표제지
목차
제출문 2
요약문 3
SUMMARY 7
세부과제 1. Microsurfacing 기술개발(Development of Microsurfacing Technology) 11
목차 12
Contents 14
제1장 서론 19
제2장 플라즈마 용사 세라믹의 dielectric properties 22
2.1. 세라믹 절연체(Ceramic Insulator) 22
2.1.1. 유전손실인자(Dielectric loss factor) 23
2.1.2. 유전상수(Dielectric constant) 24
2.1.3. 유전강도(Dielectric strength) 27
2.2. 플라즈마 용사한 alumina 코팅층의 dielectric 특성 28
2.2.1. 플라즈마 용사한 alumina 코팅층의 기본물성 28
2.2.2. 용사 코팅층의 Structure와 Dielectric 특성과의 관계 29
제3장 플라즈마 용사시험 35
3.1. 정밀 용사를 위한 플라즈마 용사장비의 정비 35
3.1.1. 용사 gun의 DSP board에 의한 제어 35
3.1.2. 용사 gun 이송속도의 정확한 제어 38
3.1.3. 플라즈마 beam의 monitoring 38
3.2. 실험재료, 시험편 및 치구의 제작 40
3.2.1. 모재 및 용사 분말 40
3.2.2. 코팅을 위한 시험편 및 치구 제작 41
3.3. 플라즈마 용사 시험 절차 41
3.3.1. Grit blasting 44
3.3.2. 플라즈마 용사 코팅 45
제4장 Al₂O₃계 세라믹 분말의 용사코팅 및 특성 분석 50
4.1. 굵은 98.5Al₂O₃-1SiO₂ 세라믹 분말의 용사거동 50
4.1.1. 용사분말의 송급에 대한 분석 51
4.1.2. 용사 코팅층의 두께, 및 효율의 측정 54
4.1.3. 코팅층의 미세조직 분석 57
4.2. 미세 99.5Al₂O₃ 세라믹 분말의 용사거동 60
4.2.1. 용사분말의 송급에 대한 분석 60
4.2.2. 용사 코팅층의 두께, 및 효율의 측정 63
4.2.3. 코팅층의 미세조직 분석 65
제5장 Al₂O₃-TiO₂계 세라믹 분말의 플라즈마 용사 및 코팅층의 물성평가 70
5.1. 용사분말 분석 및 플라즈마 용사 조건설정 70
5.2. 용사코팅층의 두께 및 표면칠기의 측정 73
5.2.1. 용사코팅층의 두께 측정 73
5.2.2. 용사코팅층의 표면 거칠기 75
5.3. 용사 코팅층의 미세구조 분석 77
5.3.1. X선 회절분석에 의한 결정상 분석 77
5.3.2. 코팅층 미세조직의 분석 84
5.4. 전기적 특성의 측정 88
5.5. 접합강도의 측정 91
제6장 검토 97
제7장 결과 98
참고문헌 99
세부과제 2. Laser Microstructuring & Cladding 기술 개발(Development of Laser Microstructuring & Cladding Technology) 101
목차 102
Contents 104
제1장 서론 109
제2장 Laser Microstructuring 112
2.1. 개요 112
2.2. 기술 현황 113
2.2.1. Subtractive method 114
2.2.2. Semi-additive method 115
2.2.3. Additive method 116
2.3. 실험 장치 116
2.3.1. X-Y Table에 의한 Focusing System 117
2.3.2. Scanner에 의한 Focusing System 127
2.3.3. UV & Visible 레이저 Focusing System 132
2.4. CO₂ Laser Modification 140
2.4.1. 연구의 배경 및 목표 140
2.4.2. 유도 천이에 의한 레이저빔의 증폭 140
2.4.3. Single Pass에 의한 레이저빔의 증폭 143
2.4.4. 시스템 구성 계획 145
2.4.5. Seed Laser 빔 특성 148
제3장 Laser cladding 150
3.1. 개요 150
3.2. 기술 현황 151
3.3. 분말공급 시스템 153
3.3.1. 분말공급시스템의 설계 153
3.3.2. 분말공급 시스템의 특성 평가 158
3.3.3. Laser Cladding 기초 실험 163
3.4. 특성 평가 및 기초 실험 결과 174
제4장 결론 175
참고문헌 176
Appendix 179
Appendix 1. XY Table 구동 Program 179
Appendix 2. Keys.h 194
Appendix 3. Timer_.c 196
세부과제 3. MICRO JOINING 접합부의 성능평가 기술개발(EVALUATION OF INTERFACE STRENGTH FOR MICRO JOINED COATING/SUBSTRATE) 200
목차 201
Contents 205
1. 서론 212
2. 적층접합체의 역학적 특성 215
2.1. 열응력의 해석 215
2.1.1. 열응력에 영향을 미치는 인자 215
2.1.2. 열응력 해석의 개념 216
2.2. 적층접합체의 열적특성 218
2.2.1. 재료정수와 열응력 218
2.2.2. 적층접합체의 열응력 해석 222
2.2.3. 적층접합계면 단부근방의 열탄성응력 특성 224
2.2.4. 열응력의 탄소성해석 228
2.3. 적층접합체의 열응력특성의 지배인자 229
2.3.1. 접합체의 크기, 형상의 영향 229
2.3.2. 재료 특성값의 영향 232
2.3.3. 금속-Ceramics의 접합에서의 잔류응력 233
2.4. 박막의 내부응력 특성의 평가 234
2.4.1. 박막형성시 내부응력의 발생 234
2.4.2. 박막의 잔류응력 측정 235
2.4.3. 용사 피막의 잔류응력 237
3. 적층접합체의 잔류응력 측정법의 제안 239
3.1. 3차원 잔류응력 측정방법 239
3.1.1. 3차원 잔류응력 측정법의 배경 239
