비정질 금속섬유 혼입율에 따른 모르타르의 유동성 및 경화특성

이봉춘(Lee, Bong-Chun),최세진(Choi, Se-Jin) 대한건축학회 2014 大韓建築學會論文集 : 構造系 Vol.30 No.4

Generally, steel fiber is broadly used to improve the mechanical and flexural strength properties of concrete, however, the steel fiber have some disadvantages including high density, fiber ball and corrosion etc. Recently, a new type of amorphous metallic fiber was developed to improve some properties of normal steel fiber such as non-corrosion and flexible properties of fiber itself. In this paper, we used the amorphous metallic fiber with 30mm of length at additional ratios of 0%, 0.5%, 1.0%, 1.5%, 2.0%, 3.0% and 4.0% to estimate the properties of the mortar with amorphous metallic fiber. And the effects of contents of amorphous metallic fiber on the flow, compressive strength, flexural strength, drying shrinkage, crack reducing property and thermal conduction property of mortar were investigated. Test results indicated that using amorphous metallic fiber in mortar resulted in improvement in the flexural properties of mortar. The flexural strength of mortar with contents of Rf 4.0% amorphous metallic fiber was about 29% higher than that of the plain mortar. The drain shrinkage using amorphous metallic fiber was improved as compared to the mortar without the amorphous metallic fiber. In addition, the thermal conduction property was similar in all mortar mixtures regardless of contents of amorphous metallic fiber.

Joining of carbon nanotube fiber by nickel–copper double‑layer metal via two‑step meniscus‑confined localized electrochemical deposition

Yecheng Wang,Zhen Luo,Di Zhang,Yue Yang,Jianming Hu,Muse Degefe Chewaka,Sansan Ao,Yang Li 한국탄소학회 2023 Carbon Letters Vol.33 No.1

Carbon nanotube fiber is a promising material in electrical and electronic applications, such as, wires, cables, batteries, and supercapacitors. But the problem of joining carbon nanotube fiber is a main obstacle for its practical development. Since the traditional joining methods are unsuitable because of low efficiency or damage to the fiber structure, new methods are urgently required. In this study, the joining between carbon nanotube fiber was realized by deposited nickel–copper doublelayer metal via a meniscus-confined localized electrochemical deposition process. The microstructures of the double-layer metal joints under different deposition voltages were observed and studied. It turned out that a complete and defect-free joint could be fabricated under a suitable voltage of 5.25 V. The images of the joint cross section and interface between deposited metal and fiber indicated that the fiber structure remained unaffected by the deposited metal, and the introduction of nickel improved interface bonding of double-layer metal joint with fiber than copper joint. The electrical and mechanical properties of the joined fibers under different deposition voltages were studied. The results show that the introduction of nickel significantly improved the electrical and mechanical properties of the joined fiber. Under a suitable deposition voltage, the resistance of the joined fiber was 37.7% of the original fiber, and the bearing capacity of the joined fiber was no less than the original fiber. Under optimized condition, the fracture mode of the joined fibers was plastic fiber fracture.

Metal-coated carbon fiber for lighter electrical metal wires

Kang, Sung Soo,Ji, Hyunjin,Gul, Hamza Zad,Sakong, Won Kil,Kim, Ji Yeon,Kim, Won Seok,Lee, Jhony,Han, Songhee,Park, Minyoung,Choi, Young Chul,Lim, Seong Chu Elsevier 2016 Synthetic metals Vol.222 No.2

<P><B>Abstract</B></P> <P>In this study, we plated thin conducting Cu layer in a thickness of 200–300nm on the surface of carbon fiber that was supposed to replace the core of Cu wire for weight reduction. The metal-coated carbon fibers (MCF) exhibit comparable electrical properties to the bulk Cu including the electrical conductivity of 5.9×10<SUP>−6</SUP> Ωcm, temperature coefficient of resistance (TCR) of 1.14×10<SUP>−3</SUP>/K, and featureless 1/f noises. In addition to electrical properties, the Joule heating of MCF revealed that the MCF terminated itself when the temperature of MCF significantly rose. This was due to the much lower burning temperature of carbon fiber, comparing to that of Cu, which can be beneficial in the prevention of a fire sparked by a hot metal wire.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation of metal-coated carbon fiber for lighter electrical metal wires. </LI> <LI> Superb electrical properties of metal-coated carbon fiber along with lower weight. </LI> <LI> Excellent interfacial quality between copper and carbon fiber. </LI> </UL> </P>

