• 전기학회논문지
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• 제67권10호
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• pp.1375-1381
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• 2018

In this paper, we studied coatings of the DLC thin film for improving loosening torque of dental implant screw. We used a filtered arc ion plating process which can realize the most dense DLC layer by coating the DLC thin film on the surface of the dental abutment screw. It showed both hardness comparable to diamond and low friction coefficient similar to graphite, and to improve the loosening phenomenon by increasing the screw tightening force Cr/CrN, Ti/TiN or Ti/TiN/Cr/CrN buffer layers were deposited for 5 to 10 minutes to improve the adhesion of the DLC thin film to the surface of the Ti (Gr.5), and then the DLC thin film was coated for about 15 minutes. As a result, the Cr/CrN buffer layer exhibited the highest hardness of 29.7 GPa, the adhesion of 18.62N on average, and a very low coefficient of friction of less than 0.2 as a whole. And we measured loosening torque after one million times with masticatory movement simulator. As a result, the values of the coated screw loosening torque were clearly higher than those of the uncoated screw. From this, it was found that the DLC coating was effective methods improving the loosening torque. In addition, it was confirmed that the cytotoxicity test and cell adhesion test showed high biocompatibility.

• 한국분말재료학회지
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• 제16권3호
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• pp.185-190
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• 2009

Fe-Cr steels are the most promising candidate for interconnect in solid oxide fuel cells. In this study, an effective, dense and well adherent (LaSr)(CrCo)$O_3$ [LSCC] coating layer was produced onto 430 stainless steel (STS-430) by atmospheric plasma spraying and the oxidation behavior as well as electrical properties of the LSCC coated STS-430 were investigated. A significant oxidation of pristine STS-430 occurred at $800^{\circ}C$ in air environment, leading to the formation of $Cr_2O_3$ and $FeCr_2O_4$ scale layer up to ${\sim}7{\mu}m$ after 1200h, and consequently increased an area specific resistance of $330\;m{\Omega}{\cdot}cm^2$. Although the plasma sprayed LSCC coating contained the characteristic pore network, the coated samples presented apparent advantages in reducing oxidation growth of STS-430, resulting a decrease in oxide scale thickness of ${\sim}1{\mu}m$ at $800^{\circ}C$ after 1200h. The area specific resistance of the LSCC coated STS-430 was much reduced to ${\sim}7\;m{\Omega}{\cdot}cm^2$ after exposure at $800^{\circ}C$ for 1200h, compared to that of the pristine STS-403.

• 한국재료학회지
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• 제10권7호
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• pp.505-514
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• 2000

플라즈마 침탄한 저 탄소 Cr-Mo 강(0.176C-1.014Cr-0.387Mo)의 침탄 특성과 피로성질을 고찰하였다. 플라즈만 침탄한 시편의 유효경화깊이는 가스 침탄한 시편에 대해 상대적으로 침타나시간이 짧고 침탄온도가 낮음에도 불구하고 50%정도까지 증가되었다. 플라즈만 침탄시 유효경화깊이의 증가는 표면탄소농도의 증가와 같은 경향을 보였으며, 표면탄소농도의 증가와 같은 경향을 보였으며, 표면탄소농도의 증가율이 침탄시간의 증가에 따라 감소하였다. 플라즈만 침탄간의 피로한도는 가스 침탄강의 경우보다 높았다. 이를 표면근처의 미세구조, 경화깊이 잔류, 오스테나이트와 압축잔류응력으로 조사한 결과 경화깊이와 압축잔류응력의 차이가 거의 없었다. 따라서 플라즈만 침탄의 피로강도 향상은 가스침탄에 비해 표면이 상승층이 저감되어 표면에서의 미소균열의 발생 및 초기 균열 전파과정이 지연 되어진 것으로 판단된다. 파단면 관찰결과 표면에서 균열이 시작되고 플라즈마 침탄의 경우 입내파괴가 현저하였다.

• 한국표면공학회지
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• 제40권5호
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• pp.241-244
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• 2007

$MgF_2$/Cr/$MgF_2$, $MgF_2$/Cu/$MgF_2$ and $MgF_2$/Al/$MgF_2$ multi-layered thin films were fabricated by evaporation system. $MgF_2$ and Cr(Cu, And Al) was selected as a low refractive index material and mid reflector layer, respectively. Optical properties including color effect were systematically studied in terms of different film layer by using spectrophotometer. Experimental results were compared to the simulation result. The films consistings of $MgF_2$/Cr/$MgF_2$, $MgF_2$/Cu/$MgF_2$, $MgF_2$/Al/$MgF_2$ multi-layered thin films showed wavelength range of $430{\sim}780nm$, typically color range between greenish yellow and orange at view angle of $45^{\circ}$. It was confirmed that this experimental result was well matched with simulation result.

