• Composites Research
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• 제26권4호
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• pp.218-222
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• 2013

본 연구에서는 제강 과정의 부산물로 발생하는 슬래그의 구조용 충전제로써의 사용 가능성을 검토하였다. 고분자 기지 슬래그 복합재료를 제작하여 슬래그 입자의 크기(8~12 ${\mu}m$ and 12~16 ${\mu}m$), 체적 비(0-30 vol.%)에 따른 슬래그 복합재료의 기계적 특성에 대한 실험적 연구를 수행하였다. 복합재료 물성에 영향을 주는 요인인 입자 분산 도와 계면상태를 고찰하기 위해 각각 시편에 대하여 조직사진을 촬영하였다. 인장 시험 결과 슬래그 복합재료의 재료강성은 슬래그 체적비가 증가할수록 증가하였고 인장 강도는 체적비가 증가할수록 감소하였다. 슬래그 복합재료의 재료강성은 슬래그 입자의 크기의 변화에 따른 뚜렷한 경향성을 띄지 않았고 인장강도는 입자의 크기가 작을수록 높은 값을 가졌다. 조직 사진 촬영 결과 슬래그 복합재료가 양호한 계면상태를 보였고, 낮은 체적 비에서는 좋은 분산 도를 나타냈지만 체적비가 높아지면 입자들의 뭉침 현상이 발생하는 것을 알 수 있었다.

• 소성∙가공
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• 제18권6호
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• pp.482-487
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• 2009

A finite element based microstructural modeling for the size dependent strengthening of particle reinforced aluminum composites is presented. The model accounts explicitly for the enhanced strength in a discretely defined "punched zone" around the particle in an aluminum matrix composite as a result of geometrically necessary dislocations developed through a CTE mismatch. The density of geometrically necessary dislocations is calculated considering volume fraction of the particle. Results show that predicted flow stresses with different particle size are in good agreement with experiments. It is also shown that 0.2% offset yield stresses increases with smaller particles and larger volume fractions and this length-scale effect on the enhanced strength can be observed by explicitly including GND region around the particle. The strengths predicted with the inclusion of volume fraction in the density equation are slightly lower than those without.

• 수산해양기술연구
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• 제49권4호
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• pp.492-499
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• 2013

The characteristics of abrasive wear of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The range of volume fraction of silica particles tested are between 11% to 25%. The cumulative wear volume and friction coefficient of these materials on particle volume fraction were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, deboding of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase nonlinear with increase of sliding distance. As increasing the silica particles of these composites indicated higher friction coefficient.

• 대한기계학회논문집B
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• 제28권7호
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• pp.863-870
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• 2004

The temperature and soot particle measurement technique in a laminar diffusion flame has been studied to investigate the characteristics of soot particle with temperature using a co-flow burner. The temperature distribution in the flame were measured by rapid insertion of a R-type thermocouple and the soot particles by LEM/LIS techniques. In these measurement, soot volume fraction, number density and soot diameters were analyzed experimentally. As a results, the spacial distributions of particle volume fraction, soot diameter, and number density are mapped throughout the flame using the Rayleigh theory for the scattering of light by particles. A laser extinction method was used to measure the soot volume fraction and laser induced scattering method was used to measure the soot particle diameter and number density. Also, we measured temperature without the effect of soot particles attached to the thermocouple junction, which is close to the nozzle. In this result, we found that upstream zone has a unstable flowing in co-flow diffusion flame and the y-axis temperature of flame has a uniform temperature distribution in the most soot volume fraction zone.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1267-1273
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• 2004

The temperature and soot particle measurement technique in a laminar diffusion flame have been studied to investigate the characteristics of soot particle with temperature using a co-flow burner. The temperature distributions in the flame were measured by rapid insertion of a R-type thermocouple and the soot particles were detected were detected by LEM/LIS techniques. In these measurement, soot volume fraction, number density and soot diameters were analyzed experimentally. As a results, the spacial distributions of particle volume fraction, soot diameter, and number density are mapped throughout the flame using the Rayleigh theory for the scattering of light by absorbing particles. A laser extinction method was used to measure the soot volume fraction and Laser induced scattering method was used to measure the soot particle diameter and number density. Also, we measured temperature without the effect of soot particles attached to the thermocouple junction, which is close to the nozzle. In this result, we found that upstream zone has a unstable flowing in co-flow diffusion flame and the y-axis temperature of flame has a uniform temperature distribution in the most soot volume fraction zone.

