Jianliang Lin, Sterling Meyers, Brajendra Mishra, Sudipta Bhattacharyya,Peter Ried,, John J. Moore

Advanced Coatings and Surface Engineering Laboratory (ACSEL)

Colorado School of Mines

Acknowledgements: NADCA/DOE

•Premier Tool & Die Cast, SPX Contech, GM Powertrain, H-L, Leggett and Platt, St. Clair•Balzers, Hardchrome, Ion Bond, Phygen, Teer Coatings

THE DEVELOPMENT OF A SURFACE THE DEVELOPMENT OF A SURFACE ENGINEERED COATING SYSTEM FOR ENGINEERED COATING SYSTEM FOR

ALUMINUM PRESSURE DIE CASTING DIES:ALUMINUM PRESSURE DIE CASTING DIES:TOWARDS A ‘SMART’ DIE COATINGTOWARDS A ‘SMART’ DIE COATING

MethodologyMethodology

2.00E+08

2.50E+08

3.00E+08

3.50E+08

18 20 22 24

distance (microns)in

-pla

ne

str

es

s (

Pa

)

Graded interlayer

“working layer”

H1350 nm adhesion layer

Determine the most promising working layer

- Sessile drop- Soldering (DSC)- Ease of release- Tribological - In-plant trial

test

Design an optimal coating architecture by FEM

Develop the optimized coating architecture by P-CFUBMS

Field and Service testing

Work done by K.Kearn, O. Salas, A. Kunrath, J.Lin

Work done by S.Carrera

- Multimode tester- Coating degradation- Soldering (DSC)- Ease of release

J. Lin & S. Myers is working on this

Optimized Coating SystemOptimized Coating System

Overall coating thickness is about 5-8 m

Deposition of CrN and AlN binary phase

Deposition of CrAlN

Deposition of (Al,Cr)2O3 working layer

Deopsition of CrN/CrAlN graded layer

Deposition of the overall optimized coating architecture

Steps to the goal:

H13 die substratePlasma nitro-

carburized

Cr (60-100nm)

CrN

CrxAl1-xN

Multilayer or Compositionally graded

(Al,Cr)2O3

Cr-Al-N film Deposition Using P-CFUBMSCr-Al-N film Deposition Using P-CFUBMS

• Optimize the substrate to chamber wall distance (fixed substrate position)

• Deposit CrAlN film with rotation system

• Optimize the working pressure and N2 partial pressure

• Optimize the Al concentration in CrAlN films

Cr-Al-N films deposited at different substrate to Cr-Al-N films deposited at different substrate to chamber wall distanceschamber wall distances

Cr

Al

The ion energy in the plasma is different at different substrate

positionsPulsed closed field unbalanced magnetron sputtering system

GIXRD resultsGIXRD results

20 40 60 80 100

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

400220

200

111

(8 inches)

(7 inches)

( 6 inches)

( 5 inches)

2mTorr, 1000W/1100W, 75:25, -50V bias, different substrate position

Inte

nsity

2 Theta (Degree)

All Cubic

1000W Cr-1100W Al 20 at% Al in film

Nano-hardness and Young’s ModulusNano-hardness and Young’s Modulus

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.00

5

10

15

20

25

30

35

40

45

50

Hardness

Har

dnes

s (G

Pa)

N2(N

2+Ar) (%)

50

100

150

200

250

300

350

400

You

ng's

Mod

ulus

(G

Pa)

Young's Modulus

Substrate to chamber wall distance (inches)

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.00

5

10

15

20

25

30

35

40

45

50

Hardness

Har

dnes

s (G

Pa)

N2(N

2+Ar) (%)

50

100

150

200

250

300

350

400

You

ng's

Mod

ulus

(G

Pa)

Young's Modulus

Substrate to chamber wall distance (inches)

Ball-on-disk test and coefficient of frictionBall-on-disk test and coefficient of friction

0 1000 2000 3000 4000 5000 60000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

5 inches 6 inches 7 inches 8 inches 9 inches

Fric

tion

of C

oeffi

cien

t

Time (seconds)

