• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
• /
• pp.10-17
• /
• 2003

The amount of production orders from Japanese car and construction machine industries have slightly increased in 2002, but the costs of the forged parts have decreased due to severe competitions with the other Asian countries. Most of the forging industries and some universities are making more efforts for technological researches and developments to meet the demand for higher accuracy and higher quality products, shortening of delivery time, and development of forged parts for new industrial fields. Some helical gears of which surfaces can be net-shaped have been started for commercial base production to be shipped to car industries. Some non-graphite lubricants for hot forging and some conversion coating free lubricants for cold forging have been developed to improve some environmental problems.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1992년도 추계학술발표강연 및 논문개요집
• /
• pp.144-144
• /
• 1992

• Bulletin of the Korean Chemical Society
• /
• 제34권3호
• /
• pp.960-962
• /
• 2013

• 한국표면공학회지
• /
• 제42권1호
• /
• pp.1-7
• /
• 2009

Resistive heating sources are widely used to prepare thin films by vapor deposition because they are cheap, and easy to install and handle in vacuum system. Graphite is one of materials used to make the resistive heating source, but until now only limited applications have been possible as it reacts easily with evaporating materials at high temperature. In this study, evaporation characteristics of aluminum have been investigated by using graphite boat thermally treated with BN powder. The employed graphite boat has been prepared by spray-coating BN power onto the cavity surface of the boat and thermal treatment with aluminum in vacuum at the temperature of more than $1400^{\circ}C$. The voltage-current characteristics as well as resistivity changes of the graphite boat have been investigated during aluminum evaporation according to the applied voltage and time. The evaporation aspect has been picturized during flash evaporation for 40 seconds based on the characterization results. The evaporation rate of the graphite boat has been compared with that of BN boat. The graphite boat showed some different characteristics compared with BN boat, in that the evaporation occurred at the last stage of flash evaporation. The film appearance according to the applied voltage has been compared, and also the reflectance of the resulting film has been investigated according to the film thickness. It has been found that the graphite boat thermally treated with BN powder can be used for aluminum evaporation without problem.

• 한국재료학회지
• /
• 제15권1호
• /
• pp.66-72
• /
• 2005

Surface modification of the silicon-coated graphite was carried out at $200^{\circ}C\~800^{\circ}C$ under hydrogen atmosphere. The silicon-coated graphites were prepared by fluidized-bed spray coating method. The components of silicon films prepared on the graphite consist of SiO, $SiO_x\;(1. The components of silicon films at $200^{\circ}C$ of heat treatment brought on the higher fraction of SiO and $SiO_x$ than that of $SiO_2$. However, inactive $SiO_2$ fraction increases with increase of the heat treatment temperature. The high content of SiO and $SiO_x$ in the silicon film on graphite leads to the higher discharge capacity in our experimental range.

• Korean Chemical Engineering Research
• /
• 제59권3호
• /
• pp.410-416
• /
• 2021

본 연구에서는 천연 흑연의 용량과 안정성을 개선하기 위해 석유계 피치로 코팅된 천연 흑연을 제조하여 전기화학적 성능을 평가하였다. 천연흑연과 피치를 건식 스피드 믹서를 이용해 코팅하였으며, 믹서의 회전 속도, 시간, 흑연과 피치의 조성, 피치의 연화점을 변화시키면서 음극 활물질을 제조하였다. 제조된 음극 활물질의 물리적 특성은 SEM, TEM, PSD를 이용해 분석하였으며, 전기화학적 성능은 사이클, 율속, 임피던스, 순환전압 전류 테스트를 통해 조사하였다. 9000 RPM, 10 wt%, 2 h, 연화점 150 ℃ 조건에서 코팅된 천연 흑연을 0.1 C에서 전기화학적 특성을 테스트 하였을 때, 324.5 mAh/g 의 가장 높은 용량과 50 사이클 이후 98.9%의 용량 유지율을 보였다. 고속 충·방전을 위한 테스트에서는 5 C/0.1 C 용량 유지율은 80.3%로 나타났으며, 코팅되지 않은 천연흑연보다 약 1.7 배로 향상된 용량 유지율을 확인할 수 있었다.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
• /
• pp.45-48
• /
• 1997

ZrO$_2$ coated flake graphite powders were prepared by the controlled hydrolysis of zirconium oxichloride. The stirring process plays an important role in the coating process. There are two types of coated ZrO$_2$ particles: (a)primary particles with few nm size were obtained by the direct formation of the shell by precipitation of the surface of the graphite and (b) Secondary particles of ZrO$_2$ with ∼0.1$\mu\textrm{m}$ size were obtained by the independent formation of primary particles ZrO$_2$ and subsequent heterocoagulation at the graphites surface.