• 한국세라믹학회지
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• 제37권7호
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• pp.638-644
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• 2000

The sintering behaviors of the glass-alumina composites for low firing temperature were investigated as functiions of the volume fraction of alumina powder and the particle size with respect to porosity and pore shape. As the volume fraction of alumina powder was increased or the particle size of it was decreased, the sintering temperature of open pore-closing was raised. When the volume fractions of alumina which had 2.19$\mu\textrm{m}$ median diameter were increased with 20, 30, 40, and 50%, the sintering temperatures of open pore-closing were 425, 450, 475, and 500$^{\circ}C$. And when the median particle size of alumina was diminished from 2.19$\mu\textrm{m}$ to 0.38$\mu\textrm{m}$, the sintering temperature of open pore-closing was increased from 450$^{\circ}C$ to 475$^{\circ}C$. Especially, the sintering temperature, which showed maximum density, was corresponded with the stage of open pore-closing and after achieving maximum density over heating resulted in dedensification of specimen, so called, over-firing behavior.

• 수산해양기술연구
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• 제51권3호
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• pp.454-460
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• 2015

The present study is undertaken to evaluate the effect of volume fraction on the results of Charpy impact test for the rubber matrix filled with nano sized silica particles composites. The Charpy impact tests are conducted in the temperature range $0^{\circ}C$ and $-10^{\circ}C$. The range of volume fraction of silica particles tested are between 11% to 25%. The critical energy release rate $G_{IC}$ of the rubber matrix composites filled with nano sized silica particles is affected by silica volume fraction and it is shown that the value of $G_{IC}$ decreases as volume fraction increases. In regions close to the initial crack tip, fracture processes such as matrix deformation, silica particle debonding and delamination, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact fracture surfaces.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.119-124
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• 2004

Experimental study was conducted to characterize the flow effect of particle migration in a microchannel which can be used to deliver small amount of liquids, drugs, biological agents and particles in microfluidic devices. Fluorescent particles of $1\{mu}m$ diameter were used to obtain velocity profiles of the fluid in which large particles of $10\{mu}m$ diameter were suspended at different volume fraction of 0.6 and $0.8\%$. Measurements were obtained by using micro-PIV system which contains a Nd:YAG laser with a light of 532-nm wavelength, an inverted epi-fluorescent microscope and a cooled CCD camera to record particle images. The volume fraction of $\phi$ and the particle Reynolds number $Re_p$Rep were used as a parameter to assess the influence of the velocity profile of the suspensions. To expect the slip velocity between the particle and fluids, experiments were carried out at low volume fraction. It was shown that the velocity profile was not influenced by Rep but influenced by the volume fraction, which is in similar trend with the previous study.

• 한국분말재료학회지
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• 제10권1호
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• pp.51-56
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• 2003

To investigate the effect of the parameters of the plasma arc discharge process on the particle formation and particle characteristics of the iron nano powder, the chamber pressure, input current and the hydrogen volume fraction in the powder synthesis atmosphere were changed. The particle size and phase structure of the synthesized iron powder were studied using the FE-SEM, FE-TEM and XRD. The synthesized iron powder particle had a core-shell structure composed of the crystalline $\alpha$-Fe in the core and the crystalline $Fe_3O_4$ in the shell. The powder generation rate and particle size mainly depended on the hydrogen volume fraction in the powder synthesis atmosphere. The particle size increased simultaneously with increasing the hydrogen volume fraction from 10% to 50%, and it ranged from about 45nm to 130 nm.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.622-627
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• 2013

콜로이달 실리카는 실리콘과 사파이어 웨이퍼의 정밀연마슬러리, 유-무기 하이브리드 코팅제, 정밀주조의 바인더 등 다양한 제품으로 사용되는 물질이다. 이러한 실리카 졸의 입자크기 및 분산 안정성은 웨이퍼의 표면, 코팅 막 혹은 벌크의 기계적, 화학적, 광학적 특성에 영향을 주기 때문에 정확한 측정값이 요구된다. 본 연구에서는 제조사에서 제시한 입자 크기 및 표면 특성이 다른 8종류 실리카 졸의 부피 분율에 따라 입자 크기, 졸 점도 및 입자 전기영동이동도의 측정결과에 미치는 영향을 논의하였다. 높은 표면활성을 지닌 실리카 입자의 특성 및 실리카 졸의 희석에 의한 안정화 이온 농도의 변화로 인해 실리카의 측정 입자 크기와 이동도는 졸의 부피 분율 혹은 입자 크기에 따라 변한다. 60 nm 보다 작은 입자는 부피 분율이 증가함에 따라 측정된 입자 크기가 증가한 반면에, 그 보다 큰 입자에서는 측정된 입자 크기가 감소하였다. 12 nm와 같이 작은 입자는 부피 분율이 증가함에 따라 점도가 상승하면서 측정 입자의 이동도가 감소한 반면에 100 nm의 큰 입자는 0.048의 낮은 부피 분율까지 이동도가 증가하다가 그보다 높은 부피 분율부터 감소하였다.