Ceramic Applications in the Automotive Industry
Michael. J. Hoffmann
Institute for Applied Materials - Ceramics in Mechanical Engineering
S
E
KIT – University of the State of Baden-Württemberg and
National Large-scale Research Center of the Helmholtz Association
www.kit.edu
Ceramics
Ceramicscomponents
componentsininautomotive
automotiveapplications
applications
filter, catalyst carrier
fuel injectors
high pressure pump
electronic device
Functional Ceramics
spark and
glow sensor
plugs, oxygen sensor,
knocking
knocking sensor, parking distance control,
PTC heaters, fuel injection systems
PTC heater
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Ceramics
Ceramicscomponents
componentsininautomotive
automotiveapplications
applications
filter, catalyst carrier
fuel injectors
high pressure pump
electronic device
Structural Ceramics
knocking sensor
pump components
(sealings), brake discs,
catalyst support, particulate filter,
PTC heater
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Projection
Projectionof
ofTotal
TotalEnergy
EnergyDemand
Demandand
andEnergy
EnergyMix
Mix
• Liquid fuels will still significantly contribute
to up-coming energy demands
• Combustion engines are necessary
in the next decades
• Individual transport: long range distance,
trucks, hybrids
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European
EuropeanFuel-Economy
Fuel-EconomyGoal
Goalup
upto
to2025
2025
150
CO2 Emission [g/km]
140
37,3 mpg
130
42 mpg
120
110
100
57,4 mpg
90
US Goal: 100 g/km
80
70
60
78,4 mpg
2010
2015
2020
2025
2030
Year
Goal can only be obtained by more efficient combustion engines
→ Downsizing concept (smaller, but more efficient engines)
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Downsizing
Downsizingconcept
concept
Downsizing is based on the principle of a reduction
in engine size in order to reduce consumption
without affecting power.
Measures:
- Reduction of number of cylinders
- Supercharging (use compressed air)
- Direct injection systems
Challenges and Needs:
- Injection control system
- High pressure fuel pump
- High thermal and mechanical loading
Downsizing can reduce the CO2 emissions between 5% for diesel models and
40% for gasoline models by 2020. These engines should be able to remain
dominant for a long time in the car market.
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Downsizing
Downsizingconcept
concept
Downsizing is already reality in the present US market
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Piezoelectric
PiezoelectricDriven
DrivenCommon
CommonRail
RailFuel
FuelInjection
InjectionTechnology
Technology
fuel injector
high pressure pump
electronic device
courtesy: Robert Bosch GmbH
Piezo technology increases efficiency and reduces emission
→ already used in Diesel systems, but with a high potential for gasoline systems
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Piezoelectric
PiezoelectricDriven
DrivenCommon
CommonRail
RailFuel
FuelInjection
InjectionTechnology
Technology
metal parts
ceramic parts
-40 %
Pfister et al. Cer. Trans. (2011)
High fuel injection pressure is needed to reduce droplet size (-40%),
→ decrease of fuel consumption and pollutant emissions (-80%)
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Fuel
Fuelevaporation
evaporationinincombustion
combustionchamber
chamber
source: Spicher, KIT-IFKM
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3-Piston
3-PistonHigh
HighPressure
PressurePump
Pumpfor
forGasoline
GasolineEngines
Engines
KIT / IFKM,
Pfister, Spicher
Cam/sliding-shoe contact is tribological highly loaded due to an insufficient lubrication
of petrol with increasing pressure → ceramic components can be a solution
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Friction
Frictioncoefficient
coefficientininthe
thecam/sliding-shoe
cam/sliding-shoecontact
contact
SSiC / SSiC
SiAlON / SiAlON
Pfister et al. Cer. Trans. (2011)
Silicon carbide and SiAlONs indicate a similar behaviour with a very
low friction coefficients at a system pressure of 50 MPa
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Effect
Effectof
ofsurface
surfacetexturing
texturingof
ofthe
thecam/sliding-shoe
cam/sliding-shoecontact
contact
-75 %
Pfister et al. Cer. Trans. (2011)
The texture significantly improves the performance of self-mated
silicon carbide at low speed or low contact force
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Gasoline
Gasolinedirect
directinjection
injectionsystem
system
Source: KIT / IFKM, Spicher
An ignitable mixture for low and high loads is only formed
in a very narrow spatial zone
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Future
Futuretrends
trendsfor
forspark
sparkplugs
plugsininfuel-efficient
fuel-efficientengines
engines
Microstructure with a glassy phase and pores
4 µm
Challenges
• Distance between electrodes will increase
• Higher voltage will be applied
→ longer spark
• Pressure increase in combustion chamber
→ higher thermal and mechanical loading
• reduction in size
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Strength
Strengthdistribution
distributionand
andtypical
typicalfailure
failuremechanisms
mechanisms
of
ofcommerical
commericalspark
sparkplugs
plugs
Manufacturer
compaction defects
Strength distribution reflects also the electric breakthrough behaviour
→ Most current commercial materials do not match the requirements
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Future
Futuretrends
trendsfor
forspark
sparkplugs
plugsininfuel-efficient
fuel-efficientengines
engines
Challenges:
• smaller diameter → higher thermal and mechanical loading
→ strength must be increased by enhanced processing conditions
• adjustable resistance
• high voltage → increase in electrical breakthrough
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Metal
MetalMatrix
MatrixComposites
Compositesfor
forHighly
HighlyLoaded
LoadedEngine
EngineParts
Parts
Engine part manufactured by pressure die casting of Al-based alloys
after German, 1994
Inhomogeneous cooling causes thermal stresses that can be minimized by
a local reinforcement with ceramics (preform concept).
