고체 산화물 연료전지용 Cr계 금속 연결재 제조 및 특성 연구

송락현 한국수소및신에너지학회 2005 한국수소 및 신에너지학회논문집 Vol.16 No.1

The LaCrO3-dispersed Cr alloys for metallic interconnect of solid oxide fuel cell were prepared as a function of LaCrO3 content in the range of 5 to 25 vol.% and were sintered at 1500 under an Ar atmosphere with 5 vol.% H2. The sintering and oxidation behaviors of these alloys were examined. The alloys indicated a good sinterability above 95% relative density at a given sintering condition, and their sintering densities is independent on LaCrO3 content. The LaCrO3 particles of the sintered alloys were concentrated on interfaces of Cr particles, and the size of the Cr particles increased with decreasing LaCrO3 content, which is caused by inhibited grain growth of Cr particle by LaCrO3 particle. The oxidation test showed all LaCrO3-dispersed Cr alloys have good oxidation resistance as compared with pure Cr, which is attributed to presence of LaCrO3 at the interface at which the oxidation reaction occurs rapidly. The Cr alloys with about 15 vol.% LaCrO3 are very resistant to oxidation.

고체 산화물 연료전지 금속 연결재용 $LaCrO_3$가 분산된 Cr 합금의 특성 연구

전광선,송락현,신동렬,Jeon, Kwang-Sun,Song, Rak-Hyun,Shin, Dong-Ryul 대한전기학회 1999 전기학회논문지C Vol.48 No.8

$LaCrO_3$-dispersed Cr alloys for metallic interconnector of solid oxide fuel cell have been studied as function of $LaCrO_3$ content in the range of 5 to 25 vol.% in order to examine the electric conductivity, the oxidation property and the thermal expansion behavior of these alloys. The $LaCrO_3$-dispersed Cr alloys showed high electrical conductivities of $3~5\times10^4$ S/cm at room temperature, and as the $LaCrO_3$content increased the conductivity decreased slightly. During the cyclic oxidation test at $1100^{\circ}C$, the weight change of the Cr alloys decreased with increasing number of oxidation cycle except first cycle, which is attributed to the vaporization of the oxide scale. More addition of the $LaCrO_3$ content reduced also the weight change of the Cr alloys. These mean that the oxide scale formed at the surface of the Cr alloy becomes stable with increasing number of oxidation cycle and$LaCrO_3$ content. The measured thermal expansion of the Cr alloy was well fitted to that of 8 mol% $Y_2O_3$-stabilized $ZrO_2$ electrolyte. These results demonstrate that $LaCrO_3$-dispersed Cr alloy is a useful material for metallic interconnector of solid oxide fuel cell.

가열방법에 따른 LaCrO$_3$ 연소합성분말의 특성

정층환,박홍규,오석진,박지연 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.10

금속 질산염과 urea를 사용하여 연소합성법에 의해 LaCrO3 분말을 제조하고, 용액의 pH를 HNO3와 NH4OH로 조절한 후, 용매의 가열방법에 따른 연소 생성물인 LaCrO3의 형상을 고찰하였다. 연소생성물의 수율은 용액의 pH에 의해 크게 좌우되었다. 용액의 pH가 0.7~4 사이에서는 90% 이상의 수율이 얻어졌으나, 5 이상 또는 0.5 이하의 pH에서는 수율이 크게 감소하였다. 한편, 연소생성물의 형상은 용액의 pH에 무관하였고 용액의 가열방법에 좌우되었다. 용액을 저항가열법으로 가열하여 연소반응시킨 경우의 분말은 미세한 일차입자들이 2차원적으로 연결된 응집체를 형성하고 있었으나, 마이크로파를 인가하여 가열한 경우에는 용액의 pH에 관계없이 미세한 LaCrO3 분말이 얻어졌다. BET 분석 결과, 마이크로파 가열에 의해 얻어진 입자의 비표면적은 25~32m2/g으로 저항가열법으로 가열한 경우의 10-14m2/g에 비해 더 큰 값을 보였다. 이러한 결과는 마이크로파에 의한 연소반응물의 균일한 가열이 연소생성물의 2차원적인 강항 응집체 형성을 억제할 수 있음을 보여 주었다. lanthanum chromite(LaCrO3) powder was synthesized by the combustion of a solution of metal nitrates La(NO3).6H2O and Cr(NO3)3.9H2O and urea. The pH of solution affected a yield of the combustion products but did not influence the morphology of the products. When the pH of the solution was in the range of 0.7-4, the yield of the combustion products was more than 90% The morphology of the combustion products was af-fected by heating methods for the solution. The hot-plate induced heating of the solution yielded powders hav-ing two-dimensionally interconnected agglomerates whereas microwave-induced heating produced a fine and non-agglomerated powders. The specific surface area(BET) of the combustion products using microwave-in-non-agglomerated powders. The specific surface area(BET) of the combustion products using microwave-in-duced heating method were larger(25~32m2/g) than that of hot plate heating method(10-14m2/g)

