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Integrated Surface ModificationTechnology Development
Stephen M. Hsu
National Institute of Standards & Technology
September 15, 2005
This presentation does not contain any proprietary or confidential information
Project ID 9407
21CTP Technical Goal:
Program Structure Sub-Program Element R&D Phase DateProject ID/Agreement ID
Develop and demonstrate an emissions compliant engine system for Class 7-8 highwaytrucks that improves the engine system efficiency from ~42% today to 50% by 2010.
Integrated Surface ModificationIntegrated Surface Modification
Principal Investigator(s)Stephen Hsu, National Institute of Standards and Technology(301) 975-6120; [email protected]
Technology Development ManagerSid Diamond, DOE/OFCVT(202) 586-8032; [email protected]
PM_9407 Materials Technology HV Propulsion Materials Applied Research 8-15-05
Project ObjectivesDevelop surface texture features and patterns that will control frictionand increase durability. Develop cost-effective fabrication techniques.Develop thin films to enhance/protect the textures. Develop lubricantchemistry to further increase the robustness of the surface technology.Work with industrial partners to validate the technology. Develop adesign guideline (tool chest) for various materials and applicationconditions
FY 2005 FocusDevelop ISM processing, modeling, and validation.Planned DurationOctober 2004 to September 2007
DOE Funding/Industry Cost ShareFY04: $200K; FY05: $200K
AccomplishmentsDemonstrated size and shape effect on friction under high speed low loadconditionsDeveloped a low-cost lithographic-electrochemical etching technique tofabricate surface textures on metal surfaces suitable for high speed lowload applicationsDeveloping a new texturing design based on size and built-in wedge forhigh load medium speed conditions
Significant Future MilestonesWorking with industrial partners to develop thin films and lubricantchemistry to demonstrate the friction reduction potential of the combinedeffects ( 9-30-06)
0
0.02
0.04
0.06
0.08
0.1
0.0000001 0.000001 0.00001 0.0001
Sommerfeldnumber
Friction
coefficien
Notexture
Circle
EllipseA
EllipseW
TV
TA
Effect of shape & orientation of texture on friction
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Objectives
Overall Project ObjectiveIntegrating surface texture, thin films/coatings, and lubricatingchemistry to achieve durable friction control of enginecomponents under a wide operating conditions to reduceparasitic energy losses by 3-5%
Last years objectives:Develop lithography/electrochemical etching technique to fabricate
controlled surface textures at low cost without damage
Conduct experiments to assess the effects of size, shape, & pattern
under high speed low load conditions and to understand the frictionreduction mechanism(s) of surface feature in this regime
Moving into medium load & speed conditions, develop surfacetextures that will reduce friction
Moving into high load, low speed conditions, develop surfacetextures that will reduce friction
Develop low-cost fabrication technique for features
Initiate modeling to develop design guidelines for surface textures
4
Approach1. Fabricate surface features such as grooves, dimples,
triangles using two techniques:
o micro-mechanical actions for precisely controlledsize & shape
o Lithographic/electrochemical etching for low costfabrication
2. Design surface texture patterns based on theory3. Conduct friction experiments to measure friction reduction4. Conduct controlled experiments to test various friction
reduction mechanisms5. Develop models to develop surface feature design
principles for next generation of surface features6. After the optimum textural features are determined, add
thin films to protect the surface features; use rightchemistry to protect the thin films
7. Use surface chemistry to achieve additional frictionreduction
8. Repeat steps 1-7 for more severe contact conditions
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History of surface texturingHistory of surface texturing
(J.N.Anno, 1968)
Island
Photoengraving
Grooves
(T. Lai, 1993)
Laser
Micro-Groovedbearing
(R. Ranjan, 1991) (P. Baumgart, 1995)
(H. Haeflke, 2000)
(M. Geiger, 2000)
(M. Wakuda, 2002)
Micro-Blaster
TAIHO, 1995
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Current state-of-the-art surface texture friction reduction
technology as a function of speed and load
- I. High speed, low load: hydrodynamic effects, demonstrated success in seals
- II. High-medium speed, medium load: combing effects of hydrodynamics and
contact mechanics; increases friction
- III. Low-medium speed, high load: combing effects of contact mechanics,
lubricant compressibility, and wear particle trapping, feasibility not yet shown
Regime III: piston-liner,
transmission, bearingsHigh
Regime IIMedium
Regime I: seals,
thrust bearingsLow
HighMediumLowSpeed
Load
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Would geometric shapes affect friction?
Shape factor?
pitch
Orientation of features?
Pattern design?
Regime I study: validation of bench test procedures
The effect of shape, distribution with same number, same area density, different shape and distribution
at low loads and high speeds 10
Micro-lithograph and Electrochemical etching
NaCl
Spin coating Photoresist
UV expose
Mask
Develop
Electrochemical etching bycontrolling the electrolyte andvoltage
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Features of surface texture:
7176715008300/75Ellipse
Pattern &Sliding dir.
