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Ductile Regime Nano-Machining of Silicon Carbide by Biswarup Bhattacharya Advisor: Dr. John A Patten

Ductile Regime Nano-Machining of Silicon Carbide by Biswarup Bhattacharya Advisor: Dr. John A Patten. Introduction Research Background Ductile Regime Machining of Poly crystalline Silicon Carbide

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Ductile Regime Nano-Machining of Silicon Carbide by Biswarup Bhattacharya Advisor: Dr. John A Patten

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  1. Ductile Regime Nano-Machiningof Silicon CarbidebyBiswarup BhattacharyaAdvisor: Dr. John A Patten

  2. Introduction Research Background Ductile Regime Machining of Poly crystalline Silicon Carbide Determination of Ductile to Brittle Transition (DBT) depth for Chemically Vapor Deposited (CVD) Silicon Carbide (SiC) Single Point Diamond Turning (SPDT) of CVD coated SiC Determination of DBT depth for Quartz Conclusion Future Work AGENDA

  3. Defining important terms: High Pressure Phase Transformation Nano – Machining Ductile Regime Ductile to Brittle Transition Depth INTRODUCTION

  4. PROJECT GOALS Polycrystalline SiC • Record and analyze the machining forces with respect to the depth of cuts (10 and 25 nm) • Map surface roughness values with change of depth • Determine tool wear CVD coated SiC • Determination of DBT depths for two different kinds of material, one from Coors Tek other from Poco Graphite • Develop process parameters for diamond turning of CVD SiC • Achieve SPDT of 6 inch CVD coated SiC plate • Minimize tool wear using cutting fluids

  5. DUCTILE REGIME NANO-MACHINING OF POLY CRYSTALLINE SILICON CARBIDE

  6. Fixture with SiC tube Dynamometer with the fixtures DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Experimental Setup: Front view of the SiC tube

  7. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Tools Used:

  8. Difference between Chardon and Edge Tool: DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC 7µm 150 µm Rake Face Clearance face Schematic showing the side view of Chardon tool Schematic showing the side view of Edge tool

  9. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Experimentation Matrix: Note: The depth of cut equals the feed/rev

  10. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Force Plots: Comparison of forces for different depths of cut using Chardon Tool

  11. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Comparison chart for forces achieved from Chardon and Edge tool at 10nm depth of cut

  12. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Force Ratio for different tools and different depths of cut

  13. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Surface Profiles: Optical image of the SiC tube showing cutting through or across the complete thickness of the tube, using Chardon Tool (100% Engagement) at 25 nm depth of cut Surface from 10nm cuts, using Edge Tool Surface from 25nm cuts, using Chardon Tool

  14. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC Tool Wear: -45 degree chamfer on the flat nose tool Starting point of wear Clearance Face Rake Face Schematic representation of tool wear 40 X Optical microscope image of tool wear, the tool is at 45 deg to the microscope’s lens, looking perpendicular to the rake face.

  15. DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC TEM Analysis: Amorphous and Nanocrystalline region TEM image of a ductile chip from machining SiC at 25 nm depth of cut from Chardon Tool TEM EDAX analysis of the ductile chip Image of diffraction pattern showing the halo ring for amorphous nature of the material

  16. DETERMINATION OF DUCTILE TO BRITTLE TRANSTION DEPTH (DBT) FOR CHEMICALLY VAPOR DEPOSITED (CVD) SILICON CARBIDE (SiC)

  17. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Experimental set up: Load Sensor Flat nose single crystal diamond toolwith holder AE Sensor Diamond Stylus with holder CVD coated SiC Set up for scratching experiment using diamond stylus Leveling Stage Set up for inclined plane experiment using flat nose tool

  18. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Table showing the time line of experiments to account for tool wear:

  19. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Scratching using 5µm diamond stylus: Scratching parameters Tool: Diamond Stylus with 5 µm radius Speed: 0.005 mm/sec Scratch length: 5 mm Load Range: 10 to 25 grams for Poco Graphite sample and 1 to 10 grams for Coors Tek Polished Samples used Poco Graphite CVD coated SiC surface roughness of <100 nm (Ra) and Coors Tek CVD coated SiC surface roughness of <10 nm

  20. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Fractured tip of 5µm diamond stylus used for the scratches Wyco image of scratch of Coors Tek sample using 5 µm diamond stylus Wyco image of scratch of Poco Graphite sample using 5 µm diamond stylus

  21. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Inclined plate experiment: Scratching parameters Tool: Flat nose single crystal diamond tool with -45 degree rake angle Speed: 0.005 mm/sec Scratch length: 5 mm Load Range: 10 to 25 grams Polished Samples used Poco Graphite CVD coated SiC surface roughness of <10 nm (Ra)

  22. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Schematic representation of inclined plane experiment geometry for Poco Graphite sample

  23. DETERMINATION OF DBT DEPTH FOR CVD coated SiC SEM of the failed tool edge used for inclined plane experiment Wyco image of scratch on Poco Graphite using inclined plane experiment Force plot of scratch on Poco Graphite using inclined plane experiment

  24. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Scratching details for CVD coated SiC: Scratching parameters Tool: Diamond stylus 12.5 µm tip radius Speed: 0.005 mm/sec Scratch length: 5 mm Load Range: 80 to 120 grams Polished Samples used Coors Tek CVD coated SiC and Poco Graphite CVD coated SiC both surface roughness of <10 nm (Ra)

  25. DBT depth = 550 nm DBT depth DETERMINATION OF DBT DEPTH FOR CVD coated SiC DBT depth for Poco Graphite Sample: SEM of the used 12.5 micron diamond stylus for Poco Graphite sample Wyco image for DBT depth of Poco Graphite sample using 12.5 µm stylus Force and AE plot for DBT depth of Poco Graphite sample using 12.5 µm stylus

  26. DBT depth = 400 nm DETERMINATION OF DBT DEPTH FOR CVD coated SiC DBT depth for Coors Tek Sample: SEM of the used 12.5 micron diamond stylus for Coors Tek sample Wyco image for DBT depth of Coors Tek sample using 12.5 µm stylus Force and AE plot for DBT depth of Coors Tek sample using 12.5 µm stylus

  27. DETERMINATION OF DBT DEPTH FOR CVD coated SiC Optical image of a typical DBT transition in a scratch

  28. SINGLE POINT DIAMOND TURNING (SPDT) OF CHEMICALLY VAPOR DEPOSITED (CVD) SILICON CARBIDE (SiC)

  29. SPDT of CVD coated SiC Experimental set up: Cutting Direction Coolant System Blown up image of the tool and sample set up Experimental set up for SPDT of CVD SiC

  30. SPDT of CVD coated SiC Machining parameters Tool: Round nose single crystal diamond tool with nose radius 3 mm with -45 degree rake and 5 degree clearance angle Depth of cut: 500 nm Feed/rev: 1 µm/rev Spindle speed: 60 rpm Cutting speed: 0.24 mm/sec Feed Speed: 0.001 mm/sec Programmed load: 8.22 grams

  31. SPDT of CVD coated SiC Surface Finish: Picture showing the optical quality of the surface finish of the machined CVD SiC CAD model showing the surface roughness distribution for 6 inch CVD SiC plate

  32. 100 X 100 X SPDT of CVD coated SiC Wyco image of the machined Surface (region 2) Optical image of the unmachined surface Optical image of the machined surface (region 1) Wyco image of the unmachined surface Wyco image of the machined Surface (region 1) Optical image of the machined surface (region 2) showing feed marks

  33. SPDT of CVD coated SiC Calculation for programmed load: Schematic of the chip cross sectional area calculated for scratching experiments* Summary of scratching experiments for Poco Graphite sample using 12.5µm diamond stylus Specific cutting energy calculated from scratching experiment: Cross-sectional area of the chip from scratching, A = 1.3 x 10-5 mm2 Cutting force, Fx = 0.4 N Cutting Energy, Esc = Fx / A = 30.769 N-m/mm3 *Note: The figure shown in this slide is not to scale