LaCrO_(3) 후막의 가스 감도 특성

신정호,장재영,김정규,박기철 경북대학교 센서기술연구소 1998 센서技術學術大會論文集 Vol.9 No.1

LaCrO_(3) thick film sensors were fabricated on an alumina substrate by screen printing method. The sensitivities for gases were investigated by varying the heat treatment temperatures of the films. The sensitivities of LaCrO_(3) thick film for Gallo and NH_(3) gases were better than for CO and NO gases. The best condition of heat treatment was 450℃ and the optimal operating temperature of LaCrO_(3) thick film for the highest sensitivity was 400℃. Sensitivities of LaCrO_(3) thick films about at 3000ppm for C_(4)H_(10) and NH_(3) gases were 85% and 95%, respectively.

고체산화물 연료전지용 (Ca,Sr)도핑된 LaCrO₃계 세라믹 연결재 코팅층의 특성 연구

이길용,백동현,송락현,Lee, Gil-Yong,Peck, Dong-Hyun,Song, Rak-Hyun 한국전기화학회 2005 한국전기화학회지 Vol.8 No.4

본 연구는 Pechini법을 이용하여 Ca과 Sr이 도핑된 $LaCrO_3$계의 $La_{0.6}Ca_{0.41}CrO_3$ (LCC41), $La_{0.8}Sr_{0.05}Ca_{0.15}CrO_3$, (LSCC), $La_{0.75}Ca_{0.27}CrO_3$ (LCC27) 분말들을 제조하여, 분말의 소결 특성 및 코팅층의 특성을 조사하였다. 제조된 LCC41, LSCC, LCC27 분말은 각각 0.6, 0.9, $1.5{\mu}m$의 평균 입자크기를 가졌으며, LCC41의 경우 $1400^{\circ}C$에서 98% 이상의 소결 밀도를 나타내었다. 연료극 지지체상의 LSCC 코팅은 LCC41층에 있는 Ca의 이동을 어느 정도 억제하는 역할을 하는 것으로 나타났다. 대기 용사 코팅된 LCC27은 치밀한 코팅막을 형성하였으며, 이 코팅층 위에 LCC41을 습식 코팅할 경우 더욱 치밀하고 높은 전기전도도를 갖는 코팅막을 얻을 수 있었다. 용사코팅된 LCC27, 습식 코팅된 LCC41는 높은 전기전도도를 나타내었으나, LSCC의 경우 낮은 소결성으로 인해 전기전도도가 작게 나타났다. Using Pechini method, we synthesized the $La_{0.6}Ca_{0.41}CrO_3$ (LCC41) and $La_{0.8}Sr_{0.05}Ca_{0.15}CrO_3$ (LSCC) powders for slurry dip coating, and $La_{0.75}Ca_{0.27}CrO_3$ (LCC27) powder for air plasma spray coating. The sintering property of the powders and their coating properties were investigated. The average particle sizes of the LCC41, LSCC, LCC27 were 0.6, 0.9, $1.5{\mu}m$, respectively. The relative density of LCC41 bulk was to be found about 98%. The LSCC coating on anode support prevented Ca migration of the coated LCC41 on the anode some or less, which was confirmed from EDS result. The air plasma spray-coated LCC27 with the dip-coated LCC41 were more dense and showed better electrical conductivity than those of the air plasma spray-coated LCC27 and the dip-coated LSCC and LSCC41. The LCC41 and LCC27 showed good electrical conductivities, but the LSCC had a poor electrical conductivity probably due to low sinterability

고체산화물 연료전지용 (Ca, Sr) 도핑된 LaCrO3계 세라믹 연결재 코팅층의 특성 연구

송락현,백동현,이길용 한국전기화학회 2005 한국전기화학회지 Vol.8 No.4

본 연구는 Pechini법을 이용하여 Ca과 Sr이 도핑된 LaCrO3계의 La0.6Ca0.41CrO3 (LCC41), La0.8Sr0.05Ca0.15CrO3 (LSCC), La0.75Ca0.27CrO3 (LCC27) 분말들을 제조하여, 분말의 소결 특성 및 코팅층의 특성을 조사하였다. 제조된 LCC41, LSCC, LCC27 분말은 각각 0.6, 0.9, 1.5 ㎛의 평균 입자크기를 가졌으며, LCC41의 경우 1400 ℃에서 98% 이상의 소결 밀도를 나타내었다. 연료극 지지체상에 LSCC 코팅은 LCC41층에 있는 Ca의 이동을 어느 정도 억제하는 역할을 하는 것으로 나타났다. 대기 용사 코팅된 LCC27은 치밀한 코팅막을 형성하였으며, 이 코팅층 위에 LCC41을 습식 코팅할 경우 더욱 치밀하고 높은 전기전도도를 갖는 코팅막을 얻을 수 있었다. 용사코팅된 LCC27, 습식 코팅된 LCC41는 높은 전기전도도를 나타내었으나, LSCC의 경우 낮은 소결성으로 인해 전기전도도가 작게 나타났다.