• 한국결정성장학회지
• /
• 제32권3호
• /
• pp.89-95
• /
• 2022

본 연구에서는 페놀수지를 사용하여 흑연표면에 유리질 카본 코팅을 진행하였다. 코팅액은 균일한 표면을 가지는 유리질 카본 코팅층 형성을 위해 페놀수지와 경화제, 희석제, 첨가제 등을 혼합하였다. 코팅된 페놀수지는 25~60℃에서 건조 100~200℃에서 경화 500~1,500℃에서 열처리하여 유리질 카본으로 전환하였다. 유리질 카본의 특성 분석을 위해 FTIR, XRD, SEM 분석, 밀도/기공율/접촉각 측정을 진행하였다. 유리질 카본 형성에 있어 최적 온도는 약 1,000℃로 확인되었다. 그리고 첨가제의 함량이 높아질수록 코팅 표면의 결함감소, 기공율 감소, 접촉각 증가, 밀도 증가 등의 효과를 보였다. 첨가제를 통한 유리질 카본 코팅층 형성 방법은 흑연 코팅 및 다른 분야에 적용이 가능할 것으로 기대된다.

• 전기화학회지
• /
• 제18권3호
• /
• pp.130-135
• /
• 2015

흑연 분말을 프탈로시아닌 또는 구리 프탈로시아닌과 함께 비활성 분위기에서 각각 열처리하여 표면처리를 진행하였고, 이의 속도특성과 저온 작동특성을 조사하였다. 표면처리 후 흑연 분말의 표면에 비정질 탄소와 구리의 코팅 층이 균일하게 형성되었다. 표면처리를 통하여 흑연 전극의 속도특성이 개선되는 것을 확인하였는데, 특히 구리 프탈로시아닌으로 처리한 경우 속도특성의 향상이 두드러졌다. 흑연 전극의 저항을 교류 임피던스와 펄스 저항측정법을 활용하여 조사하였는데, 구리 프탈로시아닌으로 처리된 흑연 전극의 경우가 저항이 가장 작았다. 프탈로시아닌으로 부터 유도된 비정질 탄소 층이 리튬이온의 확산을 용이하게 하고, 구리 프탈로시아닌으로부터 유도된 금속상태의 구리는 전자 전도도를 증가시키기 때문에 저항을 감소시키는 것으로 판단된다.

• 한국표면공학회지
• /
• 제49권2호
• /
• pp.218-224
• /
• 2016

Thermal radiation pastes were prepared by dispersing carbon materials as fillers with a content of 1 weight percent in an acrylic resin. The kind of fillers was as follows; $25{\mu}m$ graphite, $45{\mu}m$ graphite, $15{\mu}m$ carbon nanotube(CNT), a 1:1 mixture of $25{\mu}m$ graphite and $15{\mu}m$ CNT, and a 1:1 mixture of $45{\mu}m$ graphite and $15{\mu}m$ CNT. Thermal emissivity was measured as 0.890 for the samples with graphite only, 0.893 for that with CNT only, and 0.892 for those containing both. After coating prepared pastes on a side of 0.4 mm thick aluminium plate and placing the plate over an opening of a box maintained at $92^{\circ}C$ with the coated side out, the temperatures on the uncoated side of the plates were measured. The samples containing graphite and CNT showed the lowest temperatures. The paste with mixed fillers was coated on the back side of the PCB of an LED module and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. The thermal resistance of the module with coated PCB was measured as 14.34 K/W whereas that with uncoated PCB was 15.02 K/W. The structure function analysis of T3ster data revealed that the difference between junction and ambient temperatures was $13.8^{\circ}C$ for the coated case and $18.0^{\circ}C$ for the uncoated. From the infrared images of heated LED modules, the hottest-spot temperature of the module with coated PCB was lower than that of the uncoated one for a given period of LED operation.