Removal of Cu(II) and Cr(VI) ions from aqueous solution using chelating fiber packed column: Equilibrium and kinetic studies

Ko, Young Gun,Chun, Yong Jin,Kim, Choong Hyun,Choi, Ung Su Elsevier 2011 Journal of hazardous materials Vol.194 No.-

<P><B>Graphical abstract</B></P><P><ce:figure id='fig0005'></ce:figure></P><P><B>Highlights</B></P><P>► The crystal growth of Cu(II) ions on the novel chelating fiber. ► Adsorption capacity of Cu(II) and Cr(VI) ions in the chelating fiber packed column. ► This work demonstrates the adsorption process system with the chelating fiber for the removal of Cu(II) and Cr(VI) ions in the aqueous solution.</P> <P><B>Abstract</B></P><P>Herein, we demonstrate the adsorption process system with the diethylenetriamne coupled polyacrylonitrile fiber for the removal of Cu(II) and Cr(VI) ions in the aqueous solution. The synthesized chelating fiber showed a high adsorption capacity of 11.4mequiv/g. Interestingly, the crystal growth of copper ions on the chelating fiber was observed during the adsorption process. The chelating fiber packed column showed the high performance of the removal of Cu(II) in the aqueous solution due to the distinct characteristic of the crystal growth of metal ions on the chelating fiber. After Cu(II) adsorption on the chelating fiber, the color of the fiber changed to light blue from yellow. The isotherm parameter <I>n</I> of 1.991 was obtained with Freundlich isotherm model for the adsorption equilibrium study which indicates that Cu(II) adsorption on the chelating fiber is very favorable due to <I>n</I>>1. The pseudo-first-order and pseudo-second-order model equations were used for the kinetic study.</P>

비정질 강섬유의 길이 및 혼입률에 따른 섬유보강 시멘트복합체의 직접인장특성

김홍섭,김규용,이상규,최경철,남정수 한국건축시공학회 2019 한국건축시공학회지 Vol.19 No.3

In this study, the direct tensile properties of amorphous metallic fiber-reinforced cement based composites according to the strain was evaluated. A thin plate-shape amorphous metallic fiber with 15mm and 30mm in length was used. And fiber-reinforced cement based composites were prepared with contents of 1.0, 1.5, 2.0%. The direct tensile test was conducted under the conditions of 10-6/s(static) and 101/s(dynamic) strain rate. As a results, amorphous metallic fiber with a length of 15mm was observed in pull-out behavior from the cement matrix because of the short fiber length and large portion of mixed fiber. On the other hand, amorphous metallic fiber with a length of 30mm were not pulled out from matrix because the bonding force between the fiber and matrix was large due to rough surface and large specific surface area. However, fracture occurred because thin plate shape fibers were vulnerable to shear force. Tensile strength, strain capacity and toughness were improved due to the increase in the fiber length. The dynamic increase factor of L15 was larger that of L30 because the bonding performance of the fiber-matrix interface is significantly affected by the strain rate. 본 연구에서는 변형속도에 따른 비정질 강섬유보강 시멘트복합체의 직접인장특성에 대하여 평가하였다. 길이 15, 30mm의 박판형 비정질 강섬유를 각각 1.0, 1.5, 2.0% 혼입한 섬유보강 시멘트복합체를 제작하였으며, 변형속도 10-6/s(정적), 101/s(동적)의 조건에서 직접인장시험을 수행하였다. 그 결과, 길이 15mm의 비정질 강섬유는 섬유의 섬유의 길이가 짧고 혼입개체수가 많기 때문에 섬유가 매트릭스로부터 인발되었다. 반면, 길이 30mm의 비정질 강섬유는 섬유의 표면이 거칠고 비표면적이 크기 때문에 매트릭스와의 부착성능이 우수하지만, 박판형의 섬유 형상이 전단력에 약하기 때문에 섬유가 인발되지 않고 파단 되었다. 섬유의 길이가 길수록 인장강도, 변형능력 및 인성이 큰 것으로 나타났다. 반면, 길이 30mm의 비정질 강섬유는 매트릭스로부터 인발되지 않고 파단 되지만 길이 5mm의 비정질 강섬유는 매트릭스로부터 인발되기 때문에 변형속도의 영향을 받는 섬유-매트릭스 계면의 부착효율이 크게 되어, 인장강도, 변형능력 및 인성에 대한 동적증가계수가 큰 것으로 나타났다.

