Interactions between ZnO nanoparticles and amorphous g-C₃N₄ nanosheets in thermal formation of g-C₃N₄/ZnO composite materials: The annealing temperature effect

Jung, Haewon,Pham, Thanh-Truc,Shin, Eun Woo Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.458 No.-

<P><B>Abstract</B></P> <P>In this study, C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite materials were prepared at various annealing temperatures and systematically characterized to investigate the role of ZnO in the thermal formation of graphitic C<SUB>3</SUB>N<SUB>4</SUB> (g-C<SUB>3</SUB>N<SUB>4</SUB>), and to understand effect of annealing temperatures on the interaction between g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO in the composite materials. ZnO nanoparticles in the composite materials facilitated the thermal formation of the g-C<SUB>3</SUB>N<SUB>4</SUB> structure due to the strong interaction between g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO nanoparticles, resulting in a decrease in thermal polymeric condensation temperatures. Moreover, the morphological structure of g-C<SUB>3</SUB>N<SUB>4</SUB> was significantly influenced by the presence of ZnO nanoparticles with an amorphous g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheet structure in the composite materials and a crystalline interlayered g-C<SUB>3</SUB>N<SUB>4</SUB> structure in g-C<SUB>3</SUB>N<SUB>4</SUB> only. The higher annealing temperatures for composite materials induced the stronger interaction between ZnO nanoparticles and g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets. The strong interaction in a core-shell g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO structure not only gradually decreased the electronic density of ZnO nanoparticles but also proportionally inhibited the recombination of photo-generated electron-hole pairs in the composite materials, with increasing the annealing temperature. The g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite material prepared at 500 °C exhibited the highest photocatalytic reaction rate constant for photocatalytic degradation of methylene blue, which might be caused by the slowest recombination rate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite materials were prepared at various annealing temperatures. </LI> <LI> Non-crystalline g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets were formed from DCDA over ZnO nanoparticles. </LI> <LI> The strong interaction between ZnO and g-C<SUB>3</SUB>N<SUB>4</SUB> decreased the electron density of ZnO. </LI> <LI> The g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite prepared at 500 °C showed the slowest recombination rate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A study on mechanical properties of carbon fiber reinforced plastics by transverse static response

Cho, Gyu-Jae,Lee, Seung-Chul,Jeong, Seong-Ta다 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

CFRP composite materials are used increasingly in vanous fields such as space and aviation industry, architectural structures, shipbuilding materials, sporting goods, and interior and structural materials of automobiles due to the excellence of mechanical characteristics as well as light weight, heat resistance, and control characteristics. Stacking plates of CFRP composite materials, which are used increasingly because of these unique characteristics, have the properties of uneven quality and anisotropic nature unlike general metallurgical materials as they are stacking plates of composite materials in the combination of different types of materials. Hence. in this thesis, specimens of stacking composition of stacking plates of CFRP composite materials were manufactured by changing orientation angles in three kinds of quasi-isotropic such as (0°/45° /90° / -45°)6S, (03°/453°/903°/-453°)2S, and (06°/456°/906°/-456°)S and also in three kinds of orthotropic such as (0° /90° /0° /90°)6S. (03°/903° /03° /903°) 2S. and (06°/906%6°/906°)S. In this study, it was possible to obtain the following results by carrying out 3- point bending testing and transverse bending test in order to find out mechanical characteristics according to orientation angles by stacking in 6 different types with the changes of stacking composition methods of CFRP composite materials. As inter face number increases, the maximum load was increased and specimens stacked in quasi-isotropic hadlarge operations in its maximum load rather than orthotropic. Therefore, it is judged that it is correct to stack in quasi-isotropic when composing stacking of CFRP composite materials.

Effect of intermetallic compound on the Al-Mg composite materials fabricated by mechanical ball milling and spark plasma sintering

Park, Kwangjae,Park, Jehong,Kwon, Hansang Elsevier 2018 Journal of Alloys and Compounds Vol.739 No.-

