• Title/Summary/Keyword: thermal propertis

Search Result 4, Processing Time 0.019 seconds

Characterization of Alumina Gel Prepared by Hydrolysis of Al(OC3H7i)3 (Al(OC3H7i)3의 가수분해로부터 얻어진 Al2O3 겔의 특성에 관한 연구)

  • 이서우;문종수;조성백
    • Journal of the Korean Ceramic Society
    • /
    • v.25 no.2
    • /
    • pp.89-94
    • /
    • 1988
  • Alumina gel was prepared by the hydrolysis of aluminum isopropoxide Al(OC3H7i)3 at low temperature. Sample were calcined at the various temperatures for 10 houres in the electric furnace, respectively. In order to investigate the various propertis-thermal properties, pore size and distribution, and the transition of crystals, infrared spectroscopy, thermal analysis, particle size analysis, scanning electron microscopy, and porosimetry were employed. Transparent alumina gel was opalized at 1200$^{\circ}C$. Porosity was about 87% with pores below 0.7$\mu\textrm{m}$ and 55% at 1200$^{\circ}C$. The gel was transformed along the rising of temperature as follows; Boehmite\longrightarrow$\delta$-Al2O3\longrightarrow$\theta$\longrightarrowAl2O3\longrightarrow${\alpha}$-Al2O3.

  • PDF

Characteristics of Hydrogen Storage Alloy powder Compacts Using Polymer Binders (고분자 결합제를 이용한 수소저장합금 분말 성형체의 특성)

  • Kim, Chan-Jung;Kim, Dai-Ryong
    • Journal of Hydrogen and New Energy
    • /
    • v.10 no.2
    • /
    • pp.81-89
    • /
    • 1999
  • Various characteristics - mechanical propertis, thermal cyclic hydriding characteristics and resistance to degradation by $H_2O$, CO in hydrogen - of hydrogen storage alloy powder compacts using PTFE and silicon sealant as a polymer binder were studied. Diametral tensile strength of 10wt% PTFE and 5wt% silicon sealant added compacts showed relatively high value of $4kg/cm^2$ and $10kg/cm^2$, respectively. Compacts show a good resistance to degradation by $H_2O$ in hydrogen. But hydrogen absorption rate and capacity of compacts were decreased by CO in hydrogen with the number of cycles. Cu coated and PTFE bonded compacts showed very small decrease of capacity and a good strength even after 1000 cycles of thermal hydriding and dehydriding.

  • PDF

A Study of Relations of Chain Lengths and Properties for Bifunctional linear DGEBF/Linear Amino (EDA, HMDA) Cure Systems (선형 이관능성 DGEBF/선형아민(EDA, HMDA) 경화계의 경화제 사슬길이와 물성과의 관계에 대한 연구)

  • Myung In-Ho;Lee Jae-Rock
    • Composites Research
    • /
    • v.17 no.6
    • /
    • pp.37-43
    • /
    • 2004
  • To determine the effect of chain length and chemical structure of linear amine curing agents on thermal and mechanical properties, a standard bifunctional linear DGEBF epoxy resin was cured with EDA and HMDA having amine group at the both ends of main chain in a stoichiometrically equivalent ratio in condition of preliminary and post cure. From this work, the effect of linear amine curing agents on the thermal and mechanical properties is significantly influenced by numbers of carbon atoms of main chain. In contrast, the results show that the DCEBF/EDA system having two carbons had higher values in the thermal stability, density, shrinkage (%), grass transition temperature, tensile modulus and strength, flexural modulus and strength than the DGEBF/HMDA system having six carbons, whereas the DGEBF/EDA cure system had relatively low values in maximum ekothermic temperature, maximum conversion of epoxide, thermal expansion coefficient than the DGEBF/HDMA cure system. These findings indicate that the packing capability (rigid property) in the EDA structure affects the thermal and mechanical properties predominantly. It shows that flexural fracture properties have a close relation to flexural modulus and strength.

Investigation of Mechanical Property of Polypropylene and CF/PP Composites with Number of Recycle (재활용 횟수에 따른 폴리프로필렌 및 탄소섬유 강화 PP 복합재료의 물성 변화 관찰)

  • Kwon, Dong-Jun;Wang, Zuo-Jia;Lea, Tea-Ung;Park, Joung-Man
    • Composites Research
    • /
    • v.26 no.5
    • /
    • pp.303-308
    • /
    • 2013
  • Carbon fiber (CF) reinforced polypropylene (PP) compositeis was increased to amount consumed. In this study, recycle of composites by recycle times. CF was containing 20%. Mechanical and interfacial propertis of CF/PP was evaluation for number of recycle time. Mechanical assessment of CF/PP was tension, bending, fatigue tension test and izod test method. Interfacial assessment of CF/PP was wettability test and FE-SEM of fracture surface method. Fiber and matrix was changed to recycle time. The more recycle of CF/PP, the more interfacial bonding was decreased. Because fiber and matrix was damaged to thermal damage. And then reinforced CF was shorter than original shape.