Ball on disk wear test:• Micro-tribometer

• Counter part: 1mm WC ball

• Applied force: 3N

• Travel length: 100m

5 6 7 8 9

0.30

0.35

0.40

0.45

0.50

0.55

0.60

COF v.s STD

Coe

ffici

ent o

f Fric

tion

Substrate to chamber wall distance (inches)

Photomicrographs of wear tracks Photomicrographs of wear tracks after 100m travelafter 100m travel

5 inches 6 inches 7 inches

8 inches 9 inches

Wear volume and wear factor of Cr-Al-N filmsWear volume and wear factor of Cr-Al-N films

4 5 6 7 8 9 100

2

4

6

8

10

12

14

16

18

Wea

r V

olum

e (1

0-3 m

m3 )

Wea

r F

acto

r (1

0-7 m

m3 N

-1M

-1)

Substrate to Chamber Wall Disance (Inches)

Wear Factor Wear Volume

3D profile of the wear track

2D profile of the wear track

)()(

)()/(

33

mlengthTravelNLoad

mmvolumeWearNmmmfactorwear

Ion energy distribution (IED) of N(29) in plasmaIon energy distribution (IED) of N(29) in plasma

0 20 40 60 80 100 120 140 1600

200000

400000

600000

800000

1000000

1200000

1400000

1600000 1000W, pulsing both targets at 350Khz, 1.4us, 2mtorr, 75:25

8 inches 4 inches

SE

M C

/S

Energy (eV)

SEM photomicrographs at cross-section of Cr-Al-N filmsSEM photomicrographs at cross-section of Cr-Al-N films1000W Cr-1100W Al pulsing both 100kHz at 1 1000W Cr-1100W Al pulsing both 100kHz at 1 ss

5 inches 6 inches

7 inches8 inches

Cr-Al-N film Deposition Using P-CFUBMSCr-Al-N film Deposition Using P-CFUBMS

• Optimize the substrate to chamber wall distance (fixed substrate position)

• Deposit Cr-Al-N film with rotation system

• Optimize the working pressure and N2 partial pressure

• Optimize the Al concentration in CrAlN films

Cr-Al-N film deposited with rotation systemCr-Al-N film deposited with rotation system

• Deposition parameters:

• Total Pressure: 2mTorr; N2:Ar = 75:25

• 1000W to Cr target, 1100W to Al target

• -50V substrate bias

• Planetary rotation system with substrate

to chamber wall distance ~ 4.5 inches

• To avoid the formation of superlattice

structure, the minimum rotation linear

speed is 10 cm/sec, which was calculated

from the system geometry and deposition

rates

• Rotation linear speed used: ~ 12 cm/sec

20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

400

220

200

111

Fixed @ 7"

With rotation

2mtorr, 1000W/1100W, -50V bias, 75:25

Inte

nsity

2-Theta

Cr

Al

Cr-Al-N film deposited with rotation Cr-Al-N film deposited with rotation systemsystem

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.00

5

10

15

20

25

30

35

40

45

50

Hardness

Har

dnes

s (G

Pa)

Substrate to chamber wall distance (inches)

50

100

150

200

250

300

350

400

With Rotation

Yo

un

g's

Mo

du

lus

(GP

a)

Young's Modulus

Ra=30.33nm

The mechanical properties and surface roughness of Cr-Al-N film deposited with rotation system can be compared with those films deposited at fixed far positions

Ra=28.67nm

Ra=7.01nm

Cr-Al-N film Deposition Using P-CFUBMSCr-Al-N film Deposition Using P-CFUBMS

• Optimize the substrate to chamber wall distance (fixed substrate position)

• Deposit CrAlN film with rotation system

• Optimize the working pressure and N2 partial pressure

• Optimize the Al concentration in CrAlN films

Optimized working pressure and NOptimized working pressure and N22 partial pressure partial pressure

