• Title/Summary/Keyword: Ni-Cr-Al

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Effects of Alloying Elements on Corrosion Resistance of Low Alloyed Steels in a Seawater Ballast Tank Environment (Seawater ballast tank 환경에서 저합금강의 내식성에 미치는 합금원소의 영향)

  • Kim, Dong Woo;Kim, Heesan
    • Korean Journal of Metals and Materials
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    • v.48 no.6
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    • pp.523-532
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    • 2010
  • Co-application of organic coating and cathodic protection has not provided enough durability to low-alloyed steels inseawater ballast tank (SBT) environments. An attempt has made to study the effect of alloy elements (Al, Cr, Cu, Mo, Ni, Si, W) on general and localized corrosion resistance of steels as basic research to develop new low-allowed steels resistive to corrosion in SBT environments. For this study, we measured the corrosion rate by the weigh loss method after periodic immersion in synthetic seawater at $60^{\circ}C$, evaluated the localized corrosion resistance by an immersion test in concentrated chloride solution with the critical pH depending on the alloy element (Fe, Cr, Al, Ni), determined the permeability of chloride ion across the rust layer by measuring the membrane potential, and finally, we analyzed the rust layer by EPMA mapping and compared the result with the E-pH diagram calculated in the study. The immersion test of up to 55 days in the synthetic seawater showed that chromium, aluminium, and nickel are beneficial but the other elements are detrimental to corrosion resistance. Among the beneficial elements, chromium and aluminium effectively decreased the corrosion rate of the steels during the initial immersion, while nickel effectively decreased the corrosion rate in a longer than 30-day immersion. The low corrosion rate of Cr- or Al-alloyed steel in the initial period was due to the formation of $Cr_2FeO_4$ or $Al_2FeO_4$, respectively -the predicted oxide in the E-pH diagram- which is known as a more protective oxide than $Fe_3O_4$. The increased corrosion rate of Cr-alloyed steels with alonger than 30-day exposure was due to low localized corrosion resistance, which is explained bythe effect of the alloying element on a critical pH. In the meantime, the low corrosion rate of Ni-alloyed steel with a longer than 30-day exposure wasdue to an Ni enriched layer containing $Fe_2NiO_4$, the predicted oxide in the E-pH diagram. Finally, the measurement of the membrane potential depending on the alloying element showed that a lower permeability of chloride ion does not always result in higher corrosion resistance in seawater.

Effect of RF Sputtering Conditions on Properties of Thin Film Resistor for Microwave Device (초고주파용 박막저항의 특성에 미치는 RF 스파터링 조건의 영향)

  • Ryu, Sung-Rok;Koo, Bon-Keup;Kang, Beong-Don;Ryu, Jei-Chun;Kim, Dong-Jin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.913-917
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    • 2003
  • In the electronic components and devices fabrication, thin film resistors with low TCR(temperature coefficient of resistance) and high precision have been used over 3 GHz microwave in recent years. Ni-Cr alloys thin films resistors is one of the most commonly used resistive materials because it has low TCR and highly stable resistance. In this work, we fabricated thin film resistors using Evanohm alloys target(72Ni-20Cr-3Al-4Mn-Si) of s-type with excellent resistors properties by RF-sputtering. Also we reported best deposited conditions of thin film resistors for microwave to observe microstructure and electronic properties of thin film according to deposited conditions(between target and substrate, power supply)

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Underlayer for Coercivity Enhancement of Ti/CoCrPt Thin Films (보자력 향상을 위한 Ti/CoCrPt박막의 하지층)

  • Jang, Pyung-Woo
    • Journal of the Korean Magnetics Society
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    • v.12 no.3
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    • pp.94-98
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    • 2002
  • Sputtering conditions and various underlayer such as Al, Cu, Ni, Cr, Ag, Mg, Fe, Co, Pd, Au, Pt, Mo and Hf were investigated for coercivity enhancement of 20 nm Ti/CoCrPt thin films in order to increase the coercivity of the films thinner than 20 nm. Among them, Ag and Mg were effective to increase the coercivity. Particularly 2 nm Ag was very effective to increase the coercivity and nucleation field as well as to reduce ${\alpha}$ value in CoCrPt thin film such that the coercivity of 2 nm Ag/18 nm Ti/10 nm CoCrPt film was 2200 Oe. However, it seemed that other coercivity enhancement mechanism operated in CoCrPt films because Ti (002) preferred texture was not developed with Ag underlayer contrary to a general expectation. And the coercivity and nucleation field were decreased when glass substrate with rougher surface was used.

