• Title/Summary/Keyword: Aluminum compound

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Effect of Interfacial Reaction Layer on Mechanical Properties of 3-plyMg/Al/STS Clad-metal (Mg/Al/STS 3층 클래드재의 기계적 특성에 미치는 계면반응층의 영향)

  • Kim, In-Kyu;Song, Jun-Young;Lee, Young Sun;Hong, Sun Ig
    • Korean Journal of Metals and Materials
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    • v.49 no.8
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    • pp.664-670
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    • 2011
  • 3-ply Mg/Al/STS clad-metal was fabricated by the roll bonding process. An interfacial reaction layer was formed at the Mg/Al interface at and above $300^{\circ}C$ whereas no interfacial reaction layer was observed up to $400^{\circ}C$. The effect of the interfacial reaction layer on the mechanical and fracture properties in clad metals after heat treatments were investigated The chemical compositions were analyzed at the Mg/Al interface by an Energy dispersive X-ray analysis (EDX). A tension test was performed to examine the interfacial cracking properties. The Mg layer fractured first, causing a sudden drop of the stress and Al/STS layer continued to deform until the final fracture. Periodic cracks and crack propagation was observed at the reaction layer between Mg and Al.

Preparation of Hydrazinium 5-aminotetrazolate(HAT) with High Nitrogen Content and Energetic Material (고질소 에너지 물질 Hydrazinium 5-aminotetrazolate (HAT)의 제조)

  • Lee, Woonghee;Kim, Seung Hee
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.5
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    • pp.53-59
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    • 2019
  • Solid fuel reacts with an oxidizer during combustion of a propellant to increase performance. Representative solid fuels are aluminum, cyclotrimethylenetrinitramine (RDX) and octahydro-1, 3,5,7-tetra nitro-1,3,5,7-tetrazocin (HMX). During combustion, these compounds generate white smoke by reacting with moisture and produce materials that are harmful to the environment, such as carbon monoxide, carbon dioxide, and methane gas. This study prepared a high-nitrogen-containing energetic material, hydrazinium 5-aminotetrazolate (HAT), which could be applied as a solid fuel. The compound was characterized by nuclear magnetic resonance (NMR) spectroscopy, and a thermal analysis was measured by differential scanning calorimetry (DSC). Also, the specific impulses and volumes of detonation gases were calculated using the EXPLO5 program.

Interfacial Reaction on Heat Treatment of Roll-bonded STS304/Al1050/STS439 Clad Materials and its Effect on the Mechanical Properties (압연 제조된 STS439/Al1050/ STS304 Clad소재의 열처리에 따른 계면 반응과 기계적 특성에서의 계면 반응 효과)

  • Song, Jun-Young;Kim, In-Kyu;Lee, Young-Seon;Hong, Sun Ig
    • Korean Journal of Metals and Materials
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    • v.49 no.11
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    • pp.910-915
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    • 2011
  • The microstructures and mechanical properties of roll-bonded STS439/Al1050/STS304 clad materials were investigated after an annealing process at various temperatures. Interfacial layer was developed at the STS439/Al1050 and Al1050/STS304 interfaces at $550^{\circ}C$. STS439/Al1050/STS304 clad metals fractured suddenly in a single step and the fracture decreased with increasing annealing temperatures at $450^{\circ}C$. After annealing at $550^{\circ}C$, samples fractured in three steps with each layer fracturing independently. Interfacial layers formed at $550^{\circ}C$ with a high Vickers microhardness were found to be brittle. During tensile testing, periodic parallel cracks were observed at the interfacial reaction layer. Observed micro-void between Al1050 and the interfacial layer was found to weaken the Al1050/reaction layer interface, leading to the total separation between Al1050 and the reaction layer.

Preparation of (n-BuCp)2ZrCl2 Catalyst Supported on SiO2/MgCl2 Binary Support and its Ethylene-1-hexene Copolymerization (SiO2/MgCl2 이원 담체에 담지된 (n-BuCp)2ZrCl2 합성과 에틸렌-1-헥센 공중합)

