표제지
국문요약
영문요약
목차
제1장 서론 16
1.1. 서론 17
1.2. 참고 문헌 19
제2장 이론적 배경 22
2.1. 바이오매스 보일러 발전 산업 23
2.2. 바이오매스 보일러 부식 24
2.2.1. 연료공급부의 연소가스에 의한 부식(chlorine/chloride corrosion) 24
2.2.2. 염화물과 산화물의 반응에 의한 부식(Alkli corrosion) 25
2.2.3. 고온용융염부식 (hot corrosion) 26
2.2.4. 황화물에 의한 부식 26
2.3. 열용사공정기술 (Thermal spray process) 28
2.3.1. 전기 아크 용사 공정(Electric-Arc spray) 31
2.3.2. 고속 화염용사 코팅 공정(high velociry oxi-fuel spray(HVOF)) 33
2.3.3. 진공 플라즈마 용사 코팅 공정(vacuum plasma spray(VPS)) 35
2.3.4. 화염 용사 코팅 공정(Flame spray) 37
2.4. Fe계 비정질 38
2.4.1. Fe 계 metallic glass 38
2.5. Ni계 초내열 합금 42
2.6. 참고 문헌 44
제3장 용사 코팅 공정으로 제조된 신 Fe계 metallic glass 합금의 미세조직 및 부식 거동 48
3.1. 실험 방법 49
3.2. 결과 및 고찰 54
3.2.1. 합금조성 설계 및 후보 조성 합금 제조 54
3.2.1. Melt-Spinning 공정으로 제조된 Fe계 비정질 합금의 부식 특성 54
3.2.2. Thermal spray 선정을 위한 코팅층 제조 및 미세조직 관찰결과 65
3.2.2. Fe계 metallic glass 분말 제조 및 HVOF 공정을 이용한 코팅층 제조 67
3.2.2. Fe계 metallic glass 코팅층의 기계적 특성 평가 결과 75
3.2.2. Fe계 metallic glass 코팅층의 부식 거동 78
3.3. 결론 88
3.4. 참고 문헌 90
제4장 HVOF코팅 공정으로 제조된 Ni-based alloy 코팅층의 미세조직 및 부식 거동 93
4.1. 실험 방법 94
4.2. 결과 및 고찰 98
4.2.1. Ni-based alloy 분말의 제조 및 HVOF 코팅층의 미세조직 98
4.2.2. Ni-based alloy 코팅층의 기계적 특성 평가 결과 103
4.2.3. HVOF 공정으로 제조된 Ni-based alloy 코팅층의 부식 거동 105
4.3. 결론 117
4.4. 참고 문헌 118
제5장 바이오매스 보일러 실증화 test 121
5.1. 실험 방법 122
5.2. 결과 및 고찰 128
5.2.1. 바이오매스 보일러 환경에서 HVOF 코팅 공정으로 제조된 Fe계 합금의 부식 및 산화 128
5.2.2. 바이오매스 보일러 환경에서 HVOF 코팅 공정으로 제조된 Ni-based alloy 부식 거동 132
5.2.3. 바이오매스 보일러 환경에서 T91(substrate) 합금의 부식거동 136
5.2.4. 바이오매스 보일러 환경에서 보일러 내부 반응 모식도 및 부식 메커니즘 141
5.3. 결론 145
5.4. 참고 문헌 147
제6장 결론 148
1. HVOF sprayed Fe-based metallic glass와 Ni-based alloy 코팅층의 제조 및 부식 거동 149
2. Fe-based metallic glass 및 Ni-based alloy 코팅을 적용한 pilot test 150
Table. 3-1. Process parameters of Arc spray, Flame powder and HVOF processes in this study 53
Table. 3-2. design of Fe-based metallic glass composition 58
Table. 3-3. Chemical composition of Fe-based metallic glass (ICP, NOH) 73
Table. 4-1. Chemical composition of Ni-based alloy (ICP, NOH) 97
Table. 5-1. Boiler internal environment parameters 124
Table. 5-2. Chemical composition of ash 125
Fig. 2-1. Schematic diagram of Thermal spray process 29
Fig. 2-2. Type of thermal spray process 30
Fig. 2-3. Schematic diagram of atmosphere plasma spray process 32
Fig. 2-4. Schematic diagram of HVOF spray process 34
Fig. 2-5. Schematic diagram of vacuum plasma spray process 36
Fig. 2-6. Mechanical properties of Fe-based metallic glass 40
Fig. 2-7. Atomic radius and size 41
Fig. 3-1. Schematic diagram of the electrochemical measurement apparatus used for the experiment. 52
Fig. 3-2. XRD analysis of Fe-based metallic glass ribbon 59
Fig. 3-3. DSC analysis of Fe-based metallic glass ribbon 60
Fig. 3-4. Corrosion rate of Fe-based metallic glass ribbon 61
Fig. 3-5. Microstructure of 7.5% Cr Fe-based metallic glass ribbon 62
Fig. 3-6. Corrosion rate of Cr addition Fe-based metallic glass ribbon; (a) corrosion rate, (b) microstructure 63
Fig. 3-7. EPMA image of Fe-based metallic glass coating layers; (a) before corrosion (b) after corrosion 64
Fig. 3-8. Microstructure and macro image of coating layers 66
Fig. 3-9. EPMA image of Fe-based metallic glass powder 70
Fig. 3-10. XRD analysis results and DSC curves of Fe-based metallic glass powder; (a) XRD analysis, (b) DSC curves 71
