• Journal of Welding and Joining
• /
• v.11 no.1
• /
• pp.62-72
• /
• 1993

Recently there is an increased interest in joining of ceramics to metals and brazing now an accepted method of joining for a wide variety of ceramic to metal combination. The present research work is aimed at establishing the basis of the metal-ceramic joining of $Al_{2}$O$_{3}$ to STS 304 with using Cu-7.5wt% Zr insert metals. Also the microstructures of the brazed joints were observed by using optical microscope and SEM and the reaction products were analyzed by using EDX, WDX and XRD. As a result, the following findings were obtained. The reaction layers of the brazed joints of $Al_{2}$O$_{3}$ to STS 304 are composed of four layers at the bonded interlayer. Double reaction layers are formed at the interface of $Al_{2}$O$_{3}$ insert metal. Layer I was composed of ZrO$_{2}$ particles, Fe-Cr-Ni compounds in Cu matrix, while layer II ZrO$_{2}$ band phase containing Fe-Cr-Ni compounds.

• Journal of Korean Society on Water Environment
• /
• v.28 no.5
• /
• pp.723-728
• /
• 2012

In this study, zeolites were synthesized by a fusion and a hydrothermal methods using a coal fly ash and a waste catalyst. The recovery performance of metal ions on the structure property of synthetic zeolites was evaluated as comparing the adsorption kinetics (Lagergen 2nd order model) and isotherm (Langmuir model) of $Co^{2+},\;Ni^{2+}$, and $Cu^{2+}$ ions. The synthetic zeolites (Z-C1 and Z-W5) were similarly assigned to XRD peaks in a reagent grade Na-A zeolite (Z-WK : $Na_{12}Al_{12}Si_{12}O_{48}\;27.4H_2O$). Adsorption rates of Z-W5 and Z-C1 were in the order of $Cu^{2+}\;>\;Co^{2+}\;>\;Ni^{2+}\;and\;Ni^{2+}\;>\;Cu^{2+}\;>\;Co^{2+}$, respectively. They had influenced upon structure properties of zeolite. Selectivities of metal ions and maximum equilibrium adsorption capacities, $q_{max}$, in Z-C1 and Z-W5 were in the order of $Ni^{2+}$ (127.9 mg/g) > $Cu^{2+}$ (94.7 mg/g) > $Co^{2+}$ (82.6 mg/g) and $Cu^{2+}$ (141.3 mg/g) > $Co^{2+}$ (122.2 mg/g) > $Ni^{2+}$ (87.6 mg/g), respectively. The results show that the synthetic zeolites, Z-C1 and Z-W5, are able to recover metal ions selectively in wastewater.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1652-1654
• /
• 2000

고상반응법을 이용하여 $Ni_{0.6-x}Cu_{x}Zn_{0.4}Fe_{2}O_4$(x=0, 0.1, 0.2, 0.3) ferrite 분말을 제조하고 1200$^{\circ}C$에서 열처리하여 Cu 첨가에 따른 입자변화와 전자파흡수 특성과의 관계를 조사하였다. Ni를 Cu로 0.1 mol 치환했을 때 까지는 포화자화 및 전자파흡수능이 치환하지 않았을 때와 거의 비슷하였으나, 그 이상 첨 가시는 직선적으로 감소하였다.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.1
• /
• pp.64-73
• /
• 2007

The catalytic activity of transition metals (Cu, Co, Mn, Fe and Ni) supported on ${\gamma}-Al_2O_3$ for the oxidation of toluene was investigated in the microreactor of fixed-bed type. The catalytic activity of transition metals for the oxidation of toluene turned out to be increasing in the order of Ni$Cu/{\gamma}-Al_2O_3$ catalysts for the oxidation of toluene increased with the increasing loadings of copper, reached the maximum activity at 5% loadings of copper, and decreased with higher loadings of copper in the catalysts. The activity of $Cu/{\gamma}-Al_2O_3$ catalysts for the oxidation of toluene decreased with the increasing calcination temperatures. This might result from the decreasing surface area of catalysts due to the sintering of copper oxide as well as ${\gamma}-Al_2O_3$ supports. The 5wt% $Cu/{\gamma}-Al_2O_3$ catalysts calcined at $400^{\circ}C$ for 4 hrs in the air showed the highest activity for the oxidation of toluene. Mutual inhibition was observed for the binary mixture of toluene and xylene. The activity of the easy-to-oxidize toluene was greatly decreased while the difficult-to-oxidize xylene was slightly decreased in the binary mixture of toluene and xylene. It might suggest that the inhibition of toluene and xylene in the binary mixture resulted from the competitive adsorption for the adsorbed oxygen on the catalytic surface.