  • Carino, Ann Charise;Park, Sang Jun;Ko, Young Soo
    • Applied Chemistry for Engineering
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    • v.29 no.4
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    • pp.461-467
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    • 2018
  • In this study, $(n-BuCp)_2ZrCl_2$, was supported on $SiO_2/MgCl_2$ binary support. Before supporting the catalyst, the $SiO_2/MgCl_2$ binary support was surface treated with three different alkyl aluminum compound, namely trimethylaluminum, triethylaluminum, and ethylaluminum sesquichloride. The synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts were used for the copolymerization of ethylene and 1-hexene. Their catalytic properties and performances were analyzed through BET, XPS analysis, ICP-AES analysis, and FE-SEM. While the resulting copolymers were analyzed through DSC analysis, GPC analysis, 13C-NMR analysis, and FE-SEM. The analysis of synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts showed that the Zr content of these catalysts is relatively lower compared to that of the catalyst supported on $SiO_2$. This could be attributed to the reduction in the surface area of $SiO_2$ due to the presence of recrystallized $MgCl_2$ and alkyl aluminum. Furthermore, they exhibited a better copolymerization activity compared to that of $SiO_2$ supported catalyst, particularly the EASC-surface treated binary support, which has the highest activity of 1.9 kg PE/($mmol-Zr^*hr$) because EASC acts as a strong Lewis acid. It could also be observed that the larger the ligand of alkyl aluminum used, the rougher the particle surface of the resulting polymer.

A Study on the Flame Retardance and Electrical Properties of Silicone Composites (실리콘 복합체의 내화 및 전기 특성에 관한 연구)

  • Lee, Sung-Ill;Lee, Hae-Joon
    • Elastomers and Composites
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    • v.38 no.3
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    • pp.227-234
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    • 2003
  • Silicone composites for high voltage insulator (HVI SC) were prepared by adding aluminum trihydrate(ATH) treated by surface treatment agent to base silicone compound at the ratio oi 100:20, 100:40, 100:60, 100:80, and 100:100, respectively And also, ATH was treated by various surface treatment agents, such as stearic arid, acryl silane, and vinyl silane under compounding process. Mechanical properties and electrical properties were investigated for the various contents of ATH and surface-treatment agents. Mechanical properties such as tensile strength, elongation, and tear strength decreased as the load of ATH increased. Volume resistivity, AC break down strength, and tracking resistance for HVI SC containing ATH treated by vinyl silane were better than those for HVI SC containing ATH treated by other surface treatment agents, such as stearic acid and acryl silane. Polymer-filler interaction of silicone composites according to surface treatment agents was studied by measuring bound rubber contend(BR). From the experimental results, BR of silicone composite containing ATH treated with vinyl silane was higher than that of the others. The degree of rule for silicone composite was investigated using Rheometer. Maximum torque of silicone composites contaning ATH treated with vinyl silane was higher than that of silicone composite contaning ATH treated with other surface agents.

Comparison of sample storage containers for the analysis of volatile organic compounds (VOC) (휘발성유기물(VOC) 분석을 위한 시료보관 용기의 비교)

  • Kim, Seokyung;Kim, Dalho
    • Analytical Science and Technology
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    • v.35 no.3
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    • pp.116-123
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    • 2022
  • Polymer bags, metallic canisters, and glass bottles have been used as containers for analyzing the volatile organic compounds (VOCs) in air. In this study, various sampling containers were compared to investigate the short-term stability of VOCs, that is, from the time they are sampled to the time they are analyzed. Polyvinyl fluoride (PVF), polypropylene (PP), polyester aluminum (PE-Al) bags, canisters, and glass bottles were used as sample containers. A 100 nmol/mol standard gas mixture of benzene, toluene, ethylbenzene, m-xylene, styrene, and o-xylene was used for the VOC comparison. Changes in the concentrations of samples stored for 10~20 day in each container were measured using a thermal desorption-gas chromatograph-flame ionization detector (TD-GC-FID). As a result, VOCs stored in a canister and two kinds of amber glass bottles have shown immaterial decreases in concentration in one week, and more than 80 % of the initial concentration was maintained for two weeks. In the case of polymer bags, the concentration of all VOCs, except benzene and toluene, were remarkably decreased below 70% of the initial concentration in one day. Particularly, ethylbenzene, xylene, and styrene have shown dramatic decreases in concentration below 30 % of the initial concentration in all polymer bags in one day.