Fig. 3-11. Microstructure of Fe-based metallic glass; (a) coationg layer (b) EDS mapping results 72
Fig. 3-12. XRD and DSC curve of Fe-based metallic glass powder; (a) XRD (b) DSC analysis results 74
Fig. 3-13. The analysis result of the adhesion test for the coating layer(a). Optical images of the coating layer (b) before and (c) after wear resistance test. 77
Fig. 3-14. Potentiodynamic polarization curves of HVOF sprayed Fe-based metallic glass coating layers and T91 alloy 82
Fig. 3-15. Microstructure of Fe-based matallic glass coating layer(surface) and EDS analysis results (a) passive current region (b),(c) after corrosion (d) EDS... 83
Fig. 3-16. Microstructure of Fe-based matallic glass coating layer(cross-sectional image) and EDS analysis results 84
Fig. 3-17. Cross-sectional microstructure observation results of HVOF sprayed Fe-based metallic glass coating layer using EPMA 85
Fig. 3-18. XPS results of HVOF sprayed Fe-based metallic glass passive film 86
Fig. 3-19. Schematic diagram of corrosion behavior of Fe-based metallic glass alloy 87
Fig. 4-1. Shape, size and microstructures of Ni-based alloy powder 96
Fig. 4-2. EDS mapping(TEM) of HVOF sprayed Ni-based alloy powder 100
Fig. 4-3. Microstructure and EDS mapping image of HVOF sprayed Ni-based alloy coating layers 101
Fig. 4-4. XRD analysis results of Ni-based alloy powder 102
Fig. 4-5. The analysis result of the adhesion test for the coating layer(a). Optical images of the coating layer (b) before and (c) after wear resistance test. 104
Fig. 4-6. Potentiodynamic polarization curves of HVOF sprayed Ni-based alloy coating layers and T91 alloy 110
Fig. 4-7. XRD analysis results of Ni-based alloy coating layer 111
Fig. 4-8. Microstructure of Ni-based alloy coating layer(surface) and EDS analysis results 112
Fig. 4-9. Microstructure of Ni-based alloy coating layer(cross-sectional image) and EDS analysis results (a)(b)(c) cross-sectional image and (d) EDS analysis results 113
Fig. 4-10. Microstructure of Ni-based coated alloy interface and EDS mapping results 114
Fig. 4-11. XPS results of HVOF sprayed Ni-based alloy passive film 115
Fig. 4-12. Schematic diagram of corrosion behavior of Ni-based alloy 116
Fig. 5-1. Schematic of bolier assembly 126
Fig. 5-2. Specimen of tube materials for pilot test 127
Fig. 5-3. Microstructure of pilot tested Fe-based matallicglass alloy; (a)before corrosion, (b) after corrosion, (c) after corrosion(surface) and (d) after corrosion(interface) 130
Fig. 5-4. XRD analysis result of pilot tested Fe-based metallic glass coating layer 131
Fig. 5-5. Microstructure of pilot tested Ni-based alloy; (a)before corrosion, (b) after corrosion, (c) after corrosion (surface) and (d) after corrosion (surface) 134
Fig. 5-6. XRD analysis result of pilot tested Ni-based alloy coating layer 135
Fig. 5-7. Microstructure of pilot tested T91 alloy (a) before corrosion, (b) after corrosion, (c) after corrosion (crack area) and (d) after corrosion (surface) 138
Fig. 5-8. XRD analysis result of pilot tested T91 alloy 139
Fig. 5-9. Microstructure of pilot tested T91 alloy and EDS analysis results 140
Fig. 5-10. Schematic diagram of biomass bolier corrosion reaction 144