• Title/Summary/Keyword: wetting properties

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Fabrication and Characteristics of SiCp/AC8A Composites by Pressureless Metal Infiltration Process (무가압함침법에 의한 SiCp/AC8A 복합재료의 제조 및 특성)

  • 김재동;고성위
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.139-142
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    • 2000
  • The SiCp/AC8A composites were fabricated by the pressureless metal infiltration process successfully. The effect of additional Mg, which were mixed with SiC particles to promote interfacial wetting between the reinforcement and matrix alloy, and particle size on the mechanical properties was investigated. By increasing the additional Mg content the hardness of SiCp/AC8A composites was increased due to the hard reaction products, but the bending strength was decreased by the excess reaction of Mg and high porosity level when the additional Mg content is over 7%. The Hardness and bending strength was increased by decreasing the size of SiC particle.

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An Experimental Study on the Salt Resistance Properties with Concrete Materials under Marine Environment (해양환경에 노출시킨 콘크리트의 내염성능 평가)

  • Ko Jeong-Jae;Kim Young-Ung;Kim Dong-Chul;Shin Do-Chul;Kim Sang-Yong;Byun Dae-Bong
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.790-793
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    • 2004
  • The factors influencing concrete deterioration in marine environment can be generally divided into the physical and chemical action. The physical attack due to drying and wetting would increase the internal stress of concrete. The chemical attack resulting from the diffusion of ions$(i,e,\;Cl^-,SO_4^{2-},Mg^+)$ from seawater through the pores in concrete. The objective of this study is to evaluate corrosion characteristics of steel when using the various concrete materials under marine exposure environment. After 3 years of exposure, concrete specimen incorporating $40\%$ blast-furnace slag as replacement for type I cement with low w/c ratio of 0.42 and using the inhibitor shows excellent performance.

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An Experimental Study on the Salt Resistance Properties with Concrete Materials under Marine Environment (Exposure period : 5 years) (해양환경에 폭로한 콘크리트의 내염특성에 대한 실험적 연구 (폭로기간 : 5년))

  • Kim, Yong-Chul;Suk, Jun-Yeoll;Shin, Do-Chul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.169-172
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    • 2006
  • The IIA structures exposed to marine environment is subject to many different types of potential attack. The physical attack due to drying and wetting would increase the internal stress of concrete. The chemical attack resulting from the diffusion of ions$(Cl^-,SO_4^{2-},Mg^+)$ from seawater through the pores in concrete. Therefore the sea water resistance of concrete must be considered when it is used for structure in the ocean. The objective of this study is to evaluate chloride diffusion and corrosion characteristics of concrete when using the various concrete materials under marine environment. After 5 years of exposure, concrete incorporating 40% blast-furnace slag as replacement for type I cement with low w/c ratio of 0.42 and using the inhibitor shows excellent performance.

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Preparation of Si-SiC Composites by Si-Infiltration (Si 침윤에 의한 Si-SiC 복합체 제조)

  • 김인술;장주민;오기동;박홍채
    • Journal of the Korean Ceramic Society
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    • v.29 no.9
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    • pp.750-756
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    • 1992
  • Reaction bonded si-SiC composites were prepared by silicon infiltration technique at temperature of 1$600^{\circ}C$ for 30 minutes in vaccum atmosphere. The microstructure and mechanical properties of Si-SiC composites were investigated and characterized. UF-15 and SE-10 as SiC powders, phenolic resin and carbon black as carbon source, and metallic silicon powder as molten Si source were used as starting materials. New SiC crystallines nucleatd and grown by reaction of Si and C were detected by TEM and SEM-EDS. The bonding between new and original SiC was found to be strong. But the wetting of SiC by unreacted metallic Si and the rapid grain growth of new SiC decreased density and fracture toughness. Fracture toughness and modulus of rupture of Si-SiC composite were about 3.2 MPa.m1/2 and 480 MPa, respectively.

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Expansion Factors of Cement Mortar Containing Expanding Admixture (팽창재를 포함한 시멘트 모르터의 팽창 요인)

  • 황인동;염희남;정윤중
    • Journal of the Korean Ceramic Society
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    • v.37 no.6
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    • pp.576-582
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    • 2000
  • Two type of expanding cement generally referred to as CSA with Hauyne(3CaO 3Al2O3 CaSO4) and Quick lime(CaO). Hauyne is formed to ettringite when there are presented with CaO and CaSO4, and CaO reacts wtih water to form Ca(OH)2. REcently, the mechanism of compensation and expand mortar or concrete tend to same and it has been used improving on its shrink property. The volume of cement paste varies with its water content shrink with drying and re-wetting. Concrete and mortar works are required shrinking compensation and expansion properties to reduce of potential crack. The use of expansion cement may improve on its shrinking volume changes. CSA dosages for shrinking compensation limited by cement weight, but obtained difference expansion rate with varied W/C or inorganic admixture. This paper studies expansion rate according to expansion cement dosages, water and inorganic admixtures as Silica fume. Therefor, the expansion factor has to considered before the application.

