Surface Engineering for Increased Durability and Energy ... · Surface Engineering for Increased Durability and Energy Efficiency in Extreme Conditions Mark Gee National Physical

Surface Engineering for Increased Durability

and Energy Efficiency in Extreme Conditions

Mark Gee

National Physical Laboratory

9th December 2009

Wednesday, 06 January 2010

2

Summary

• Introduction to Surface Engineering

• Benefits of surface engineering

• Examples from manufacturing

– Dies

– WC/Co hardmetal tools

• Thermal barrier coatings (TBCs)

• Sliding wear

• Conclusions


3

Surface Engineering• The design of surface and substrate together as a functionally

graded system to give a cost effective performance enhancement of which neither is capable on its own

• Many applications often in aggressive environments

• Many different types of surface engineering


4

Benefits for Surface Engineering

• Mechanical– Wear

• Decrease - most rubbing surfaces in equipment, abrasion resistant

• Control - abradable seals

• Increase - when used in manufacturing (grinding, polishing)

– Friction

• Increase - anti-slip surfaces

• Control - brakes

• Decrease - efficient engines

• Chemical– High Temperatures

• Oxidation - power plant

• Corrosion - power plant

• Direct reaction - cutting tools

– Low temperatures

• Corrosion - bridges


5

• Physical– Electrical - lacquer on wires, generating plant

– Thermal - TBCs on turbine blades

– Optical - anti reflectance coatings on lenses

• Decorative– Taps

– Jewelry

Benefits for Surface Engineering


6

Summary




– Dies



• Sliding wear

• Conclusions


7

Press DiesRequirements

• High stresses -substrate deforms

• Low friction

• Low wear

• Flat and smooth surface

Areas needing SE

• Working surface of die

SE Solution

• PVD coatings – DLC and MoS2


8

Testing for Dies – Scratch Testing

0 20 40 60 80 100

0

10

20

30

40

Friction F

orc

e, N

Load, N

0 20 40 60 80 100

0

2

4

6

8

10

Friction F

orc

e, N

Applied Load, N

A

A

B

B


9

WC/Co Hardmetals

• Two phase composites of WC and metal binder

• Used as tool materials, wear parts

• Subject to high stresses, high impact loading, corrosion, high

temperature

• In abrasion surface acts “smart” by fragmenting and re-embedding to form more wear resistant surface

Normal microstructure

Abraded surface


10

Flexure Elements

Micro-scratch Test System

• Deadweight loading

• Fibre-optic probe measurement of friction flexures

• Flexures, servo, ball screw are all leading commercially available technologies

Lever arm

LVDT

Servo

Height and position

adjustment

Friction measurement

flexures

IndenterCounterweight

Sample

Lever arm

LVDT

Servo

Height and position

adjustment

Friction measurement

flexures

IndenterCounterweight

Sample

Flexure pivots

Outer ring

Inner ring

Middle ring

Lever arm

Flexure pivots

Outer ring

Inner ring

Middle ring

Lever arm

Miniature Lead Screw

Gimbal


11

MA11 Single Scratch 300 mN 25 µµµµm Radius Indenter


12

50 pass 30 micrometre


13

100 pass 30 micrometre


14

Gas Borne Particle Erosion – Stepwise Analysis

Supply tube

Mixing

cha mber

Gas

supply

Abra sive

reservoir

Nozzle tube

Spec imen

Workingdista nce

Ga s bla st erosion test

Nozzle

length

Schema tic diagra m of ga s bla st erosion test system, ASTM G 76 (11)

� 75 ms-1

� 200 µm sand

� Normal incidence

� 20 mm stand-off

� 5 mm nozzle

� Increments from 0.1 gm to 4 or 15 gm (later stages)

0 50 100 150 200 250 300

0.000

0.005

0.010

0.015

0.020

Ma

ss L

oss, g

Mass of Erodant, g

M4

M6

Erosion Damage

Area Examined


15

Stepwise Erosion Large Grain WC/Co Hardmetal

8 µm

27.5 g27.5 g 33.5 g33.5 g


16

Summary




– Dies



• Sliding wear

• Conclusions


17

Rolls Royce TRENTgas turbine

The Modern Gas TurbineHigh

Pressure Turbine Blade


18

EB-PVD ZrO2-8wt%Y2O3

thermal barrier coatings

Electron Beam Physical Vapour Deposited Thermal Barrier

Coating (EB-PVD TBC)

100 µµµµm

Hot Gas

Temperature

CoolantTemperature

Metal WallCeramic

Temperature Profilewith TBC

Temperature Profilewithout TBC


19

19

TGO Fluorescence

• TBC transparent to laser

light

• TGO (alumina) flouresces

• Peak shifts when alumina is stressed

– In-situ measurement of TGO

residual stress

• Spectral deconvolution

TGO (Al2O3)

