• Title/Summary/Keyword: Softening Point

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Electrochemical Performance of PFO Pitch coated Natural Graphite using Dry Speed Mixer (건식 스피드 믹서를 이용한 PFO 피치 코팅 천연 흑연의 전기화학적 성능)

  • Youn, Jae Woong;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.59 no.3
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    • pp.410-416
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    • 2021
  • To improve the capacity and stability of natural graphite, the electrochemical performances were investigated by using the prepared natural graphite coated with petroleum pitch for anode materials. The pitch coated natural graphite was prepared using a dry speed mixer by adjusting the rotation speed of the mixer, time, composition of graphite and softening point of the pitch. The physical properties of the anode material were analyzed using SEM, TEM, and PSD. The electrochemical performances were investigated by cycle, C-rate, EIS and CV test. When the pitch coated natural graphite was tested in the condition of 9000 RPM, 10 wt%, 2 h, and softening point of 150 ℃, it showed the highest capacity of 324.5 mAh/g at 0.1 C and a capacity retention rate of 98.9% after 50 cycles. In the test for evaluating rate performance, the capacity retention rate (5 C/0.1 C) was 80.3% and was improved by about 1.7 times over the pristine natural graphite.

Determination of Structural Performance Point Utilizing The Seismic Isolation Rubber Bearing Design Method (면진격리 고무베어링 설계법을 이용한 구조물의 성능점 예측)

  • 김창훈;좌동훈
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.3
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    • pp.23-30
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    • 2003
  • The seismic base isolation design approach has been reviewed and modified to fit the nonlinear static analysis procedure for determination of the performance point of structures in a simpler way, such an adaptation may be possible for the fact that a structural system under development of damage due to earthquake loading keeps softening to result in period shifting toward longer side. The superiority of the proposed method to the state-of-the-practice approach is that the reasonably accurate performance point can be obtained without constructing the so-called acceleration displacement response spectrum required in application of capacity spectrum method. The validity of the proposed approach was verified by comparing the predicted values to the exact ones presented in the literature.

Optimization of Boiling Process and Texture Change in Heating (밤 가공품 자숙 공정 중 물성의 변화 및 최적화)

  • 김영찬;이주백
    • Food Science and Preservation
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    • v.4 no.3
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    • pp.337-341
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    • 1997
  • Texture is an important quality factor of processed chestnut products, which changes depending on the conditions of boiling process. The conventional boiling process consists of three stage(1st : 70 minutes at 60$^{\circ}C$; 2nd : 20minutes at 70$^{\circ}C$; 3rd : 80minutes at 98$^{\circ}C$). To improve the conventional boiling process of processed chestnut products, we investigated the changes of texture at different stages of boiling process and undertook the optimization of boiling process by response surface method on heating times of 2nd and 3rd heating, and amount of softening agent. The initial hardness and cohesiveness, the most important textural characteristics of chestnut, were 7.876kg and 0.189, respectively. In the third boiling stage, hardness decreased to 0.313kg and cohesiveness increased to 0.310. Using response surface method the minimum point of hardness and maximum point of cohesiveness was examined and model equations for predicting the changes of hardness and cohesiveness in the optional boiling condition were developed.

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Effects of Upset Pressure on Weldability in the Friction Welding of Cu to Cu-W Sintered Alloy (동-텅스텐 소결합금(Cu-W)과 동(Cu)의 마찰용접 특성에 미치는 업셋압력의 영향에 관한 연구)

  • 강성보;민택기
    • Journal of Welding and Joining
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    • v.17 no.5
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    • pp.69-76
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    • 1999
  • A copper-tungsten sintered alloy(Cu-W) has been friction welded to a tough pitch copper in order to investigate the effect of upset pressure on friction weldability. Under the condition of friction time 0.8sec, upset pressure 150MPa, the tensile strength and Charpy impact value of the friction welded joint were 336MPa, $400KJ/m^2$ respectively. And highest temperature of the weld measured was below $800^{circ}K$ which is very lower than melting point of Cu($1356^{circ}K$). Under the same conditions, W grains picked up in Cu matrix from Cu-W profitably affected on these mechanical fracture, and were dispersed in Cu by plastic flow during brake time.

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Effect of Frit and Sintering Conditions on the Microstructure and Electrical Property in Ag and Ag/Pd Thick Film Conductors (프릿트 및 소결조건이 Ag 및 Ag/Pd계 후막도체의 미세구조와 전기적성질에 미치는 영향)

  • 구본급;김호기
    • Journal of the Korean Ceramic Society
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    • v.25 no.6
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    • pp.623-630
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    • 1988
  • As a function of the composition and content of frit, the electrical property of Ag and Ag/Pd thick film conductors were investigated with microstructure. With increasing sintering temperature in Ag-frit thick film conductors, electrical sheet resistivity decreased, but again increased above 80$0^{\circ}C$. And when frit contents is 5wt%, compact and homogenious microstructure can be obtained, then electrical sheet resistivity has minimum value. In Ag/Pd-frit film conductor, the electrical sheet resistivity decreased with increasing sintering temperature. The system which having frit with low softing point has lower sheet resistivity then to add high softening point frit.