• 한국광학회지
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• 제11권5호
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• pp.360-364
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• 2000

반도체 포화 흡수거울 (Semiconductor Saturable Absorber Mirror:SESAM)을 이용하여 Cr:LiSAF 레이저를 제작하고 이를 모드록킹 시켰다. 펌핑 레이저는 파장이 667 nm이고, 출력이 500mW인 두 대의 고출력 레이저(Coherent S-67-500C-100-H)가 사용되었으며, 레이저 결정은 Brewster-Brewster 모양인 $Cr^{+3}$의 농도가 1.5%이고 길이가 6mm인 것을 사용하였다. 공진기는 X-형 구조로, 곡률반경이 10cmdls 오목거울과, 군속도 보상을 위한 SF10 프리즘, 투과율이 1%의 출력거울을 사용하였다. 포화흡수체로 사용되는 SESAM의 구조는 맨위층에 10nm의 $AlAs/Al_{0.15}Ga_{0.85}As$ 양자우물과 30쌍의 $AlAs/Al_{0.15}Ga_{0.85}As/GaAs/Al_{0.15}Ga_{0.85}As$반사경으로 구성되어 있다. 펌핑 레이저의 출력이 800mWdlfEo 레이저 출력은 3mW였고, 중심파장은 833nm이었으며 스펙트럼 대역폭은 4nm, 레이저 펄스폭은 220fs 였다.

• 한국재료학회지
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• 제4권6호
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• pp.704-709
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• 1994

Crystal Structure and Magnetic Properties of $(LaS)_xCrS_2(x \approx 1.20$)가 1273K에서 $La_S_3$ , Cr, S의 혼합물의 반응으로부터 합성되었다. $(LaS)_xCrS_2( x\approx 1.20$)의 XRD회절 pattern은 monoclinic의 LaS-부격자, triclinic의 $CrS_{2}$-부격자와 그들의 초격자로서 해석되었다. 부격자의 온도의존성을 저온에서 X-선 회절분석으로 조사하였다. 77K~실온의 온도역에서 $(LaS)_xCrS_2(x \approx 1.20$)의 자기자화율을 Faraday balance법으로 측정하였다. $(LaS)_xCrS_2(x \approx 1.20$)은 실온 $\sigma$ -H plot에서 paramagnetic한 거동을 나타내었다. 관측된 유효자기 moment($\mu_{eff}$)는 $Cr^{3+}$을 spin-only에 의한 것과 $La^{3+}$을 spin-only와 orbital에 의한 것으로 계산할 경우 잘 일치되었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.167-168
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• 2012

Films of CrN, $Cr_{40}Zr_9N$, and $Cr_{31}Zr_{16}N$ were deposited on a steel substrate by closed field unbalanced magnetron sputtering, and their oxidation behaviors at $700^{\circ}C$ and $800^{\circ}C$ for up to 60h in air were investigated. All the deposited films were composed of the CrN phase. Zirconium atoms in $Cr_{40}Zr_9N$ and $Cr_{31}Zr_{16}N$ films partially dissolved in the CrN phase. They advantageously refined the columnar structure, reduced the surface roughness, and increased the microhardness. The CrN film displayed relatively good oxidation resistance, owing to the formation of the highly protective $Cr_2O_3$ on its surface. The $Cr_{40}Zr_9N$ and $Cr_{31}Zr_{16}N$ films oxidized to $Cr_2O_3$ as the major phase and ${\alpha}-ZrO_2$ as the minor one. They oxidized primarily by the inward transport of oxygen. The addition of Zr could not increase the oxidation resistance of the CrN film, because the formed $ZrO_2$ that was intermixed in the $Cr_2O_3$-rich oxide layer was oxygen permeable, and developed the compressive stress in the oxide scale owing to the volume expansion during its formation.

• 한국표면공학회지
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• 제21권4호
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• pp.160-167
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• 1988

Electrochemical behaviors od chromium electrodeposition from 0.05M chromium (III) sulface complexes in aqueous solutions using sodium formate-glycine mixtures as a complexing agent were studied. In the cathodic current-potential cures, it is found that the intial limiting current of Cr(III) is proportional to square root of scan rate and activiation energy from Arrhenius plot is s obtained 3.05Kcal/mol. From this results, the reaction is considered, Cr3++e longrightarrow Cr2+, which is controlled diffusion of Cr (III). It is also found that the chromium is deposited when the potential reaches to hydrogen evolution potential. Effects of NaSCN as a catalyser in the electrolyte were investigated NCS- anion seems to react strongly by specific absorption at the inner HelmholtZ layer, so that, it is considered to suppress the electrodeposition reaction reaction for chromjum, and also it is considered multipe-bridge such as Cr(III)-NCS---M(M;cathode).

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.101-102
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• 2014

수소제조용 SMR(steam methane reforming) 공정에 사용될 수 있는 FeCrAl 다공체의 지지체-촉매의 결합력을 향상시키기 위하여 PEO(plasma electrolytic oxidation)법을 이용하여 FeCrAl 표면에 산화물을 형성시켰다. 열처리, 저전압, 고전압, 전해질 농도 등의 공정 조건에 따른 산화막의 형성 거동 및 형성된 산화물의 상분석 등을 진행하였다. PEO 공정을 이용하여 형성된 산화막은 다른 공정에 의하여 형성된 산화막과 비교할 때 치밀한 특징을 보였다. 따라서 본 연구를 통하여 향후 SMR 공정에 사용될 수 있는 FeCrAl 다공체의 내구성 및 수명 향상에 도움을 줄 것으로 기대되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1320-1322
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• 1997

The distribution of coercivity in the thickness direction were investigated by using Kerr hysteresis loop tracer for the Co-Cr films deposited by Facing Targets Sputtering apparatus. It $H_{c{\bot}}(S)- H_{c{\bot}}(I)$ correlated strongly with ${\Delta}H_c$, which represents the degree of distribution of coercivity. Furthermore, the Cr content was varied in order to improve the coercivity of intial growth layer $H_{c{\bot}}(I)$ took a maximum value of 750 Oe and the distribution of coercivity became sharper at the Cr content of 25 at.%.