• 한국표면공학회지
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• 제43권5호
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• pp.238-242
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• 2010

In the present work, the influence of oxide on the Cr-Si-N coatings was investigated for the Cr-Si-O-N coatings on AISI 304 and Si wafer deposited by hybrid system, which combines the DC magnetron sputtering technique and arc ion plating (AIP) using Cr and Si target in an $Ar/N_2/O_2$ gaseous mixture. As the O content in the Cr-Si-N coatings increased, the diffraction patterns of the Cr-Si-O-N coatings showed CrN and $Cr_2O_3$ phases. However, as the O content increased to 28.8 at.%, diffraction peak of $Cr_2O_3$ was disappeared in the Cr-Si-O-N coating. The $d_{200}$ value was decreased with increasing of O content. The average grain size increased from about 40 nm to 65 nm as the O content increased. The maximum micro-hardness of the Cr-Si-O-N coating was obtained 4507 Hk at the O content of 24.8 at.%. The average friction coefficient of the Cr-Si-O-N coatings was gradually decreased by increasing the O content and the average friction coefficient decreased from 0.37 to 0.25 by increasing the O content. These results indicated that amorphous phase was increased in the Cr-Si-O-N coatings by increasing of O content.

• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.14-17
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• 1995

In this study, fur the use of portable communication multilayer devices. 0.15wt% V$_2$O$\_$5/ added BiNbO$_4$which is low-fire microwave dielectric ceramic as able to co-fire with high conductors was made into specimens with the additions of Cr$_2$O$_3$0.04, 0.2, 0.4, 0.8, 1.2wt%. These specimens were sintered at 930, 960. 990, 1030$^{\circ}C$ respectively to make the microwave dielectric resonators. These resonators were investigated by measuring the structure and dielectric properties. The density of the specimens was increased by the amounts of the Cr$_2$O$_3$and increased by increasing the temperature. 0.8wt% Cr$_2$O$_3$added and sintered at 960$^{\circ}C$ specimen skewed 49 dielectric constant. Q$.$f values were increased by the amounts of Cr$_2$O$_3$. And Q value was deteriorated by the additions of Cr$_2$O$_3$at sufficiently sintered temperatures. Negative resonant temperature coefficients were moved to positive by the amounts of Cr$_2$O$_3$and returned negative again at 1.2wt%. Temperature characteristics were deteriorated at 1030$^{\circ}C$.

• Nuclear Engineering and Technology
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• 제33권4호
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• pp.386-396
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• 2001

Mixtures Of AUC-UO$_2$and Gd$_2$O$_3$ Powders doped With Cr$_2$O$_3$ or Cr$_2$O$_3$-SiO$_2$ were Pressed and sintered at 1730 t in hydrogen gas witk various water-vapor contents. The density of UO$_2$- 6wt% Gd$_2$O$_3$ pellets can be increased from 91% TD to 94.5% TD in 1 vol% $H_2O$-H$_2$ gases by the addition of 0.02wt% Cr$_2$O$_3$-(0.01~0.04) wt% SiO$_2$. The magnitude of density increase is much larger in (1~3 vol%) $H_2O$-H$_2$ gases than in 0.05 vol% $H_2O$-H$_2$ gas. The densification of U0$_2$- Gd$_2$O$_3$ compact is significantly delayed in the temperature range between 1300 and 1500 t , but that of compacts with Cr$_2$O$_3$-SiO$_2$ is not. The role of Cr$_2$O$_3$ and SiO$_2$ in densification is discussed.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.107-107
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• 2016

TiCrAlSiN films were developed in order to improve the high-temperature oxidation resistance, corrosion resistance, and mechanical properties of conventional TiN films that are widely used as hard films to protect and increase the lifetime and performance of cutting tools or die molds. In this study, a nano-multilayered TiAlCrSiN film was deposited by cathodic arc plasma deposition. It displayed relatively good oxidation resistance at $700-900^{\circ}C$, owing to the formation protective oxides of $Al_2O_3$, $Cr_2O_3$, and $SiO_2$, and semiprotective $TiO_2$. At $1000^{\circ}C$, the increased temperature led to the formation of the imperfect oxide scale that consisted primarily of the outer ($TiO_2$,$Al_2O_3$)-mixed scale and inner ($TiO_2$, $Al_2O_3$, $Cr_2O_3$)-mixed scale.

• Nuclear Engineering and Technology
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• 제35권1호
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• pp.14-24
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• 2003

This work investigates the effects of Cr$_2$O$_3$ and oxygen potential on grain growth and densification of UO$_2$ pellets. Powder mixtures of UO$_2$ and 0.03-0.4wt% Cr$_2$O$_3$ were pressed and sintered in 3 different gas atmospheres: the $H_2O$-to-H$_2$ ratios were 5$\times$10$^{-4}$ , 1$\times$10$^{-2}$ and 3$\times$10$^{-2}$ In the first gas atmosphere the Cr$_2$O$_3$ contents below 0.2 wt% have an insignificant effect on grain size, but the Cr$_2$O$_3$ contents more than 0.3 wt% promote grain growth in the inner zone of a pellet but not in the outer zone. In both the second and third atmospheres, the grain size increases with the Cr$_2$O$_3$ content. With the same level of Cr$_2$O$_3$ content the grain size is larger in the second atmosphere than in the third. Sintering behavior and developed microstructure are discussed in terms of the reduction of C$r^2$O$^3$ to Cr, the dissolution of C$r^2$O$^3$ in UO$_2$, and liquid phase sintering.