50 55 60 65 70 75 8012

14

16

18

20

22

24

26

28

30

32

34

2mtorr, 1000/1100w, -50Vbias, at 7 inches 3mtorr, 1000/1100w, -50Vbias, at 7 inches

Har

dnes

s (G

Pa)

N2 ratio (%)

1.5 2.0 2.5 3.0 3.5 4.010

15

20

25

30

35

75:25, 1000/1100w, -50V bias, 1hr deposition

Har

dnes

s (G

Pa)

Working pressure (Mtorr)

The optimized working pressure is 2 mtorr and N2 partial pressure is 75%

Cr-Al-N Films Deposited at 2mTorr with –50V Substrate BiasCr-Al-N Films Deposited at 2mTorr with –50V Substrate Bias

pN2=1 mTorr, 50% N2

pN2=1.2 mTorr, 60% N2

P N2=1.5 mTorr, 75% N2

pN2=1.6 mTorr, 80% N2

2 m

Decreased deposition rates

Cr-Al-N film Deposition Using P-CFUBMSCr-Al-N film Deposition Using P-CFUBMS

• Optimize the substrate to chamber wall distance (fixed substrate position)

• Deposit CrAlN film with rotation system

• Optimize the working pressure and N2 partial pressure

• Optimize the Al concentration in CrAlN films

P-CFUBMS Deposition MatrixP-CFUBMS Deposition Matrix

Cr target power (W)

Al target power (W)

Al/Cr target power ratio

Working distance (inches)

Working pressure (mtorr)

N2:Ar

Bias (V)

400 400 1

8 2 75:25 -50

400 600 1.5

400 800 2

400 1000 2.5

400 1200 3

400 1400 3.5

200 800 4

200 1000 5

200 1200 6

200 1400 7

Optimized in previous work

Multilayer or Compositionally graded

CrxAl1-xN or

TixAl1-xN

(Al,Cr)2O3

Increasing Al content in the intermediate layer

X=?

XPS of Cr-Al-N filmsXPS of Cr-Al-N films

Al:Cr target power ratio C Ar O Al Cr N Al/(Al+Cr)

1 11.4 1.5 10.6 5.8 35.9 34.8 13.9 at%

3.5 7.1 1.7 10.0 18.5 22.3 40.3 45.3 at%

6 4.5 2.1 10.3 20.1 19.1 44.0 51 at%

7 3.8 2.2 10.4 21.3 16.7 45.6 58 at%

All samples exhibit similar Cr 2p, Al 2p, N 1s high energy spectra

Cr 2p photoelectron spectra Al 2p photoelectron spectra N 1s photoelectron spectra

Survey spectrum results:

CrN 584.8eV and 575.4eVAlN 74.2eV

Al2O3 75.2eV

CrN/AlN 397eV

Optimize Al contents in Cr-Al-N filmsOptimize Al contents in Cr-Al-N films

20 30 40 50 60 70

0

200

400

600

C (220)

C (200)C (111)

H (100)

1.5

3.5

5

6

7

Cr : Al target power ratio

GIXRD of CrAlN films deposited at:different Cr:Al target ratio (pulsing at 100KHz, 1.0us)2mtorr, 75% N2, -50V bias, 2 hours deposition

Inte

nsity

2-Theta

Hexagonal phase appeared

Al:Cr target ratio

Al/(Al+Cr)

58

51

45.3

Lattice parameter changeLattice parameter change

0 1 2 3 4 5 6 7

0.404

0.406

0.408

0.410

0.412

0.414

Cubic

58% Al51% Al

Hexagonal+Cubic

45% Al

13.9%Al

CrN

Lattice parameter v.s Al contents in Cr-Al-N films

Latt

ice

para

met

er (

nm)

Al/Cr target power ratio

Nano-harness and Young’s Modulus of Cr-Al-N Nano-harness and Young’s Modulus of Cr-Al-N filmsfilms

0 1 2 3 4 5 6 7 815

20

25

30

35

40

45

50

Al /Cr target powerratio

Har

dnes

s (G

Pa)