Unit Loadings of Heavy Metals by Non-point Sources - Case Study in a Valley Watershed - (비점원에 의한 중금속 원단위 부하량 - 곡간지 유역을 중심으로 -)

  • Kim, Jin-Ho;Han, Kuk-Heon;Lee, Jong-Sik
    • Korean Journal of Environmental Agriculture
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    • v.27 no.1
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    • pp.35-43
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    • 2008
  • The study was carried out to estimate runoff loads of heavy metals in the valley watershed at the middle of South Korea, during farming season. There were no other pollution sources except agricultural activity. From 27 April 2006 to 31 October 2007, water samples were collected using two methods. The first method was regular sampling wherein water samples were taken every two weeks; and the other method was through regular sampling when water were collected during each rainfall event. Results showed that heavy metals were found in the water from the regular samples, and were highest during May and June. It was presumed that this might have been contributed by farming activities. Heavy metal concentration of the irregular samples was lower than regular samples. The correlation coefficient between each heavy metal of the regular samples were as follows: Fe-Al>Cr-Al>Fe-Cr>Mn-Fe. The correlation coefficient of the irregular samples were the following: Fe-Al>Fe-Cu is positive; and Pb-Cu>Ni-Al is negative. Measured pollutant loads of heavy metals in the valley watershed were : 2.047 kg $day^{-1}$ of Al, 0.008 kg $day^{-1}$ of Cd, 0.034 kg $day^{-1}$ of Cr, 0.311 kg $day^{-1}$ of Cu, 0.601 kg $day^{-1}$ of Fe, and 0.282 kg $day^{-1}$ of Zn in 2006; while in 2007, the following were observed: 2.535 kg $day^{-1}$ of Al, 0.026 kg $day^{-1}$ of Cd, 0.055 kg $day^{-1}$ of Cu, 0.727 kg $day^{-1}$ of Fe, and 0.317 kg $day^{-1}$ of Zn. In the analysis of data gathered, the loading rates of effluents from the valley watershed during the rainy season were : 79.8% of Al, 69.1% of Cu, 82.5% of Fe, and 69.1% of Zn in 2006; while 69.9% of Al, 67.5% of Cu, 70.4% of Fe, and 67.5% of Zn in 2007.

Characteristics of ($AI_2$ $O_3$40%$YiO_2$)NiCr thermal sprayed composite coatings (($AI_2$ $O_3$40%$YiO_2$)NiCr 복합용사피막의 특성)

  • 김경호;박경채;김태형
    • Proceedings of the KWS Conference
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    • 2003.05a
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    • pp.114-116
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    • 2003
  • The multi function sprayed coating is used for direct-heating, wear resistance and high bonding strength. The merits of surface direct-heating coatings are short warming time, low power consumption and better wear resistance that can be used in many organization parts. In this study, the surface direct-heating and wear resistance can be improved by spraying the proper materials on the surface $Al_2$O$_3$40%TiO$_2$ powder and Ni-20%Cr powder that had the properties of conduction and high wear resistivity are used in order to improve wear resistance, electrical properties and bonding strength.

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The fabrication and study of NiCr thin film resister (NiCr 박막저항의 제작 및 특성연구)

  • Ryu, Je-Cheon;Kim, Dong-Jin;Park, Jong-Wan;Kim, Yong-Il;Kim, Kyu-Tae;Song, Yang-Sup;Yu, Kwang-Min
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1640-1642
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    • 2000
  • We were fabricated of NiCr thin film resitors(TFR) on $Al_{2}O_3$ substrates by dc magnetic sputtering, system. The characteristics of electrical resistance by substrates & annealing condition on the resistors were studied by X-ray Diff. and SEM, ESCA.

