metal matrix composites (mmcs) - improve.it metal matrix composites (mmcs) properties, applications...

Metal Matrix Composites (MMCs)

Properties, Applications & Machining

6. Internationales IWF-Kolloquium18/19.04.2002, Egerkingen, CH

EMPA, Swiss Federal Laboratories for Materials Research and TestingDept. Materials TechnologyFeuerwerkerstrasse 39CH-3602 [email protected]

Olivier Beffort

structure of the talk

• introduction to MMCs

• typical properties of MMCs

• applications of MMCs

• machining of MMCs

• outlook - trends in R&D, market forecasts

sources: NASA & AFRL

ca. 1975

Space Shuttle - main cargo bay strutsmaterial: MMC - 6061/B/50ftotal weight saving: 145 kg (-44% vs Al)materials costs: > 1’000 US-$ / kg

source: VW

ca. 1999

VW-Lupo (Tdi) - rear brake drumsmaterial: MMC - A359/SiC/20pweight of drum: 1.55 kgmaterials costs: < 5 US-$ / kg

MMCs - materials with tailored properties ...

metals......... toughnessAl electrical & thermal conductivityMg heat resistance, "environmental stability"(Ti) processability

... by combination of metals and ceramics

ceramics..... Young’s Modulus, hardness, wear resistanceSiC strengthAl2O3 low coefficient of thermal expansionC, B4C (shape of ceramic: fibres, particles)

specific properties of metals and ceramics

Types of reinforcement for MMCsparticles and "foams"

particles (ceramics, carbon, ...)volume fraction: 5 - 75%size: 0.1 - 500 µm

"foams" (ceramics, graphite, ...)cearmic volume fraction: 20 - 90%pore size: 50 nm - 1 mm

short fibres (ceramics, carbon, ...)volume fraction: 10 - 30%size: ∅ : 1 - 6 µm, L: 10-500 µm

Types of reinforcement for MMCsfibres

100 �m

cont. fibres (ceramics, carbon, ...)volume fraction: 40 - 70%size: ∅ : 6-150 µm, L: ∞

particle reinforced MMCs

(PRM) vp: 5-75 %

• isotropic properties• high wear resistance• low density ............................................... 2.6 - 3.1 g/cm3

• high elastic modulus ............................... 90 - 300 GPa• high strength ............................................ 300 - 1000 MPa• good thermal conductivity ...................... 120 - 200 W/mK• low coeff. of thermal expansion (CTE) ... 7 - 20 10-6/K

fibre reinforced MMCs

(FRM) vf: 10-70 %

• anisotropic properties

• low density ........................ 1.8 - 3.2 g/cm3

• high strength ..................... 500 - 2000 MPa

• high elastic modulus ....... 120 � 300 GPa

• low CTE ............................. 0 - 10 10-6/K

• elevated temperature resistance (strength, fatigue, creep)



•typical properties of MMCs




MMC brake discs & drums applications

MMC - type: AlSiMg/SiC/20-30ptrains (ICE) source:

Knorr Bremse

source: Lotus Cars Ltd.

VW LupoToyota RAV-4EVPlymouth ProwlerGM EV-1, Precept, ImpactFord ProdigyLotus Elise (1st series)race carts (various)....

source: Kolbenschmidt

automotive applications - engine

source: Honda

cylinder blocks and pistons(local reinforcement for wear and creep resist.)material: AlSi + short fibres and/or particlesPorsche 911, BoxsterToyota CelicaHonda Prelude, NSX, ...?

Toyota Celica

max rated voltage: VCE = 3300 VNominal current IC = 1200 A

50 mm

power conversion / electr. packaging applications

IGBT-modules (Insulated Gate Bipolar Transistor)

source: EUPEC

MMC - type:AlSi/SiC/70pCTE: 7-9 10-6/K

"thermal management applications"

structure of an IGBT-module

source: ABB Semiconductors

Si Si

Al2O3 or AlN Insulation

Si

Cu or Al Heats Spreader

Cooler

SolderCopper

Bond Wire

Grease 17 / 23.5

4.2

6.7 / 4.4

17 / 23.5Heat

CTE [ppm/K]CTE [ppm/K]

further MMC applications:

• racing, sports, leisure• cylinder liners, push rods, brake calipers, ...• spikes for racing shoes & tires, golf clubs, bicycle frames, ....

• aerospace applications• Space Shuttle - main cargo bay struts• Boeing 777 / Pratt & Whitney - fan exit guide vanes• Eurocopter - blade sleeves• F16 - ventral fins, fuel access door covers

• thermal and electric transportation• heat sinks, electronic packaging, ....• cooking ware• power transmission cables (electric conductors)

• robotics, linear technology, weaving machines, ........• military applications, .....




• applications of MMCs in transportation



frequent statements concerning MMC machining

• MMC cannot be machined.................................... no !

• conventional tools cannot be used for MMCs.... yes !

• diamond tools are a must for MMC machining... yes !

