표제지
국문요약
영문요약
목차
제1장 서론 23
1.1. 연구 배경 24
1.2. 참고 문헌 27
제2장 이론적 배경 30
2.1. Fe-Cr-B 기반 metamorphic alloy 합금 (metamorphic alloy) 31
2.2. 다양한 코팅 공정 33
2.1.1. High-Velocity Oxygen Fuel (HVOF) 공정 33
2.1.2. 레이저 클래딩 공정 35
2.1.3. Plasma transferred arc welding (PTA) 공정 37
2.3. 참고 문헌 39
제3장 일반적인 공정으로 제조된 novel Fe-based metamorphic alloy의 미세조직과 물리, 기계적 특성 42
3.1. 서론 43
3.2. 실험 방법 45
3.2.1. 미세조직 분석 45
3.2.2. 기계적 특성 평가 45
3.2.3. 마모 및 부식 시험 46
3.3. 결과 48
3.3.1. 초기 미세조직 48
3.3.2. 기계적 특성 53
3.3.3. 마모 특성 57
3.3.4. 부식 특성 62
3.4. 고찰 67
3.5. 결론 69
3.6. 참고문헌 70
제4장 High-Velocity Oxygen Fuel 공정으로 제조된 novel Fe-based metamorphic alloy의 미세조직과 마모 및 부식 특성 76
4.1. 서론 77
4.2. 실험 방법 80
4.2.1. 초기 분말 80
4.2.2. High-velocity oxygen fuel (HVOF) 공정을 이용한 코팅 소재 제조 80
4.2.3. 코팅 소재의 경도 및 마모 특성 평가 81
4.3. 결과 및 고찰 84
4.3.1. 초기 분말 분석 84
4.3.2. HVOF 코팅 소재의 미세조직학적 특성 86
4.3.3. 상온 경도 및 마모 특성 96
4.3.4. High-velocity oxygen fuel 공정으로 제조된 Fe계 metamorphic alloy 합금의 부식 특성 및 거동 104
4.4. 고찰 110
4.3.1. HVOF 공정 중의 amorphization 110
4.3.2. Fe계 metamorphic alloy 합금의 상온 마모 거동 112
4.5. 결론 114
4.6. 참고 문헌 116
제5장 Laser cladding 공정으로 제조된 novel Fe-based metamorphic alloy의 미세조직과 마모 및 부식 특성 124
5.1. 서론 125
5.2. 실험 방법 127
5.2.1. Laser cladding으로 제조된 코팅 소재의 미세조직 분석 127
5.2.2. 경도 및 마모 시험 127
5.2.3. 부식 시험 128
5.3. 결과 130
5.3.1. Laser cladding 공정으로 제조된 Fe계 metamorphic alloy 합금의 초기 미세조직 130
5.3.2. 경도 및 마모 시험 결과 138
5.3.3. 3.5 wt.% NaCl 수용액에서의 부식 특성 147
5.4. 고찰 153
5.5. 결론 155
5.6. 참고문헌 156
제6장 Plasma transferred arc 공정으로 제조된 novel Fe-based metamorphic alloy의 미세조직과 마모 및 부식 특성 161
6.1. 서론 162
6.2. 실험 방법 164
6.2.1. 초기 분말 164
6.2.2. Plasma transferred arc (PTA) 공정을 이용한 코팅 소재 제조 164
6.2.3. 경도 및 마모 시험 165
6.2.4. 부식 시험 165
6.3. 결과 및 고찰 167
6.3.1. 초기 분말 분석 167
6.3.2. PTA 코팅 소재의 미세조직학적 특성 172
6.3.3. 경도 및 마모 시험 결과 181
6.3.4. Plasma transferred arc 공정으로 제조된 Fe계 metamorphic alloy 합금의 부식 특성 및 기구 188
6.4. 고찰 194
6.4.1. 마모 시험 중 비정질화 (Solid state amorphization reaction) 194
6.4.2. PTA 코팅 소재의 마모 거동 195
6.4.3. PTA 코팅 소재의 부식 거동 196
6.5. 결론 199
6.6. 참고문헌 200
제7장 결론 205
7.1. Fe-Cr-B 기반 metamorphic alloy의 마모 특성 206
7.2. Fe-Cr-B 기반 metamorphic alloy의 부식 특성 209
7.3. 결론 211
7.3.1. Conventional process로 제조된 Fe계 metamorphic alloy의 미세 조직과 물리, 기계적 특성 211
7.3.2. High-velocity oxygen fuel process로 제조된 Fe계 metamorphic alloy의 미세조직과 마모 및 부식 특성 211
7.3.3. Laser cladding process로 제조된 Fe계 metamorphic alloy의 미세조직과 마모 및 부식 특성 212
7.3.4. Plasma transferred arc welding 공정으로 제조된 Fe계 metamorphic alloy의 미세조직과 마모 및 부식 특성 213
Table 3-1. Chemical composition of HXA5. 47
Table 4-1. Chemical composition of HXA5. 83
Table 4-2. High-velocity oxygen fuel process conditions. 83
Table 5-1. Process parameters for HXA5 coating layer manufactured by laser cladding. 129
Table 6-1. Plasma transferred arc process parameters. 166
Table 6-2. Phase fraction of 0W, 10W and 20W. 176
Table 6-3. Nano indentation results of 0W, 10W, 15W show the reduced modulus (E r), hardness (H), H/Er and H³/Er².[이미지참조] 183
Figure 2-1. Schematic of high-velocity oxygen fuel spray process. 34
Figure 2-2. Schematic diagram of laser cladding process (coaxial powder system and preplaced powder system). 36
Figure 2-3. Schematic of plasma transferred arc welding process. 38
Figure 3-1. Initial microstructure of HXA5 manufactured by arc melting: (a) low magnification and (b) high magnification image. 50
Figure 3-2. Element distribution map observation using FE-EPMA of HXA5. 51
