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CMC Materials for Aircraft Brakes
Bernhard Heidenreich, Linda Klopsch, Dietmar Koch DLR– German Aerospace Center, Institute of Structures and Design, Stuttgart, Germany 11th International Carbon Festival 2nd Global Carbon Cluster Forum October 5-7, 2016 Jeonju, Korea
www.DLR.de • Chart 1
C/C-SiC Materials - From Space to Brakes
www.DLR.de • Chart 2
- High temperature stability (thermal shock, hot spots)
- High abrasion resistance
Expert Reentry Capsule Nosecap
www.DLR.de • Chart 3
Know how in processing and design of
hard and high temperature stable materials and parts
Expert Reentry Capsule Nosecap
C/C-SiC Materials - From Space to Brakes
Why Ceramic Brake Systems are Attractive
Reduced weight 20 – 25 kg per car Density: 2 g/cm³ (cast iron: 7 g/cm³ ) High hardness, low wear rates Improved performance and comfort (short braking distance, no judder, no fading) Corrosion resistance, low dust pruduction
www.DLR.de • Chart 4
Costs
Performance
Advanced braking systems for heavy and fast cars, escalators, trains, planes
Manufacturing Process: Liquid Silicon Infiltration
www.DLR.de • Chart 5
Precursor Additives Fibers Silicon Granules
CFRP
CFRP (Shaping) Pyrolysis Siliconization
T < 250 ºC T > 900 ºC Si + C → SiC T > 1500 ºC
C/C C/C-SiC
Effect of Fiber Reinforcement in Ceramics
www.DLR.de • Chart 6
brittle vs. non catastrophic
XB
XD Variation parameter Raw Materials
• Fibre type • Fibre preform • Fibre orientation • Precursor • Additives • Si type
Processes
• Fibre pretreatment • Process times • Graphitizing • Coatings
Tailorable Material Properties
Tailored C/C-SiC Materials
Strength Stiffness
Thermal expansion Thermal conductivity
Wear Oxidation
Cost
SF
XG
UD
www.DLR.de • Chart 7
MPA Stuttgart
Friction samples Ø 70 mm
Variation of: • SiC, C, Si content • Fibre type • Fibre architecture • …
Tribological Properties of C/C-SiC Materials
0 20 40 60 800
0,2
0,4
0,6
0,8
1
Time [s]
Coe
ffici
ent o
f fric
tion
SiC
C/C-SiC basic material
low energy
C/C
0 20 40 60 800
0,2
0,4
0,6
0,8
1
Time [s]C
oeffi
cien
t of f
rictio
n
SiC
high energy
C/C-SiC basic material
C/C
Low Energy Braking (0.1 MPa; 6 m/s 0.3 W/mm²; 20 kJ)
High Energy Braking (0.35 MPa; 16 m/s, 3 W/mm²; 80 kJ)
MPA
www.DLR.de • Chart 8
Graded C/C-SiC With SiC Rich Friction Surface
www.DLR.de • Chart 9
RTM Autoclave Frieß et al., Adv.Sci.Tech., 2003
SiCralee Coating
www.DLR.de • Chart 10
thick and stable SiCralee coating on segmented brake disc (≈ 290 x 100 x 12 mm³) after high performance testing no spallation visible deposition of sintermetallic brake pad material
Basic research
(from 1990)
Commercial car brakes
(2001)
Other friction application
(2004)
Propeller brake (2012)
Brake Development at DLR
www.DLR.de • Chart 11
Porsche / SGL Schindler / FCT Umbra / SKT ICE brake (Matech-project)
Propeller Brake for A400M
Source:Turboprop_operation.png: Emoscopes
Propeller brake unit Rot
or
Stat
or
Stat
or
Brake pads
Compact multidisc brake system (Umbra). One rotor disc linked with propeller, two stator discs fixed in brake casing. Four C/C-SiC brake pads (Ø 120 mm x 6 mm) rivetted to steel discs.