7176715008187Triangle
7176715008150Circle
Areadensity (%)
Area of adimple (m2)
Pitch(m)
Depth(m)
Dimension(m)
Same 12
Load
Modified flat-on-disk test conditions
Material: steel/steel
Diameter of small disk: 6.35 mm
Load range: 1-35 NPressure: 0.03-1.1 MPa
Speed range: 0.023-0.23 m/s
Lubricant : purified parafin oil withTCP & antioxidant(Saybolt number 125/135)
Temperature: room temperature
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0
0.02
0.04
0.06
0.08
0.1
0.0000001 0.000001 0.00001 0.0001
Sommerfeld number
Friction
coefficie
Notexture
Circle
Ellipse A
Ellipse W
TV
TA
Flow direction
V /P14
Regime I : Apparent contact Pressure < 15MPa
Possible Mechanisms additional hydrodynamic lift
- Back flow
- Cavi tation
Examples- Seals
- Thrust bearings
- Cylinder liners
Hydrodynamiceffects
Hydrodynamiceffects?
V
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0.00
0.02
0.04
0.06
0.08
0.10
0.05
0.10
0.15
0.20
510
1520
2530
35
Friction
coefficient
Spe
ed,m/s
Load,N
Untextured
0.000.020.040.060.080.10
0.00
0.02
0.04
0.06
0.08
0.10
0.05
0.10
0.15
0.20
510
1520
2530
35
Friction
coefficient
Spe
ed,m/s
Load,N
Circle
0.000.020.040.060.08
Speed and load boundaries for friction reduction
0.00
0.02
0.04
0.06
0.08
0.10
0.05
0.10
0.15
0.20
510
1520
2530
35
Friction
coefficient
Speed,
m/s
Load,N
Ellipse Sliding
0.00
0.020.04
0.060.08
ellipse to sliding
Circular dimplesUntextured
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Regime II: Medium Speed, Medium Load Region: Apparent
contact Pressure 15-120MPaFriction change mechanisms
increase:increase in roughness
contact pressure increaseturbulence & mixing
High edge stresses
reduction:hydrodynamic pressure lift
fluid compression lift forceleakage rate vs sealing rate
EHL dominatedcontactHydrodynamic
effects
V
Edgeeffect
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Diameter= 6.35 mm Diameter= 4 mm
When the apparent contact pressure exceeds 150 MPa,friction increases with resultant wear
Why?
Edge stresses = equivalent roughness increases
What does the elastohydrodynamic theory tell us?
Eaton & Northwestern EHL model confirmed friction increase 18
New surface texture design principle:
Built-in artificial wedge
Under elastic or plastic deformation conditions
Dimples lubricant reservoirs incompressible liquid
DeformationChange depth
Lubricant pushedalong the wedge-shaped bottomTo provide lift
LowerFriction
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New texture design
Sliding
direction
Sloped bottom to artificially generatehydrodynamic pressure
Diameter: 40-60, Pitch: 100 m, Depth: 8 m
Load: 5, 10 Kg (maxima pressure 500MPa)Speed: 600 rpm, others: room temperature.
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0
0.01
0.02
0.03
0.04
0.05
0.06
0 1000 2000 3000 4000 5000 6000
Rotation speed
Frictioncoefficien
Untextured
Textured
At2Kg
Ball-on-three-flats test done in a Four Ball wear tester
2 Kg
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0 1000 2000 3000 4000 5000 6000
Rotation speed
Frictioncoefficien
5 KgSteel on Brass
0
0.02
0.04
0.06
0.08
0.1
0 500 1000 1500 2000 2500 3000 3500 4000
Rotational speed, rpm
Friction
coefficient
Untextured
Tex 11
Tex 13
Tex 22
Tex 31
Tex 33
10 Kg
Steel on steel10 kg
0
0.02
0.04
0.06
0.08
0.1
0.12
0 500 1000 1500 2000 2500 3000 3500 4000
Rotational speed, rpm
Friction
coefficient
Untextured
Tex 11
Tex 13
Tex 22
Tex 31
Tex 33
20 Kg
20 kg
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Summary of accomplishments
Developed a low cost lithographic electrochemicaletching technique to fabricate simple surface featureson metal surfaces
Show for the first time, the dependence of geometricshape, orientation effects on friction reduction
Developed a new designed principle of artificialwedge features that overcame the high contactpressure and slower speed
Demonstrated for the first time, consistent friction
reduction under GPa contact pressures in steel-on-steel surfaces Test methods have been developed to evaluate
friction of textured surfaces The design principle needs further development and
validation via modeling and experiments; Coating andchemistry to protect the textures need to bedeveloped
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Technology Transfer Organizing a domestic surface modification working groupwithin the IEA activity (the following companies haveexpressed interest in joining: Caterpillar, GM, Timken, Ford,United Technology, John Crane, Waukesha, Eaton, Fricso,Federal Mogul).
Other partners: ANL (low friction DLC), ORNL (ceramictexturing), PNWL (friction stirring), Lubrizol (lubricantchemistry), Beamalloy (thin films), Northwestern University(modeling)
Internationals: UK, Finland, Sweden, Japan, Australia, China,
Norway, Israel through IEA (technical information exchange,see symposium in supplemental information) Technology validation through domestic working group via
actual component testing and implementation Projected time frame: establishment of the working group (Fall
05); test method/characterization round robin (summer 06);design guideline for some components (Fall 06); demonstratethin film/chemistry (winter 07); component validation (summer07)
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