Figure 3-3. X-ray diffraction results of HXA5 (●: Fe(BCC), ■: (Cr,Fe)₂B, ▲: Cr₂B). 52
Figure 3-4. Strength-strain curve for arc melted HXA5 showing extremely brittle behavior. 55
Figure 3-5. (a,b) Fracture surface and (c,d) cross section on fracture sample after 3 point bending test; (a,c) low magnification and (b,d) high magnification images. 56
Figure 3-6. (a) wear volume, (b) wear rate graph of HXA5 compared to SCM440, and (c) coefficient of friction for various load conditions of HXA5. 59
Figure 3-7. Wear surface for (a,b) 3 kgf, (c,d) 4 kgf and (e,f) 5 kgf load condition; (a,c,e) low magnification and (b,d,f) high magnification images. 60
Figure 3-8. Wear surface images on (a) 3 kgf, (b) 4 kgf, (c) 5 kgf load condition samples and (d) chemical composition of tribofilm... 61
Figure 3-9. Potentiodynamic test results of HXA5 and SCM440. 64
Figure 3-10. (a) low magnification and (b) high magnification observed on cross section of corroded sample. 65
Figure 3-11. XPS results showing (a) Fe 2p spectrum, (b) Cr 2p spectrum and (c) Mo 3d spectrum on corroded sample surface. 66
Figure 4-1. (a₁) Morphology, (a₂) cross-section image, (b) image quality map, (c) phase map, (d) size distribution graph, and (e) X-ray diffraction result of initial HXA5 powder. 85
Figure 4-2. Optical microscope images of (a) HXA5, (b) WC-12Co, (c) WC-10Co-4Cr coating layer. 89
Figure 4-3. (a) BSE image, (b) image quality map, and (c) phase map of HXA5 coating layer. 90
Figure 4-4. Initial microstructure of (a) WC-12Co, and (b) WC-10Co-4Cr. 91
Figure 4-5. X-ray diffraction results of HXA5, WC-12Co, and WC-10Co-4Cr coating layer. 92
Figure 4-6. DSC curve of HXA5 coating layer showing crystalline temperature. 93
Figure 4-7. (a) TEM image, SAED pattern of (b) metallic glass, (c) precipitation, (d) un-melted area, EELS image of (e) splat area, and (f) un-melted area. 94
Figure 4-8. Optical microscope image of HXA5 coating layer after severe chemical etching. 95
Figure 4-9. Micro-Vickers hardness results of HXA5, WC-12Co, and WC-10Co-4Cr. 99
Figure 4-10. (a) Wear volume results, (b) wear rate results, coefficient of friction graph during wear test at (c) 3 kgf, (d) 4 kgf, and (e) 5 kgf load condition. 100
Figure 4-11. Surface image of HXA5 after wear test at (a), (b) 3 kgf, (c), (d) 4 kgf, and (e), (f) 5 kgf load condition. 101
Figure 4-12. EDS results on HXA5 surface after wear test at (a) 3 kgf, (b) 4 kgf, and (c) 5 kgf load condition. 102
Figure 4-13. Surface image of (a) WC-12Co, (c) WC-10Co-4Cr, and EDS results of (b) WC-12Co, (d) WC-10Co-4Cr after wear test at 5 kgf load condition. 103
Figure 4-14. Potentiodynamic test results of HXA5, WC-12Co, and WC-10Co-4Cr. 107
Figure 4-15. Cross-section image of (a,d) HXA5, (b,e) WC-12Co, and (c,f) WC-10Co-4Cr after potentiodynamic test. 108
Figure 4-16. XPS spectrum results on surface of (a,b,c) HXA5, (d,e) WC-12Co, and (f,g,i) WC-10Co-4Cr. 109
Figure 5-1. SEM observation image on cross section microstructure of laser cladded HXA5. 133
Figure 5-2. FE-EPMA images showing element distribution about the all elements constituting HXA5; (a) low magnification and (b) high magnification. 134
Figure 5-3. X-ray diffraction resultof laser cladded HXA5 result showing Fe (BCC) and (Cr,Fe)₂B. 135
Figure 5-4. EBSD observation results showing (a) IQ map, (b) IPF map and (c) phase map of laser cladded HXA5 cross section. 136
