Multi wall carbon nanotube 첨가 비율에 따른 양극산화 알루미늄과 필플라이 처리된 CFRP 이종 접합부의 접착 특성

다국어 초록 (Multilingual Abstract)

This study systematically analyzed the optimal process for maximizing shear bond strength in dissimilar joints between lightweight materials such as aluminum (Al) and carbon fiber-reinforced plastic (CFRP). To achieve this, a hybrid surface modification strategy was employed, combining sulfuric acid anodization of Al and peel-ply treatment of CFRP, with the addition of multi-walled carbon nanotubes (MWCNTs) to strengthen the bonding layer. The anodization of Al significantly increased the surface roughness (Ra) by approximately 6.7 times compared to the untreated state, forming a uniform micro- to nano-scale porous oxide layer that enhanced the mechanical bond. Simultaneously, the contact angle was significantly reduced from 77.55° to 14.7°, securing a superhydrophilic surface. This superhydrophilicity played a crucial role in enhancing the bonding strength by enabling the adhesive to fully penetrate the pores and minimizing interfacial voids. Furthermore, the Peel-Ply treatment of CFRP significantly increased the mechanical interlocking area and enhanced the interfacial shear load dissipation capacity by transferring the woven pattern of the fabric to the resin surface, creating microscopic irregularities. Multi-walled carbon nanotubes (MWCNTs) introduced into the adhesive layer effectively formed a stress-dispersing network and enhanced fracture toughness by inhibiting crack bridging and propagation. This nano-reinforcing effect was maximized when the MWCNT content was 0.6 wt.%. The optimized CF2/AA 0.6 specimen achieved a maximum shear strength of 15.094 MPa, which was approximately 178% higher than that of the untreated specimen. At 0.9 wt.%, a decrease in shear strength was observed due to excessive agglomeration of MWCNTs, which acted as stress concentration points. Analysis of the failure mechanism confirmed that the typical interfacial adhesive failure mode observed in the untreated specimen was converted to an internal failure mode (cohesive failure) within the adhesive layer in the optimized specimen. This technically verifies that the hybrid process successfully increases the interfacial strength beyond the internal strength of the adhesive layer itself.

목차 (Table of Contents)

• 1. 서론 1
• 1.1. 연구 배경 1
• 2. 실험 및 방법 6
• 2.1. 실험 재료 6
• 2.2. 표면 처리 및 시편 준비 10
• 2.2.1. 알루미늄 양극 산화 처리 11
• 2.2.2. CFRP 제조 13
• 2.2.3. MWCNTs 분산 에폭시 접착제 제조 14
• 2.2.4. 단일 랩 전단 시편 제조 15
• 2.3. 주사전자현미경(Scanning Electron Microscope, SEM) 17
• 2.4. 접촉각 분석(Water contact angle) 18
• 2.5. 원자현미경(Atomic Force Microscope, AFM) 19
• 2.6. 만능재료시험기(Universal Testing Machine, UTM) 20
• 3. 결과 및 고찰 21
• 3.1. 표면 개질에 따른 미시적 구조 및 거칠기 분석(SEM, AFM) 21
• 3.1.1. 알루미늄 표면 미세 구조 및 거칠기 변화 21
• 3.1.2. CFRP 표면 미세 구조 및 거칠기 변화 23
• 3.2. 표면 개질에 따른 Al, CFRP의 접촉각 분석 27
• 3.3. 접착 강도 분석 30
• 3.3.1. CFRP 제조 공법 차이에 의한 강도 분석 30
• 3.3.2. 알루미늄 양극 산화 처리에 의한 강도 분석 31
• 3.3.3. MWCNTs 나노 입자 첨가 효과 및 최적 함량 33
• 3.4. MWCNTs 함량에 따른 접착제의 미세구조 분석 36
• 3.5. 파괴 매커니즘 분석 39
• 4. 결론 42
• 참고 문헌 44
• Abstract 52