• Title/Summary/Keyword: Cr-O-N

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Effect of Si Addition on the Friction Coefficients of CrZrN Thin Films at high temperature (Cr-Zr-N 박막의 Si 첨가에 따른 고온 마모특성에 미치는 영향에 관한 연구)

  • Kim, Beom-Seok;O, Jong-Ho;Kim, Jae-Yong;Lee, Sang-Yul
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2011.05a
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    • pp.189-189
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    • 2011
  • CrZrN 박막은 CrN 박막에 비해서 향상된 기계적 특성과 우수한 표면 조도특성을 가지고 있다. 그러나 $500^{\circ}C$ 이상에서 기계적 특성이 급격히 감소하는 현상이 알려져 있다. 본 연구에서는 CrZrN 박막에 Si를 첨가하여 Si 함량에 따른 고온에서의 기계적 특성을 CrZrN 박막과 비교하였다. $500^{\circ}C$에서 마모 실험한 결과 CrZrN 박막에 비하여 소량의 Si의 첨가만으로 고온에서의 마모 특성이 향상되는 것을 확인하였다. 이것은 Si 첨가에 따라 고온에서 안정한 비정질상의 형성 영향으로 판단된다.

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Corrosion of Fe-(8.5~36.9) wt% Cr Alloys at 600~800℃ in (N2, H2S, H2O)-Mixed Gases (Fe-(8.5~36.9) wt% Cr합금의 600~800℃, (N2,H2S,수증기)-혼합 가스분위기에서의 부식)

  • Kim, Min Jung;Lee, Dong Bok
    • Korean Journal of Metals and Materials
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    • v.50 no.3
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    • pp.218-223
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    • 2012
  • Fe-(8.5, 18.5, 28.3, 36.9) wt% Cr alloys were corroded between 600 and $800^{\circ}C$ for up to 70 h in a 1 atm gas mixture that consisted of 0.0242 atm of $H_2S$, 0.031 atm of water vapor, and 0.9448 atm of nitrogen gas. Their corrosion resistance increased with an increment in the Cr content. The Fe-8.5%Cr alloy corroded fast, forming thick, fragile, nonadherent scales that consisted primarily of an outer FeS layer and an inner (Fe, Cr, O, S)-mixed layer. The outer FeS layer grew into the air by the outward diffusion of $Fe^{2+}$ ions, whereas the inner mixed layer grew by the inward diffusion of oxygen and sulfur ions. At the interface of the outer and inner scales, voids developed and cracking occurred. The Fe-(18.5, 28.3, 36.9)% Cr alloys displayed much better corrosion resistance than the Fe-8.5Cr alloy, because thin $Cr_2O_3$ or $Cr_2S_3$ scales formed.

Effects of oxidized CrN buffer layer on the growth of epitaxial ZnO film on Si(111) by Plasma Assisted Molecular Beam Epitaxy

  • Kim, Jung-Hyun;Han, Seok-Kyu;Hong, Soon-Ku;Lee, Jae-Wook;Lee, Jeong-Yong;Song, Jung-Hoon;Yao, Takafumi
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.115-115
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    • 2009
  • Epitaxial ZnO film was grown on Si(111) substrate with oxidazed CrN buffer by plasma-assisted molecular beam epitaxy (PAMBE). The growth and structural properties are investigated. The single crystalline growth was revealed by in-situ RHEED analysis. Crystalline quality of ZnO film grown on oxidized CrN buffer was investigated by the X-ray rocking curves. The FWHMs of (0002) XRCs was $1.379^{\circ}$. This value was smaller than the ZnO film grown directly on (111) Si substrate.