3.1.2. 3차원 잔류응력의 간이측정법 240
3.1.3. 3차원 잔류응력의 간이측정법에 대한 고찰 242
3.2. 3차원 잔류응력 측정이론 243
3.2.1. 고유 strain법에 의한 3차원 잔류응력 측정이론 243
3.2.2. 3차원 고유 strain성분의 분리 244
3.2.3. 횡단면내 고유 strain에 의한 3차원 응력 246
3.2.4. 용접선 방향 고유 strain에 의한 3차원 응력(δB)[이미지참조] 247
3.2.5. 고유 strain법에 의한 3차원 잔류응력 측정이론의 고찰 247
3.3. 적층접합체의 잔류응력 측정 247
3.3.1. 적층접합체에 대한 잔류응력 측정법의 기초적 검토 248
3.3.2. 적층접합체의 잔류응력 측정법의 실험적 검토 248
3.3.3. Coating에 의한 적층접합체의 잔류응력 측정 252
4. 적층접합체의 계면강도 255
4.1. 적층접합계면강도의 평가법 255
4.2. 서로다른 bulk재의 적층접합체의 계면 강도 특성 256
4.3. 접합계면 강도에 미치는 인자 및 그 영향 257
4.3.1. 잔류응력, 열응력 257
4.3.2. 중간층 258
4.4. Coating층의 강도 259
4.4.1. Coating층의 역학적 특성 259
4.4.2. Coating층의 성능평가법 261
5. 적층접합체의 파괴강도 266
5.1. 적층접합체의 파괴 역학적 특성 266
5.1.1. 크랙을 가진 강도적 불균질재료 267
5.1.2. 크랙주변의 응력, strain 특성 267
5.1.3. 강도적 불균질재의 파괴조건 269
5.2. 적층접합체의 파괴지표 parameter의 의미 269
5.3. 크랙전파방향 응력의 특성 271
5.3.1. 실험방법 및 실험결과 271
5.3.2. 고찰 273
5.4. 크랙 근방의 응력, strain의 해석 273
5.4.1. 실험결과의 해석적 검토 274
5.4.2. 해석에 의한 검토의 확장 279
6. 결론 289
참고문헌 290
List of Tables
세부과제 1. Microsurfacing 기술개발(Development of Microsurfacing Technology) 16
Table 2.1. Dielectric constants of some crystals and glasses(at 25℃ and 10⁶Hz) 25
Table 2.2. Typical values of ceramic insulation 25
Table 3.1. Chemical composition, physical and mechanical properties of 7075 Al alloy substrate 40
Table 3.2. Plasma spray coating condition for ceramic powder 48
Table 3.3. Plasma spray coating condition for Ni-5Al bond coating powder 49
Table 4.1. Experimental arrangement to estimate powder feeding characteristics of... 52
Table 4.2. Changes of the coating weight, coating thickness and coating efficiency... 54
Table 4.3. Experimental arrangement to estimate powder feeding characteristics of... 61
Table 4.4. Changes of the coating weight, coating thickness and coating efficiency... 65
Table 5.1. Summary of the characteristics of three Al₂O₃-TiO₂ and bond coating powder 73
Table 5.2. Coating thickness and surface roughness 76
Table 5.3. Electrical properties of the coatings 89
Table 5.4. Some properties of two high alumina ceramics of different composition 90
Table 5.5. Tensile adhesion test results of the coatings according to ASTM C-633 91
세부과제 2. Laser Microstructuring & Cladding 기술 개발(Development of Laser Microstructuring = Clgy) 106
Table 2.1. System Specification for Microstructuring 119
Table 2.2. CW laser power vs lamp current 121
Table 2.3. Pulse energy and peak power by external modulation 122
Table 2.4. Pulse energy and peak power by internal modulation 123
Table 2.5. System spec. of galvano-scanner 128
Table 2.6. Specification of UV Ar - Ion laser INNOVA 328 133
Table 2.7. Specification of Visible Ar - Ion laser 2017-04S 134
Table 2.8. Measured characteristic of the 2017-04S 135
Table 2.9. Optics specification 146
Table 2.10. FEHA laser and CO₂ specification 146
Table 3.1. Feed rate vs rpm 159
Table 3.2. Chemical composition(wt %) of powder MP1 163