• MMCs cannot be machined cost effectively........ no !

• MMCs are difficult to machine............................. yes !

why are MMCs difficult to machine ?

because of the relative hardness of the reinforcing materials

tool wear mechanisms occuring duringMMC machining

• abrasion due to hardness of reinforcement

• impact fatigue, break-outs

• PCD or CVD diamond tools are the best

• do not use CBN tools

• do not use HSS tools (not even coated ones)

• do not use un-coated WC/Co tools

tools suitable for MMC machining

influence of tool material on tool wear

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10 12 14

time, [min]

flan

k w

ear

v B, [

mm

]

PKD, vc 500 m/min

WC/TiN, vc 150 m/min

MMC material: Al/Al2O3/20pvc: 500 m/minfeed: 0.4 mm/revDOC: 1.5 mmoperation: turning

source: Duralcan machining guidelines

parameters affecting machinability

the influencing parameters are :

machining performance or machinability isdefined in terms of tool life, material removal rateor surface quality of machined part

• MMC material - particle type, vol. fract, temper, ...

• tool - type and grade

• machining parameters - feed, speed, DOC

influence of MMC - reinforcement

the following characteristics decrease tool life:

• increasing particle volume fraction

• increasing particle size

• increasing particle hardness

• increasing aspect ratio of particles

influence of MMC - quality & temper

the following characteristics decrease tool life:

• defects (porosity, inclusions, segregations, ...)

• age hardening (peak aged condition T6)

influence of tool - type and grade

controversy - PCD or CVD diamond ???

for PCD tools, influence of diamond grain size:

• three common PCD grades: 2, 10 and 25 �m

• 25 �m best wear resistance; for roughing

• 2 �m best edge quality for finishing

roughing and finishing operations

for roughing coarse grained PCD (or CVD)and the most possible aggressive feed rateand depth of cut are recommended: besttool life performance

for finishing fine grained PCD or CVD andmoderate feed rate and depth of cut arerecommended: best surface finish quality

influence of machining parameters

the following characteristics increase tool life:

• high feed rate (< 0,5 mm/rev)

• high depth of cut (< 5 mm)

• medium cutting speed (300-500 m/min)

influence of feed rate on material removal

source: Duralcan machining guidelines

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0,1 0,2 0,4

feed rate, [mm/rev]

volu

me

rem

ove

d (

MM

C),

[cm

3 ]MMC material: Duralcan F3S.20Stool material: PCDvc : 300m/minDOC: 0.5 mmoperation: turning (stop @ 0.25 vB mm)

machining operations

• turning feasible, PCD or CVD diamond tools

• milling feasible, PCD or CVD diamond tools

• drilling difficult, PCD or CVD diamond tools

• tapping critical, CVD tools in development stagetap forming is an alternative to tap cutting

• sawing feasible, WC- or PCD tipped blades

• grinding feasible, diamond grinding

MMC machining cost issues - example

US-study concerning machining costs of brake rotors

PCD - tools cast iron rotor MMC rotorparts per day: 1900 3131

tool costs, $/day 402 2048

cost savings reference 0.15 $/rotor

CVD - tools

tool costs, $/day 568.75

MMC drilling cost issues - sp3 examples

Ford Motors Co.drilling 6.8 mm diam. holes 1.00´´ deep into Al/SiC/20pdrilling conditions: speed:1350 rpm, feed: 0.0075 ipr

WC/Co-drills: 1 - 2 holes per drill ⇒ $9 - $18 /holeCVD-drills: 330 holes per drill ⇒ $0.40 /hole

MSEdrilling 0.25´´ diam. holes into Al/SiC/20-48pWC/Co-drills: < 1 hole per drill

CVD-drills: >200 holes per drill ⇒ $0.52 /hole(cost of CVD drill: $115/drill

machining - conclusions

• recommended machiningguidelines should be respected

• only diamond tools should beused for machining MMCs

• an MMC with an ultrafine and low hardnessreinforcement is preferred

• except tapping, most common machiningoperations are possible




• applications of MMCs in transportation



materials and process development - future

materials development• selectively reinforced structures• functional, adaptive materials• graded materials

process technology• "reactive" in-situ generation of MMCs• near net shape MMC processing technologies• low cost MMC processing technologies

machining• adapted tools (materials, coatings, geometries, ...) and lubricants• optimised machining parameters• alternative machining processes

MMC market forecasts 1999-2004

1600

3400

668

1000

137 161 152 220

0

500

1000

1500

2000

2500

3000

3500

ann

ual

MM

C w

orl

d m

arke

t, [

t]

groundtransportation

thermalmanagement

aerospace /defense

industrial /recreational equip.

1999

2004

market share: 62.2 %market share: 70.3 %AAGR: + 16.3 %




source: BCC, USA

1999: 2.5 Mio kg, 103 Mio US-$2004: 4.9 Mio kg, 173 Mio US-$

http://mmc-assess.tuwien.ac.at

http://www.empathun.ch

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