Title Page
Abstract
국문 요약
Contents
Chapter 1. Introduction 13
Chapter 2. Background 15
2.1. Vacuum Ejector 15
2.1.1. Background of Vacuum Ejector 15
2.1.2. Roughness Issue of Vacuum Ejector 16
2.2. Metal 3D Printing 17
2.2.1. PBF(Powder Bed Fusion) 17
2.2.2. DED (Direct Energy Deposition) 21
2.3. Inconel 718 23
2.4. Electro-Chemical Polising(ECP) 25
2.4.1. Fundamental Principal of Electro-Chemical Polishing(ECP) 25
2.4.2. Theory of Electro-Chemical Polising(ECP) 29
Chapter 3. Electro-Chemical Polishing for Inconel 718 33
3.1. Experimental Setup 33
3.1.1. Specimens 33
3.1.2. Electrolyte 35
3.1.3. Zig 35
3.2. Experimental Result 36
3.2.1. Roughness According to Applied Current 39
3.2.2. Roughness According to Polishing Time (10A) 40
3.2.3. Roughness According to Polishing Time (20A) 45
3.2.4. Roughness According to Polishing Time (30A) 49
Chapter 4. Electro-Chemical Polishing for Inconel 718 Ejector 53
4.1. Experimental Setup 53
4.1.1. Specimens 54
4.1.2. Electrolyte 55
4.1.3. Systems 55
4.2. Experimental Result 56
Chapter 5. Conclusion 57
References 58
Table 2.1. Properties of the Inconel 718 24
Table 3.1. Compositions(wt%) of Inconel 718 powder 33
Table 3.2. SLM 3D Printing Parameter 33
Table 3.3. SLM 3D Printer specifications 34
Table 3.4. Compositions(vol%) of electrolyte 35
Table 3.5. Polishing parameters for experiment 36
Table 3.6. Polishing value(current/time) for experiment 36
Table 3.7. According to applied current of the surface roughness value 38
Table 4.1. Polishing parameters for ejector 53
Fig. 2.1. Schematic of the ejector 15
Fig. 2.2. Schematic of PBF process 17
Fig. 2.3. Schematic of sintering effects 18
Fig. 2.4. Schematic of SLM process 19
Fig. 2.5. Powder Spreading of EBM 3D Printing 20
Fig. 2.6. Schematic of DED process 21
Fig. 2.7. Repairing a turbine blade by DED 22
Fig. 2.8. DED hybrid machine(LASERTEC 65, DMG Mori) 22
Fig. 2.9. SEM images of the Inconel 718 23
Fig. 2.10. Process of ECP 25
Fig. 2.11. ECP effects (a) before polishing, (b) after polishing 26
Fig. 2.12. Current density-voltage curve of ECP 27
Fig. 2.13. Pitting effect of ECP (a) different corrosion regions along the sample surface, (b) zoomed optical image of the localised corrosion region 28
Fig. 3.1. SLM 3D Printer(MLAB 100R, GE) 34
Fig. 3.2. Zig for Inconel 718 plate 35
Fig. 3.3. The microscope image of the specimens (20A/20min) 37
Fig. 3.4. The microscope image of the specimens (30A/7min) 37
Fig. 3.5. Surface roughness increasing the current (1min to 5min) 39
Fig. 3.6. Surface roughness increasing the Time (10A) 40
Fig. 3.7. The microscope image of the specimens (10A/1min) 41
Fig. 3.8. The microscope image of the specimens (10A/2min) 41
Fig. 3.9. The microscope image of the specimens (10A/3min) 42
Fig. 3.10. The microscope image of the specimens (10A/4min) 42
Fig. 3.11. The microscope image of the specimens (10A/5min) 43
Fig. 3.12. The microscope image of the specimens (10A/7min) 43
Fig. 3.13. The microscope image of the specimens (10A/10min) 44
Fig. 3.14. The microscope image of the specimens (10A/15min) 44
Fig. 3.15. Surface roughness increasing the Time (20A) 45
Fig. 3.16. The microscope image of the specimens (20A/1min) 46
Fig. 3.17. The microscope image of the specimens (20A/2min) 46
Fig. 3.18. The microscope image of the specimens (20A/3min) 47
Fig. 3.19. The microscope image of the specimens (20A/4min) 47
Fig. 3.20. The microscope image of the specimens (20A/5min) 48
Fig. 3.21. The microscope image of the specimens (20A/7min) 48
Fig. 3.22. Surface roughness increasing the time (30A) 49
Fig. 3.23. The microscope image of the specimens (30A/1min) 50
Fig. 3.24. The microscope image of the specimens (30A/2min) 50
Fig. 3.25. The microscope image of the specimens (30A/3min) 51
Fig. 3.26. The microscope image of the specimens (30A/4min) 51
Fig. 3.27. The microscope image of the specimens (30A/5min) 52
Fig. 4.1. Schematic of vacuum ejector 54
Fig. 4.2. Systems for experiment 55
Fig. 4.3. Difference in vacuum pressure before and after ECP 56