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Trace metals and selenium in organs and tissues of the striped field mice, Apodemus agratius, collected from Korea (한국산 등줄쥐 각 조직에 분포하는 미량금속류 및 셀레늄에 관한 연구)

  • 윤명희;노영희
    • Journal of Environmental Science International
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    • v.8 no.4
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    • pp.515-523
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    • 1999
  • Nine trace metals (Zn, Fe, Al, Pb, Mn, Cu, Ni, Cr, and Cd) and Se concentrations were determined in organs and tissues(muscle, bone, kidney, liver and skin) of the striped field mice, Apodemus agrarius collected at Daejeo-dong, Pusan city and the Sorak Mt., Kangwon Province. All the trate elements were detected from all the mice examined. As for the metal concentrations in the mice from Daejeo-dong, Zn, Fe, Al, Mn, Ni and Cr were significantly higher than those in Sorak Mt.(p<0.05), suggesting that pesticides including Zn and factory wastes containing several metals might contaminated the environment of Daejeo-dong. As regards the element concentrations in each organ and tissue, Fe, Al, Pb, Mn, Cu, Cr and Cd concentrations were high in liver or kidney; Zn in skin and bone; Ni in bone, skin and kidney; and Se in muscle, liver and skin in all the mice examined. There were significant differences(p<0.05) between juveniles and adults in average concentration of metals(Zn, Fe, Pb, Mn, Ni, and Cd) in every organs and tissues of mice collected at Daejeo-dong. Much higher average levels of metals in juveniles indicate that considerable burdens fo metals might be transferred through the placenta. However, there were no significant differences between males and females, and between young and old adults in average metal concentrations, which suggests that the mice might accumulate the metals during their life time, although they might excrete the metals not only through reproductive activities, such as parturition, lactation and ejaculation of semen, but also through molting, judging from higher accumulating ratios of most metals in skin of adults than of juveniles.

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Determination of Thermal Conductivity and Numerical Analysis of Al-Cr-N-O Composites Layer Formed by Hydro-thermal Process (수열합성된 Al-Cr-N-O계 도포층의 열전도 측정과 수학적 해석)

  • Kim, Ma-Ro;Yang, So-Eun;Lee, Jong-Jae;Kim, Byeong-Du;Choe, Yong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2014.11a
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    • pp.215-215
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    • 2014
  • Composites layer of Al-Cr-Ni-O system was prepared on a steel plate by hydro-thermal process at $700^{\circ}C$ for 12 hours, which phase identification and thermal conductivity were determined. The composites layer consisted of aluminum nitride, alumina, chromium carbide and aluminium, which density was $3.7kg/m^3$. The thermal conductivity of the coating layer determined by thermal data acquisition system was about 98.0 W/m/ which depended on the AlN content. Numerical modelling of the heat transfer behavior of the coating layer was well agreement with the empirical data.

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Interfacial Structure of Inconel/$Si_3N_4$ Joint Using Ag-Cu-Ti Brazing Metal (Ag-Cu-Ti Brazing 금속을 이용한 Inconel/$Si_3N_4$ 접합의 계면구조)

  • 정창주;장복기;문종하;강경인
    • Journal of the Korean Ceramic Society
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    • v.33 no.12
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    • pp.1421-1425
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    • 1996
  • Sintered Si3N4 and Inconel composed of Ni(58-63%) Cr(21-25%) Al(1-17%) Mn(<1%) fe(balance) were pressurelessly joined by using Ag-Cu-Ti brazing filler metal at 950℃ and 1200℃ under N2 gas atmosphere of 1atm and their interfacial structures were investigated. In case that the reaction temperature was low as 950℃ its interfacial structure was "Inconel metal/Ti-rich phase layer/brazing filler metal layer/Si3N4 " Ti used as reactive metal existed in between inconel steel and brazing metal and moved to the interface of between brazing filler metal nd Si3N4 according as reaction temperature increased up to 1200℃. The interfacial structure of inconel steel-Si3N4 reacted at 1200℃ was ' inconel metal/Ni-rich phase layer containing of Fe. Cr and Si/Cu-rich phase layer containing of Mn and Si/Si3N4 " Cr Mn, Ni and Fe diffused to the interface of between brazing filler metal and Si3N4 and reacted with Si3N4 The most reactive components of ingredients of inconel metal were Cr and Mn. On the other hand Ti added as reactive components to Ag-Cu eutectic segregated into Ni-rich phase layer,.

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