Insights Into Emissions and Exposures From Use of Industrial-Scale Additive Manufacturing Machines

  • Stefaniak, A.B.;Johnson, A.R.;du Preez, S.;Hammond, D.R.;Wells, J.R.;Ham, J.E.;LeBouf, R.F.;Martin, S.B. Jr.;Duling, M.G.;Bowers, L.N.;Knepp, A.K.;de Beer, D.J.;du Plessis, J.L.
    • Safety and Health at Work
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    • v.10 no.2
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    • pp.229-236
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    • 2019
  • Background: Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators. Methods: Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes. Results: Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from $4.1{\times}10^{10}$ (Ultem filament) to $2.2{\times}10^{11}$ [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (${\mu}g/min$) ranged from $1.9{\times}10^4$ (acrylonitrile butadiene styrene and polycarbonate) to $9.4{\times}10^4$ (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open ($2.3{\times}10^{10}number/min$) than when the lid was closed ($1.5-5.5{\times}10^9number/min$); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels. Conclusion: Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial-scale AM process emissions and exposures.

Nondestructive Determination of Reinforcement Volume Fractions in Particulate Composites : Eddy Current Method (비파괴적 방법에 의한 입자 강화 복합재료의 부피분율 평가: 와전류법)

  • Jeong, Hyun-Jo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.18 no.2
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    • pp.112-120
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    • 1998
  • A nondestructive evaluation technique was developed for the quantitative determination of the reinforcement volume fractions in particulate reinforced metal matrix composites. The proposed technique employed a composite micromechanics which accounts for the microstructure of the composite medium together with the measurement of anisotropic electrical conductivity. When the measured conductivity was coupled with the theoretically predicted conductivity, the unknown reinforcement volume fraction was calculated. An analytical model based on the Mori-Tanaka method was described which relates the NDE signatures to the composite microstructure. The volume fractions were calculated using eddy current measurements made on a wide range of silicon carbide particulate ($SiC_p$) reinforced aluminum (Al) matrix composites. The calculated $SiC_p$ volume fractions were in good agreement with the measured volume fractions in the range of 0-30%. The technique was also found to be effective in estimating the total volume percentage of reinforcement and intermetallic compound formed during the processing stage.

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The analytical study on synthesis and purification of high purity ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (이온성 액체 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4)의 합성과 정제에 관한 분석 연구)

  • Yang, Kyung-Chul;Lee, Young-Hwan
    • Analytical Science and Technology
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    • v.24 no.6
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    • pp.477-483
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    • 2011
  • This work is on the synthesis of EMI-$BF_4$ (1-ethyl-3-methylimidazolium tetrafluoroborate) and purification of spectroscopic grade using aluminium oxide method, activated charcoal method, and liquid/liquid fractional extraction method in order to make supercapacitor finally. But the aluminum oxide method and the activated charcoal method were not suitable for obtaining high-purity ionic liquids. The liquid/liquid fractional distillation method turned out that as the concentration of solvent ($H_2O$) was increased, the higher purity of EMI-$BF_4$ was obtained and the electrical capacity of this compound was increased to higher value. When the solvent was changed to from methylene chloride to 1,2-dichloroethane, the higher purity of EMI-$BF_4$ was obtained.

Comparison of Two Experimental Approaches to Test Temporal Storability of Reduced Sulfur Compounds in Whole Sampling Method (환원황화합물에 대한 용기채취법의 비교 연구)

  • Jo, Sang-Hee;Kim, Ki-Hyun
    • Journal of Korean Society for Atmospheric Environment
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    • v.28 no.3
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    • pp.306-315
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    • 2012
  • In this study, storage stability of reduced sulfur compounds ($H_2S$, $CH_3SH$, DMS, $CS_2$, and DMDS) and $SO_2$ in sampling bags was investigated in terms of two contrasting storage approaches between forward (F) and reverse (R) direction. The samples for the F method were prepared at the same time and analyzed sequentially through time. In contrast, those of reverse (R) method were prepared sequentially in advance and analyzed all at once upon the preparation of the last sample. In addition, relative performance between two different bag materials (PVF and PEA) was also assessed by using 100 ppb standard. The response factors (RF) of gaseous RSC samples were determined by gas chromatography/pulsed flame photometric detector (GC/PFPD) combined with air server (AS)/thermal desorber (TD) system at storage intervals of 0, 1, and 3 days. There is no statistical difference in all RSCs between two storage methods. However, the results of relative recovery indicated 2.58~12.8% differences in compound type between the two storage methods. Moreover, loss rates and storage stability of $H_2S$ and $SO_2$ were considerably affected by bag materials than any other variables. Therefore, some considerations about storage methods (or bag material types) for sulfur compounds are needed if stored by sampling bag method.