Development of hybrid process using lase and dry particle deposition system
레이저와 건식 분말 적층 장치를 사용한 하이브리드 공정 개발

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dc.description학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 8. 안성훈.-
dc.description.abstractA nanoparticle deposition system (NPDS) was developed as an alternative to aerosol deposition, with advantages including cold spray (room temperature) processing, the use of various materials (metal and ceramic), high deposition rates (versus molecular and atomic deposition), and a green manufacturing process with no wet chemical processing, binder, or post-processing step. This NPDS was shown to be useful in the deposition of particles on soft matter for flexible substrate applications.
With the aim of enhancing adhesion between the film and the fabricated substrate in NPDS, a laser was used initially on flying nanoparticles, referred to as laser-assisted NPDS (LaNPDS). In other fabrication methods, the laser has been used to shape objects by sintering and melting target materials. In contrast, a coherent laser can transfer thermal energy inside the tube to flying nanoparticles and deposited nanoparticles, without thermal damage, for the fusion and dissolution of substrates. This indicates that thermal energy transfer plays a role in preheating, with an increase in the diffusion rate at the interface between nanoparticles, resulting in enhanced necking phenomena over the mechanism of solid-state sintering. Given this, LaNPDS was expected to improve not only surface integrity, but also adhesion among nanoparticles in the film, as well as the interfaces between the film and substrate. However, the intrinsic role of the laser in relation to surface integrity and adhesion has not been reported previously, so the effect of laser irradiation was examined in this study.
In this study, Al2O3 and TiO2 ceramic particles were deposited on ceramic (sapphire) and polymer substrates (PET and ITO-PET) by LaNPDS. The surface morphology, hardness, elastic modulus, and interface were characterized by field emission scanning electron microscopy (FE-SEM), surface profile, nano indentation, and X-ray diffraction (XRD). To demonstrate the heating effect and changes in the mechanical properties of ceramic films, as influenced by the laser, a finite-element method was used.
Using LaNPDS, applications of this research include fabricated dye-sensitized solar cells (DSSCs) and electrochromic windows (ECWs). As the intensity of the laser was increased, the efficiencies of the DSSCs and ECWs increased.
Flying particle velocity was analyzed by a computational fluid dynamics (CFD) method and a microparticle image velocimetry (micro-PIV) method. Through these measurements, the effects of the laser on flying particles were analyzed. The flying particle kinetic energy and laser activation energy were calculated and compared with a CFD analysis. The laser activation energy added to the kinetic energy, so the total impact energy increased. From these results, the LaNPDS process can deposit ceramic materials on various substrates more effectively, because the laser energy is transferred to the flying nanoparticles.
dc.description.tableofcontentsChapter 1 Introduction 1
1.1. Overview 1
1.2. Review of particle deposition methods 1
1.2.1. History of low temperature deposition processes 2
1.2.2. Nano particle deposition system (NPDS) 4
1.3. Review of laser assisted sintering process 4
1.3.1. Classification of laser assisted sintering methods 6
1.3.2. Limitation of existing laser assisted deposition process 8
1.3.3 Approaches for a laser assisted hybrid process 9

Chapter 2 System design and configuration 10
2.1. System configuration 10
2.2. Direct laser method 11
2.3. In-direct laser method 13

Chapter 3 Evaluation of deposition results 14
3.1. Overview 14
3.2. Al2O3 ceramic particle deposition 17
3.2.1. Direct laser method results 19
3.3. TiO2 particle deposition 25
3.3.1. Direct laser method results 26
3.3.2. In-direct laser method results 29

Chapter 4 Effect of laser on flying particle 32
4.1. Overview 32
4.2. Evaluation of laser effect on flying particle 33
4.3. Particle velocity measurement 38
4.3.1. Hardware set up of micro PIV system 40
4.3.2. Measurement of Zn particle velocity 43
4.4. Computational fluid dynamics 47
4.4.1 CFD modeling 49
4.4.2. CFD analysis 50

Chapter 5 Applications 53
5.1. Overview 53
5.2. Fabrication and evaluation of Dye Sensitized Solar Cell (DSSC) and Electro Chromic Window (ECW) 54

Chapter 6 Bonding mechanism 61
6.1. Overview 61
6.2. Particle heating in coaxial laser 62
6.3. Thermal effect of laser in LaNPDS 63
6.4. Relationships between the kinetic energy of the particles and laser activation energy in LaNPDS 66
6.4.1 ANSYS modeling for particle velocity 66
6.4.2 Laser activation energy 72
6.4.3 Comparison of kinetic energy and laser activation energies 74

Chapter 7 Conclusions 76

Bibliography 78

Abstract 85
dc.format.extent5242121 bytes-
dc.publisher서울대학교 대학원-
dc.subject건식 분사적층-
dc.subject하이브리드 시스템-
dc.titleDevelopment of hybrid process using lase and dry particle deposition system-
dc.title.alternative레이저와 건식 분말 적층 장치를 사용한 하이브리드 공정 개발-
dc.contributor.AlternativeAuthorChoi. Jung-Oh-
dc.citation.pagesiX, 85-
dc.contributor.affiliation공과대학 기계항공공학부-
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Mechanical Aerospace Engineering (기계항공공학부)Theses (Ph.D. / Sc.D._기계항공공학부)
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