Si-C 반응접합을 이용한 대면적 탄화규소 접합 연구

다국어 초록 (Multilingual Abstract)

Silicon carbide (SiC) is a promising structural ceramic for extreme-environment applications owing to its excellent mechanical strength and thermal and chemical stability. However, its strong covalent bonding and intrinsically low self-diffusivity severely limit conventional sintering to simple geometries, thereby necessitating reliable joining technologies for the fabrication of large and complex SiC components. Among various approaches, Si–C reaction bonding is particularly attractive because it enables SiC joint formation at relatively low temperatures, within short processing times, and without external pressure, making it well suited for large-area SiC joining.
In this study, a comprehensive processing framework for SiC joining via Si–C reaction bonding was established by systematically investigating the effects of key joining parameters, including molten-Si infiltration pathway (direct versus indirect), joining temperature and holding time, supplied Si quantity, substrate surface condition, filler tape thickness, and SiC/C filler composition. SiC/C filler tapes with compositions ranging from 10/90 to 90/10 wt% were fabricated by tape casting, inserted between SiC substrates, and joined under vacuum at approximately 1430 °C. The results clearly demonstrate that the continuity of molten-Si infiltration is the dominant factor governing uniform reaction-bonded SiC (RBSC) formation within the joint. Optimized direct infiltration, sufficient Si supply, and joining at 1430 °C for 20 min effectively suppressed incomplete reaction and pore formation, while substrate flatness and surface roughness were found to regulate wetting behavior and infiltration pathways. Thinner filler tapes promoted complete conversion owing to shorter infiltration distances, whereas thicker tapes increased the likelihood of residual unreacted regions.
Microstructural analyses further revealed that excessive carbon content hindered complete infiltration and resulted in unreacted phases, whereas overly SiC-rich fillers restricted RBSC formation. Among the compositions examined, the SiC/C = 70/30 wt% filler produced a dense and homogeneous joint microstructure with well-controlled residual Si. This condition yielded the highest flexural strength of approximately 268 MPa, with fracture consistently initiating in the SiC substrate rather than at the joint, confirming strong interfacial integrity and effective load transfer.
Overall, this work elucidates the critical processing–microstructure–property relationships governing Si–C reaction bonding and defines an optimal joining window for fabricating high-strength, large-area SiC structures. These findings provide a solid foundation for extending reaction-bonded joining technologies to advanced SiC-based components operating in demanding structural environments.

목차 (Table of Contents)

• 제 1 장 서론 11
• 제 2 장 이론적 배경 17
• 2.1 탄화규소(SiC)의 구조와 물리적 특성 17
• 2.2 SiC 의 접합 기술 20
• 2.2.1 고상확산 접합법 20
• 2.2.2 일시적 액상 접합 20
• 2.2.3 직접 접합 21
• 2.2.4 유리-세라믹 접합 22
• 2.2.5 금속 브레이징 25
• 2.2.6 Si-C 반응접합법 25
• 2.2.7 전구체 폴리머 접합 26
• 2.2.8 MAX 상 접합 26
• 2.3 반응접합 SiC 의 원리 32
• 2.4 SiC 접합 기술의 중요성과 응용 36
• 제 3 장 실험 방법 38
• 3.1 접합용 모재 준비 38
• 3.2 접합재 테잎 제조 39
• 3.3 접합 공정 41
• 3.4 접합용 지그 설계 44
• 3.5 미세조직 분석 및 기계적 특성 평가 46
• 제 4 장 실험 결과 및 고찰 48
• 4.1 용융 Si 함침 조건에 따른 접합 거동 분석 48
• 4.1.1 용융 Si 함침 방법 48
• 4.1.2 열처리 조건 52
• 4.2 SiC 접합 모재 표면 특성에 따른 접합 거동 분석 56
• 4.2.1 표면 평탄도 56
• 4.2.2 표면 거칠기 58
• 4.3 테잎 특성에 따른 접합 거동 분석 63
• 4.4 테잎 조성에 따른 접합 거동 분석 및 최적 조건 선정 68
• 4.4.1 접합부 미세구조 상 분석 68
• 4.4.2 함침 거동 분석 75
• 4.4.3 접합강도와 파단면 분석을 통한 최적 접합 조성 선정 79
• 4.5 대면적 접합에 최적 조건 적용 81
• 제 5 장 결론 84
• References 87