• 센서학회지
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• 제28권1호
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• pp.41-46
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• 2019

In order to develop novel thermal imaging materials for microbolometer applications, $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ ($0.18{\leq}x{\leq}0.26$) thin films were fabricated using metal-organic decomposition. Effects of Cu content on the electrical properties of the annealed films were investigated. Spinel thin films with a thickness of approximately 100 nm were obtained from the $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ films annealed at $380^{\circ}C$ for five hours. The resistivity (${\rho}$) of the annealed films was analyzed with respect to the small polaron hopping model. Based on the $Mn^{3+}/Mn^{4+}$ ratio values obtained through x-ray photoelectron spectroscopy analysis, the hopping mechanism between $Mn^{3+}$ and $Mn^{4+}$ cations discussed in the proposed study. The effects of $Cu^+$ and $Cu^{2+}$ cations on the hopping mechanism is also discussed. Obtained results indicate that $[(Ni_{0.3}Mn_{0.7})_{1-x}Cu_x]_3O_4$ thin films with low temperature annealing and superior electrical properties (${\rho}{\leq}54.83{\Omega}{\cdot}cm$, temperature coefficient of resistance > -2.62%/K) can be effectively employed in applications involving complementary metal-oxide semiconductor (CMOS) integrated microbolometer devices.

• 한국세라믹학회지
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• 제52권4호
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• pp.264-268
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• 2015

Cu films were plated in an eco-friendly electroless bath (No-Formaldehyde) on Ni/screen printed Ag pattern/PET substrate. For electroless Cu plating, we used sodium-phosphinate ($NaH_2PO_2{\cdot}H_2O$) as reducing agent instead of Formaldehyde. All processes were carried out in electroless solution of pH 7 to minimize damage to the PET substrate. According to the increase of sodium-phosphinate, the deposition rate, the granule size, and rms roughness of the electroless Cu film increased and the Ni content also increased. The electroless Cu films plated using 0.280 M and 0.575 M solutions of sodium-phosphinate were made with Cu of 94 at.% and 82 at.%, respectively, with Ni and a small amount P. All electroless Cu plated films had typical FCC crystal structures, although the amount of co-deposited Ni changed according to the variation of the sodium-phosphinate contents. From these results, we concluded that a formation of higher purity Cu film without surface damage to the PET is possible by use of sodium-phosphinate at pH 7.

• 한국재료학회지
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• 제14권7호
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• pp.462-469
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• 2004

The effect of Cu addition on the corrosion characteristics of Zr alloys that developed for nuclear fuel cladding in KAERI (Korea Atomic Energy Research Institute) was evaluated. The alloys having different element of Nb, Sn, Fe, Cr and Cu were manufactured and the corrosion tests of the alloys were performed in static autoclave at $360^{\circ}C$, distilled water condition. The alloys were also examined for their microstructures using the optical microscope and the TEM equipped with EDS and the oxide property was characterized by using X-ray diffraction. From the result of corrosion test more than 450 days, the corrosion rate of the Zr-based alloys was changed with alloying element such as Nb, Sn, Fe, Cr and especially affected by Cu addition. The corrosion resistance was increased with increasing the Cu content and the tetragonal $ZrO_2$ layer was more stabilized on the Cu-containing alloys.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.464-465
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• 2006

Monodispersed and nano-sized Cu powders were synthesized from copper sulfate pentahydrate $(CuSO_4{\cdot}5H_2O)$ inside a nonionic polymer matrix by using wet chemical reduction process. The sucrose was used as a nonionic polymer network source. The influences of a nonionic polymer matrix on the particle size of the prepared Cu powders were characterized by means of X-ray diffraction), scanning electron microscopy), and particle size analysis). The smallen Cu powders with size of approximately 100 nm was obtained with adding of 0.04M sucrose at reaction temperature of $60\;^{\circ}C$. The particle size of the Cu powders prepared by the reduction inside polymer network was strongly dependent of the sucrose content and reaction temperature.