Nanohardness

100

200

300

400

500

Hexagona+cubicCubic

58at%51at%

45.3at%

13.9at%

Young

's Modulus (G

Pa)

Young's Modulus

1 2 3 4 5 6 7

0.080

0.082

0.084

0.086

0.088

0.090

0.092

0.094

0.096

58at% Al

51at% Al

45.3at% Al

13.9at% Al

H/E

rat

io

Al/Cr target power ratio

Higher H/E ratio indicates good wear resistance and good toughness

The highest hardness is about 36GPa

hexagonal

cubic cubic+ hex

Wear resistance and COFWear resistance and COF

0 1000 2000 3000 4000 5000 60000.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

Al/Cr target power ratio

1 2 2.5 3 3.5 4 5 6 7

Coe

ffic

ient

of

Fric

tion

Time (mins)Ball-on-Disk wear test:

• Micro-tribometer

• Normal load: 3N

• Counterpart: 1mm WC ball

• Travel length: 100m

1 2 3 4 5 6 7

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0.48

0.50

58at%

51at%

45.3at%Al

13.9at%Al

COF of Cr-Al-N films at different Al contents

Coef

ficie

nt o

f Fric

tion

Al/Cr target power ratio

Summary of P-CFUBMS of Cr-Al-N filmsSummary of P-CFUBMS of Cr-Al-N films

• An Optimized coating ‘architecture’ used for Al pressure die casting dies has been proposed

• Cr-Al-N intermediate layer with good mechanical properties and dense microstructure has been successfully deposited.

• Deposition of Cr-Al-N coatings with a planetary rotation system has been successfully demonstrated.

• The critical Al concentration in the Cr-Al-N coatings has been determined.

• On-going work:– Deposition of the (Al,Cr)2O3 working layer

– Deposition of the compositionally-graded Cr-Al-N intermediate layer

•After each trial, half of pins:

Dissolved in NaOH/Industrial Degreaser and characterized using Stereography and SEM

Removing lubricant and Al from pins quite painstaking.

Typical removal times at least 3 weeks in ultra-sonicator.

•Other half of in-plant trial pins

No dissolving

Cross-x cut and prepared for metallographic & SEM characterization

Becoming quite difficult due to coating removal while performing metallographic prep work

22ndnd In-Plant Trial Pins: Leggett & Platt In-Plant Trial Pins: Leggett & Platt

Selected Core Pins 3n 2n1n

100% of Typical pin life

Shots / Cycles (n)

11stst In-Plant Trial Pins: Premier Tool & Die In-Plant Trial Pins: Premier Tool & Die

In-Plant Trial PinsIn-Plant Trial Pins

Same Pin; Lubricant RemovedConclusion: Pin after 10k shots contains no visible defects

New Pins

¼ ins

Preliminary ResultsPreliminary Results

•Stereographic Results•CrN, CrC-TiAlN coatings show few signs of wear • TiN-TiAlN, Cr/TiN-TiAlN illustrate more signs of wear •FeNC surface treatment show most signs of wear and soldering

SEM Results•Data still not produced•Edge retention of coating lost during metallography

One can measure the adhesion/soldering strength of the pin by separating the pin and solidified Al using a tensile testing machine with

a calibrated load cell

The pin must be pulled perpendicular to the solidified Al axis to assure same stress levels

‘‘Ease of Release’ TestEase of Release’ Test

Load/time curves – ‘ease of release’ testLoad/time curves – ‘ease of release’ test

‘critical load’ (Lc)

0 10 20 30 40 50 600

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500 6

54

3

2

1

1 CFUBMS-TiN/TiAlN m (Lc 2468lb)2 MS-CrC/TiAlN (Lc 3937lb)3 CFUBMS-MoZrN (Lc 4025lb)4 MS-CrN (Lc 2371lb)5 CAE-graded CrN (Lc 1456lb)6 FeNC (Lc 5298lb)

Load

(lb

)

Time (second)

Experimental program: ease of release testsExperimental program: ease of release tests

