• 한국자기학회지
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• 제3권1호
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• pp.41-47
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• 1993

Co-Cr계 수직자기기록매체에서 비교적 낮은 기판온도에서 높은 보자력을 얻기위하여 제 3원소로서 Ta의 첨가효과에 대하여 연구하였다. Cr함량이 17-21 at.%로 다른 Co-Cr 계에 Ta함량을 3.2 at.%까지 첨가시켜서 여러조성의 Co-Cr-Ta 박막을 제조하고, 자기적 성질 및 미세구조를 조사하였다. Ta첨가로 인한 수직보자력의 향상효과는 Cr함량이 낮은 박막의 경우에 컸으며, 특히 기판온도가 $100^{\circ}C$인 경우 그 향상효과가 더욱 뚜렷하였다. Ta의 첨가로 인한 수직보자력 향상은 결정립 미세화나, c-축 배향성향상에 의한 것이기 보다는 비강자성원소의 편석이 심화됨에 기인하는 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.178-188
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• 2017

To study the effects of zirconium (Zr) addition on the microstructure, hardness and the tensile properties of oxide dispersion strengthened (ODS) ferritic-martensitic steels, two kinds of 9Cr-ODS ferritic-martensitic steels with nominal compositions (wt.%) of $Fe-9Cr-2W-0.3Y_2O_3$ and $Fe-9Cr-2W-0.3Zr-0.3Y_2O_3$ were fabricated by the mechanical alloying (MA) of premixed powders and then consolidated by hot isostatic pressing (HIP) techniques. The experimental results showed that the average grain size decreases with Zr addition. The trigonal ${\delta}$-phase $Y_4Zr_3O_{12}$ oxides and body-centered cubic $Y_2O_3$ oxides are formed in the 9Cr-Zr-ODS steel and 9Cr non-Zr ODS steel, respectively, and the average size of $Y_4Zr_3O_{12}$ particles is much smaller than that of $Y_2O_3$. The dispersion morphology of the oxide particles in 9Cr-Zr-ODS steel is significantly improved and the number density is $1.1{\times}10^{23}/m^3$ with Zr addition. The 9Cr-Zr-ODS steel shows much higher tensile ductility, ultimate tensile strength and Vickers hardness at the same time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.399-402
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• 2000

For improvement of B constant in $CaMnO_3$-$CaTiO_3$ perovskite type thermistors, effect of $Cr_2$$O_3$ addition ranged from 0.0wt% to 5.0wt% on electrical properties were investigated with contents and sintering temperatures in the view of crystal and microstructures. The solubility limit of Cr$_2$O$_3$was up to 0.5wt% judging from the result of lattice parameter. The grain size was decreased and the resistance at room temperature and B constant were increased with the addition of $Cr_2$$O_3$.On particular, B constant of$CaMnO_{3-x}$$Cr_2$$O_3$ system was increased greatly from 1574k to 2598k at 0.5wt% $Cr_2$$O_3$addition. Further addition of $Cr_2$$O_3$, however, resulted in the decrease of the resistance and B constant due to the $Cr_2$$O_3$ precipitation on the grain boundary. As the$CaTiO_3$contents increased in the $CaMnO_3$-$CaTiO_3$ system, the resistance at room temperature and B constant were highly changed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.22-29
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• 2001

Plasma-sprayed coatings were prepared using by spray-dried Cr$_2$O$_3$ powder with and without MoO$_3$ addition. A reciprocal type tribe-tester was employed to examine friction and wear behavior of the specimens at room temperature. The worn surfaces of plasma spray coated specimens were observed by SEM. The results showed that friction coefficient of the MoO$_3$-added coatings were lower than those without MoO3 addition. However pure Cr$_2$O$_3$ coating showed the lowest wear loss at the self-mated test. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with MoO$_3$ addition.

• 한국주조공학회지
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• 제21권1호
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• pp.15-23
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• 2001

The changes in the microstructures and $D0_3{\leftrightarrow}B2$ transition temperature were investigated for Fe-30at.%AI-5at.%Cr alloy with the ordered $D0_3$, structure when Ti, Hf and Zr were added respectively. The addition of Cr has no effect on the microstructure. However, as the amount of Ti addition increased, the grain size became smaller. Addition of Ti+Hf, Ti+Zr and Ti+Hf+Zr also showed the similar effect. When 20at.% of Ti was added, the second phase precipitates on the substrate. The addition of Cr, Hf and Zr alone has no effect on $D0_3{\leftrightarrow}B2$ transition temperature. However, as the amount of Ti addition increased by 5, 10, 15 and 20at.%, the transition temperatures showed 929, 930, 960 and $930^{\circ}C$ respectively.

• 열처리공학회지
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• 제10권2호
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• pp.101-108
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• 1997

In high carbon steels, the cementite phase is more unstable thermally than graphite, and it can lead to a marked deterioration in the formability. Many studies have been carried out to evaluate the effect of the fundamental elements on the graphitization of cementite in high carbon steels. In this present work, the effect of Mn, Cr addition on graphitization in Fe-0.65%C-1.0%Si steel has been investigated by means of hardness testing, optical microscopy and EPMA. The nucleation of graphite may mostly depend on the dissolution rate of cementite into ferrite and the number of the nucleation sites of graphite. The graphitization was promoted by the addition of 0.1%Mn in high carbon steel, but retarded by more addition than 0.5% of Mn. By the more addition of Cr than 0.1%, the graphitization of high carbon steel was strongly retarded. Because Mn was moderate anti-graphitizer, but Cr was stroug anti-graphitizer.