High Temperature Fiber Fragmentation Characteristics of SiC Single-Fiber Composite With Titanium Matrices

Matikas, Theodore E. The Korean Society for Composite Materials 2008 Advanced composite materials Vol.17 No.1

Aerospace structural applications, along with high performance marine and automotive applications, require high-strength efficiency, which can be achieved using metal matrix composites (MMCs). Rotating components, such as jet-engine blades and gas turbine parts, require materials that maximize strength efficiency and metallurgical stability at elevated temperatures. Titanium matrix composites (TMCs) are well suited in such applications, since they offer an enhanced resistance to temperature effects as well as corrosion resistance, in addition to optimum strength efficiency. The overall behavior of the composite system largly depends on the properties of the interface between fiber and matrix. Characterization of the fiber.matrix interface at operating temperatures is therefore essential for the developemt of these materials. The fiber fragmentation test shows good reproducibility of results in determining interface properties. This paper deals with the evaluation of fiber fragmentation characteristics in TMCs at elevated temperature and the results are compared with tests at ambient temperature. It was observed that tensile testing at $650^{\circ}C$ of single-fiber TMCs led to limited fiber fragmentation behavior. This indicates that the load transfer from the matrix to the fiber occurs due to interfacial friction, arising predominantly from mechanical clamping of the fiber by radial compressive residual and Poisson stresses. The present work also demonstrates that composite processing conditions can significantly affect the nature of the fiber.matrix interface and the resulting fragmentation of the fiber.

특정용제 Target 형 활성금속첨착 활성탄소섬유의 개발(Ⅱ)

최강용(Kang Yong Choi),김광수(Kwang Su Kim),김태원(Tae Won Kim),전민기(Min Kee Jun),박해경(Hea Kyung Park) 大韓環境工學會 2013 대한환경공학회지 Vol.35 No.7

기존 흡착제들보다 우수한 흡착성능을 확보하고, 특히 특정한 용제에 대한 흡착성능을 극대화하기 위하여 활성탄소섬유를 기본흡착제로 적용하였고, 여기에 활성금속을 첨착시켜 흡착성능과 선택성을 제고하고자 하였다. 선행 연구를 통하여 선정된 Cu, Cr을 기본 활성금속으로 하고 여기에 활성보조금속으로서 Pt, Pd를 복합 첨착시킨 활성탄소섬유를 첨착온도 및 시간을 변수로 하여 제조하였다. 복합첨착 활성탄소섬유의 흡착 성능이 단일첨착 활성탄소섬유와 비교하여 향상되었으며, 첨착온도100℃, 첨착시간 5시간 조건에서 최상의 흡착 성능을 확인할 수 있었다. Cu-Cr-Pt-Pd 복합첨착 활성탄소섬유가 가장 뛰어난 흡착성능을 보였으며, 기존 활성탄소섬유보다 2배 이상의 높은 흡착성능을 확인하였다. 한편, 활성금속첨착 활성탄소섬유상에의 확산 및 흡착에 필요한 최소 접촉시간은 0.5초 이상은 유지해야 함을 확인 할 수 있었다. Cu and Cr as a base metal and Pt, Pd as a supportive metal were selected for improving adsorption capacity of activated carbon fiber in eliminating especially targeted VOCs. Preparing variables such as .metal loading, loading temperature, loading hours and kinds of loaded metals were changed. Properties measurement was carried out by SEM (scanning electron microscope), XRF (x-ray fluorescence analysis) and EDX (Energy Dispersive X-ray spectrometer) and adsorption capacity evaluation were also performed by gas analyzer. Under this study, the adsorption capacity of complex metal loaded activated carbon fiber was improved positively than that of single metal loaded activated carbon fiber. And we found that the best conditions for metal loading were 5 hours loading time at 100℃ and the adsorption capacity was enhanced almost double compared with other condition based activated carbon fiber. Cu-Cr-Pt-Pd loaded activated carbon fiber showed the best adsorption capacity. Also we confirmed that more than 0.5 second is necessary for adsorbate diffusion and adsorption over activated carbon fiber.

