• 열처리공학회지
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• 제12권2호
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• pp.99-107
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• 1999

The graphitization is affected by the addition of small amount of the elements(such as Si, Al, Ni, B, Cr and Mn etc.) and the pre-treatment(such as cold rolling). Boron is well known element to accelerate the graphitization of cementite in high carbon steels. Also, cold rolling is known to accelerate the graphitization. But the graphitization nucleation mechanism by cold rolling is few reported. Therefore the effect of cold rolling in Fe-0.5%C-1.0%Si-0.47%Mn-0.005%B steel on the graphitization is investigated quantitatively using hardness test, optical microscope and scanning electron microscope, neutron induced microscopic radiography. The nucleation of graphite in cold-rolled Fe-0.5%C-1.0%Si-0.47%Mn-0.005%B steel is formed at void which is formed at pearlite/pearlite boundary by cold rolling. But the effect of cold rolling on graphitization in boron addition steel is more effective than that of no boron addition steel due to segregation of BN at void in boron addition steel.

• 대한화학회지
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• 제17권5호
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• pp.346-352
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• 1973

양이온교환수지관($Dowex 50w{\times}12$, $35cm{\times}3.14cm^2$)을 사용하여 0.1M의 V(V), Cu(II), Ni(II), Co(II), Cr(III), Mn(III), Fe(II), 용액을 각기 1ml씩 섞은 혼합 용액 7ml를 다음과 같은 용리액으로 용리시켜 정량적으로 분리하였다. 즉 Fe(II), V(V), Cu(II), Ni(II), Co(II)에 대하여는 0.6M 염화나트륨과 0.1M 타르타르산나트륨의 혼합용액 (pH 2.00과 4.50)을 Mn(II)과 Cr(III)에 대하여는 3M 염화나트륨과 0.1M 타르타르산나트륨의 혼합용액 (pH 4.50과 5.00)을 용리액으로 사용하여 단계적으로 용리하였다. 많은 양($97\%$ 정도)의 Fe(II)과 V(V), Cu(II), Ni(II), Mn(II), Cr(III)을 섞은 시료용액은 먼저 음이온교환수지관($Dowex 1{\times}8$, $15cm{\times}3.14cm^2$)을 사용하여 4.0M 염산으로 용리하여 대부분의 철을 분리한다. 이때 V(V), Ni(II), Mn(II), Cr(II)은 같은 위치에서 용출되므로 함께 받고 다음에 Cu(II)는 소량의 철과 함께 용출된다. 이것을 다시 양이온수지관($Dowex 50w{\times}12$, $10cm{\times}3.14cm^2$)을 사용하여 여러 가지 이온들을 분리할 수 있었으며 철강중에 들어있는 양이온 성분들도 같은 방법으로 분리할 수 있었다.

• 한국환경과학회지
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• 제5권4호
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• pp.463-471
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• 1996

In order to investigate the characteristics of dustfall at eight sites in Pusan, the dustfal1 samples were collected with dust jar method from May to September 1995, and Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb were analyzed, The main results of this study are summarized as follows; 1) The total mean value of dustfall was 11.30 ton/$^{\circ}C$/month. 2) The maximum and minimum values of dustfall were industrial and resident area respectively, 3) The dustfall showed the general trend in order as May>Jun>September>July. 4) The general trend of the heavymetals in dustfall was in order as Fe>Cu>Zn>Pb>Ni>Cd>Cr>Mn any the concentrations of heavymetals had different tendencies according to sources of Pollutant meterials. 5) The Concentrations of Fe, Cu, Pb, Ni, Cd and Cr in industrial area and Mn, Pb and Zn in traffic area were high. The concentrations of heavymetals in residence area and unpolluted area were generally low. 6) Cr, Cu and Cd were influenced by the steel industry and the metal products plant and Zn was influenced by the automobiles. Mn, Fe and Ni were influenced by the soil as wet as artificial outlet. 7) The correlation between the total amount of dustfall and the concentrations of the heavymetals by month was high and the correlation between the heavymetals of the same origin was high.

