표제지
목차
국문초록 11
제1장 서론 13
제2장 문헌연구 16
2.1. 산화물반도체식 가스센서 16
2.1.1. SnO₂ 나노선 네트웍 구조 기반 NO₂ 센서 21
2.1.2. 기타 반도체식 가스센서 23
2.2. 고체전해질을 이용하는 전기화학센서 24
2-2-1. 제I형식 평형전위형 센서(Type I Equlibrium potentiometric type sensor) 26
2-2-2. 제 II형식 평형전위형 센서(Type II Equlibrium potentiometric type sensor) 28
2-2-3. 제 III형식 평형전위형 센서(Type III Equlibrium potentiometric type sensor) 32
2-2-4. 혼합전위형 센서 40
제3장 실험방법 46
3.1. NO₂ 센서의 제작 46
3.1.1. Heater 제조 48
3.1.2. Solid Electrolyte Buffer Layer 제조 48
3.1.3. Solid Electrolyte 제조 50
3.1.4. Sensing Electrode 제조 55
3.1.5. Reference Electrode 제조 55
3.1.6. Wire bonding과 packaging 55
3.2. 분광학적 분석 58
3.3. 센서의 기전력측정 58
제4장 결과 및 고찰 60
4.1. NO₂ 센서용 용사코팅법에 의해 제조한 전해질 특성에 연구 60
4-1-1. 용사코팅을 위한 Al₂O₃ 기판 조도형성 및 특성 60
4-1-2. Buffer Layer와 YSZ 용사코팅 전해질층에 관한 접착 특성 73
4-1-3. 8YSZ 용사코팅 전해질층에 관한 미세구조 특성 76
4-1-4. 8YSZ 용사코팅층 결정구조 및 X-ray 회절 pattern 분석 81
4-1-5. 8YSZ 용사코팅 전해질 층의 이온전도도 특성 84
4-1-6. 8YSZ 용사코팅 전해질 층의 NO₂ 가스 감도 특성 89
4.2. NO₂ 가스 센서 감지물질 및 감도 특성 향상에 관한 연구 92
4-2-1. 센서 감지물질에 관한 미세구조 특성 92
4-2-2. 감지물질에 따른 NO₂ 가스 감응 특성 97
제5장 결론 113
References 116
Abstract 120
Table 1-1. Government NO₂ Gas Classification and Emission Standards 15
Table 1-2. According to YSZ electrolyte manufacturing method 15
Table 2-1-1. Toxic gases of gas sensor 17
Table 2-1-2. Gas detection principles and detectable gases 17
Table 2-1-3. Examples of resistive type CO₂ sensors in the literature 23
Table 2-2-1. Classification of potentiometric type sensors 25
Table 3-1-1. Heating condition of oxide sensing materials 56
Table 4-1-1. Surface roughness value according to viscosity of Al₂O₃ slurry 65
Table 4-1-2. Adhesion test value of Al₂O₃ coating layer at various slurry... 68
Table 4-1-3. Adhesion test of 8YSZ film with surface roughness of Al₂O₃... 75
Table 4-1-4. Summary of results of porosity measurement of casting and... 79
Table 4-1-5. Quantitative value of solid electrolyte pore size... 80
Table 4-2-1. EMF of various oxide to NO or NO₂ gas 93
Table 4-2-2. EDS analysis results of NiO and NiO + YSZ sensing materials 96
Table 4-2-3. Response and recovery time 112
Fig. 2-1-1. A model of a potential barrier to electric conduction at a... 20
Fig. 2-1-2. An experimental procedure for the gas sensor fabrication. 22
Fig. 2-1-3. Effect of the distance between the electrodes on the network... 22
Fig. 2-1-4. NO₂ gas sensing characteristics of SnO₂ nanowire sensor. (a)... 22
Fig. 2-2-1. The operating principle of type I equilibrium potentiometric... 26
Fig. 2-2-2. The operating principle of type II equilibrium... 31
Fig. 2-2-3. Type II potentiometric SO₃ sensor using Ag₂SO₄ electrolyte 31
Fig. 2-2-4. Schematic view of the structure of CO₂ sensor using NASICON... 34
Fig. 2-2-5. EMF of NASICON/Li₂CO₃-CaCO₃ as correlated with CO₂... 35
Fig. 2-2-6. SEM photograph : (a) and EPMA analysis, (b) of selected points... 36
Fig. 2-2-7. Response transients to 250 and 2000ppm CO₂ for the sensor... 38
Fig. 2-2-8. Response transients to 250 and 1500ppm CO₂ of the sensor... 38
Fig. 2-2-9. Structure of planar type CO₂ sensor based on NASION thick film 39
Fig. 2-2-10. Response transients of the device to various CO₂ concentration... 39
Fig. 2-2-11. Schematic diagram of mixed potential type sensor 45
Fig. 2-2-12. Electrical behaviors of mixed potential type sensor 45
Fig. 3-1-1. Fabrication process of sensors chip 47
Fig. 3-1-2. Model diagram of NO₂ sensor device 47