<P><B>Abstract</B></P> <P>We successfully prepared aluminum(Al)-magnesium(Mg) composite materials using a spark plasma sintering (SPS) process with pure Al and Mg powders as the raw materials. Composite materials containing 20, 50, or 80 vol% Mg (Al-20 vol% Mg, Al-50 vol% Mg, and Al-80 vol% Mg, respectively) were sintered at 410 °C and 50 MPa for 5 min. Using X-ray diffraction, intermetallic compounds such as Al<SUB>3</SUB>Mg<SUB>2</SUB> and Al<SUB>12</SUB>Mg<SUB>17</SUB> were detected, which were formed in the Al-Mg composite materials owing to the reaction between Al and Mg during SPS. The results of scanning electron microscopy with energy-dispersive spectroscopy and elemental mapping also confirmed the existence of the intermetallic compounds. The mechanical properties of the composite materials, analyzed using a Vickers hardness tester, showed that the Al-50 vol% Mg composite material exhibited the highest hardness value of approximately 189 HV. In conclusion, the composite materials manufactured with SPS may act as lightweight and high-efficiency materials, applicable in various fields, such as the aerospace and automobile industries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Al-Mg composite materials were fabricated using a spark plasma sintering process. </LI> <LI> The Al-50 vol% Mg composite material exhibited approximately 189 HV. </LI> <LI> Strengthening mechanism of Al-Mg composite materials is presented. </LI> <LI> These materials are expected to applicable as lightweight-multifunctional material. </LI> </UL> </P>

환경조건간 합동을 이용한 복합재료 허용치 생성 기법

이승윤,Rhee, Seung Yun 항공우주시스템공학회 2016 항공우주시스템공학회지 Vol.10 No.3

The properties of composite materials, when compared to those of metallic materials, are highly variable due to many factors including the batch-to-batch variability of raw materials, the prepreg manufacturing process, material handling, part-fabrication techniques, ply-stacking sequences, environmental conditions, and test procedures. It is therefore necessary to apply reliable statistical-analysis techniques to obtain the design allowables of composite materials. A new composite-material qualification process has been developed by the Advanced General Aviation Transport Experiments (AGATE) consortium to yield the lamina-design allowables of composite materials according to standardized coupon-level tests and statistical techniques; moreover, the generated allowables database can be shared among multiple users without a repeating of the full qualification procedure by each user. In 2005, NASA established the National Center for Advanced Materials Performance (NCAMP) with the purpose of refining and enhancing the AGATE process to a self-sustaining level to serve the entire aerospace industry. In this paper, the statistical techniques and procedures for the generation of the allowables of aerospace composite materials will be discussed with a focus on the pooling-across-environments method.

CFRP 복합재료의 적층 구성에 따른 정적시험 평가

조규재(Gyu-Jae Cho),이승철(Seung-Chul Lee),정성택(Seong-Taek Jeong) 한국기계가공학회 2007 한국기계가공학회 춘추계학술대회 논문집 Vol.2007 No.-

CFRP composite materials are used increasingly in various fields such as space and aviation industry, architectural structures, shipbuilding materials, sporting goods, and interior materials of automobiles due to the excellency of mechanical characteristics as well as light weight, heat resistance, and control characteristics. Stacking plates of CFRP composite materials, which are used increasingly because of these unique characteristics, have the properties of uneven quality and anisotropic nature unlike general metallurgical materials as they are stacking plates of composite materials in the combination of different types of materials. Hence, in this thesis, specimens of stacking composition of stacking plates of CFRP composite materials were manufactured by changing orientation angles in three kinds of quasi-isotropic such as (0˚/45˚/90˚/-45˚)6S, (0₃˚/45₃˚/90₃˚/-45₃˚)2S, and (0₆˚/45₆˚/90₆˚/-45₆˚)S and also in three kinds of orthotropic such as (0˚/90˚/0˚/90˚)6S, (0₃˚/90₃˚/0₃˚/90₃˚)2S, and (0₆˚/90₆˚/0₆˚/90₆˚)S. In this study, it was possible to obtain the following results by carrying out 3-point bending testing and transverse bending testing order to find out mechanical characteristics according to orientation angles by stacking in 6 different types with the changes of stacking composition methods of CFRP composite materials. As interface number increases, the maximum load was increased and specimens stacked in quasi-isotropic haulage operations in its maximum load rather than orthotropic. Therefore, it is judged that it is correct to stack in quasi-isotropic when composing stacking of CFRP composite materials.

Technology of Light Weight Railway Vehicle using Composite Materials

Jae-Moon Im,Kwang-Bok Shin 한국철도학회 2019 International Journal of Railway Vol.12 No.2

Nano Si embedded SiO_x-Nb₂O₅-C composite as reversible lithium storage materials

Kim, Moon-Soo,Kim, Kyungbae,Cha, Pil-Ryung,Kang, Hee-Kook,Woo, Sang-Gil,Kim, Jae-Hun Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.699 No.-