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Local
Localreinforcement
reinforcementof
ofpressure
pressuredie-casted
die-castedAl-MMCs
Al-MMCs
local reinforcement
(cermic preform)
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Preparation
Preparationof
ofPorous
PorousCeramic
CeramicPreforms
Preforms
Pore filler concept
40 µm
Porosity: up to 75%
Pore size and shape
depend on filler
Freeze casting
Ceramic foams
250 µm
100 µm
Porosity: 20-85%
Ice crystals form final
pores
Porosity: 85-95%
cell size depends on
polymer foam
Mattern et al., JECS (2004).
Different types of ceramic preforms can be manufactured by
using powder technology processes.
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Preparation
Preparationof
offreeze-casted
freeze-castedAl-MMCs
Al-MMCs
100 µm
ceramic wall
Ice lamella
Cooled plate
Waschkies et al., JACS (2009)
2 mm
S. Roy & A. Wanner, Compos. Sci. Technol. (2008)
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Estimation
Estimationof
offailure
failureprobability
probabilityfor
fordifferent
differentperform
performtypes
types
1 E -9
MPa]
foams
permeability strength [m
2
.
freeze casting
1 E -1 0
1 E -1 1
.
Survival region
with pore fillers
Failure region
1 E -1 2
1 E -1 3
0 ,0 1
squeeze0 ,1
e ffe c tiv e
casting
1
m e lt v e lo c ity
pressure
10
[m /s ]casting
Mattern et al., JECS (2004).
Freeze casted preforms can be used for pressure casting,
while preforms with pore fillers and bottle neck pores will break
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Mechanisms
Mechanismsof
ofhigh
highfield
fieldstrain
strainininferroelectric
ferroelectricceramics
ceramics
Piezoelectric effect (intrinsic)
Strain behaviour
d hkl E-Feld
d hkl
S
Domain switchung (extrinsic)
E
∆L
E-Feld
→ High strain materials rely on both intrinsic and extrinsic effect
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Strain
Strainbehaviour
behaviourof
of aaferroelectric
ferroelectricceramic
ceramicat
at20
20kV/cm
kV/cm
20.000 Volt
High field strain [%]
0,20
PZT
-
0,16
1 cm
0,12
0,08
+
20 µm strain at 20 kV/cm
0,04
0,00
0,0 0,5 1,0 1,5 2,0 2,5
Electric field [kV/mm]
80 Volt
80 µm
+
0,16 µm strain at 20 kV/cm
Typical strain of a donor-doped Pb(Zr,Ti)O3 ceramic (PZT): 0.15 - 0.2 % at 20-30 kV/cm
→ Multilayer device
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Piezoelectric
PiezoelectricDriven
DrivenCommon
CommonRail
RailFuel
FuelInjection
InjectionTechnology
Technology
electronic
PZT-layers
courtesy: Robert Bosch GmbH
→ typical driving voltage: 100 V, total strain 20-30 µm
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termination
internal electrodes (AgPd)
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Requirements
Requirementsfor
forpiezoelectric
piezoelectricactuators
actuatorsfor
forfuel
fuelinjection
injectionsystems
systems
• cofiring with internal electrodes (multilayer device)
• high strain
• operating temperatures from -40 to 150 °C
• small temperature dependence of strain
• high reproducibility (mass production)
• “low cost“
• challenge: replacement of PZT by lead free ferroelectrics
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Comparison
Comparisonof
ofPb(Zr,Ti)O
Pb(Zr,Ti)O33and
andaalead-free
lead-freeceramic
ceramic
E = 2 kV / mm
1000
RB KNN‐PSU reference samples
E = 2 kV / mm
600
600
LFL493 ( ‐ ref)
ML172 ( ‐ 61 mu)
ML503 ( ‐ 144 mu)
20 kV/cm
500
500
33%
600
400
La-PZT
53/47
53.5/46.5
200
0
0
50
100
Temperature (°C)
150
d33
* (pm/V)
d33*, pm/V
d33* (pm/V)
800
400
400
300
300
160%
200
200
100
100
00
(Li,Sb)-doped KNN
00
50
50
100
100
150
150
Temperature, °C
Temperature
(°C)