Preparation and Characterization of Acrylic Fiber-Based Chelate Resin Modified With Diethylenetriamine

Joon-Pyo Jeun,Phil-Hyun Kang,Byung-Seon Choi,Chang Hyun Roh 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

Chelate resin is a resin that has an exchange group which can form chelates with various metal ions. It shows higher selectivity for metal ions than ion exchange resin and can selectively remove characteristic metal ions. In an aqueous solution containing metal ions, chelate resin can adsorb specific metal ions, and the separated chelate resin can desorb the adsorbed metal ions by changing temperature or pH, so chelate resin has the advantage of being reusable. Chelate resin has been used industrially as an adsorbent to adsorb and separate heavy metal ions in wastewater, and is also used for the purpose of recovering precious or rare metals contained in industrial wastewater or industrial waste. Against this background, there is a need to develop chelate resins with higher adsorption capacity. Acrylic fiber is defined as a man-made fiber made from a linear synthetic polymer with fiberforming ability consisting of more than 85% acrylonitrile. It is a man-made fiber that is often used as a substitute for wool because it has good thermal insulation properties like wool and is warm and soft to the touch. It is a fiber rich in cyano groups due to its high content of acrylonitrile, and has the advantage of being able to be used as a variety of functional fibers through modification of cyano groups. In this study, the amination reaction of acrylic fiber was performed using diethylenetriamine, and the adsorption characteristics for metal ions were evaluated according to the reaction conversion rate. In order to improve the amination efficiency, 400 kGy was irradiated using a 2.5 MeV electron beam accelerator, and through this, the crosslinking rate of acrylic fiber was able to be improved up to 80%. Water and ethanol were used as cosolvents for the amination reaction in a ratio of 60/40 vol/vol, respectively, and a reaction yield of 178% was obtained after 120 minutes of reaction. Using the chelate resin prepared in this way, the adsorption performance for metal ions was evaluated through Atomic Absorption Spectrometry analysis.

A Study on the Reinforced Fibrous Concrete Elements Subjected to Uniaxial Tensile Loading

Rashid Hameed,Anaclet Turatsinze,Frederic Duprat,Alain Sellier 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.4

The structural response of prisms of cross section 100×100 mm and length of 500 mm constructed with reinforced fibrous concrete and subjected to pure tensile loading has been presented in this contribution. The main focus was to study the effects of adding different metallic fibers in mono and hybrid form in the conventionally reinforced concrete on the tension stiffening and strain development. Two metallic fibers with different geometrical, mechanical and physical properties were investigated: amorphous metallic straight fibers and carbon steel hooked-end fibers. A total of four concrete mixtures: control, single fiber and hybrid fiber reinforced concretes were prepared. The fibers were investigated at content of 20 kg/m3 for single fiber reinforced concretes, and for hybrid fiber reinforced concrete, at content of 40 kg/m3. Through studying load-deformation response of composites and strain development in steel bar and concrete, it has been found that the metallic fibers improve tension stiffening effect and influence significantly the strain development. The effect of two metallic fibers on tension stiffening was seen to be different at different loading stages. On the other hand, when fibers were used in hybrid form, the behaviour of the composite was improved at all loading stages in terms of tension stiffening and resistance to cracking.

보강섬유의 종류에 따른 섬유보강 콘크리트의 휨특성

강영태 ( Kang Young-tai ),김규용 ( Kim Gyu-yong ),이보경 ( Lee Bo-kyeong ),이상규 ( Lee Sang-kyu ),김경태 ( Kim Gyeong-tae ),남정수 ( Nam Jeong-soo ) 한국건축시공학회 2017 한국건축시공학회 학술발표대회 논문집 Vol.17 No.2

In this study, the flexural behavior of fiber-reinforced concrete by fiber type were evaluated. As a result, the flexural strength of the hooked steel fiber-reinforced concrete(HSFRC) was lower than that of the amorphous metallic fiber reinforced concrete(AFRC), however it was shown strain-softening behavior by the pull-out of fiber. The flexural strength and the equivalent flexural strength of polyamide fiber-reinforced concrete(PAFRC) were lower than other specimens, but the equivalent flexural strength ratio was similar to that of AFRC. The flexural behavior of the fiber-reinforced concrete was associated with the bonding and pull-out properties of the fiber and matrix depending on the fiber type.