  34. SPDT of CVD coated SiC Schematic of the chip profile for area calculations during SPDT** Weight required for 500 nm depth of cut: Chip cross-sectional area, Ac= 2.4898 x 10-7 mm2 Cutting force, Fx = Esc x Ac= 8.19 x 10-3 N COF = 0.1 (assumed from previous work) Thrust Force, Fz = 8.19 x 10-2 N Weight required, w = 8.19 grams *All areas are calculated using MATLAB program **Note: The figure shown in this slide is not to scale

  35. SPDT of CVD coated SiC Table showing actual Vs Programmed depth of cut:

  36. SPDT of CVD coated SiC Comparison of depth of cut and achieved surface roughness data

  37. SPDT of CVD coated SiC Ongoing work: Note: Machining parameters and the kind of tool used are same as used for SPDT of 6 inch Poco Graphite sample.

  38. DETERMINATION OF DUCTILE TO BRITTLE TRANSITION DEPTH FOR QUARTZ (INFRASIL 302)

  39. Top surface of Infrasil 302 DETERMINATION OF DBT depth FOR QUARTZ Scratching of Quartz: Scratching parameters Tool: Diamond stylus 5 µm tip radius Speed: 0.005 mm/sec Scratch length: 5 mm Load Range: 20 to 50 grams Picture of the Quartz sample

  40. DETERMINATION OF DBT depth FOR QUARTZ DBT depth from scratching: DBT depth of 120 nm Wyco image showing the DBT depth in Quartz using 5 µm stylus Force and AE data showing DBT depth for Quartz using 5 µm stylus

  41. DETERMINATION OF DBT depth FOR QUARTZ Wyco image showing a typical brittle fracture in Quartz (Infrasil 302) after DBT depth from scratch using 5 µm stylus

  42. DETERMINATION OF DBT depth FOR QUARTZ Inclined plate experiment: Scratching parameters Tool: Flat nose diamond tool Speed: 0.005 mm/sec Scratch length: 5 mm Load Range: 20 to 50 grams Schematic representation for geometry of inclined plate experiment

  43. DETERMINATION OF DBT depth FOR QUARTZ DBT depth = 120 nm SEM image showing the tool edge used for scratching Wyco image showing the DBT depth in Quartz using inclined plate experiment Force and AE data showing DBT depth for Quartz using inclined plate experiment

  44. DETERMINATION OF DBT depth FOR QUARTZ Wyco image showing a typical brittle fracture in Quartz (Infrasil 302) after DBT depth from scratch using inclined plate experiment

  45. SUMMARY of SCRATCHING EXPERIMENTS

  46. SUMMARY OF scratching EXPERIMENTS Formula used for calculation DBT – dc = 0.15. (E/H). (Kc/H)2 where Kc – Fracture Toughness of the material H- Hardness of the material E- Modulus of elasticity

  47. VALIDATION OF scratching RESULTS Formula used for validation: If 2a – width of the scratch (derived from Y-profiles of wyco image) R – radius of the tool used d – depth of the scratch (derived from Y-profiles of wyco image) Then R = {(a2/d)+d}/2

  48. VALIDATION OF scratching RESULTS

  49. CONCLUSION AND FUTURE WORK

  50. Ductile regime machining of polycrystalline SiC is possible at penetration depths of 10 and 25nm The ductile to brittle transition depth (DBT depth), or critical depth of cut or penetration, for the CVD coated SiC from Poco Graphite Inc. was found to be 550 nm and, the DBT depth for the CVD coated SiC from Coors Tek Inc. was determined to be 400 nm SPDT of CVD SiC was done at depths of 200-400 nm for ductile regime machining The DBT transition depth for Quartz were found to be 120nm for both stylus and cutting tool scratch tests CONCLUSION

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