HIP처리가 플라즈마 용사된 열차폐 코팅층의 접착강도와 고온특성에 미치는 영향

박영규; 김성휘; 김두수; 이영찬; 최철; 정진성; 김길무; 김재철; Young Kyu Park; Sung Hwi Kim; Doo Soo Kim; Young Chan Lee; Cheol Choi; Jin Sung Jung; Gil Moo Kim; Jae Chul Kim

Korean Journal of Materials Research, Vol.10, No.4, 312-316, April, 2000

Export Citation

HIP처리가 플라즈마 용사된 열차폐 코팅층의 접착강도와 고온특성에 미치는 영향

Effects of Hot Isostatic Pressing on Bond Strength and Elevated Temperature Characteristics of Plasma sprayed TBC

박영규, 김성휘¹, 김두수¹, 이영찬¹, 최철¹, 정진성¹, 김길무, 김재철¹

충남대학교 재료공학과
¹전력연구원 발전연구실 발전설비지원그룹

Young Kyu Park, Sung Hwi Kim¹, Doo Soo Kim¹, Young Chan Lee¹, Cheol Choi¹, Jin Sung Jung¹, Gil Moo Kim, and Jae Chul Kim¹

Dept. of Materials Engineering, Chungnam National University, Tejon, 305-764, Korea
¹Power Generation Laboratory, KEPRI, Taejon 305-380, Korea

초록

HIP처리가 가스터빈 고정익 등 고온부품에 적용되는 열차폐 코팅층의 접착강도 및 고온특성에 미치는 영향을 조사하였다. 시편은 IN738LC 초합금 표면에 8wt%Y 2 O 3 - ZrO 2 분말을 플라즈마 용사법으로 코팅한 후 1200 ? C , 100MPa의 고온, 고압에서 4시간 동안 HIP 처리하여 준비하였다. 실험결과 HIP 처리된 코팅의 경우 미세균열과 기공이 상당량 감소하였으며 EDX분석을 통해 계면에서 원자간 상호확산이 발생한 것을 확인하였다. 이러한 코팅층의 치밀화 및 상호확산으로 인해 HIP처리된 코팅층의 접착강도는 48% 이상 크게 증가하였으며 조직 또한 균질화 되었다. 반면 가열과 냉각이 반복되는 환경에서 코팅층의 내구력은 HIP 처리된 경우가 다소 저하되었다. 이는 코팅과 모재와의 열팽창 차이로 인한 변형을 완화시켜주는 기공과 미세균열이 감소되었기 때문으로 판단된다.

A study has been made to investigate the effects of hot isostatic pressing(HIP ping) on bond strength and elevated temperature characteristics of thermal barrier coating(TBC). The specimens were prepared by HIPping of TBC which is composed of the ceramic top coat(8wt% Y 2 O 3 - ZrO 2 ) and the metallic bond coat on the matrix of IN738LC superalloy. The results showed that the porosity and microcracks in the ceramic top coat of TBC were significantly decreased by HIP. As a result, the bond strength of the HIPped coating was increased above 48% compared to that of as-coated specimen and microstructure was homogenized. It was found that the thermal cycle resistance of HIPped coating was inferior to that of as-coated specimen. It was considered that this result was mainly caused by the reduction of internal defects in the top coat layer which could play a role in relaxing the thermal stress due to a large difference in thermal expansion between TBC and matrix.

Keywords:hot isostatic pressing;plasma spray;coating;ceramics

[References]

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[1] Khor KA, Loh NL, Materials Manufacturing Processing, 10(6), 1241 (1995)

[2] Miller RA, Lowell CE, Thin Solid Films, 95, 265 (1982)

[3] Hancun C, Zhengyi L, Yuzhi Z, Linkang X, Chinese J. Mechanical Eng., 5(3), 183 (1992)

[4] Chen HC, Pfender E, Heberlein J, Thin Solid Films, 293(1-2), 227 (1997)

[5] Gu YW, Koh KA, Fu YO, Wang Y, Surf. Coat. Technol., 96, 305 (1997)

[6] Radavich JF, Desai PD, MIAC Report 4, 18 (1994)