• 대한기계학회논문집B
• /
• 제22권3호
• /
• pp.399-407
• /
• 1998

The infrared reflection coatings with pigment can be used to protect the surfaces of combustible materials exposed to fire. To obtain high reflectivities in the infrared range (0.5-10.mu.m) important to fire, several dielectric pigments, such as titanium dioxide, iron oxide, and silicon, can be synthesized to polymer coatings. The theoretical analysis shows that the coating design with particles diameter in the 1.5 to 2.5.mu.m range and volume fraction in the 0.1 to 0.2 range is estimated to be optimal. In the analysis of the radiation, the dependent scattering, absorption by polymeric binder, and the internal interface reflection are considered. In addition, the temperature distribution in the semi-transparent coating layer and an opaque substrate (PMMA) is also presented.

• 한국자기학회지
• /
• 제2권1호
• /
• pp.15-21
• /
• 1992

침상형의 ${\gamma}-Fe_{2}O_{3}$ 입자를 $Co^{+2}/Fe^{+2}$의 몰비가 0.5인 2가 금속혼합용액을 함유하는 알카리성 용액에서 $90^{\circ}C$로 가열하였다. 코발트 함량이 증가함에 따라 생성물의 보자력은 거의 직선적으로 증가하였으며 비표면적은 감소하였다. 코발트 훼라이트는 ${\gamma}-Fe_{2}O_{3}$ 결정 표면상에 에피탁시얼하게 성장되며, 보자력의 증가는 피착층인 코발트 훼라이 트의 결정 자기이방성에 기인하는 것으로 사료된다. 당량비 2이상에서 우수한 자기적 특성을 기대할 수 있 었으며 반응공정도 코발트 훼라이트 에피탁시얼 산화철의 보자력 특성에 영향을 미친다. $Co-{\gamma}-Fe_{2}O_{3}$의 온도 및 경시변화에 대한 안정성은 피착층 조성에 의해 크게 지배된다.

• 한국세라믹학회지
• /
• 제45권10호
• /
• pp.605-609
• /
• 2008

This work describes the preparation of functionalized magnetic nanoparticles(MNPs) and their bioapplication to human DNA separation. Silica coated MNPs were prepared by changing the volume ratio of tetraethyl orthosilicate(TEOS) for controlled coating thickness on the original nanoparticle of MNPs. The sol-gel process in silica coating on MNPs surface was adapted for relatively mild reaction condition, low-cost, and surfactant-free. And then amino functionalized magnetic nanoparticles were synthesized using amine groups as surface modifiers. The result of adsorption efficiency for human DNA with amino-functionalized silica coated MNPs was calculated as a function of the number of amine groups.

• Corrosion Science and Technology
• /
• 제14권2호
• /
• pp.76-84
• /
• 2015

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600~2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipments were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

• 한국표면공학회지
• /
• 제50권2호
• /
• pp.85-90
• /
• 2017

The carbon steel formed the thick, somewhat porous, loosely adherent iron oxide scale when oxidized at $500-800^{\circ}C$ for 15 h in air. It formed the thicker, more porous, nonadherent scale consisting of FeS plus iron oxides in $Ar/1%SO_2$-mixed gas. It formed the much thicker, more porous, nonadherent scale consisting of FeS plus iron oxides in Ar/0.1% $H_2S$-mixed gas. However, the aluminized carbon steel formed the thin, protective $Al_2O_3$ surface scale even in $Ar/1%SO_2$-, and $Ar/0.1%H_2S$-mixed gas. Aluminizing drastically improved the corrosion resistance in (O, S, H)-containing gas.

• 공업화학
• /
• 제30권2호
• /
• pp.151-154
• /
• 2019

코디어라이트 허니컴 표면에 알루미나 워시코트 지지체를 형성시키고 비교적 단순한 건식 코팅 공정으로 산화철 촉매를 코팅함으로써 실제 환경에 효과적으로 적용이 가능한 모노리스 구조 촉매를 제조하였다. 허니컴 통로 벽 구석으로 형성된 워시코트 알루미나 미세 기공으로 균일하게 코팅된 산화철 촉매를 확인하였으며, 일산화탄소 산화 반응에 적용하기 위하여 산화철 촉매의 열처리 효과를 검증하였다. $350^{\circ}C$ 부근에서 열처리한 산화철 촉매가 가장 우수한 촉매 성능을 발휘하였고, $200^{\circ}C$ 이상의 온도 영역에서 100% 전환율을 나타내었다.

