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3-D Nano-scratching in silicon and silicon carbide
Dr John A PattenJerry Jacob
Western Michigan University, Kalamazoo, MIManufacturing Research Center
Overview of presentation
• Introduction to HPPT in ceramics• Examples of HPPT in ceramics• Scratching experiments on silicon • Scratching experiments on silicon carbide• Simulations of scratching experiments
– Silicon– Silicon Carbide
• Results and Discussion• Conclusions
Basics of HPPT and importance in Ceramics
• Definition of HPPT and relation to hardness of the material.
• D-B-T depth in ceramics.• Importance of HPPT in ceramic manufacturing.
Examples of HPPT in ceramics
Scratching experiments in silicon
Simulation setup for silicon scratching
Process parameters Value Unit Schematic
(Actual) Depth of Cut, doc 115* nm
Length of Cut, loc 10.0 µm
Cutting Speed, v 0.305 mm/s
Friction factor 0.1 -
Custom tool file for simulations
* Programmed depth of cut was 125 nm
Silicon Simulation result
Pressures at the tool-workpiece interface are at least 12GPa or higher. 12 GPa is the hardness of this silicon material.
Silicon Simulation result – cont’d
• Thrust force value from simulation at 115 nm is lower than experimental value at 75 nm.
Scratching experiments in silicon carbide
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 CoorsTek
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 D-B-T depth
Optical image of a typical D-B-T in a scratch
Wyko RST image of Ductile scratch on CVD coated SiC
Simulation setup for silicon carbide
Parameters Value Unit Geometry
Programmed Depth (feed) 125 nm
Actual depth, doc 103 nm
Length of Cut, loc 10.0 µm
Cutting Speed, v 0.305 mm/s
Friction factor, µ 0.1, 0.26, 0.6 -
Result from simulations of silicon carbide
• Cutting force values are lower because simulation depth (105 nm) is smaller than experimental depth (120 nm).
• Thrust force values show good agreement.
Summary of simulations and conclusion• Summary of 3-D scratching simulations
– Si simulations show simulation thrust force is lower than experimental value.
• Material model needs to be validated
– SiC simulations show thrust forces in good agreement with the experiment.
– SiC simulations show cutting forces that are not in very good agreement with the experiment.
• depths are different
• 3-D scratching work shows encouraging results– initial attempts at simulations of ductile behavior of ceramic
materials • nanometer depths,• below the DBT depth of these nominally brittle materials.
Acknowledgements• National Science Foundation for the research grant (DMR).• Andy Grevstad and Third Wave Systems for software and funding
support.• Dr Guichelaar (WMU) for equipment at the Tribology lab.• Lei Dong at University of North Carolina at Charlotte Si work)• Biswarup Bhattacharya (WMU) for CVD coated SiC work.