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Study on Mold-Metal Reaction in Castings of Mn-Steel and Cr-Steel (Mn 및 Cr 주강의 주형반응에 관한 연구)

  • Lee, J.H.;Jeong, J.Y.;Lee, J.N.
    • Journal of Korea Foundry Society
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    • v.5 no.4
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    • pp.271-282
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    • 1985
  • In order to investigate the mold reaction characteristics of Mn steel and Cr steel castings individually, the mold reaction products were examined by scanning electron microscopy, electron prove microanalyzer and X-ray diffractometer. From this experiment, the results were summarized as follows: 1) The mold reaction depth increased with increase of Mn content, while it decreased with increase of Cr content. 2) Mold reaction depth decreased with Mn content at $1200^{\circ}C$. 3) Mn, among the reaction products, forms a low fusion silicate, Mn $O.SiO_2$ while Cr forms a stable oxide, $CrO_3$ which hindering the reaction between FeO and $SiO_2$ thus the formation of $FeO.SiO_2$ was depressed.

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Studies on the formation of CrN surface layer by chromizing and plasma nitriding (Chromizing과 이온 질화에 의한 CrNvyaus층 형성에 관한연구)

  • Park, H. J.;Lee, S. Y.;Yang, S. C.;Lee, S. Y.;Kim, S. S.;Han, J. G.
    • Journal of the Korean institute of surface engineering
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    • v.31 no.6
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    • pp.334-344
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    • 1998
  • Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.

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Sintering behavior of $\textrm{La}_{0.68}\textrm{Ca}_{0.32}\textrm{Cr}_{0.97}\textrm{O}_{3}$ Interconnector Material for SOFC (SOFC용 $\textrm{La}_{0.68}\textrm{Ca}_{0.32}\textrm{Cr}_{0.97}\textrm{O}_{3}$연결재료의 소결거동)

  • Lee, Yu-Gi;Park, Jong-Wan
    • Korean Journal of Materials Research
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    • v.7 no.4
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    • pp.276-286
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    • 1997
  • SOFC용 L $a_{0.68}$Ca/ sub 0.32/C $r_{0.97}$ $O_{3}$분말은 수산염법에 의해 제조되었고, 이 합성된 분말을 이용한 슬러리의 최적제조조건과 그린 필름의 최적 소성조건을 얻었으며,이 제조 조건에서 소결 시간과 온도에 따라 제조된 연결재료의 결정구조, 미세구조 및 소결거동을 각각X-선 회절, 주사전자현미경 그리고 에너지 분산 분광계를 이용하여 조사하였다. L $a_{0.68}$C $a_{0.32}$C $r_{0.97}$ $O_{3}$의 저온소결은 $Ca_{m}$ (Cr $O_{4}$)$_{n}$에 의해 이루어졌음이 관찰되었고, 이때 $Ca_{m}$ (Cr $O_{4}$)$_{n}$은 불규칙하게 녹아서 L $a_{1-x}$C $a_{x}$Cr $O_{3-}$$\delta$/와 반응하고 이 현상이 질량 이동을 증가시켜 시편의 급격한 결정립 성장과 조밀화를 야기시켰다. 이러한 결정립 성장과 조밀화는 소결온도 140$0^{\circ}C$부터 일어났다.X>부터 일어났다.

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A Study of Soil and Water Pollutions in Kyungsan Province (경산지역 토양 및 수질오염에 관한 연구)