• 한국세라믹학회지
• /
• 제20권3호
• /
• pp.211-216
• /
• 1983

This work aims at characterizing silicon grains and its compacts. In order to remove iron silicon grains were washed with 5N hydrochloride at 60-7$0^{\circ}C$ for 170 hrs, and then followed the chemical analysis by atomic absorption spectrophotometer X-ray diffraction analysis SEM observation and specific surface area determination by B. E. T. Mixtures of graded silicon particles with two or three different sizes were made into packings by mechanical vibration. The mixtures were used to make compacts with 10 mm in diameter and 70mm in length by isostatically pressing at 1, 208 kg/$cm^2$ (20 kpsi) and 4, 255kg/$cm^2$ (60 kpsi) respectively. Bulk densities of packings and compacts were measured. A slip made of magnesium nitrate solution and fine silicon particles was spray-dried and then decomposed at 30$0^{\circ}C$ for the purpose of coating the uniform layer of magnesium oxide on the surface of particles. The results obtained are as follows: (1) About two thirds of iron content could be removed from silicon by washing silicon powders with hydrochloride. (2) Uniform layer of magnesium oxide on the surface of silicon could be prepared by spray-drying suspension and by decomposing it. (3) B. E. T. specific surface area of fine silicon particles was 2, 826.753$m^3$/kg. (4) In the binary system with two sizes of 40-53$\mu\textrm{m}$ particles and <10$\mu\textrm{m}$ particles the maximum bulk density of packing was 55% of theoretical value and that of compacts made at the pressure of 4, 255 kg./$cm^2$ (60 kpsi) was 73% of theoretical value. (5) In the ternary system with three sizes the maximum bulk density of packing was 1.43 g/$cm^3$and that of compacts was 1.80g/$cm^3$which is equivalent to 77.6% of theoretical value. The composition of the closest compact was consisted of 50% of 40-53$\mu\textrm{m}$ particles 20% of 10-30$\mu\textrm{m}$ particles and 30% of <10$\mu\textrm{m}$ parti-cles.

• 대한자기공명의과학회:학술대회논문집
• /
• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
• /
• pp.107-107
• /
• 2001

목적： 초상자성 nano-particle 조영제의 자기이완효과에 관한 out sphere 기전에 기초하여 각각의 자기장의 세기에서 T1/T2 자기이완율을 나타내는 NMRD profile을 수치적으로 simulation 하는 프로그램을 개발하고자 하였다. 대상 및 방법： 초상자성 nano-particle 조영제의 경우 초상자성 물질을 생체적합성 고분자로 표면 coating하기 때문에 상자성 조영제와는 달리 전적으로 "out sphere"기여도만을 고려하였고 또한 초상자성 물질의 경우 자기적 에너지의 크기가 매우 크기 때문에 상자성 조영제의 기전에서 사용되는 "low field"근사를 사용할 수 없으므로 Brillouin 함수로 표현되는 총자화에 대한 표현을 적용하였다. nano-particle내에 포함된 Fe 원자수에 따른 T1 및 T2 NMRD Profile과 온도에 따른 T1 및 T2 NMRD Profile 그리고 초상자성 nano-particle size에 따른 T1 및 T2 NMR Profile을 PC (CPU=800 Mhz, memory=128 MB) 환경하에서 symbolic computation tool 인 MathCad (MathCad, USA)를 사용하여 구현하였다.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2015년도 춘계학술대회 논문집
• /
• pp.128-129
• /
• 2015

Al-rich coatings were prepared on hot rolled low carbon steel by hot dipping method in molten Al-bath to investigate the corrosion resistance with the possible outcomes and defects of aluminized coatings in air and $Ar-0.2%SO_2$ mixed gases. Coating microstructure was composed of an inner Al-Fe intermetallic layer and outer Al-rich layer. Aluminum oxidized preferentially to the thin, outer, protective ${\alpha}-Al_2O_3$ layer, without forming the nonprotective iron/sulfur-oxide layer after heating at $800^{\circ}C$ for 20 h, in both the gases and provided the resistance against corrosion.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2015년도 춘계학술대회 논문집
• /
• pp.122-122
• /
• 2015

Al-rich coatings were prepared on hot rolled low carbon steel by hot dipping method in molten Al-bath to investigate the corrosion resistance with the possible outcomes and defects of aluminized coatings in air and $Ar-0.2%SO_2$ mixed gases. Coating microstructure was composed of an inner Al-Fe intermetallic layer and outer Al-rich layer. Aluminum oxidized preferentially to the thin, outer, protective ${\alpha}-Al_2O_3$ layer, without forming the nonprotective iron/sulfur-oxide layer after heating at $800^{\circ}C$ for 20h, in both the gases and provided the resistance against corrosion.