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Fabrication of Stable Water/Oil Separation Filter Using Effect of Surface Wettability (표면 젖음성을 이용한 물/오일 분리막 제작)

  • Kim, Dohyeong;An, Taechang
    • Journal of Sensor Science and Technology
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    • v.25 no.3
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    • pp.213-217
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    • 2016
  • The superhydrophobic and superoleophobic meshes surfaces have been used in various applications such as self-cleaning, anti-icing, gas exchange, oil-water separation, sound-wave penetrable anti-wetting structures, etc. In particular, there are many studies for oil-water separation with environmental issues. Because of high pressure and dynamic environment, oil-water separation filters must have stable surface properties as super-hydrophobicity and superoleophobicity. The oleophobicity of surface depends on the surface chemistry and roughness of the surface. The roughness of oleophobic surface enhances its static contact angle and stability. The multi-scale hierarchical structure provides a stable superhydrophobic state by maintaining a Cassie state. In this research, we fabricated a superoleophobic mesh with a multi-scale hierarchical structure to increase the pressure resistance and adjusted a size of the mesh hole.

Durability Characteristics of Cellulose Fiber Reinforced Cement Composite (셀룰로우스 섬유 보강 시멘트 복합체의 내구성에 관한 연구)

  • 원종필;문제길
    • Proceedings of the Korea Concrete Institute Conference
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    • 1996.04a
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    • pp.1-6
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    • 1996
  • Cellulose fiber reinforced cement composites manufactured by the slurry-dewatering process have found broad applications in thin cement products as replacement for asbestos cement. This paper focuses on the durability characteristics of these composites under different aging conditions. The effects of wetting-drying and freezing-thaw cycles, carbonation, and exposure to hot and humid environments on the structure and properties of cellulose fiber-cement composites were investigated. The predominant mechanisms of aging in the composites were identified through investigation of structure-property relationships. Measures to control these aging mechanisms were diversed and evaluated. Refined cellulose fiber-cement composites are shown to possess excellent durability characteristics under the effects of various aging processes.

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Powder Production of CuAINi Base Alloy via Rotating Disk Atomization (회전원반분사법에 의한 CuA1Ni계 합금 분말제조)

  • 류봉선
    • Journal of Powder Materials
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    • v.1 no.2
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    • pp.145-152
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    • 1994
  • Atomizing mode and powder characteristics of CuA1Ni base shape memory alloy in rotating disk atomization were investigated in accordance with disk materials and additional elements. Produced powders were classified into two types of spherical and flake shape. In the case of CuAlNiBTi and CuAlNiZr alloy, high yield rate and fine powder were obtained. This tendency was same when we used oxide coated disks. We concluded that this results were steno from the wetting characteristics change between molten metal and disk surface. Especially, due to the reactive properties of Ti and Zr with ceramic disk, the change of atomizing appearance and powder characteristics were noticeable.

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Bioinspired Nanoengineering of Multifunctional Superhydrophobic Surfaces

  • Choi, Chang-Hwan
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.102-133
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    • 2015
  • Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. Especially, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing. Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing.

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Superhydrophobic and Hydrophobic Anodic Aluminum Anodic Oxide Layer: A Review (초발수성 및 발수성 알루미늄 양극산화피막의 최신 연구 동향)

  • Lee, Junghoon
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.11-20
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    • 2018
  • Hydrophobic and Superhydrophobic surfaces are promising technology for the surface finishing of metallic materials due to its water-repellency. Realization of highly water-repellent surface on aluminum and its alloys provides various functionalities for real application fields. In order to realize the hydrophobic/superhydrophobic surfaces on aluminum and its alloys, various technologies have been demonstrated. Especially, traditional anodic oxidation for aluminum has been widely employed for the morphological texturing of surfaces, which is essential to enhance the hydrophobic efficiency. De-wetting superhydrophobic surface on aluminum provides various exceptional properties, such as anti-corrosion, anti-/de-icing, anti-biofouling, drag reduction, self-cleaning and liquid separation. Nevertheless, the durability and stability of superhydrophobic surfaces still remain challenges for their actual applications in engineering systems and industry. In this review, the theoretical/experimental studies and current technical limitations on the hydrophobic and superhydrophobic surface using anodic oxidation of aluminum have been summarized.