• 한국농공학회지
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• 제30권2호
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• pp.55-66
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• 1988

This study was conducted to investigate the various engineering properties and correlationshops among the soil constants of alluvial clayey deposits distributed in the bay of Asan and their results are summarized as follows : 1. Grain size distribution of soil was consisted of 12 % of clay, 46-73 % of silt, 2-23 % of sand, and as for the consistency characteristics, 26-36 % of liquid limit, 18-21 % of plastic limit and 6-16 % of plastic index, and so the soil belonging to as a lower plastic nonorganic clay, it's specific gravity was 2,66-2.70, and the location on the plastic chart was approximately above the A-line. Z The natural moisture content and unit weight were 30-43 % and 1.76-1.87 g I cm$_3$, respectively, and according to increment of natural moisture content, the unit weight was decreased, and the initial void ratio and degree of saturation were shown of 0,87-1119 and 92- 100 %, most of saturated. 3. Cone resistance value which was shown 2.4 - 6.5 kg / $cm^2$ was a little lower and it was increased with the depth of layer and shown the formular $q_c=0.7_z+1.32$. 4. Unconfined compression strength was about 0.18-0.43kg /$cm^2$, cu, 0.1-0.22kg / $\psi$, $2-6^{\circ}$ under uu-test condition of triaxial, and CCU, 0.08-0.3 kg/cm , $\psi$, $12-18^{\circ}$ under the condition of cu-test. 5. Pre-consolidation load of characteristics of consolidation was 0.4-0.8 kg / $cm^2$, compression index, about 0.17-0.33. 6. Liquid limit and plastic index were incresased with the increment of clay content but most of alluvial clay was appeared as a normal through non-activity clay soil shown more natural moisture content than liquid limit, and their relationship as follows : LL=0.38( cy+54.8), PI=0.836(LL -17.8), PI =0.468(LL -0.48) 7. The initial void ratio presented correlationship of positive among clay content, natural moisture content and liquid limit, and that of reverse with unit weight, and their results as follws : $e_o=0.024(w_n+0.2)$, $e_o=e_o=0.0003c_y+0.0005 LL+0.0151 W_n+\frac{3.58}{r-t}-1.52$ 8. It was shown that the compression index has correlationship of postive among the clay content, liquid limit, plastic index, natural moisture content and initial void ratio, and their relationships as follows ; $c_c=0.44(e_o-0.47)$, $c_c=0.001$

• 자원리싸이클링
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• 제16권2호
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• pp.32-39
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• 2007

폐자동차 ASR의 소각재를 대상으로 물리화학적 물성측정 및 리싸이클링을 위한 경량재료 제조실험을 수행하였다. 대상시료는 국내 ASR 소각장에서 채취한 바닥재 2종류와 비산재 4종류이었으며, 이들의 주요 성분 및 입도분석을 실시하고 공정시험법에 의한 중금속 용출량을 조사하였다. 또한, 비산재인 boiler ash를 원료로 하여 경량물질과 무기바인더를 첨가하여 성형 및 소성하는 방법으로 경량재료를 제조하였다. 바닥재에 Cu 함량이 3wt% 내외로 상당히 높은 것으로 나타나 Cu의 사전 분리가 필수적인 것으로 나타났다. 수용성물질을 많이 함유한 SDR(semi-dry reactor) ash와 Bag filter ash의 주성분은 각각 $CaCl_2{\cdot}Ca(OH)_2{\cdot}H_2O$ 및 $CaCl_2{\cdot}4H_2O$인 것으로 나타났다. boiler ash를 원료로 사용하여 제조한 경량재료 시편의 경우 중금속 용출이 크게 감소하였으며, 그 이유는 중금속 성분이 불용성 화합물천 안정화 또는 encapsulation 되었기 때문으로 판단되었다.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.147-150
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• 2020