플라즈마 스프레이 (Ca, Co)-Doped LaCrO₃ 코팅층의 치밀화 및 전기전도도

박희진,백경호,Park, Hee-Jin,Baik, Kyeong-Ho 한국재료학회 2017 한국재료학회지 Vol.27 No.3

Doped-$LaCrO_3$ perovskites, because of their good electrical conductivity and thermal stability in oxidizing and/or reducing environments, are used in high temperature solid oxide fuel cells as a gas-tight and electrically conductive interconnection layer. In this study, perovskite $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC) coatings manufactured by atmospheric plasma spraying followed by heat treatment at $1200^{\circ}C$ have been investigated in terms of microstructural defects, gas tightness and electrical conductivity. The plasma-sprayed LCCC coating formed an inhomogeneous layered structure after the successive deposition of fully-melted liquid droplets and/or partially-melted droplets. Micro-sized defects including unfilled pores, intersplat pores and micro-cracks in the plasma-sprayed LCCC coating were connected together and allowed substantial amounts gas to pass through the coating. Subsequent heat treatment at $1200^{\circ}C$ formed a homogeneous granule microstructure with a small number of isolated pores, providing a substantial improvement in the gas-tightness of the LCCC coating. The electrical conductivity of the LCCC coating was consequently enhanced due to the complete elimination of inter-splat pores and micro-cracks, and reached 53 S/cm at $900^{\circ}C$.

SOFC 연결재용 Al이 도핑된 (La0.8Ca0.2)(Cr0.9Co0.1)O3(LCCC)계 세라믹스의 합성 및 치밀화 특성

이호영,이준형,강보경,이호창,허영우,김정주,김재육 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

In the (La0.8Ca0.2)(Cr0.9Co0.1)O3 (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x=0.02 in (La0.8Ca0.2)(Cr0.9Co0.1-xAlx)O3 (x= 0∼0.1), the samples showed the relative densities above ≥95%when those were sintered at ≥1,350℃. In the case of the x≥0.06 the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC). 고체 연료전지의 연결재로 사용되어온 (La0.8Ca0.2)(Cr0.9Co0.1)O3 (LCCC)에서 Co 이온반경과 거의 같아 치환을 하여도 LCCC의 tolerance factor에는 거의 영향을 주지 않을 것으로 생각되는 Al 이온을 Co 이온과 치환한 후 치환량에 따른 치밀화 거동, 고온 전기전도도, 열팽창거동을 조사하였다. (La0.8Ca0.2)(Cr0.9Co0.1-xAlx)O3 (x= 0∼0.1)에서 x= 0 및 x= 0.02 소결체의 경우, 1,350℃ 이상의 온도에서 95% 이상의 상대 밀도를 나타내었다. x≥0.06인 경우 저온에서는 소결밀도가 급격히 저하되어 치밀화에 악영향을 끼쳤다. 고온 전기전도도는 x값이 증가할수록 감소하는 거동을 나타내었다. 이것은 B-자리에 치환되는 Al 이온이 Cr이나 Co 이온과 같이 전자가 변화를 일으켜 전기전도에 기여할 수 없기에 일어난 현상으로 생각된다. 열팽창 계수는 Al 치환량이 증가할수록 감소하는 것으로 나타났다.

SOFC 연결재용 Al이 도핑된 (La_0.8Ca_0.2)(Cr_0.9Co_0.1)O₃(LCCC)계 세라믹스의 합성 및 치밀화 특성

이호영,강보경,이호창,허영우,김정주,김재육,이준형,Lee, Ho-Young,Kang, Bo-Kyung,Lee, Ho-Chang,Heo, Young-Woo,Kim, Jeong-Joo,Kim, Jae-Yuk,Lee, Joon-Hyung 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

In the $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x= 0.02 in $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1-x}Al_x)O_3$ (x= 0~0.1), the samples showed the relative densities above ${\geq}95%$ when those were sintered at ${\geq}1,350^{\circ}C$. In the case of the $x{\geq}0.06$ the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC).