• 한국대기환경학회지
• /
• 제20권3호
• /
• pp.291-302
• /
• 2004

The CuO/$3AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters for nitrogen oxides removal were prepared by porous mullite($3AL_2O_3{\cdot}2SiO_2$) support and CuO catalyst deposited on this support to achieve uniformly dispersed CuO deposition, which are impregnated into the pores of available alumino-silicate ceramic candle filter. The CuO/3$AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters were characterized by XRD, BET, air permeability, pore size, SEM and catalytic tests in the reduction of NOx by NH$_3$. The observed effects of CuO/3$AL_2O_3{\cdot}2SiO_2$ impregnated ceramic candle filters in SCR reaction are as follows : (1) when the content of CuO catalyst increased further, activity of NO increased. (2) NO conversion at first increased with temperature and then decreased at high temperatures (above 40$0^{\circ}C$), possibly due to the occurrence of the ammonia oxidation reaction. (3) In pilot plant test for 3 months, NO conversion was greater than 90%.

• 한국분말재료학회지
• /
• 제7권3호
• /
• pp.149-153
• /
• 2000

In this study, the fabrication of $Al_2O_3$/5vol.%Cu nanocomposite and its mechanical property were discussed. The nanocomposite powders were produced by high energy ball milling of $Al_2O_3$ and Cu elemental powders. The ball-milled powders were sintered with Pulse Electric Current Sintering (PECS) facility. The relative densities of specimens sintered at $1200^{\circ}C$ and $1250^{\circ}C$ after soaking process at $900^{\circ}C$ were 96% and over 97%, respectively. The sintered microstructures were composed of $Al_2O_3$ matrix and the nano-sized Cu particles distributed on grain boundaries of $Al_2O_3$ matrix. The nanocomposite exhibited the enhanced fracture toughness compared with general monolithic $Al_2O_3$. The toughness increase was explained by the crack deflection and bridging by dispersed Cu particles.

• 열처리공학회지
• /
• 제14권2호
• /
• pp.96-102
• /
• 2001

$Al_2O_3$-copper alloy has been successfully made by gas atomization, mechanical alloying and hot pressing. In order to investigate microstructure and phase, it has been studied by using scanning electron microscope, transmission electron microscope and X-ray diffractometor. Mechanical properties have been examined using hardness tester and compressive tester according to annealing temperature. Although comparatively large Cu-Al powders are milled, the reaction between Cu-Al and $Cu_2O$ occurs and very fine $Al_2O_3$ particles in the matrix particles (5-10nm) are obtained. Compressive strength of this alloy is more than that of GlidCop Al60.

• Korean Journal of Chemical Engineering
• /
• 제36권2호
• /
• pp.191-196
• /
• 2019

The phase of Cu,Zn,Al precursors strongly affects the activity of their final catalysts. Herein, the Cu,Zn,Al precursor was prepared by precipitation of $Al^{3+}$ onto primitive, amorphous Cu,Zn precipitate. This precursor turned out to be a phase mixture of zincian malachite and hydrotalcite in which the latter phase was less abundant compared to the co-precipitated precursor. The final catalyst derived from this precursor exhibited a little higher copper surface area and methanol synthesis activity than the co-precipitated counterpart. Therefore, the two precursor phases need to be mixed in an adequate proportion for the preparation of active $Cu/ZnO/Al_2O_3$ catalyst.

• Journal of Welding and Joining
• /
• 제10권4호
• /
• pp.213-221
• /
• 1992

Al$_{2}$O$_{3}$ ceramic coating layer by gas flame spraying was very porous, therefore it could not have wear and corrosion resistance at all. To get a dense and strong coating layer, a method to infiltrate an alloy into the pores of $Al_{2}$O$_{3}$ ceramic coating was investigated. Cu-Ti alloys, which had good wettability and reactivity with $Al_{2}$O$_{3}$ ceramic, were examined for infiltration. Infiltration of the alloys was performed in vacuum at 1100.deg.C. The melt of Cu-50 at % Ti alloy was well penetrated through the porous $Al_{2}$O$_{3}$ coating and tightly sealed the pores, unbounded area and microcracks in the coating. The alloy melt in the pores reacted with $Al_{2}$O$_{3}$ ceramic to produce a suboxide phase, Cu$_{2}$Ti$_{4}$O. This composite layer which was composed of $Al_{2}$O$_{3}$ and Cu$_{2}$Ti$_{4}$O phase had good microstructure and wear and corrosion resistance. Additionally, microstructures at interfaces between coating layers were greatly improved owing to the effect of vacuum heat treating.

• Bulletin of the Korean Chemical Society
• /
• 제31권5호
• /
• pp.1241-1246
• /
• 2010

Ternary Cu/ZnO/$Al_2O_3$ catalysts were prepared by a co-precipitation method. The precursor structures were monitored during the aging. The first precipitate structure was amorphous georgeite, which transformed into the unknown crystalline structure. The transition crystalline structure was assigned to the crystalline georgeite, which was suggested with elemental analysis, IR and XRD. The final structure of precursors was malachite. The Cu surface area of the resulting Cu/ZnO/$Al_2O_3$ was maximized to be 30.6 $m^2$/g at the aging time of 36 h. The further aging rapidly decreased Cu surface areas of Cu/ZnO/$Al_2O_3$. ZnO characteristic peaks in oxide samples almost disappeared after 24 h aging, indicating that ZnO was dispersed in around bulk CuO. TOF of the prepared catalysts of the Cu surface area ranges from 13.0 to 30.6 $m^2/g_{cat}$ was to be 2.67 ${\pm}$ 0.27 mmol/$m^2$.h in methanol synthesis at the condition of $250^{\circ}C$, 50 atm and 12,000 mL/$g_{cat}$. h irrespective of the XRD and TPR patterns of CuO and ZnO structure in CuO/ZnO/$Al_2O_3$. The pH of the precipitate solution during the aging time can be maintained at 7 by $CO_2$ bubbling into the precipitate solution. Then, the decrease of Cu surface area by a long aging time can be prevented and minimize the aging time to get the highest Cu surface area.

• 열처리공학회지
• /
• 제22권3호
• /
• pp.149-154
• /
• 2009

Dense $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ composite was consolidated from mechanically synthesized powders by pulsed current activated sintering method within 1 min. $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ powder was synthesized from 3CuO and 2FeAI using the high energy ball milling. Dense $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ with relative density of up to 95% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. Mechanical properties and grain size of the composite were investigated.

• 대한환경공학회지
• /
• 제22권4호
• /
• pp.671-678
• /
• 2000

열중량분석기와 관형 고정층 반응기에서 $CuO/{\gamma}-Al_2O_3$ 흡수제/촉매의 SOx와 NOx 동시제거 반응특성에 대하여 고찰하였다. $CuO/{\gamma}-Al_2O_3$ 흡수제/촉매의 아황산가스 제거능은 반응온도 $450^{\circ}C$와 담지량 6wt% 이상에서 담체인 알루미나의 반응참여에 의하여 급격히 증가하였다. $CuO/{\gamma}-Al_2O_3$ 흡수제/촉매의 탈질 효율은 반응온도, $370^{\circ}C$에서 최대값을 보였으며 그 이상의 온도에서는 $NH_3$가스의 산화반응에 의하여 반응온도가 증가할수록 제거효율은 감소하였다. 흡수제/촉매 표면에 sulfate가 존재하는 경우 최대 탈질 효율을 보이는 반응온도는 증가하였다. SOx와 NOx 동시 제거반응에서 $CuO/{\gamma}-Al_2O_3$ 흡수제/촉매의 NO제거 활성은 $NH_4HSO_4$와 같은 암모늄염의 생성으로 인하여 크게 감소하였다. SOx와 NOx 동시제거 반응에 있어서 최대의 탈질 효율을 보이는 반응온도는 $SO_2$ 가스의 존재로 인하여 $400^{\circ}C$로 증가하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.675-678
• /
• 2004

[ $CuAlO_2$ ] was used as P-type transparent conducting oxide. $CuAlO_2$ ceramics was obtained from heating a stoichiometric mixture of $Cu_2O$ and $Al_2OH_3$ at $1200^{\circ}C$ for 6h. $CuAlO_2$ ceramics were doped by the rate of 0, 5, 7 and 10% of the $BeSO_4{\cdot}4H_2O$. Sintered ceramics were investigated by X-ray diffraction (XRD) and electrical measurements. The room temperature conductivity of the ceramics, which were doped with $BeSO_4{\cdot}4H_2O$ 5wt% was of the order of $3.19\times10^{-3}S\;cm^{-1}$, and the density was $4.98g/cm^3$. Therefor the conductivity and density in $BeSO+4{\cdot}4H_2O$ 5wt% were better than other cases. Additionally, Seebeck cofficient measurements revealed that these ceramics were p-type semiconductors and the ceramic conductivity increased with the growth temperature.

• 한국주조공학회지
• /
• 제17권5호
• /
• pp.480-487
• /
• 1997

Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.