  • 김용태;이부용;김동석;양소영;이동훈;박병윤
    • Journal of Environmental Science International
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    • v.11 no.7
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    • pp.713-720
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    • 2002
  • In order to provide the basic information on the environmental pollution of Kyungsan province, the contents of Pb, Cd, Cr, Cu, Mn and Zn in soil, stream water, aquatic sediment and groundwater were investigated, and also the values of pH, COD, $KMnO_4-C$,\;NH_3-N,\;NO_2-N,\;NO_3-N$ and $Cl^-$ of stream water and groundwater were determined. The results were as follows. The values of COD, $NH_3-N,\;NO_2-N$ and $NO_3-N$ of the stream waters were very low. The contents of Pb, Cd, Cr, Cu and Zn in the stream waters were respectively at range of $0.014~0.063 mg/{\ell},\;0.004~0.007 mg/{\ell$\mid$, 0~0.045 mg/{\ell},\;0~0.008 mg/{\ell}$\;and\;$0.001~0.175 mg/{\ell}$, and these values were much lower than those of contaminated stream water in Korea. The contents of Cd, Cr, Cu and Zn in the soils were respectively at range of 0.12~O.71 ppm, 0.88~2.65 ppm, 2.86~22.33 ppm and 3.89~26.39 ppm, and these values were much lower than those of ordinary polluted areas in Korea. The contents of Cd, Cr, Cu, As, Zn and Mn in the aquatic sediments were respectively at range of 3.05~3.81 ppm, 14.6~70.6 ppm, 13.74~61.59 ppm, 76.8~465.5 ppm, 12.56~190.83 ppm and 333.3~l188.3 ppm. The values of pH, $KMnO_4-C,\;NH_3-N$, and $NO_3-N$ of the groundwaters were respectively at range of 7.6~8.4, $0~3.95{\ell}$, 0.05~0.15 mg/{\ell}$ and 0.05~0.42 $mg/{\ell}$. The contents of Pb, Cd and Cr in the groundwaters were respectively at range of 0.015~0.061 $mg/{\ell}$, 0.O06~0.009 $mg/{\ell}$ and 0.005~0.045 $mg/{\ell}$.

High-Temperature Oxidation of Ti Containing Stainless Steel in O2-N2 Atmosphere

  • Onishi, Hidenori;Saeki, Isao;Furuichi, Ryusaburo;Okayama, Toru;Hanamatsu, Kenko;Shibayama, Tamaki;Takahashi, Heishichiro;Kikkawa, Shinichi
    • Corrosion Science and Technology
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    • v.3 no.4
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    • pp.140-147
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    • 2004
  • High temperature oxidation of Fe-19Cr and Fe-19Cr-0.2Ti alloys is studied at 1173-1373 K in 16.5 kPa $O_2$ - balances $N_2$ atmosphere aimed at clarifying the effect of titanium addition. Oxidation rate of Fe-19Cr alloy was accelerated with titanium. For both alloys chromium rich $(Fe,\;Cr)_2O_3$ was formed as a major oxidation product. On Fe-19Cr-0.2Ti alloy, a thin layer composed of spinel type oxide and titanium oxide was also formed and an internal oxidation of titanium was observed. Titanium was concentrated at the oxide surface and internal oxidation zone but a small amount of titanium was also found in the intermediate corundum type $(Fe,\;Cr)_2O_3$ layer. Crystals of corundum type $(Fe,\;Cr)_2O_3$ formed on Fe-19Cr alloy are coarse but that formed on Fe-19Cr -0.2Ti alloys were fine and columnar. Reason for the difference in oxidation kinetics and crystal structure will be discussed relating to the distribution of aliovalent titanium in corundum type $(Fe,\;Cr)_2O_3$ oxide layer.

Exchange Bias in Cr2O3/Fe3O4 Core/Shell Nanoparticles

  • Yun, B.K.;Koo, Y.S.;Jung, J.H.
    • Journal of Magnetics
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    • v.14 no.4
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    • pp.147-149
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    • 2009
  • We report the exchange bias in antiferromagnet/ferrimagnet $Cr_2O_3/Fe_3O_4$ core/shell nanoparticles. The magnetic field hysteresis curve for $Cr_2O_3/Fe_3O_4$ nanoparticles after field-cooling (FC) clearly showed both horizontal ($H_{EB}{\sim}$610 Oe) and vertical (${\Delta}M{\sim}$5.6 emu/g) shifts at 5 K. These shifts disappeared as the temperature increased toward the Neel temperature of $Cr_2O_3\;(T_N{\sim}$307 K). The $H_{EB}\;and\;{\Delta}M$ values were sharply decreased between the $1^{st}\;and\;the\;2^{nd}$ magnetic field cycles, and then slowly decreased with further cycling. These results are discussed in terms of the formation of single domains with pinned, uncompensated, antiferromagnetic spin and their evolution into multi-domains with cycling.