Table 3.3. Cladding conditions(I) 167
Table 3.4. Cladding conditions(II) 170
Table 3.5. Cladding conditions(III) 172
세부과제 3. MICRO JOINING 접합부의 성능평가 기술개발(EVALUATION OF INTERFACE STRENGTH FOR MICR= JOBSTRATE) 204
표 2-1. 박막의 잔류응력 측정법의 원리와 특징 237
세부과제 1. Microsurfacing 기술개발(Development of Microsurfacing Technology) 17
Fig. 2.1. Example of Hybrid IC utilizing plasma spray coating of alumina ceramic as... 20
Fig. 3.1. Scheme of Motion controller 36
Fig. 3.2. Typical wiring of DC servo motor with differential encoder 36
Fig. 3.3. Plasma spary coating system with DSP controlled gun motion 37
Fig. 3.4. Capture graph showing real gun motion 39
Fig. 3.5. Plasma beam image captured by the CCD camera 39
Fig. 3.6. Specimens for measuring various coating properties and for testing adhesive strength 42
Fig. 3.7. Jig to fix the specimens tightly during plasma spraying procedure 43
Fig. 3.8. Size and shape of the alumina grit used in the grit blasting 45
Fig. 3.9. Photographs showing surface roughness after grit blasting 46
Fig. 4.1. SEM photograph showing the shape and size distribution of 98.5Al₂O₃-1SiO₂ powder 51
Fig. 4.2. Dependence of the powder feeding rate on the powder feed setting and gas flow rate 53
Fig. 4.3. Change of the coating weight with powder feed rate 55
Fig. 4.4. Change of the coating thickness with powder feed rate 55
Fig. 4.5. Change of the deposition efficiency with powder feed rate 56
Fig. 4.6. Linear relationship between the coating weight and coating thickness 56
Fig. 4.7. Micrographs of the coatings with different powder feeding rate 58
Fig. 4.8. Comparison of the coating thickness between the thickness meter and SEM micrograph 59
Fig. 4.9. SEM photograph showing the shape and size distribution... 60
Fig. 4.10. Dependence of the powder feeding rate on the powder feed setting and gas flow rate 62
Fig. 4.11. Change of the coating weight with powder feed rate 64
Fig. 4.12. Change of the coating thickness with powder feed rate 64
Fig. 4.13. Change of the deposition efficiency with powder feed rate 66
Fig. 4.14. Linear relationship between the coating weight and coating thickness 66
Fig. 4.15. Micrographs of the coatings with different powder feeding rate 68
Fig. 4.16. Comparison of the coating thickness measured by the thickness meter with... 69
Fig. 5.1. Photographs showing the shape and size of alumina-titania powder for top... 71
Fig. 5.2. Photograph showing the shape and size of Ni-5Al metal powder for bond coating 72
Fig. 5.3. Appearance of the specimens coated with three different Al₂O₃-TiO₂ powder 74
Fig. 5.4. Comparison of the coating thickness measured by the thickness meter with... 75
Fig. 5.5. Surface roughness of three different Al₂O₃-TiO₂ coatings 76
Fig. 5.6. X-ray diffraction profiles of the Al₂O₃-TiO₂ ceramic powder 78