<P><B>Abstract</B></P> <P>This study reports a simple and effective method for preparing nanocrystalline Si embedded carbon composites as a high-capacity anode material for Li-ion batteries. Micron-sized Si and Nb<SUB>2</SUB>O<SUB>5</SUB> powders were used as starting materials for high-energy mechanical milling (HEMM) process. During the HEMM operation, Si particles obtained oxygen from Nb<SUB>2</SUB>O<SUB>5</SUB>; the nanocrystalline Si embedded SiO<SUB>x</SUB> phase was simultaneously created; and commmercial monoclinic Nb<SUB>2</SUB>O<SUB>5</SUB> was also transformed to orthorhombic Nb<SUB>2</SUB>O<SUB>5</SUB> with partial reduction. Results show that a nano Si embedded SiO<SUB>x</SUB>-niobium oxides-carbon composite was successfully synthesized. Material characterization of the composite was performed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, and electron microscopies. Electrochemical test results demonstrate that the composite electrode has a greatly enhanced performance with a reversible capacity of about 800 mAh g<SUP>−1</SUP> and excellent capacity retention of up to 200 cycles. This improvement can be attributed to the in-situ formation of the nanocrytalline Si embedded silicon suboxide phase with niobium oxides, which is dispersed in carbon matrix. It is considered that this finding will be useful in the preparation of robust Si-based anode materials for high-energy density Li-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This study reports a simple strategy for preparing nano Si embedded C composite. </LI> <LI> Nano Si embedded SiO<SUB>x</SUB>-Nb<SUB>2</SUB>O<SUB>5</SUB>-C composite was prepared by high energy ball milling. </LI> <LI> Niobium oxide plays an important role for the formation of nanocomposite. </LI> <LI> Niobium oxide is also helpful for enhancement of electrochemical performance. </LI> <LI> The composite shows a reversible capacity of about 800 mAh g<SUP>−1</SUP> up to 200 cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

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.

Green composite friction materials: A review of a new generation of eco-friendly brake materials for sustainability

Amira Sellami,Riadh Elleuch 대한환경공학회 2023 Environmental Engineering Research Vol.29 No.3

Particulate matter (PM) still poses a significant threat leading to air pollution which is responsible for continued damage to human health and the environment. Particulate matter resulting from non-exhaust emissions are considered as viable a source comes mostly from brake pad wear concept. The scientific challenge of this work is to stimulate a new generation of green friction materials to reduce particle emissions having low-environmental impact. The specificity of braking materials, their effects on the environment and human health are studied. To minimize the levels of air pollution, the use of green friction composites collected from natural elements reducing human diseases is discussed. For this purpose, the novel and high-performance friction composite materials synthesized from vegetable and animal waste used as a raw material are reported. The natural powder and fiber treatments, the optimum formulation and the binder materials related to the green friction composites are reviewed. An overview of environmentally ecofriendly green friction materials embedded by reinforcing phases of natural elements exhibiting excellent mechanical and tribological properties are mentioned. Therefore, scientific and industrial efforts should concentrate on the development of green friction materials to minimize the effect of transport related air pollution.

연료전지분리판의 제조 및 기계적 특성 연구

주원경(Wonkyung Joo),송정일(Jungil song),최환석(Hwansuk Choi) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Considering diverse needed conditions, so far many materials have been studied as materials of bipolar plate for the fuel cell. At the first, plate which was made from graphite flat board having channel is that manufacturing cost of channel is high and due to the high brittleness, it is hard to reduce the thickness of plate. On the case of using a metal like stainless steel, there are some disadvantages such as high material density, high manufacturing cost and corrosion. To make a completion of disadvantages, we are researching on a carbon conductive polymer composite material. A carbon conductive polymer composite material has advantages like taking low-cost manufacturing and making light weight and reducing the manufacturing time. And due to using polymer fiber, higher ductilities is possible. On account of the fact that PEMFC is working on low temperature (approximately 80℃) comparing with other fuel cell plate, carbon conductive polymer composite material can be used for the plate. On this study, the goals are of establishing the manufacturing process of carbon conductive polymer composite material which is used for PEMFC and examining of mechanical characteristics of carbon conductive polymer composite material having superior electrical conductivity according to the change of fillers and forming conditions. And compression molding technique was used for processing, and graphite powder and carbon fiber was used as fillers. As a result of the research, through the optimization of molding conditions using compression molding technique I made carbon conductive polymer composite material for fuel cell plate having superior electrical conductivity which is up to 180 S/㎝. on the case of powder/epoxy composite material, according to the increasing forming pressure, electrical conductivity and bending strength were increased and optimal forming pressure was 1000~1500psi that carbon powder's degree of fineness was fully made. Maximum impact load and absorbing energy of carbon fiber reinforced composite material were better than those of graphite powder/epoxy composite material. This shows that degree of fineness was fully made and strength was increased.