• Title, Summary, Keyword: Hexamethylenetetramine

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The Synthesis of Fine ZnO powder by the wet Batch process. (습식 Batch Process에 의한 ZnO미분말 합성)

  • 이일수;조성백;신건철
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.1 no.1
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    • pp.59-70
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    • 1991
  • ZnO fine powder was prepared by the batch precipitation process using $ZnCl_2$ and hexamethylenetetramine solution as a mother solution. When the concentrations of $ZnCl_2$solution were $0.1mol/\ell$ and 0.05mol/-, the particles of rod shape were obtained when the conentration of $ZnCl_2$solution was $0.01mol/\ell$, the particle of plate shape was obtained. When the hexamethylenetetramine as a precipitants was used, pH was raised slow during a few minute be-cause of slow hydrolysis rate of hexamethylenetetramine. For rapid raising of pH during initial reac-tion time, $NH_4$OH was added as nucleant. When $NH_4$OH as a nucleant was added, obtained particle was shape of granular and the mean particle size was $0.41\mu\textrm{m}$. After calcination at $500^{\circ}C$ during 1hour, all of remained organic phase was removed but the shape of particles was not changed. But pa-rticles were slightly shrunk in comparision with before calcined particles.

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Friction and Wear Characteristics of Friction Material with the Content of Hexamethylenetetramine (Hexamethylenetetramine의 함량에 따른 마찰재의 마찰.마모 특성)

  • Kim, Dae-Kyeun;Jang, Ho;Yoon, Ho-Gyu
    • Tribology and Lubricants
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    • v.16 no.4
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    • pp.266-273
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    • 2000
  • The friction characteristics of phenolic resin and model friction materials were investigated with the content of hexamethylenetetamine (HEXA). At 10 wt.% of HEXA, the phenolic resin and model friction materials showed the most stable friction coeffcient in constant temperature test at various test conditions because of its good thermal stability and proper curing reaction. It was found from constant interval test in mild condition that the friction coeffcients of friction materials cured with 10 wt.% of HEXA was the highest and stable values in the whole range of braking operations. However, at the severe condition in constant interval test, the friction coefficient of friction materials cured with 10 wt.% to of HEXA was lowered and as the number of braking operation increased, the values became stable. In order to obtain the thormal stable friction materials, the content of HEXA from 5 to 10 wt.% could be recommended.

Effects of Boron Concentration in ZnO:Al Seed Films on the Growth and Properties of ZnO Nanorods (ZnO:Al 시드 막의 보론 농도가 ZnO 나노로드의 성장 및 특성에 미치는 영향)

  • Ma, Tae-Young;Park, Ki-Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.10
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    • pp.1488-1493
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    • 2017
  • Boron-doped ZnO:Al films were deposited by rf magnetron sputtering. The structural and optical property variations of the films with the boron amounts were studied. ZnO nanorods were grown on $SiO_2/Si$ wafers and glass by a hydrothermal method. ~50 nm-thick boron-doped ZnO:Al films were deposited on the substrates as seed layers. The mixed solution of zinc nitrate hexahydrate and hexamethylenetetramine in DI water was used as a precursor for ZnO nanorods. The concentration of zinc nitrate hexahydrate and that of hexamethylenetetramine were 0.05 mol, respectively. ZnO nanorods were grown at $90^{\circ}C$ for 2 hours. X-ray diffraction was conducted to observe the crystallinity of ZnO nanorods. A field emission scanning electron microscope was employed to study the morphology of nanorods. Optical transmittance was measured by a UV-Vis spectrophotometer, and photoluminescence was carried out with 266 nm light. The ZnO nanorods grown on the 0.5 wt% boron-doped ZnO seed layer showed the best crystallinity.

PHOTOCHEMICAL TRANSFORMATION OF CARBON MONOXIDE IN AQUEOUS AMMONIA

  • Kim, Hee-Jeong;Park, Hyoung-Ryun
    • Journal of Photoscience
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    • v.6 no.4
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    • pp.177-181
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    • 1999
  • The photochemical transformation of carbon monoxide in aqueous ammonia solution has been investigated at 25${\pm}$0.1$^{\circ}C$ using 184.9 nm UV light. Amination and carbonylation processes were carried out by irradiating the aqueous ammonia solution saturated with carbon monoxide, and the formation of formamide, urea, hexamethylenetetramine, formaldehyde, glyoxal and hydrazine was observed. The formation of hydrazine was affected by the presence of ammonia, and the formation of carbonyl compounds such as formaldehyde and glyoxal was influenced by the presence of carbon monoxide. The formation of formamide, urea and hexamethylenetetramine was affected by both ammonia and carbon monoxide. The initial quantum yields of the products were determined and probable mechanisms for the photochemical reaction were presented on the basis of product analysis.

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Synthesis of plate powder coated nano sized ZnO by hydrothermal precipitation method

  • Lee, Dong-Kyu;Lee, Jin-Hwa
    • Journal of the Korean Applied Science and Technology
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    • v.24 no.4
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    • pp.369-376
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    • 2007
  • 우리는 마이카, boron nitride, bismuthoxychloride와 같은 판상 분체에 ZnO 나노입자를 코팅한 고 기능성 무기 분체를 합성하였다. 본 실험에서 우리는 수열침전법을 이용하여 합성 분체를 합성하였다. 출발물질은 $ZnCl_2$를 사용하였고 침전제로는 hexamethylenetetramine(HMT)와 urea를 사용하였다. 본 실험의 반응변수로는 출발물질의 농도, 침전제 및 반응온도를 변화시켜 실험하였다. 합성물의 형태, 결정성 및 UV-차단능은FE-SEM, XRD, FT-IR, TGA-DTA, in vitro SPF 테스트를 활용해 분석하였다. 본 실험의 결과, 나토입자 크기를 갖는 ZnO는 동일한 최적의 합성조건하에서 다양한 판상 분체의 종류에 관계없이 균일하게 코팅되었다.