Control ACSEL ACSEL G-Cr/N CrC-TiAlN

ML-TiN/TiAlN

Plain 3 3 3 3 3 3

FeCN 3 3 3 3 3 3

Ion-nitrided

3 3 3 3 3 3

‘‘Smart’ die coating: experimental architectureSmart’ die coating: experimental architecture

dedEV f .. ,312,133

Adhesion layer

Die steel

substrate

Ti/Cr

Surface modification

of the substrate

Working layer

Intermediate layer

Adhesion layer

Die steel

substrate

Ti/Cr

Surface modification

of the substrate

Working layer

Intermediate layer (TiAlN)

Adhesion layer

Die steel

substrate

Ti/Cr

Surface modification

of the substrate

Working layer

Piezo. Film

1

3

2

V3(Sensor voltage)Thin-film Electrodes(Sputtered Ti)

Stress(in-plane)

Sensor module

Stress(out of plane)

Non piezoelectric Insulation layer

(d= thickness)

Choice of active sensor materialChoice of active sensor material

Requirements:

Figure of Merits PZT AlN ZnO LiNbO3

Current response: e31,f (C m-2) -14.7 -1.0 -0.7 -5.8

Voltage response: e31,f /o33 (GV

m-1)

-1.2 -10.3 -7.2 N/A

Coupling Coefficient (kp,f)2 on Si 0.2 0.11 0.06 0.02

Curie Temperature Tc (C) ~300 ~1100 N/A 1210

CTE (10-6 K-1) 7.2 4 5 11

AlN appears to be the most promising of all, due to its high insulation, and good mechanical compatibility

with the host structure (Ti-Al-N, Ti, and Cr). CTE: H13 11x10-6 K-1; Ti 8.6x10-6K-1; Cr 4.5x10-6K-1; Pt 8. 8x10-6K-1;

(LiNbO3 also has potential with CTE match with H13)

Deposition detailsDeposition details

Base Pressure

Operating Pressure

Sputter gas

Power Time

1 X 10-6 Torr 3-30 mTorr Argon 200-500 W 5-10 min.

Electrode deposition (Ti, Pt/Ti) (DC magnetron)

Base Pressure

Operating Pressure

Sputter gas

Frequency Power Time

1 X 10-6 Torr 10-50 mTorr Argon &

Nitrogen

100 kHz 200-300 W 30 min.-

1 hr.

Deposition of the piezo-layer (AlN) (Pulsed DC magnetron)

Methods to test the prototype sensor architecture:Methods to test the prototype sensor architecture:

Dynamic testing: Indirect method (Plank method)

Static testing: Direct method

SubstrateElectrode

Aluminum nitrideElectrodeclamp

Damping element

Piezo-cantilever: cross section

In-plane tensile stress (12)

integrator

(12)

Load (Quasi-static)substrate

electrodes

Piezo-layer

Output charge 31.12

Apply pressure

Release pressure

Indu

ced

char

ge

t (Sec.)

Ease of Release Test

Surface Treatment Coating Name Quantity

None (Cr/Al)2O3 ACSEL (Multi-Layer) 3

None CrC-TiAlN Balzer 3None TiN-TiAlN Hard Chrome 3None CrN (Not Graded) Ion Bond 3None MoZrN Teer 3None CrN (Graded) Phygen 3None None None 3

Ion Nitride (Cr/Al)2O4 ACSEL (Multi-Layer) 3

Ion Nitride CrC-TiAlN Balzer 3Ion Nitride TiN-TiAlN Hard Chrome 3Ion Nitride CrN (Not Graded) Ion Bond 3Ion Nitride MoZrN Teer 3Ion Nitride CrN (Graded) Phygen 3Ion Nitride None None 3

FeNC (Cr/Al)2O4 ACSEL (Multi-Layer) 3

FeNC CrC-TiAlN Balzer 3FeNC TiN-TiAlN Hard Chrome 3FeNC CrN (Not Graded) Ion Bond 3FeNC MoZrN Teer 3FeNC CrN (Graded) Phygen 3FeNC None None 3