Fig. 5.7. X-ray diffraction profiles of the Al₂O₃-TiO₂ ceramic coatings 81
Fig. 5.8. Al₂O₃-TiO₂ phase diagram 84
Fig. 5.9. SEM cross sections of the different Al₂O₃-TiO₂ coatings 85
Fig. 5.10. Magnified micrograph of the Al₂O₃-13TiO₂ coating 88
Fig. 5.11. Tensile adhesion test method according to ASTM C-633 92
Fig. 5.12. Photographs showing fracture surface after tensile adhesion test 93
세부과제 2. Laser Microstructuring & Cladding 기술 개발(Development of Laser Microstructuring & Cladding Technology) 107
Fig. 2.1. Schematic of Nd:YAG laser microstructuring system with x-y table 118
Fig. 2.2. Photograph of the experimental set-up for microstructuring with Nd:YAG-laser... 118
Fig. 2.3. Pulse shape by external modulation 122
Fig. 2.4. Pulse shape by internal modulation 123
Fig. 2.5. Program flow chart 124
Fig. 2.6. Subprogram flow chart 126
Fig. 2.6. Schematic diagram of laser beam scanning system 127
Fig. 2.7. Coordinate of scanner 128
Fig. 2.8. Post-objective system and pre-objective system 130
Fig. 2.9. The principle of dynamic focusing 130
Fig. 2.10. Writing along straight line(Velocity=1500㎛/s) 137
Fig. 2.11. The shape of the solidified polymer... 138
Fig. 2.12. The shape of the solidified polymer... 139
Fig. 2.13. Photon absorption and emission of two level energy state 141
Fig. 2.14. Laser operation at three level and four level energy state 143
Fig. 2.15. Photon amplification at amplifier medium 143
Fig. 2.16. The diagram of CO₂ laser amplifier system 145
Fig. 2.17. The operation of A/O modulator 147
Fig. 2.18. The result of measurement for beam quality 149
Fig. 3.1. Powder feeding system 154
Fig. 3.2. A picture of powder feeding system 155
Fig. 3.3. Powder supply nozzle 155
Fig. 3.4. Rotating disc 156
Fig. 3.5. Powder exit nozzle 157
Fig. 3.6. Powder behavior at nozzle 158
Fig. 3.7. The system of feed rate measurement 159
Fig. 3.8. Feed rate measurement at various rpm 160
Fig. 3.9. Feed rate vs rpm 160
Fig. 3.10. Measurement of powder efficiency 161
Fig. 3.11. Efficiency at various spot size 162
Fig. 3.12. Photograph of the experimental set-up for cladding 164
Fig. 3.13. The focused beam radius along the beam path 165
Fig. 3.14. Spacial distribution of laser beam(1500 W, CO₂ laser) 166
Fig. 3.15. Intensity distribution near the focal point 167
Fig. 3.16. Cross-section & plane view of cladding layer(I) 168
Fig. 3.17. Cross-section & plane view of cladding layer(II) 170
Fig. 3.18. Cross-section & plane view of cladding layer(III) 173
세부과제 3. MICRO JOINING 접합부의 성능평가 기술개발(EVALUATION OF INTERFACE STRENGTH FOR MICRO JOINED COATING/SUBSTRATE) 209
Fig. 2-1. Basic concept of thermal stress analysis 217
Fig. 2-2. Relafion hetween Young's modulus and thermal expansion coefficient 219
Fig. 2-3. Stress produced by bonding of dissimilar materials 220
Fig. 2-4. Thermal stress in bonded joint of dissimilar materials... 221
