Presentation Hsu

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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

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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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