Relatively pure YBCO was first synthesized by heating a mixture of metal carbonates at temperatures between 1,000 and 1,300 K, resulting in the reaction: 4BaCO₃+Y₂(CO₃)₃+6CuCO₃+(1/2_-x)O₂ → 2YBa₂Cu₃O_7-x+1/3CO₂. Modern syntheses of YBCO use the corresponding oxides and nitrates. The superconducting properties of YBa₂Cu₃O_7-x are sensitive to the value of x, i.e., its oxygen content. Only those materials with 0≤x≤0.65 are superconducting below Tc, and when x ~ 0.07, the material superconducts at the highest temperature, i.e., 95 K, or in the highest magnetic fields, i.e., 120 T and 250 T when B is perpendicular and parallel to the CuO₂ planes, respectively. In addition to being sensitive to the stoichiometry of oxygen, the properties of YBCO are influenced by the crystallization methods applied. YBCO is a crystalline material, and the best superconductive properties are obtained when crystal grain boundaries are aligned by careful control of annealing and quenching temperature rates. However, these alternative methods still require careful sintering to produce a quality product. New possibilities have arisen since the discovery of trifluoroacetic acid, a source of fluorine that prevents the formation of undesired barium carbonate (BaCO₃). This route lowers the temperature necessary to obtain the correct phase at around 700℃. This, together with the lack of dependence on vacuum, makes this method a very promising way to achieve a scalable YBCO bulk.

• 대한화학회지
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• 제32권6호
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• pp.543-548
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• 1988

1∼5wt%의 구리가 얹혀진 ${\gamma}$-알루미나 또는 티타니아에서 금속-지지체 상호작용을 승온환원과 상자성 공명으로 연구하였다. $500^{\circ}C에서 시료를 산소로 처리했을 때 티타니아계에서는 구리 함량이 증가함에 따라 고온쪽으로 승온환원 피이크가 증가했으나 알루미나 계에서는 저온쪽의 승온 환원 피이크가 커졌다. $300^{\circ}C 처리 경우에는 알루미나계에서는 $300^{\circ}C에서 티타니아계는 120 과 $300^{\circ}C에서 각각 환원피이크를 보여주었다. ${\gamma}$-알루미나에서는 $Cu^{2+}$의 전형적인 상자성 신호가 나타났으나 티타니아에서는 넓고 작은 신호만 관찰되었다. 이들 결과들로부터 금속-지지체 상호작용은 실리카 < 티타니아 < ${\gamma}$-알루미나의 순으로 커지며 산화구리는 지지체에 따라 서로 다른 담지특성을 가짐을 알 수 있었다.

• Corrosion Science and Technology
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• 제12권5호
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• pp.253-258
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• 2013

Effects of copper hydroxide(II) on the curing and the corrosion resistance of electrocoating were investigated by MEK rubbing test, electrochemical impedance spectroscopy (EIS) and Thermo-gravimetric analysis (TGA). Curing performance of electrocoating was lowered with increasing the content of copper hydroxide(II) as evidenced by the MEK rub performance which decreased with increasing the content of copper hydroxide(II). This indicates copper hydroxide(II) affected the blocked isocyanate reaction in the coatings, by the decomposition of copper hydroxide(II) to CuO and $H_2O$ during reaction of isocyanate with nuclephiles. Corrosion resistance of coatings also decreased with the content of copper hydroxide. This reflects the higher barrier property in coatings with higher curing performance.

• 보존과학연구
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• 통권29호
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• pp.221-238
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• 2008

Roofing tiles are very important archaeological artifacts which show science, architecture of that time, as well as information about the culture. It has been studied by many researchers steadily, but only focusing on archaeological, art historical and architectural study, so it is very difficult to find natural science research. Gyeongbokgung's roofing tiles were excavated from the ruins of same site, however glaze, body colour and shape of tiles are very diverse with the naked eye. Through natural science research which analyze the chemical composition and physical characteristics of roofing tiles's body and glaze examine the physical and chemical characteristics of each roofing tiles. the result of analazed roofing tiles is following. when roofing tiles were classified by 전암대자율 and chromaticity, each group has part of some matches. When you compare with green gazed traditional brick's glaze of Silla period, Gyeongbokgung roofing tiles have more $Al_2O_3$ and less PbO than Silla period's. We can see the technology of increasing firing temperature is better. and glaze colour depends on content of $Fe_2O_3$ and CuO. A lot of CuO tend to be more blue.