• 한국재료학회지
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• 제13권1호
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• pp.36-42
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• 2003

The oxidation behaviors of Y-Cr bilayer deposited on ferritic steel by magnetron-sputtering for application of the Fe-Cr alloys as interconnectors of planar-type solid oxide fuel cells (SOFCs) were studied. After oxidation at $800^{\circ}C$ for 40 hours, the major phase of $Y_2$$O_3$and the minor phase of $YCrO_3$, $Mn_{1.5}$ $Cr_{1.5}$ $O_4$and Cr$_2$SiO$_4$were formed in the Y/Cr bilayered samples, while the major phase of Cr$_2$O$_3$and the minor phase of $Y_2$$O_3$were formed as the major phase in the Cr/Y bilayered samples. The Log(ASR/T) that expresses electric resistance of the Y/Cr coated specimen with nonconducting $_Y2$$O_3$oxide showed high value of -2.80 Ω$\textrm{cm}^2$$K^{-1}$ / and that of the Cr/Y coated specimen with conducting $Cr_2$$O_3$oxide appeared to be -4.11 Ω$\textrm{cm}^2$$^{K}$ . The electric resistance of the Y/Cr coated specimen was largely increased due to the formation of high resistance oxide scales. However, the Cr/Y coated specimen did not show any increase in the electric resistance and had the long-term stability of oxidation because there was no formation of the secondary phases with low conductivity.

• 자원환경지질
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• 제33권5호
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• pp.379-389
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• 2000

This study was focused on the investigation for the heavy metal contamination of soils derived from Yoecheon Industrial Complex in Chonnam Province. Total 201 soil samples including farmland, paddy, forest and playground soils were collected, extracted by 0.1N HCl and analyzed for Cd, Cu, Cr, Fe, Mn and Zn using AAS. Most pH values in soils were weak acidic ranges of 4-6, while some of them were over 8.0. Concentrations of Cd, Cu, Fe and Zn in the soils tend to be relatively high around the Au-Ag mine area, railroad stations and oil station, however, those of Cr, Mn and Pb show high at the northside of Pohang Steel Co (POSCO). Cadmium-Zn couples, and Cd-Zn and Zn-Cr couples have relatively good correlations in the farmland soils and paddy soils, respectively. Concentrations of Cd, Fe and Zn with depth tend to be higher in the top soils than in the bottom soils, but those of Cu and Pb do not show regular variations with depth.

• Corrosion Science and Technology
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• 제11권1호
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• pp.9-14
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• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.

• 대한금속재료학회지
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• 제49권9호
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• pp.699-707
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• 2011

P122 steel, with a composition of Fe-10.57%Cr-1.79%W-0.96Cu-0.59Mn was arc-welded and oxidized between $600^{\circ}C$ and $800^{\circ}C$ in air for up to 6 months. The oxidation rates increased in the order of the base metal, weld metal, and heat-affected zone (HAZ), depending on the microstructure. The scale morphologies of the base metal, weld metal, and HAZ were similar because it was determined mainly by the alloy chemistry. The scale consisted primarily of a thin $Fe_2O_3$ layer at $600^{\circ}C$ and $700^{\circ}C$ and an outer $Fe_2O_3$ layer and an inner ($Fe_2O_3$, $FeCr_2O_4$)-mixed layer at $800^{\circ}C$. The microstructural changes resulting from heating between $600^{\circ}C$ and $800^{\circ}C$ coarsened the carbide precipitates, secondary Laves phases, and subgrain boundaries in the matrix, resulting in softening of the base metal, weld metal, and HAZ.

• 한국지구과학회지
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• 제24권8호
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• pp.711-720
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• 2003