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Effects of Borane-Pyridine Complex on Mesophase Formation from Decant Oil

  • Han, Dong-Yun;Moon, Sook-Young;Lim, Yun-Soo
    • Carbon letters
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    • v.5 no.3
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    • pp.113-117
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    • 2004
  • The mesophase pitch was prepared by adding 1~10 wt% of the borane-pyridine complex (BPC) to decant oil. It was prepared in a reactor held at $450^{\circ}C$ for 2 h in $N_2$ atmosphere. The mesophase pitches were analyzed using thermogravimetric analyzer (TGA), melting point apparatus, X-ray diffraction (XRD) and polarized optical microscope. The coke yield, softening point, toluene insoluble, density and content of anisotropy in the mesophase pitches were increased with BPC contents. The XRD profiles did not show any effect of addition of BPC on the formation of mesophase pitch, while the crystallinity of mesophase pitches was increased when the materials were heat treated with boron compound.

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Three Point Bending Fatigue Property with Heat Treatment Condition in a Powder Metallurgical High Speed Steel JYPS-23 (분말고속도공구강 JYPS-23에서 열처리조건에 따른 3점 굽힘피로특성)

  • 홍성현;배종수;김용진
    • Journal of Powder Materials
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    • v.7 no.3
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    • pp.131-136
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    • 2000
  • The effect of tempering temperature on the three point bending fatigue behavior of a P/M high speed steel JYPS-23 (1.28% C, 4.20% Cr, 6.40% W, 5.00% Mo, 3.10% V, bal. Fe) was investigated. The number of cycles to failure of the specimen austenitized at $1175^{\circ}C$ drastically increased with increasing tempering temperature. As tempering temperature increased from 500 to $620^{\circ}C$, the volume fraction and average size of carbides (MC or M6C) did not significantly changed, while hardness decreased drastically. The reduced hardness is due to the softening of matrix, which increased the resistance of the fatigue crack propagation. For a practical application, powder compacting test were also conducted with the P/M high speed steel punches tempered at 500, 580, and $620^{\circ}C$. The number of compacting cycles to failure of the punches also increased with increasing tempering temperature.

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Measurement of an Isoelectric Point and Softness of a EO-PO Adducted Zwitterionic Surfactant (EO-PO가 부가된 양쪽성 계면활성제의 등전점 및 유연력 측정에 관한 연구)

  • Lim, JongChoo;Mo, DaHee;Lee, JinSun;Park, JunSeok;Han, DongSung
    • Korean Chemical Engineering Research
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    • v.50 no.3
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    • pp.455-463
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    • 2012
  • In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

Numerical simulation of fracture and damage behaviour of concrete at different ages

  • Jin, Nanguo;Tian, Ye;Jin, Xianyu
    • Computers and Concrete
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    • v.4 no.3
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    • pp.221-241
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    • 2007
  • Based on the experiment results, the damage and fracture behavior of concrete at the ages of 1d, 2d, 7d and 28d, in three-point bending and uniaxial tensile tests, were simulated with a finite element program, ABAQUS. The critical stress intensity factor $K_{IC}^s$ and the critical crack tip opening displacement ($CTOD_C$) of concrete were calculated with effective-elastic crack approach for the three-point bending test of grade C30 concrete. Based on the crack band model, a bilinear strain-softening curve was derived to simulate the LOAD-CMOD curves and LOAD-Displacement curves. In numerical analysis of the uniaxial tension test of concrete of grade C40, the damage and fracture mechanics were combined. The smeared cracking model coupling with damaged variable was adopted to evaluate the onset and development of microcracking of uniaxial tensile specimen. The uniaxial tension test was simulated by invoking the damage plastic model which took both damage and plasticity as inner variables with user subroutines. All the numerical simulated results show good agreement with the experimental results.

Study on Softness of an EO Adducted Amine Oxide Zwitterionic Surfactant (EO가 부가된 아민 옥사이드 양쪽성 계면활성제의 유연력에 관한 연구)

  • Kim, JiSung;Mo, DaHee;Lee, JinSun;Park, JunSeok;Han, DongSung;Lim, JongChoo
    • Korean Chemical Engineering Research
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    • v.50 no.6
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    • pp.960-968
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    • 2012
  • In this study, the measurement of physical properties of 3 different ethylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of the zwitterionic surfactants were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of the synthesized zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that all three surfactants used during this study provide better softening effect at a pH of neutral condition than at an acidic or an alkaline condition. This result indicates that the synthesized surfactants act as a cationic surfactant at a pH of neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.