• 동력기계공학회지
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• 제17권5호
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• pp.23-29
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• 2013

The activation process is the key to graphene's practical application. In this study, the effect of grinding speed in planetary ball mill on structural integrity of graphene has been studied at various grinding speed such as 100 rpm, 200 rpm, 300 rpm, 400 rpm and 500 rpm. The morphology and structure of pristine graphene and ground graphenes were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy respectively. According to these results, structural properties of graphene were improved when grinding speed was increased.

• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.681-687
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• 2003

The syntheses of LaNiO$_3$Perovskite crystalline phase from mixtures of La$_2$O$_3$and NiO via it mechanochemical(used planetary mill) and a wet ball mill process were investigated. A single and stable LaNiO$_3$perovskite crystalline phase was successfully prepared by using a heat free mechanochemical process which produced a fine amorphous powder, while that phase was not formed in a wet ball mill process which needed heat treatment ranging from 500 to 150$0^{\circ}C$ and produced a coarse powder. It was shown that the LaNiO$_3$ceramics made of the mechanochemically synthesized powder possesed a good metallic characteristic.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 춘계학술발표강연 및 눈문개요집
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• pp.135-135
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• 1999

• 대한약학회:학술대회논문집
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• 대한약학회 2000년도 춘계총회 및 학술대회
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• pp.209.1-209.1
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• 2000

• 한국전기전자재료학회논문지
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• 제15권3호
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• pp.238-243
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• 2002

The dielectric properties and synthesis of $LaAIO_3$ ceramics from mixtures of $La_2O_3$ and $AI(OH)_3$ via ground(planetary ball mill) and unground(wet ball mill) were investigated. The single phase $LaAIO_3$ of ground powder was formed at $1000^{\circ}C$, while that of unground powder was formed at $1300^{\circ}C$. Density and grains of ground sample showed 98% of theory density and a uniform size of 0.75\mu\textrm{m}$, respectively, However those of unground sample showed 93% and non-uniform sizes of 4-5 $\mu\textrm{m}$. Dielectric constant and temperature coefficient of capacitance ($\tau$c) of both ground and unground samples were 21~22 and +70~74 ppm$/^{\circ}C$, respectively. Dielectric loss of ground sample(0.0004) was 10 times as low as that of unground sample(0.003) due to a uniform and small gram size.

• 한국결정성장학회지
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• 제14권6호
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• pp.257-261
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• 2004

태백 도석은 주로 quartz와 함께 kaolinite가 포함되어 있다. 도석의 특성분석은 XRD, XRF, TG--DTA, SEM등을 이용하여 결정상과 화학성분 등을 분석하였다. 원석의 화학조성은 71.75wt%$SiO_2$, 22.10wt%$Al_2O_3$, 1.86wt%CaO, 2.97wt%$K_2O$, 0.62 wt%$Fe_2O_3$ 등이다. 3mm 크기의 도석을 $80^{\circ}C$의 10% 수산 농도에서 침출하면 탈철은 0.62wt%에서 0.24wt%로 감소하고 백색도가 증가하였다. 도석의 분쇄는 planetary ball mill을 이용하여 지르코니아 볼로 분쇄하였으며, 입도 크기는 25$\mu\textrm{m}$ 크기로 균일하게 분쇄되었다.

• 동력기계공학회지
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• 제17권1호
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• pp.91-96
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• 2013

The present paper focuses on the fabrication of materials with higher thermal conductivity. Nanofluid is a novel transfer prepared by dispersing nanometer-sized solid particles in traditional heat transfer fluid to increase thermal conductivity and heat transfer performance. The purpose of this study is making the nano-size particle. The experiment of MWCNT and $Al_2O_3$ was carried out using a planetary ball mill at several rotation speeds: 200 ~ 400 rpm. The results were examined using scanning electron microscope(SEM). In the case of the MWCNT, it could be more grinding into the small particle in the dry condition and it confirm in the case of the $Al_2O_3$ to be more grinding into the small particle contrary to the MWCNT in the wet condition. In the mixture grinding result of MWCNT and $Al_2O_3$, the dry condition showed the good result in low rotation speed than the wet condition.

• 동력기계공학회지
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• 제17권5호
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• pp.78-85
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• 2013

A high thermal conductivity material, namely graphene is treated by planetary ball milling machine to transport the heat by increasing the temperature. Experiments were performed to assess the heat transfer enhancement benefits of coating the bottom wall of copper substrate with graphene. It is well known that the graphene is unable to disperse into base fluid without any treatment, which is due to the several reasons such as attachment of hydrophobic surface, agglomeration and impurity. To further improve the dispersibility and thermal characteristics, planetary ball milling approach is used to grind the raw samples at optimized condition. The results are examined by transmission electron microscopy, x-ray diffraction, Raman spectrometer, UV-spectrometer, thermal conductivity and thermal imager. Thermal conductivity measurements of structures are taken to support the explanation of heat transfer properties of different samples. As a result, it is found that the planetary ball milling approach is effective for improvement of both the dispersion and heat carriers of carbon based material. Indeed, the heat transfer of the ground graphene coated substrate was higher than that of the copper substrate with raw graphene.

• 한국재료학회지
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• 제23권2호
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• pp.89-97
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• 2013

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.

• 자원리싸이클링
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• 제31권2호
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• pp.63-69
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• 2022

본 연구에서는 국내에 의치한 관인광산의 바나듐 함유 티탄철광(vanadium titanium magnetite, VTM) 광석 대상으로 기계적 분쇄에 의한 결정구조를 평가하고자 다양한 조건에서의 유성 볼밀을 통한 기계적 분쇄를 수행하였으며, 산물에 대하여 결정구조 거동을 평가하였다. 사용된 관인광산 VTM 광석은 자철석과 티탄철석이 주요 광종이며, 주요 맥석광종은 철기반 실리케이트로 확인되었다. 유성 볼밀에 의한 기계적 활성화 결과에 따르면 분쇄메디아(볼) 크기는 크기가 작을수록 결정화도 및 결정크기가 감소하였으며, 시료/볼 충전은 시료가 투입이 적을수록 무정형화가 크게 일어남을 확인되었다. 게다가, 분쇄운전 변수인 분쇄속도 및 시간은 증가할수록 결정구조의 변화가 크게 관찰되었으며, 볼 크기 및 시료/볼 충전비보다도 분쇄속도 및 시간에 의한 결정구조 거동의 영향을 크게 주는 것으로 확인되었다.