전주시 도로변 퇴적물의 중금속 오염을 평가하고 특성을 알기 위해 2002년 여름과 겨울 두 차례에 걸쳐 67곳에서 134개의 시료를 채취했다. 이들 시료를 Thompson and Wood (1982)와 Tessier et al. (1979)의 방법으로 화학처리한 후 Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn등의 원소를 분석했다. 전주 도로변 퇴적물에 함유된 Zn, Cu, Pb, Cd의 함량은 서울의 도로변 토양, 먼지, 하수 슬러지에 함유된 것 보다 낮지만 세계 여러 나라에서 제시하는 토양 중 환경기준값을 초과했으며 자연 토양 중의 함량 보다 2-7배 초과한 값이다 산업지역, 상업지역, 주거지역으로 구분해 분석한 결과 전반적으로 산업지역에서의 중금속 함량이 약간 높고(특히 Cr, Ni, Pb, Zn)오염지수도 높다. 상업지역과 주거지역간의 중금속 오염 정도는 비슷하며 산업지역이 아니라도 특정 금속 가공업체나 자동차 정비 관련 업체가 위치해 있는 곳은 오염이 심하다. 연속추출 결과 중금속 원소의 존재 형태는 Pb, Zn, Mn등은 주로 탄산염 광물과 수반되거나 Fe-Mn산화물과 수반된 형태로 존재하고, Cu는 유기물과 함께 존재하는 비율이 높다. 그러나 전체적으로 규산염광물과 수반된 형태로 존재하는 비율이 50% 이상을 차지한다. 따라서 서울 지역에 비해 인위적 오염의 정도가 낮은 편이지만, Cd, Co, Ni, Pb, Zn, Mn등의 원소가 탄산염 형태로 존재하는 비율이 높기 때문에 오염원으로서의 가능성이 높다.

• 한국산업보건학회지
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• 제7권1호
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• pp.113-131
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• 1997

This study was performed to evaluate the exposure levels of worker exposed to welding fume and metals in confined spaces of a shipyard. The airborne concentration of welding fumes and metal elements in confined spaces were compared with those in open working areas. Results of the study were as follows. 1. The geometric mean of welding fume concentration in a confined space was $16.6mg/m^3$, which contained $3.9mg/m^3$ Fe, $1.2mg/m^3$ Mg, $0.8mg/m^3$ Zn, $0.008mg/m^3$ Cu, $0.008mg/m^3$ Pb, $0.005mg/m^3$ Ni, $0.003mg/m^3$ Cr, $0.003mg/m^3$ Cd. The geometric mean of welding fume concentration in open working areas was $5.2mg/m^3$, which contained $1.1mg/m^3$ Fe, $0.3mg/m^3$ Mg, $0.3mg/m^3$ Zn, $0.004mg/m^3$ Cu, $0.008mg/m^3$ Pb, $0.005mg/m^3$ Ni, $0.003mg/m^3$ Cr, $0.0003mg/m^3$ Cd. The geometric mean of welding fume concentration in confined spaces was 3,2 times higher than that in open working areas. The geometric mean concentrations of such metals as Fe, Mg, Zn, or Cu within fume in confined spaces were 2-4 times higher than those in open working areas, while little difference made such metals as Pb, Ni, Cr, Cd. 2. In 32 samples out of a total of 39 samples (82.1%) collected in confined spaces, the concentrations of welding fume exceeded TLV. while so did 19 samples out of 33 samples (57.6%) in open working areas. As for the concentrations of metals in welding flume from confined spaces, Fe exceeded TLV in 14 out of a total of 38 samples (36.8%), Mn exceeded TLV in 23 out of a total of 38 samples (60.5%). As for the concentration of metals in welding fume from open working areas, Fe exceeded TLV in 3 out of a total of 34 samples (8.8%), Mn exceeded TLV in 6 out of a total of 34 samples (17.6%). Considering additive effect among metals, in 31 out of a total of 39 samples (79.5%) collected in confined spaces, the concentrations of welding fume exceeded TLV, while so did 14 out of 38 samples (55.6%) in open working areas. 3. In respect of base metal and welding type the concentration of total welding fume by $CO_2$ gas W./mild steel was the highest, followed by semiauto MMA/mild steel, then followed by TIG or $CO_2$ gas W./stainless steel. ; as for concentration of metal within fume, a decreasing order was Fe, Zn, Mn, and Pb in $CO_2$ gas W./mild steel and semiauto MMA/mild steel, but Fe, Mn, Cr, and Ni in TIG or $CO_2$ gas W./stainless steel. 4. In case of welding base metal covered by paint, contents of Zn within red paint chip and within gray paint chip were 14.0% and 0.08% respectively, which showed a little difference, while the airborne concentrations of Zn within fume during welding base metal covered red paint and gray paint were $1.351mg/m^3$ and $1.018mg/m^3$ respectively, which showed little difference. As for Pb, contents of red paint chip and gray paint chip were 0.14% and 0.08% respectively, and the airborne concentrations within fume during welding base metal covered red paint and gray paint were $0.009mg/m^3$ and $0.007mg/m^3$ respectively, both of which showed little difference.