Fig. 3-1-3. Heater manufacturing process ; (a) Al₂O₃ Substrate, (b)... 49
Fig. 3-1-4. Spray coating to improve surface roughness 49
Fig. 3-1-5. Experimental procedure to make solid electrolyte by thermal... 53
Fig. 3-1-6. SEM images after heat treatment of 8YSZ powder 54
Fig. 3-1-7. Concept of Thermal spray coating process 54
Fig. 3-1-8. NO₂ Sensor device formed Pt Electrode/ Sensing Material/ Solid... 57
Fig. 3-1-9. Images of the sensor after wire bonding and packaging 57
Fig. 3-1-10. Schematic experimental setup for gas sensing measurement. 59
Fig. 3-1-11. NO₂ gas measurement system 59
Fig. 4-1-1. Comparison of Surface roughness; (a) Al₂O₃ substrate and (b)... 61
Fig. 4-1-2. Surface roughness value of Al₂O₃ substrate with chemical... 62
Fig. 4-1-3. Surface roughness value with spray coating of Al₂O₃ and SiO₂... 64
Fig. 4-1-4. Surface roughness values at various slurry conditions;... 66
Fig. 4-1-5. Optical images of adhesion test of Al₂O₃ coating layer... 68
Fig. 4-1-6. Optical image of specimens heat-treated at various temperatures 70
Fig. 4-1-7. SEM image of cross section for Al₂O₃ coating layer at various... 70
Fig. 4-1-8. Optical image comparison of spray-coated Al₂O₃ substrate on... 71
Fig. 4-1-9. Optical image of substrate after Al₂O₃ spray coating on both sides 71
Fig. 4-1-10. Cross section image of substrate after Al₂O₃ spray coating on... 72
Fig. 4-1-11. Optical images of 8YSZ after thermal spay coating on the Al₂O₃... 74
Fig. 4-1-12. Cross-section image of 8YSZ/Buffer Layer/Al₂O₃; (a)8YSZ/Al₂O₃... 75
Fig. 4-1-13. Surface images according to 8YSZ solid electrolyte production... 77
Fig. 4-1-14. Cross section according to 8YSZ solid electrolyte production... 78
Fig. 4-1-15. Crystal structure of 8YSZ 82
Fig. 4-1-16. XRD patterns of solid electrolytes prepared by thermal spray... 83
Fig. 4-1-17. Ion conductivity according to oxygen partial pressure of 8YSZ... 86
Fig. 4-1-18. Ion Conductivity Difference between Tape Casting and Thermal... 87
Fig. 4-1-19. Ion conductivity of 8YSZ solid electrolyte prepared by... 88
Fig. 4-1-20. Sensor sensitivity characteristics of tape casting and thermal... 90
Fig. 4-1-21. Response and Recovery sensitivity characteristics of tape... 91
Fig. 4-2-1. SEM images forming the sensing material on 8YSZ solid... 94
Fig. 4-2-2. SEM images forming the sensing material on 8YSZ solid... 95
Fig. 4-2-3. Sensitivity test result of sensor according to air volume... 100
Fig. 4-2-4. NO₂ Sensing properties of Cr₂O₃ at different operating temperature 101
Fig. 4-2-5. NO₂ Sensing properties of In₂O₃ at different operating temperature 102
Fig. 4-2-6. NO₂ Sensing properties of CuO at different operating temperature 103
Fig. 4-2-7. NO₂ Sensing properties of NiO at different operating temperature 104
Fig. 4-2-8. NO₂ Sensing properties of NiO+YSZ at different operating temperature 105
Fig. 4-2-9. Comparison of sensing properties of various sensing materials at 650℃ 106
Fig. 4-2-10. Comparison of sensing properties NiO and NiO + YSZ(75:25)... 107
Fig. 4-2-11. Schematic diagram for Triple Phase Boundary 108
Fig. 4-2-12. Mixed potential generated from NO₂ gas ; (a)Schematic diagram... 109
Fig. 4-2-13. Response and recovery characteristics of NiO+YSZ(75:25) at... 110
Fig. 4-2-14. Comparison of sensitivity of various sensing materials; (a)... 111
Fig. 4-2-15. Comparison of response and recovery time 112