• 한국재료학회지
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• 제8권8호
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• pp.757-765
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• 1998

수소를 연료로 하여 HVOF 용사된 크롬카바이드 용사층의 산화거동을 이해하기 위해 용사분말의 제조방법이 서로 다른 두 종류의 용사용 분말을 ($\textrm{Cr}_{3}\textrm{C}_{2}$-20wt%NiCr로 구성된 크래드 분말과 $\textrm{Cr}_{3}\textrm{C}_{2}$-7wt%NiCr로 구성된 혼합분말)이용하여 F/O비를 3.2, 3.0, 2.8 로 변화시켜 용사한 후, $1000^{\circ}C$ 까지 등온 산화실험 후, 산화특성을 고찰하여 크롬카바이드 용사층의 F/O비에 의존하는 산화거동을 비교 검토하였다. 그 결과 NiCr이 20wt% 크래드된 분말로 용사된 용사층과 NiCr이 7wt% 혼합된 분말로 용사된 용사층은 전혀 다른 산화거동을 보였다. 혼합분말의 경우에 $1000^{\circ}C$에서 50시간 등온산화실험 후, F/O=3.2의 조건인 경우에는 산화물이 표면 요철을 따라 비교적 균일하게 성장한 반면 F/O=3.0과 F/O=2.8의 경우에는 용사층 표면이 다공성의 산화물이 형성되었으며, 또한 Ni, Cr으로 이루어진 복합산화물인 oxide cluster로 성장하였다. 반면에 크래드 분말로 용사된 용사층의표면 산화물 층은 다공성을 변화되지 않았다. 이러한 용사분말의 제조방법에 따라 산화거동이 차이를 보이는 것은 용사 중에 발생하는 카바이드분해와 밀접한 관계가 있는 것으로 생각되며 또한 일반적으로 알려진 크롬카바이드 소결체 보다 산화율이 높았다. 이러한 결과로 볼 때, 환원성의 수소의 양에 따른 용사층의산화거동에 대해서도 연구가 필요할 것으로 생각된다.

• 한국전기전자재료학회논문지
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• 제23권11호
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• pp.875-879
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• 2010

In this study, we have characterized the roles of $Cr_2O_3$ on the sintering and electrical properties of ZnO. The densification and grain growth of Cr-doped ZnO (ZCr) system was mainly influenced by Cr contents. In the beginning of sintering, the densification of ZnO was retarded as reducing the Zni concentration in ZnO lattice with Cr doping. And the densification and grain growth of ZnO was more retarded due to a formation of spinel phase with increasing the Cr contents. ZCr system revealed varistor behavior with nonlinear coefficient $\alpha$ of 3~23 depending on the sintering temperature, implying double Schottky barrier formation on the grain boundary of ZnO. Especially the best varistor characteristics should be developed with 0.1~0.5 at% Cr contents and under $1100^{\circ}C$ in ZCr systems.

• 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.

• 대한임상검사과학회지
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• 제51권2호
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• pp.205-213
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• 2019

크롬염의 일종인 중크롬산칼륨($K_2Cr_2O_7$)의 세포독성을 배양 NIH3T3 섬유모세포를 재료로 산화적 손상측면에서 조사하였으며, 또한 $K_2Cr_2O_7$의 세포독성에 대한 짚신나물(Agrimonia pilosa var., AP) 추출물의 영향을 세포생존율을 비롯한 LDH 억제능 및 superoxide anion-radical (SAR) 소거능과 같은 항산화 측면에서 분석하였다. 본 실험에서 배양 NIH3T3 섬유모세포에 $25{\sim}35{\mu}M$의 $K_2Cr_2O_7$을 각각 처리한 결과, 처리 농도에 따라 대조군에 비하여 세포생존율이 유의하게 감소되었으며, 이 때 $XTT_{50}$값은 $37.5{\mu}M$에서 나타나 고독성(highly-toxic)인 것으로 나타났다. 또한, 항산화제인 BHT는 $K_2Cr_2O_7$의 세포독성을 유효하게 방어하였다. AP 추출물은 $K_2Cr_2O_7$의 세포독성에 의하여 감소된 세포생존율을 유의하게 증가시킴으로서 세포독성을 방어하였다. 이와 동시에, AP 추출물은 LDH 활성 저해능을 비롯하여 SAR 소거능을 보임으로서 항산화 효과를 나타냈다. 위의 결과로부터 $K_2Cr_2O_7$의 세포독성에 산화적 손상이 관여하고 있는 것을 확인하였고, AP 추출물은 $K_2Cr_2O_7$의 독성을 항산화능에 의하여 효과적으로 방어하였다. 따라서, AP 추출물과 같은 천연성분은 크롬과 같은 산화적 손상과 관련된 독성을 방어할 수 있으므로 산화적 손상에 의한 질환 치료를 위한 물질로 활용적 가치가 크다고 사료된다.