• Journal of the Korean Ceramic Society
• /
• v.39 no.7
• /
• pp.669-674
• /
• 2002

Ni-Zn ferrite was sintered by microwave hybrid sintering method using microwave energy of 2.45 GHz, 700 W in the temperature range of 900$^{\circ}C$ ∼ 1070$^{\circ}C$. A high density (98%TD) Ni-Zn ferrite, added Bi$_2$O$_3$ and CuO, with a single phase was obtained by microwave sintering at 970$^{\circ}C$ for 15 min. All the sintered samples showed sintered density over 90% of TD. These results indicate that the processing time and energy consumption can be reduced significantly by microwave hybrid sintering method.

• Resources Recycling
• /
• v.16 no.6
• /
• pp.3-9
• /
• 2007

Although the ferrous material was separated by the magnetic separation before the incineration process, the municipal solid waste incineration bottom ash generated during incinerator in metropolitan area consists of many iron products which account for about $3{\sim}11%$ as well as ceramics and glasses. The formation of $NiFe_2O_4$ and $FeCr_2O_4$ with a $Fe_3O_4-Fe_2O_3$ (similar to pure Fe) on the surface of iron product was found during air-annealing in the incinerator at $1000^{\circ}C$, because Ni and Cr has a chemical attraction about iron is using to coat with Ni and Cr metals for poish or to prevent corrosion. Therefore, Fe-Ni Cr oxide can be formed on durface of the iron product and it can be separated from bottom ash through the magnetic separation. So, in this study, the separation ratio of heavy metals as magnetic separation and mineralogical formation of Fe-ion(heavy metal) in ferrous metals corroded were investigated. As the result, the separation ratio of Ni and Cr based on particle sizes accounted for about $45{\sim}50%$, and Cu and Pb accounted for below 20%. Also, the leaching concentration of Ni and Cr in bottom ash separated by magnetic separation was lower than that in fresh bottom ash.

• Journal of Korean Society of Water and Wastewater
• /
• v.28 no.2
• /
• pp.207-215
• /
• 2014

Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.

• Journal of Surface Science and Engineering
• /
• v.24 no.2
• /
• pp.103-113
• /
• 1991

Electroless Ni-Cu-P alloy plating of Al base hard disk was performed to investigate some properties according to the change of composition. It was found that the composition of Ni and Cu in deposits changed linearly with increasing the mole ratio of NiSO4.6H2O/CuSO4.5H2O. The increase in hardness by heat - treatment was confirmed to be associated with small size grained crystallization of the amorphous deposits. Acid resistance of all deposits layer. which had been heated up to 30$0^{\circ}C$, was found to be exellent when immersed in 1N-H2SO4 solution, and it showed more superior acid resistance with decreasing Cu content and with increasing P. The resistivity of the deposits heat treated became smaller at temperature more than 50$0^{\circ}C$, and it became largerly with increasing P content. Cu 44.1wt% alloy(C bath) showed the most superior non-magnetically stable characteristics after heat treatment. It was superiorly with higher temperature and with decreasing P content.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.28 no.1
• /
• pp.44-50
• /
• 2018

The improved high-performance Fe-based perovskite-type oxides ($La_{0.7}Sr_{0.3}M_xFe_{1-x}O_3$, M = Cu, Cr, Ni) were synthesized by a citrate method and characterized by SEM, EDS, XRD and NMR spectroscopy analyses. The characterization analyses revealed that the stoichiometric amounts of lattice oxygen were existed in all of perovskite samples except for a nickel-doped perovskite. Fe-based perovskites exhibited a surprising result for ortho-para $H_2$ spin conversion reaction, indicating two orders of magnitude higher conversions and conversion rates than commercial $Fe_2O_3$. It was considered that this conversion difference might be attributed to the presence of oxygen vacancies in Fe-based perovskites prepared in this study.

• Journal of the Korean Institute of Gas
• /
• v.5 no.4 s.16
• /
• pp.33-39
• /
• 2001

This paper was studied on corrosion behavior of absorption refrigeration systems using $LiBr-H_2O$ working fluids. In the various concentration of lithium bromide solution, polarization test of SS 400, Cu(C1220T-OL) and Al-Ni bronze is carried out. And the corrosion behavior of materials forming absorption refrigeration systems is investigated. The main results are as following: 1) As concentration of lithium bromide solution increases, polarization resistance of materials of each kinds is low. And open circuit potential becomes less noble, the corrosion current density is high drained 2) Open circuit potential of SS 400 is less noble than that of Cu and Al-Ni bronze, corrosion current density of SS5 400 is high drained than that of Cu and Al-Ni bronze. 3) Anodic polarization of Cu and Al-Ni bronze in $62\%$ LiBr solution continues the active state. that of Cu and Al-Ni bronze in the natural sea water maintains the active state and the critical current for passivation appears.