• 한국산업보건학회지
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• 제9권1호
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• pp.56-72
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• 1999

Airborne concentrations of welding fumes in which 13 different metals such as Al, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, Sn, Ti, and Zn were analyzed were measured at 18 factories including automobile assembly and manufactures, steel heavy industries and shipyards. Air samples were collected by personal sampler at each worker's worksite(n=339). Blood levels of Cd, Cu, Fe, Mn, Pb and Zn were also measured from samples taken from 447 welders by atomic absorption spectrometry and compared with control values obtained from 127 non-exposed workers. The results were as follows ; 1. Among various welding types, $CO_2$ welding 70.2 % were widely used, shielded metal arc welding(SMAW) 22.1 % came next, and rest of them were metal inert gas(MIG) welding, submerged arc welding(SAW), spot welding(SPOT) and tungsten inert gas(TIG) welding. 2. Welding fume concentration was $0.92mg/m^3$($0.02{\sim}15.33mg/m^3$) at automobile assembly and manufactures, $4.10mg/m^3$($0.02{\sim}70.75mg/m^3$) at steel heavy industries and $5.59mg/m^3$($0.30{\sim}91.16mg/m^3$) at shipyards, respectively, showing significant difference among industry types. Workers exposed to high concentration of welding fumes above Korean Permissible Exposure Limit(KPEL) amounted to 7.9 % and 12.5 %, in $CO_2$ welding and in SMAW at automobile assembly and manufactures and 62.7 % in $CO_2$ welding, and 12.5 % in SMAW at shipyards, and 66.2 % in $CO_2$ welding and 70.6 % in SMAW at steel heavy industries. 3. Geometric mean of airborne concentration of each metal released from welding fumes was below one 10th of KPEL in all welding types. Percentage of workers, however, exposed to airborne concentration of metals above KPEL amounted to 16.8 % in Mn and 7.6 % in Fe in $CO_2$ welding; 37.5 % in Cu in SAW, 30 % in Cu in TIG; and 25 % in Pb in SPOT welding. As a whole, 76 Workers(22.4%) were exposed to high concentration of any of the metals above KPEL. 4. There were differences in airborne concentration of metals such as Al, Cd, Cr, Cu. Fe. Mn, Mo, Ni, Pb, Si, Sn, Ti and Zn by industry types. These concentrations were higher in shipyards and steel heavy industries than in automobile assembly and manufactures. Workers exposed to higher concentration of Pb above KPEI amounted to 7.4 % of workers(7/94) in automobile assembly and manufactures. In shipyards, 19.2 % of workers(19/99) were over-exposed to Mn and 7.1 % (7/99) to Fe above KPEL. In steel heavy industries, 14.4 %(21/146), 7.5 %(11/146) and 13 %(19/146) were over-exposed to Mn, Fe and Cu, respectively. As a whole, 76 out of 339 workers(22.4%) were exposed to any of the metals above KPEL. 5. Blood levels of Cd, Cu, Fe, Mn, Pb, and Zn in welders were $0.11{\mu}g/100m{\ell}$, $0.84{\mu}g/m{\ell}$, $424.4{\mu}g/m{\ell}$, $1.26{\mu}g/100m{\ell}$, $5.01{\mu}g/100m{\ell}$ and $5.68{\mu}g/m{\ell}$, respectively, in contrast to $0.09{\mu}g/100m{\ell}$, $0.70{\mu}g/m{\ell}$, $477.2{\mu}g/m{\ell}$, $0.73{\mu}g/100m{\ell}$, $3.14{\mu}g/100m{\ell}$ and $6.15{\mu}g/m{\ell}$ in non-exposed control groups, showing significantly higher values in welders but Fe and Zn.