Effects of Precursor Concentration on the Growth of ZnO Nanorods (ZnO 나노로드 성장에 미치는 전구체 농도의 영향)

  • Ma, Tae-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.11
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    • pp.1835-1839
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    • 2016
  • In this study, ZnO nanorods were grown by a hydrothermal method. $SiO_2/Si$ wafers and glass were used as substrates. ~20 nm-thick ZnO thin films were rf magnetron sputtered for seed layers. The precursor was prepared by mixing zinc nitrate hexahydrate and hexamethylenetetramine (hexamine) in DI water. The concentration of zinc nitrate hexahydrate was fixed at 0.05 mol, and that of hexamine was varied between 0 mol to 0.1 mol. The reactor containing substrates and precursor was put in an oven maintained at $90^{\circ}C$ for 1 h. X-ray diffraction was carried out to analyze the crystallinity of ZnO nanorods, and a field emission scanning electron microscope was employed to observe the morphology of nanorods. Transmittance and absorbance were measured by a UV-Vis spectrophotometer. Photoluminescence measurements were conducted using 266 nm light.

The Effects of Hexamethylenetetramine Concentration on the Structural and Electrochemical Performances of Ni(OH)2 Powder for Pseudocapacitor Applications (헥사메틸렌테트라민 농도에 따른 수산화니켈 입자의 특성 분석 및 의사커패시터 응용)

  • Kim, Dong Yeon;Jeong, Young-Min;Baek, Seong-Ho;Son, Injoon
    • Journal of Korean Powder Metallurgy Institute
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    • v.26 no.3
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    • pp.231-236
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    • 2019
  • Ni hydroxides ($Ni(OH)_2$) are synthesized on Ni foam by varying the hexamethylenetetramine (HMT) concentration using an electrodeposition process for pseudocapacitor (PC) applications. In addition, the effects of HMT concentration on the $Ni(OH)_2$ structure and the electrochemical properties of the PCs are investigated. HMT is the source of amine-based $OH^-$ in the solution; thus, the growth rate and morphological structure of $Ni(OH)_2$ are influenced by HMT concentration. When $Ni(OH)_2$ is electrodeposited at a constant voltage mode of -0.85 V vs. Ag/AgCl, the cathodic current and the number of nucleations are significantly reduced with increasing concentration of HMT from 0 to 10 mM. Therefore, $Ni(OH)_2$ is sparsely formed on the Ni foam with increasing HMT concentration, showing a layered double-hydroxide structure. However, loosely packed $Ni(OH)_2$ grains that are spread on Ni foam maintain a much greater surface area for reaction and result in the effective utilization of the electrode material due to the steric hindrance effect. It is suggested that the $Ni(OH)_2$ electrodes with HMT concentration of 7.5 mM have the maximum specific capacitance (1023 F/g), which is attributed to the facile electrolyte penetration and fast proton exchange via optimized surface areas.

Adhesion Study of SBR-Nylon by Direct Blending Technique (직접블렌딩 방법을 이용한 SBR-나일론 접착 연구)

  • Chung, Kyung Ho;Kang, Do Kyun;Yoon, Tae Ho;Kang, Shin Young
    • Journal of Adhesion and Interface
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    • v.1 no.1
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    • pp.30-37
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    • 2000
  • This study focused on the direct blending of bonding agents (resorcinol, hexamethylenetetramine, NaOH) into rubber compound to simplify the composite manufacturing process. The mechanism of direct blending system was studied by comparing the following two cases. The one is direct blending of bonding agents into rubber compound and then allows the reaction (Case I). The other is mixing of reactant obtained by reaction of bonding agents (Case II). According to the morphology analysis, the Case II showed the clean interfacial area between bonding agents and matrix rubber, while the Case I created the new interphase under proper processing condition. Also, the optimum adhesion strength between SBR and nylon cord could be obtained with bonding agents whose molar ratios of resprcinol/hexamethylenetetramine was 1.2/1 in the recipes.

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Annealing Effects of Seed Layers on the Properties of ZnO Nanorods (ZnO 나노로드 특성에 미치는 시드 막 열처리 영향)

  • Ma, Tae-Young;Park, Ki-Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.6
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    • pp.753-758
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    • 2018
  • We investigated annealing effects of seed layers on the properties of ZnO nanorods grown on the seed layers. ZnO nanorods were grown by a hydrothermal method. ~100 nm-thick ZnO films were sputtered on oxidized Si wafers and quartz as seed layers. The ZnO films were annealed at $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$, respectively. ZnO nanorods were grown at $90^{\circ}C$ for 3 hours in the mixed solution of zinc nitrate hexahydrate and hexamethylenetetramine. X-ray diffraction was carried out to estimate the crystallinity and strain of ZnO films and nanorods. A field emission scanning electron microscope was employed to observe the morphology of the films and nanorods. PL(photoluminescence) measurements were conducted with 266 nm light. It was found that the annealing of seed layers increase the growth rate of nanorods, and change compressive strain of nanorods to tensile strain. The intensity of PL in the UV region reduced by using the annealed seed layers.