• 한국자기학회지
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• 제3권3호
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• pp.221-228
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• 1993

고밀도기록용 박막재료로서의 충족조건은 높은 보자력, 높은 포화자화, 생산성, 그리고 화학적 안정성으로써 수직자기기록매체 CoCrMo 자성박막을 RF 스퍼터링 방법으로 제조한 후, 부식 특성을 전기화학적 측정, acceleration corrosion test 및 부식후 박막의 표면분석을 통하여 조사 하였다. CoCrMo 박막의 부식특성은 스퍼터링 조건에 따라서 다르게 나타났으며, Mo의 함량이 증가 할수록 내식성은 향상되었다. 전기화학부식실험 결과 박막의 Mo 함량이 증가할수록 뚜렷한 활성- 불활성 전이를 나타내었으며 부동태전류밀도의 감소를 나타내었다. Accelerated corrosion test에 서 CoCrMo 박막의 부식은 전기화학반응에 의하여 일어났으며 Mo첨가에 따라 부식이 일어난 곳의 수는 감소하였다. AES분석결과 부식 장소에는 많은 양의 $Cl_{-}$ 이온이 존재하였고, Cr의 고갈이 부식의 원인이었다.

• 한국재료학회지
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• 제25권8호
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• pp.376-385
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• 2015

The effects of Nb and Cr addition on the microstructure, corrosion and oxide characteristics of Zr based alloys were investigated. The corrosion tests were performed in a pressurized water reactor simulated-loop system at $360^{\circ}C$. The microstructures were examined using OM and TEM, and the oxide properties were characterized by low-angle X-ray diffraction and TEM. The corrosion test results up to 360 days revealed that the corrosion rates were considerably affected by Cr content but not Nb content. The corrosion resistance of the Zr-xNb-0.1Sn-yCr quaternary alloys was improved by an increasing Nb/Cr ratio. The crystal structure of the precipitates was affected by a variation of the Nb/Cr ratio. The Zr-Nb beta-enriched precipitates were mainly formed in the high Nb/Cr ratio alloy while $Zr(NbCr)_2$ precipitates were frequently observed in the low Nb/Cr ratio alloy. The studies of oxide characteristics revealed that the corrosion resistance was related to the crystal structure of the precipitate.

• 한국자기학회지
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• 제7권4호
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• pp.205-211
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• 1997

E-Beam Evaporator로 제조된 CoCrTa/CrNi 자성박막에서 하지층인 Cr에 대한 소량첨가원소인 Ni이 자성박막의 자기적 성질에 어떤 영향을 미치는가를 조사하였다. 상온에서 제조된 시편에서 소량의 첨가원소 Ni의 영향은 보자력의 증가를 가져왔음을 알 수 있었다. 이러한 보자력 증가의 원인을 XRD와 AFM으로 그 결정배향성과 미세구조를 통하여 살펴보았다. Cr 하지층에 Ni의 첨가시 결정립의 크기가 증가함을 알 수 있었다. 280 .deg. C 기판온도에서는 CrNi 하지층을 갖는 박막이 오히려 낮은 보자력 값을 나타내었고 이것은 결정립 크기의 증가때문으로 생각된다. 높은 기판온도에서는 결정배향성보다 Cr의 편석이 보자력에 대한 주요한 기구인 것으로 생각된다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1118-1122
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• 2004

The study was conducted to evaluate the effect of chromium nanoparticle (CrNano) on growth, carcass characteristics, pork quality, and tissue chromium in finishing pigs. A total of 100 Duroc$\times$Landrace$\times$Yorkshire barrows (average initial BW of 64.78$\pm$0.83 kg) were divided into 10 pens, 10 pigs per pen. 5 pens of pigs were fed with control diet (corn-soybean meal, 1.05% Lys) and others were fed with control diet addition with 200 $\mu$g/kg Chrome (Cr) from CrNano. During the trial, all pigs were given free access to feed and water. After 35 days trial, 10 pigs from each each treatment (weight similar to average group weight, 91.34$\pm$1.31 kg for control group, and 92.26$\times$0.56 kg for CrNano treated group) were sacrificed to measure carcass characteristics, pork quality, and to collect the samples of longissimus muscle, liver, kidney and heart. The results indicated that the addition of 200 $\mu$g/kg CrNano decreased feed: gain ratio by 3.56% (p<0.05) compared to the control group. Pigs fed CrNano had 14.06% higher (p<0.05) carcass lean percentage, 19.96% (p<0.05) larger longissimus muscle area and 25.53% lower (p<0.05) carcass fat percentage, 18.22% lower (p<0.05) backfat thickness. Drip loss in chops from pigs fed CrNano was decreased by 21.48% (p<0.05) and weights of longissimus muscle and semimembranosus were increased by 16.33% (p<0.05) and 14.87% (p<0.05) respectively. In addition, supplemental CrNano resulted in 184.11% (p<0.05), 144.99% (p<0.05), 88.13% (p<0.05) and 52.60% (p<0.05) increment of Cr concentration in longissimus muscle, liver, kidney and heart, respectively. These results suggest that supplemental CrNano has beneficial effects on carcass characteristics, pork quality and individual skeletal muscle weight, increase tissue chromium concentration in selected muscle and organs.