the state of art of porous metal materials, the typical manufacturing technologies and performances of sintered metal porous materials, with emphasis on the recent research achievements of CISRI in development of porous metal materials. High performance porous metal materials, such as metallic membrane, sub-micron asymmetric composite porous metal, large dimensional and structure complicated porous metal aeration cones and tube, metallic catalytic filter elements, lotus-type porous materials, etc, have been developed. Their applications in energy industry, petrochemical industry, clean coal process and other industrial fields were introduced and discussed.

Optimization for Cooling System of Batteries Having Porous Material Using Design of Experiments

Zhen-Zhe Li,Dong-Ji Xuan,Yong Li,Yun-De Shen 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

A hybrid power composed of fuel cell and batteries has become the reasonable strategy for hybrid electric vehicles. On the contrary,the produced heat by batteries can affect the total performance of hybrid electric vehicles significantly. In this paper, analysis methodsand optimization strategy were constructed for obtaining the high performance cooling system for batteries having porous material. At first, a numerical method for obtaining the temperature distribution of battery pack including porous material was developed byusing CFD technique. In the following step, the cooling systems for batteries with porous material or not were compared for showingthe merit of the cooling system for batteries having porous material. Ultimately, an optimization strategy based on D-optimal DOEmethod was obtained through a real optimal design process. There was 13.3% reduction on the view of the root mean squaretemperature between batteries compared with the original cooling system for batteries as shown in the optimization result. Theconstructed analysis method and optimization strategy can be used to improve the performance of the cooling system for batteries,and these works have made the theoretical basis for simulation and optimization of the cooling system for batteries.

블록형 Ni-Cr-Al 분말 다공성 소재의 미세조직 및 인장 변형 거동

김철오,배정석,이기안,Kim, Chul-O,Bae, Jung-Suk,Lee, Kee-Ahn 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.2

This study investigated the microstructure and tensile properties of a recently made block-type Ni-Cr-Al powder porous material. The block-type powder porous material was made by stacking multiple layers of powder porous thin plates with post-processing such as additional compression and sintering. This study used block-type powder porous materials with two different cell sizes: one with an average cell size of $1,200{\mu}m$ (1200 foam) and the other with an average cell size of $3,000{\mu}m$ (3000 foam). The ${\gamma}$-Ni and ${\gamma}^{\prime}-Ni_3Al$ were identified as the main phases of both materials. However, in the case of the 1,200 foam, a ${\beta}$-NiAl phase was additionally observed. The relative density of each block-type powder porous material, with 1200 foam and 3000 foam, was measured to be 5.78% and 2.93%, respectively. Tensile tests were conducted with strain rates of $10^{-2}{\sim}10^{-4}sec^{-1}$. The test result showed that the tensile strength of the 1,200 foam was 6.0~7.1 MPa, and that of 3,000 foam was 3.0~3.3 MPa. The elongation of the 3,000 foam was higher (~9%) than that (~2%) of the 1,200 foam. This study also discussed the deformation behavior of block-type powder porous material through observations of the fracture surface, with the results above.

Porous Carbon Particles Derived from Natural Peanut Shells as Lithium Ion Battery Anode and Its Electrochemical Properties

Xiao-Yu Cao,Shuangqiang Chen,왕과시우 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4

Abandoned peanut shells, a common farm waste, have caused tremendous environmental pollution and huge waste deposits through burned and buried disposal approaches. In targeting to enhance the potential value of peanut shells and discover a new alternative candidate for lithium ion batteries, we adopted an easy to scale-up and highly repeated method to treat fresh and dry peanut shells via acid-treatment and pyrolysis, making porous structures on carbonized peanut shells. The pyrolysis process transformed the peanut shells to porous carbon (PC) materials in a quartz tube furnace at a series of temperatures from 500°C to 700°C in N2 under the condition of 40°C gradient temperatures with a heating rate of 2°C min−1. Scanning electron microscopy (SEM) images show that the irregular porous structures and hundreds of micropores are distributed on the PC materials. The cyclic voltammogram (CV) test and particle size analysis are employed to investigate their characteristics of voltammetry and particle size distribution. PC material obtained at 620°C (PC-620) exhibited good particle distribution, porous structure and less agglomerated particles. When applied as anode materials in lithium ion batteries, the PC-620 electrode displayed the high reversible capacity of 608 mAh g–1. Moreover, the cycling performance of PC-620 was the most stable, with a high Coulombic efficiency of 98.9% at the 20th cycle, demonstrating a reversible capacity of 418 mAh g–1, which is higher than the theoretical capacity of graphite. Most importantly, the PC materials harvested from the wastes of natural resources are turned into valuable electrode materials for the high demand energy storage devices, which can significantly reduce severe environmental pollution and alleviate an energy shortage.