Fig. 2-5. Illustration of thermal stress in bonded joints of dissimilar materials... 222
Fig. 2-6. Illustration of multi layer bonded joint 224
Fig. 2-7. Characteristics of thermal stress and strain at the edge of bond line... 226
Fig. 2-8. Stress sigularity at the edge of bond line... 227
Fig. 2-9. Variation of constant term of residual stress at the edge of bond line 227
Fig. 2-10. Effect of plastic deformation on thermal stress characteristics 228
Fig. 2-11. Effect of plate thickness on thermal stress (a) Distribation of thermal stress... 230
Fig. 2-12. Residual stress distribution at the edge of bond line 231
Fig. 2-13. Effect of Young's modulus on thermal stress 232
Fig. 2-14. Stress sigularity parameters applicable to ceramic/metal joint... 233
Fig. 2-15. Internal stress produced by coating of dissimilar meterials 235
Fig. 2-16. Measurement of residual stress by substrate deforming method... 236
Fig. 3-1. Illustration of residual stress in thick welded plate 240
Fig. 3-2. Measuring procedure of triaxial residual stress 243
Fig. 3-3. T-specimen 244
Fig. 3-4. L-specimen 245
Fig. 3-5. Test spacimen design for measuring residual stress in bonded joint 250
Fig. 3-6. Variation of residual stress depending on the plate thickness for meltrun specimen 251
Fig. 3-7. Variation of residual stress depending on the substrate thickness for... 253
Fig. 4-1. Type of fracture of bonded joints 256
Fig. 4-2. Effect of difference in thermal expansion coefficients on interface strength 258
Fig. 4-3. A model for porosity in plasma spray ceramic coating 259
Fig. 4-4. Schematic illustration of bonding state 260
Fig. 4-5. Mechanical concept of ceramic coating 261
Fig. 4-6. Material constants of thermal spray coating... 262
Fig. 4-7. Pin test 264
Fig. 5-1. Basic fracture modes for mechanical heterogeneity of dissimilar meterials 267
Fig. 5-2. Stress distribution in vicinity of interface of bonded joint 268
Fig. 5-3. Comparison of fracture modes for welded joint and bonded joint 270
Fig. 5-4. Distribution of - Ex/Er on the line of crack propagation(Experimental result)[이미지참조] 272
Fig. 5-5. Distribution of - E11/E22 on the line of crack propagation(Analytical result)[이미지참조] 275
Fig. 5-6. Geometry and modeling for analysis 276
Fig. 5-7. Distribution of stress and strain on the line of crack propagation direction... 277
Fig. 5-8. Distribution of - Ex/Er on the line of crack propagation for notched status[이미지참조] 278
Fig. 5-9. Distribution of stress and strain on the line of crack propagation direction... 281
Fig. 5-10. Distribution of - Ex/Er on the line of crack propagation for closed crack[이미지참조] 282
Fig. 5-11. Distribution of stress and strain on the line of crack propagation direction... 285
Fig. 5-12. Variation of distributions of stress perpendicular to crack propagation... 286
Fig. 5-13. Dugdale model and Barenblatt model 286