• 제목/요약/키워드: Impact property

검색결과 732건 처리시간 0.028초

지하수자원의 환경적으로 지속가능한 개발 방안 (Schemes for the Environmentally Sound and Sustainable Development of Groundwater Resources)

  • 홍상표;김정욱
    • 환경영향평가
    • /
    • 제5권2호
    • /
    • pp.49-57
    • /
    • 1996
  • On the basis of sustainable long-term water resources planning, the development of ground water resources should be interlocked with the surface water development In considering the intertemporal equity, overpumping of groundwater may diminish or eliminate the groundwater resources stock of post-generations. Regulatory landuse zoning for groundwater resources recharge area is indispensable measures to prevent groundwater pollution. Adequate treatment of polluted water from various sources such as municipal sewage, industrial wastewater, landfill site leachate, and abandoned boring wells, is also necessary for groundwater protection. To preserve groundwater resources as common property goods, groundwater use tax should be imposed upon the large scale groundwater use. Finally, the establishment of groundwater development license system is recommended to achieve the social optimal production and to avoid external diseconomy.

  • PDF

유리-탄화규소 복합재료의 고속충돌 저항물성 (A Resistance Property Against High Velocity Impact on Glass-SiC Composites)

  • 김창욱;이형복
    • 한국세라믹학회지
    • /
    • 제43권10호
    • /
    • pp.653-659
    • /
    • 2006
  • The glass-SiC composites have been manufactured via viscous flow of glass for investigating their sinterability and various properties. The relative density of 99.6% could be achieved when 5 wt% SiC was mixed with glass powder, glass-rearranged at 460$^{\circ}C$ for 3 h and then sintered at 665$^{\circ}C$ for 1 h. The sintered density was decreased as adding more than 5 wt% SiC to glass powder. The resistance properties against hyper velocity copper jet formed by explosion of K215 warhead were compared with other ceramics such as $Al_2O_3$ and pyrex, resulting in lower values than that of $Al_2O_3$.

STD61 공구강의 내충격 및 내열피로 특성에 미치는 가스 퀜칭 압력의 영향 (Effect on Anti-impact and Anti-thermal Fatigue Properties of STD61 Material Affected by Gas Quenching Pressure of Quenching Process)

  • 박현준;최광진;김종엽;신승용;문경일
    • 열처리공학회지
    • /
    • 제29권6호
    • /
    • pp.277-283
    • /
    • 2016
  • The influences of cooling pressure of quenching process on the mechanical properties such as hardness, impact endurance and anti-thermal fatigue behaviour of STD61 steel were investigated. The specimens were heat-treated using a vacuum furnace in which they were austenitized at $1,030^{\circ}C$ for 1hour under the pressure of $10^{-3}$ torr and cooled with quenching gas of various pressure, i.e. 1, 2 and 6 bar. According to the observation on the specimens prepared with quenching from austenizing temperature, the mechanical properties of the samples with higher quenching pressure were better than those of prepared at lower quenching pressure. The samples prepared with high quenching pressure showed the more homogeneous microstructure with finer carbides. The size of carbides such as VC and (Fe, Cr)C in quenched specimens decreased with increasing gas quenching pressure. It is considered that the rapid cooling with pressure may restrict the formation and growth of carbide.

7175 합금 단조재의 미세조직과 기계적 성질에 미치는 중간가공열처리 영향 (The Effect of Intermediate Thermo-Mechanical Treatment on the Microstructure and Mechanical Property of 7175 Al Alloy)

  • 이용연;송영범;;손영일;이경훈;은일상
    • 열처리공학회지
    • /
    • 제10권3호
    • /
    • pp.172-180
    • /
    • 1997
  • The microstructure, tensile and impact properties of forgings of 7175 aluminium alloy have been studied as a function of intermediate thermo-mechanical treatment(ITMT) process. The ITMT process is consisted of warm working and recrystallization. In the case that the billet was warm-worked above 60% below $250^{\circ}C$ and recrystallized at $475^{\circ}C$, the grain size revealed about $17{\mu}m$ which corresponds to one third of that of conventional process. The refinement of grain size leaded to the improved ductility and impact energy without sacrifice of tensile strength. It was found that the ITMT processed specimen behaved isotropically due to the near equiaxed grains. It was observed that the ITMT processed specimen showed the mixed fracture mode of transgranular and intergranular, instead of intergranular mode. This change of fracture mode contributed to the improved ductility and impact property.

