ductile regime nano machining of silicon carbide by biswarup bhattacharya advisor dr john a patten l.
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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

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

agenda
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
introduction
Defining important terms:

High Pressure Phase Transformation

Nano – Machining

Ductile Regime

Ductile to Brittle Transition Depth

INTRODUCTION
project goals
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
slide5
DUCTILE REGIME NANO-MACHINING

OF

POLY CRYSTALLINE SILICON CARBIDE

ductile regime nano machining of poly crystalline sic

Fixture with SiC tube

Dynamometer with the fixtures

DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC

Experimental Setup:

Front view of the SiC tube

ductile regime nano machining of poly crystalline sic8
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

ductile regime nano machining of poly crystalline sic9
DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC

Experimentation Matrix:

Note: The depth of cut equals the feed/rev

slide10

DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC

Force Plots:

Comparison of forces for different depths of cut using Chardon Tool

slide11

DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC

Comparison chart for forces achieved from Chardon and Edge tool at 10nm depth of cut

slide12

DUCTILE REGIME NANO-MACHINING of Poly Crystalline SiC

Force Ratio for different tools and different depths of cut

slide13

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

slide14

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.

slide15

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

slide16
DETERMINATION OF DUCTILE TO BRITTLE TRANSTION DEPTH (DBT) FOR CHEMICALLY VAPOR DEPOSITED (CVD) SILICON CARBIDE (SiC)
determination of dbt depth for cvd coated sic
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

determination of dbt depth for cvd coated sic18
DETERMINATION OF DBT DEPTH FOR CVD coated SiC

Table showing the time line of experiments to account for tool wear:

determination of dbt depth for cvd coated sic19
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

determination of dbt depth for cvd coated sic20
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

determination of dbt depth for cvd coated sic21
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)

determination of dbt depth for cvd coated sic22
DETERMINATION OF DBT DEPTH FOR CVD coated SiC

Schematic representation of inclined plane experiment geometry for Poco Graphite sample

determination of dbt depth for cvd coated sic23
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

determination of dbt depth for cvd coated sic24
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)

determination of dbt depth for cvd coated sic25

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

determination of dbt depth for cvd coated sic26

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

determination of dbt depth for cvd coated sic27
DETERMINATION OF DBT DEPTH FOR CVD coated SiC

Optical image of a typical DBT transition in a scratch

slide28
SINGLE POINT DIAMOND TURNING (SPDT)

OF

CHEMICALLY VAPOR DEPOSITED (CVD) SILICON CARBIDE (SiC)

spdt of cvd coated sic
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

spdt of cvd coated sic30
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

spdt of cvd coated sic31
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

spdt of cvd coated sic32

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

spdt of cvd coated sic33
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

spdt of cvd coated sic34
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

spdt of cvd coated sic35
SPDT of CVD coated SiC

Table showing actual Vs Programmed depth of cut:

spdt of cvd coated sic36
SPDT of CVD coated SiC

Comparison of depth of cut and achieved surface roughness data

spdt of cvd coated sic37
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.

determination of dbt depth for quartz

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

determination of dbt depth for quartz40
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

determination of dbt depth for quartz41
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

determination of dbt depth for quartz42
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

determination of dbt depth for quartz43
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

determination of dbt depth for quartz44
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

summary of scratching experiments
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

validation of scratching results
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

conclusion
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
future developments
Efforts should be made to optimize tool wear while machining of polycrystalline SiC by using a coolant or cutting fluid

Additional machining experiments to determine the DBT depth of polycrystalline SiC

Measuring the tool radius (cutting edge) of the single crystal diamond tool before and after machining of CVD SiC, to map the tool wear ratio

SPDT of CVD SiC in a displacement based machine (precision lathes) where there is direct control over the depths of cut or in-feeds used for machining

The potential replacement of intermediate processes like finish grinding, polishing and lapping, by SPDT, would reduce the total manufacturing cost by increasing productivity and improving surface form accuracy (flatness)

The author suggests performing SPDT of quartz and monitoring the tool wear and surface finish

FUTURE DEVELOPMENTS
acknowledgements
First, and foremost, I would like to thank my advisor Dr. John Patten for providing me the opportunity and guidance through out this project

Great thanks go to Dr. Philip Guichelaar for his immense support and providing space in his laboratory to set up my experiments, and also training me to use the white light interference microscope

I would like to thank Dr. Pnina Ari-Gur for training me to use the scanning electron microscope

Special thanks go to Dr. Muralidhar Ghantasala, Dr.Philip Guichelaar and Dr.Pnina Ari-Gur, for serving on my thesis committee and providing advice

Great thanks to Jerry Jacob, Roshan Joseph and Ramesh Chandra for working with me on various experiments in this study

I would also like to thank the Department of Mechanical Engineering at the Western Michigan University for giving me the opportunity to study in their graduate program.

I would like to acknowledge the collaborative work with the High Temperature Materials Laboratory (HTML) located at Oak Ridge National Laboratory. Many thanks go to Dr. Peter Blau for providing me with the opportunity to work at HTML

Finally, I would like to express my acknowledgements to Third Wave Systems and the National Science Foundation for having funded this work

ACKNOWLEDGEMENTS