Figure 5-5. The graph of (a) Scheil-Guillivermodel, (b) matrix phase fraction when cooling rate is 10³ ℃/s, and (c) DSC curve. 137
Figure 5-6. Vickers hardness graph from cladded surface to substrate. 141
Figure 5-7. EPMA line scannig result from resin to substrate. 142
Figure 5-8. (a) Coefficient of friction graph, (b) wear volume graph and (c) wear loss graph of laser cladded HXA5 per 3, 4, 5 kgf load conditions. 143
Figure 5-9. SEM observation on wear surface of (a,b) 3 kgf condition, (c,d) 4 kgf condition and (e,f) 5 kgf condition sample; (a), (c), (e) low magnification images showing the overall wear track and (b), (d),... 144
Figure 5-10. Element composition using EDS point analysis on wear surface of (a) 3 kgf, (b) 4 kgf and (c) 5 kgf load condition. 145
Figure 5-11. HR images and FFT images showing metallic glass of (a) 3 kgf, (b) 4 kgf, and (c) 5 kgf. 146
Figure 5-12. Potential and Current graph of laser cladded HXA5 during potentiodynamictest in 3.5% NaCl solution. 149
Figure 5-13. (a) low magnification and (b) high magnification images after potentiodynamic test. 150
Figure 5-14. Overall constituted alloying elements distribution map after potentiodynamic test. 151
Figure 5-15. XPS results showing the (a) Fe 2p, (b) Cr 2p and (c) Mo 3d peaks on corroded surface. 152
Figure 5-16. STEM image and EDS map below the wear surface during 5 kgf load condition wear test. 154
Figure 6-1. Size distribution graph of blending powder per WC-12Co content. 168
Figure 6-2. (a) Initial powder morphology image and (b) cross-section image of CA01. 169
Figure 6-3. Element distribution map of (a) CA01 and (b) WC-12Co powder. 170
Figure 6-4. X-ray diffraction results of blending powder (■: Fe(BCC), ●: (Cr,Fe)₂B, ▲: Cr₂B, ◆: WC). 171
Figure 6-5. Initial microstructure of different coating samples (a,d) 0W, (b,e) 10W and (c,f) 20W. 175
Figure 6-6. X-ray diffraction graphs of coating samples by PTA welding (0W, 10W and 20W). 177
Figure 6-7. Element distribution map of (a) 0W, (b) 10W and (c) 20W. 178
Figure 6-8. Full width at half maximum (FWHM) value and diffraction angle graph of coating layer. 179
Figure 6-9. DSC curve of (a) 0W, (b) 10W and (c) 20W. 180
Figure 6-10. (a) Coefficient of friction graph, (b) wear volume graph and (c) wear rate graph of 0W, 10W, 20W. 184
Figure 6-11. Wear track surface images of (a,d) 0W, (b,e) 10W and (c,f) 20W; (a)-(c) low magnification and (d)-(f) high magnification. 185
Figure 6-12. EDS results on wear track surface of (a) 0W, (b) 10W and (c) 20W. 186
Figure 6-13. TEM and FFT images of (a) 0W, (b) 10W and (c) 20W show the metallic glass formation. 187
Figure 6-14. Potentiodynamictest results in 3.5 % NaCl solution of 0W, 10W and 20W. 190
Figure 6-15. SEM images on the surface of (a,d) 0W, (b,e) 10W, (c,f) 20W after corrosion test; (a)-(c) low magnification images and (d)-(f) high magnification images. 191
Figure 6-16. FE-EPMA results on corroded sample cross section (a) 0W, (b) 10W and (c) 20W. 192
Figure 6-17. XPS spectra for the passive film formed on (a,b) 0W, (c,d,e) 10W and (f,g,h) 20W. 193
Figure 6-18. XPS spectrum results of 0W, 10W and 20W showing the Cr intensity difference. 198
Figure 7-1. Overall wear rate comparable graphs according to load conditions (3, 4, 5 kgf). 208
Figure 7-2. Overall corrosion properties in 3.5 wt.% NaCl solution. 210