www.DLR.de • Chart 12
Application
Propeller stopping after landing / blocking during parking (storm) Braking conditions • Ø Propeller = 5.3 m • v max. ≤ 650 rpm = 6.3 m/s • p max. ≤ 3.2 MPa
Requirements • t braking ≤ 8 s COF dynamic ≥ 0.45 • Wear max. ≤ 0.27 mm³/kJ-1
• COF static > 0.25 • E max. > 100 kJ Tmax. > 450 °C CMC brake pads
www.DLR.de • Chart 13
Development of C/C-SiC prake pads
Serial production Schunk
2011 2010 2013
Qualification (Umbra) 10 sets
Technology transfer DLR Umbra,Schunk
2012
Pre-series manufacture 30 sets (DLR)
Firs
t con
tact
Qualification (Umbra)
Lice
nce
agre
emen
t
Mat
eria
l sp
ecifi
catio
n
Mat
eria
l sel
ectio
n C
/C-S
iC X
S
C/C
-SiC
qu
alifi
ed
Screening Test (3 C/C-SiC variants)
www.DLR.de • Chart 14
What is next?
Improved materials based on new fibre preforms • Adjustment of temperature distribution
(thermal conductivity and thermal capacity) • Higher mechanical properties • Reprodrucibility
Sandwich design for lightweight structures and brake discs
Improvement and prediction of corrosion resistance Failure analysis Liefetime prediction
www.DLR.de • Chart 15 > Eurobrake – High Performance Ceramic Brakes > Dietmar Koch > 05-2014
Different Fibre Preforms
Short Fibres Circular Knitted Fabric
Woven Fabric Tufted
Tailored Fibre Placement
Different Fiber Preforms for Ceramic brake disc application
-https://www1.ethz.ch/structures/education/master/intro/compulsory/composites/Skript/151-0307-V4.0-K07_Textile-Halbzeuge.pdf
www.DLR.de • Chart 16
Brake Discs Based on Circular Knitted Fabrics
www.DLR.de • Chart 17
Warm Pressing
Pyrolysis
Siliconization
Tufted Fibre Placement (TFP)
www.DLR.de • Chart 18
Aims: Higher mechanical properties Improved thermal management Reproducible Manufacturing
Mechanical Properties
020406080
100120140160180200
Short Fibers Fabric XS knitted fabric
Bending Strength [Mpa]
0
10
20
30
40
50
60
70
80
Short Fibers Fabric XS knitted fabric
Young´s Modulus [Gpa]
www.DLR.de • Chart 19
Thermal Properties
-2
-1
0
1
2
3
4
0 500 1000 1500
Ther
mal
Exp
ansi
on [1
0-6 /k
]
Temperature [°C]
Short Fibers
Fabric XS
knitted fabric
0
5
10
15
20
25
0 100 200 300 400 500 600
Ther
mal
Con
duct
ivity
[W/(m
K)]
Temperature [°C]
short fibers
Fabric XS
knitted fabric
TFP tufted
www.DLR.de • Chart 20
Foldcore Technology
www.DLR.de • Chart 21
Y. Klett, University of Stuttgart, Institute of Aircraft Design, 2013
> HTCMC-9> B. Heidenreich> 28.06.2016
Isometric folding no internal stresses, deformation or cracks
Ventilated Brake Discs Based on Foldcores
C/C Core
C/C Skin
www.DLR.de • Chart 22
B. Heidenreich, D. Koch (DLR), N. Gottschalk, Y. Klett (IFB), 2016
C/C Skin
Joined C/C structure
Joining paste
C/C-SiC sandwich structure
Ventilated Brake Discs Based on Foldcores
C/C Core
C/C Skin
www.DLR.de • Chart 23
B. Heidenreich, D. Koch (DLR), N. Gottschalk, Y. Klett (IFB), 2016
C/C Skin
Joined C/C structure
Joining paste
C/C-SiC sandwich structure