METAL

TBC(ZrO2/Y2O3)

Bondcoat

488 nm20492 cm-1

694 nm14400 cm-1

Air

515 nm19436 cm-1

About 20 µm diameter interrogated

Laser

d8111

0

50

100

150

200

250

300

350

400

450

14250 14300 14350 14400 14450 14500 14550

Original

Fitted

R1a

R2a

R1b

R2b


20

Stress Mapping and Debonding

• Coupons exposed in laboratory furnace

• Stress maps

• Potential for non-contact evaluation

• Thermography is alternative

High stress,

R2b

Low stress,

R2a

100 h 600 h


21

Summary




– Dies



• Sliding wear

• Conclusions


22

Dry Running Properties of Sliding Materials

Sliding distance [m]

Coefficient of friction

0

0.1

0.2

0.3

0.4

0.5

0.6

0 500100 200 300 400 600 700

Coating

with PTFE

Coating

with MoS2

MoS2

PVD

BALINIT® C (WC/C)nearly no wear

x x x

xx

CuSnPbbronze

Ni-PTFE

x End of test due to adhesive wear

Sliding distance [m]

Coefficient of friction

0

0.1

0.2

0.3

0.4

0.5

0.6

0

0.1

0.2

0.3

0.4

0.5

0.6

0 500100 200 300 400 600 700

Coating

with PTFE

Coating

with MoS2

MoS2

PVD

BALINIT® C (WC/C)nearly no wear

x x x

xx

CuSnPbbronze

Ni-PTFE

x End of test due to adhesive wear


23

Transmission Applications – Gear Wear by Seizure

FZG-Test

Test dataSpeed: 1,000 rpmSurface pressure:1,000 N/mm²carb. 16MnCr5

Lubricant: ESSO CL46B(on biological base)

Source:IMM, TU Dresden

Tolerated load changes

Uncoateddry

Uncoatedlubricated

BALINIT® Cdry

BALINIT® Clubricated

Oil quantity:1 drop per Minute

29,000

1,400

106

107

105

104

103

102

10

1

Interruption after 2,000,000

150,000

29,000

1,400

140°C 90 °C 60 °C

FZG-Test

Test dataSpeed: 1,000 rpmSurface pressure:1,000 N/mm²carb. 16MnCr5

Lubricant: ESSO CL46B(on biological base)

Source:IMM, TU Dresden

Tolerated load changes

Uncoateddry

Uncoatedlubricated

BALINIT® Cdry

BALINIT® Clubricated

Oil quantity:1 drop per Minute

29,000

1,400

106

107

105

104

103

102

10

1

Interruption after 2,000,000

150,000

Interruption after 2,000,000Interruption after 2,000,000

150,000150,000

29,000

1,400

140°C 90 °C 60 °C


24

•wrist pins

•followers• roller, bucket, lifter, fingers•cams•rocker shafts

Highly Loaded Applications of Carbon Coatings


25

Reduced Valve Train Power

Consumption, Trucks

(DLC coated) cast iron tappet

uncoatedBALINIT® DLC coated

engine speed (rpm)

Power consumption (kW)


26

1980 1990 2000

1E-3

0.01

0.1

Friction C

oeffic

ient

Transfer film contact

After I L Singer

S Hogmark

Ball on disc, smooth surfaces

Tribochemical film

Low friction

Ultralow friction

Atomic friction

Superlow frictionNear frictionless

carbonNFC

MoS2

DLC

MoS2

Teflon

Development of Low Unlubricated Friction

Context

• Methods to generate low friction

– Low friction carbon films

– Low friction CN films

– Low friction fullerene like

materials

– Quasi-crystalline materials

– Non-wetting films

– Superlubricity

– Tribochemistry

Issues

• Achieving it

• Getting correct conditions

• Keeping it

• Measuring it

Future Vision

• Develop measurement methods for the characterisation and prediction

of performance of these coatings

• Develop durable materials

• Use them


27

Near Frictionless Films

A Erdimir, Tribology International, 37(2004)1005-1012

Dry nitrogen

Chhowalla and Amaratunga, Nature 207(2000)164-167


28

Conclusions

• Surface engineering is all pervasive

• Surface engineering has potential for tackling issues of performance or endurance in many applications

• Challenge is to move from largely empirical approach to knowledge based design

Documents

Surface Engineering for Increased Durability and Energy ... · Surface Engineering for Increased Durability and Energy Efficiency in Extreme Conditions Mark Gee National Physical