  • PDF

Investigation on Mechanical Property and Adhesion of Oxide Films Formed on Ni and Ni-Co Alloy in Room and High Temperature Environments

  • Oka, Yoshinori I.;Watanabe, Hisanobu
    • Corrosion Science and Technology
    • /
    • 제7권3호
    • /
    • pp.145-151
    • /
    • 2008
  • Material degradation such as high temperature oxidation of metallic material is a severe problem in energy generation systems or manufacturing industries. The metallic materials are oxidized to form oxide films in high temperature environments. The oxide films act as diffusion barriers of oxygen and metal ions and thereafter decrease oxidation rates of metals. The metal oxidation is, however, accelerated by mechanical fracture and spalling of the oxide films caused by thermal stresses by repetition of temperature change, vibration and by the impact of solid particles. It is therefore very important to investigate mechanical properties and adhesion of oxide films in high temperature environments, as well as the properties in a room temperature environment. The oxidation tests were conducted for Ni and Ni-Co alloy under high temperature corrosive environments. The hardness distributions against the indentation depth from the top surface were examined at room temperature. Dynamic indentation tests were performed on Ni oxide films formed on Ni surfaces at room and high temperature to observe fractures or cracks generated around impact craters. As a result, it was found that the mechanical property as hardness of the oxide films were different between Ni and Ni-Co alloy, and between room and high temperatures, and that the adhesion of Ni oxide films was relatively stronger than that of Co oxide films.

극저온용 오스테나이트계 고망간강의 인장 및 충격 특성에 미치는 C, Mn, Al 첨가의 영향 (Effect of C, Mn and Al Additions on Tensile and Charpy Impact Properties of Austenitic High-manganese Steels for Cryogenic Applications)

  • 이승완;황병철
    • 한국재료학회지
    • /
    • 제29권3호
    • /
    • pp.189-195
    • /
    • 2019
  • The effect of C, Mn, and Al additions on the tensile and Charpy impact properties of austenitic high-manganese steels for cryogenic applications is investigated in terms of the deformation mechanism dependent on stacking fault energy and austenite stability. The addition of the alloying elements usually increases the stacking fault energy, which is calculated using a modified thermodynamic model. Although the yield strength of austenitic high-manganese steels is increased by the addition of the alloying elements, the tensile strength is significantly affected by the deformation mechanism associated with stacking fault energy because of grain size refinement caused by deformation twinning and mobile dislocations generated during deformation-induced martensite transformation. None of the austenitic high-manganese steels exhibit clear ductile-brittle transition behavior, but their absorbed energy gradually decreases with lowering test temperature, regardless of the alloying elements. However, the combined addition of Mn and Al to the austenitic high-manganese steels suppresses the decrease in absorbed energy with a decreasing temperature by enhancing austenite stability.

알루미늄 평판 및 50 ㎛ 간격 격자 표면에 대한 에탄올 액적 충돌 거동 가시화 (Ethanol Droplet Impact Behavior Visualization on the Flat and 50㎛ grating groove Al Surface)

  • 강동국;권대희;천두만;염은섭
    • 한국가시화정보학회지
    • /
    • 제18권1호
    • /
    • pp.18-25
    • /
    • 2020
  • The droplet impact behavior is dominated by some parameters such as surface temperature, We number, surface and fluid property. Especially, Leidenfrost effect which prevents the contact between surface and droplet is very powerful phenomenon for determining droplet impact behavior. Due to this effect, the impact regime is divided into contact boiling regime and film boiling regime whether the droplet contact with the surface. Many studies have found that surface micro-structures which processed by surface processing are effective to overcome the Leidenfrost effect. In this study, droplet impact behaviors were compared using ethanol both on flat and laser-ablated Al surface. On the flat surface, impact regime was mainly divided by surface temperature. And there is key dominant parameter for each regime. On the laser-ablated surface, we could see changed impact regime and different impact behavior such as jetting and ejection of tiny droplets despite of same impact conditions.

바닥 충격음 저감용 소재의 동탄성 계수에 관한 연구 (A Study on the Dynamic Elastic Modulus of the materials for Floor Impact Sound Reduction)

  • 박춘근;이종필
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2005년도 추계학술대회논문집
    • /
    • pp.930-935
    • /
    • 2005
  • In order to synthesis of the materials and modulus for floor impact sound reduction, we investigated effect on dynamic elastic modulus of floor impact sound reduction materials and module made by inorganic porous materials, EVA chips and so on. We find correlation property between dynamic elastic modulus and light-weight impact noise. And we measured the dynamic elastic modulus of materials and module for floor impact sound reduction. And we predicted reduction efficiency on floor Impact Noise of those. The dynamic elastic modulus is reduced by increase of filler contents and filler species. When the materials for floor impact sound reduction is consisted of l5wt% EVA Chip and l5wt% inorganic porous materials, its dynamic elastic material is the lowest. And when the module is consisted of PE (upper side), PS embossing board(lower side) and the materials for floor impact sound reduction(middle), its dynamic elastic material is the lowest.

  • PDF