Lead-free ceramics show a lower strain for a similar electric field strength
and exhibit a much stronger temperature dependence of strain
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Heat
Heatdeficiency
deficiencyfor
forcar
carheating
heatingsystems
systemswith
withefficient
efficientengines
engines
source: eberspächer catem, Germany
The increasing efficiency of fuel saving cars requires a supplementary heat system based
on functional ceramics showing a positive temperature coefficient resistance (PTCR) effect.
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(Bi0,5K 0,5)
250
10
7
10
6
10
5
10
4
10
TC
3
0
50 100 150 200 250 300 350 400
Temperature [°C]
Curie Temperature TC [°C]
Specific Resistance [Ω/cm]
PTC
PTCeffect
effectinindonor-doped
donor-dopedBaTiO
BaTiO33-based
-basedceamics
ceamics
(Bi0,5Na 0,5)
200
Pb
150
Ca
100
50
Zr
0
0
5
10
15
20
25
30
35
x [mol %]
• PTC-effect is based on the temperature depended potential barrier at the grain
boundary Æ high electrical resistance above TC
• The ferroelectric phase equals the charge of the potential barrier below TC
Æ low electrical resistance
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BaTiO
BaTiO33-based
-basedPTC
PTCheating
heatingelements
elements
1 Vaporizer
2 Car Heater
3 PTC auxiliary heater
source: eberspächer catem, Germany
Highly efficient cars do not produce enough „waste energy“ for heating
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PTC
PTCeffect
effectinindonor-doped
donor-dopedBaTiO
BaTiO33-based
-basedceamics
ceamics
Seat heater for convertibles
OEMs favour different local heating elements to reduce total energy consumption
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Outline
Outline
• High pressure pump systems for gasoline engines
• Spark plugs
• Porous ceramics for local reinforcement of
metal matrix composites
• Piezoelectric injection systems
• PTC heating elements
• General conclusions
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Requirements
Requirementsand
andChallenges
Challengesfor
forMaterials
MaterialsResearch
Research
Complexity in materials preparation
Complexity of requirement profiles for the system
Structural
Properties
Functional
Properties
Composites
37
37
Multifunctional
Properties
Multimaterial
Composites
Thermomechanical
Treatment
RTC | 06/23/2007 | © 2007 Robert Bosch LLC and affiliates. All rights reserved.
Reliability
Quality
Costs
Weight…
Powder
Technology
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Requirements
Requirementsand
andChallenges
Challengesfor
forProduct
ProductDevelopment
Development
Return
+
Prototype
06
07
08
09
10
11
12
13
14
15
SOP
Reduction of product
development time
-
Reduction of
product life cycle
Support through modeling
and simulation and better
coordination
Time
→ Reduction of product development time due to shorter product life cycles
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Modeling
Modelingand
andsimulation
simulationacross
acrossthe
thewhole
wholelength
lengthscale
scale
length scale
10-10 - 10-9 m
10-7 - 10-5 m
10-2 - 10-1 m
courtesy: P.F. Becher
Ab-initio calculations
MD- simulation
→ New materals
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Phase field or vertex dynamic
simulation
→ Microstrutural design
FE-methods for calculation
of coupled loading conditions
→ Design optimization
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Conclusion
Conclusion
Fixed first idea
from the first idea to the product
Raw project
Board project
Product in the market
Accepted products
Economically successful products
source: Kienbaum, Bullinger
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